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03680 - Technical Information Report
p D. R. STRONG D CONSULTING ENGINEERS i lir ht \5cup ciassiN/G1 im . . _.• �O ••■• Engineers 1 , " \ \\j k<to. ..I. \ F., NENE p\tyypYbV I I Oat O 1% Surveyors `er031i lii 6, I I I, Ia% Landscape Architects WOjai .. 11111111141191 Full Service Engineering Since 1981 TECHNICAL INFORMATION REPORT (TIR) for KELSEY'S CROSSING NE corner of intersection of SE 192nd Street and 120th Avenue SE Renton; Washington 'ERf WAA.SJOY i,e) ii`1.S ' TER. 730 1....v- , 1 f IOlak IP DRS Project No. 12061 City of Renton Project No. LUA-08-069 Owner/Applicant Harbour Homes, LLC 1441 N. 34th Street, Suite 200 Seattle, Washington 98103 Report Prepared by D ' S D. R. STRONG Consulting Engineers, Inc. 10604 N.E. 38th Place, Suite 232 Kirkland WA 98033 (425) 827-3063 Report Issue Date September 26, 2012 ©2012 D.R.STRONG Consulting Engineers Inc. TECHNICAL INFORMATION REPORT KELSEY'S CROSSING TABLE OF CONTENTS SECTION I PROJECT OVERVIEW 1 General 1 Predeveloped Site Conditions 1 Developed Site Conditions 1 Natural Drainage System Functions 2 SECTION II CONDITIONS AND REQUIREMENTS SUMMARY 10 Core Requirements 10 Hearing Examiner's Preliminary Plat Conditions of Approval: 12 SECTION III OFF-SITE ANALYSIS 13 SECTION IV FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 14 Existing Site Hydrology (Part A) 14 Pre-developed Hourly Time Step Modeling Input: 15 Pre-developed Hourly Time Step Modeling Output 15 Developed Site Hydrology (Part B) 17 Developed rdin (to flow control facility) Hourly Time Step Modeling Input: 18 Developed Bypass Hourly Time Step Modeling Output: 19 Performance Standards (Part C) 21 Flow Control System (Part D) 21 Flow Control BMP Selection 21 Flow Control Facility Design Output 22 Flow Frequency Analysis 32 Duration Analysis 32 Water Quality Treatment System (Part E) 33 SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN 35 General Parameters 35 Pond Outfall 35 Developed 15-Minute Time Step Modeling Input: 36 Developed 15-Minute Time Step Modeling output: 36 Backwater Analysis 37 Backwater Table 37 Backwater Analysis Map 39 BackWater Computer Program for Pipes 40 ©2012 D. R.STRONG Consulting Engineers Inc. Page i of ii Technical Information Report Kelsey's Crossing September 26,2012 SECTION VI SPECIAL REPORTS AND STUDIES 44 SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS 45 SECTION VIII CSWPPP ANALYSIS AND DESIGN 46 ESC PLAN ANALYSIS AND DESIGN (PART A) 46 KCRTS Analysis for Sediment Trap 47 Developed 15-Minute Time Step Modeling Input: 47 Developed 15-Minute Time Step Modeling output: 47 SWPPS Plan Design (Part B) 49 SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 50 Bond Quantity Worksheet 50 Flow Control and Water Quality Facility Summary Sheet and Sketch 51 Stormwater Facility Summary Sheet 51 Water Quality Summary Sheet 52 SECTION X OPERATIONS AND MAINTENANCE MANUAL 53 List of Figures Figure 1 TIR Worksheet 3 Figure 2 Vicinity Map 6 Figure 3 Drainage Basins, Subbasins, and Site Characteristics 7 Figure 4 Soils 8 Figure 5 Predevelopment Area Map 16 Figure 6 Post Development Area Map 20 Figure 7 Detention & Water Quality Facility Details 34 Appendices Appendix A Bond Quantity Worksheet 54 Appendix B CSWPPP 55 ©2012 D.R.STRONG Consulting Engineers Inc. Page ii of ii Technical Information Report Kelsey's Crossing September 26,2012 SECTION I PROJECT OVERVIEW GENERAL The Site is located at the NE corner of the intersection of SE 192nd St & 120th Avenue SE, in Renton Washington, also known as King County Tax Parcel Numbers 6199000160 & 6199000161. The project is the subdivision of the existing parcel into 13 single family residential lots. PREDEVELOPED SITE CONDITIONS The total parcel area is approximately 2.13 acres and previously contained a single family residence that has since been demolished. A driveway and foundation still remain onsite, and will be removed with the site development. The onsite vegetation consists of grass, brush and trees. In general, the majority of the property has slopes ranging from 2-10%. Generally, the land slopes to the easterly across the site. The predeveloped Site has one Natural Discharge Areas (NDA); located along the east property line. The entire site is contained within one Threshold Discharge Area (TDA). For purposes of flow control analysis and design, the Site will be considered till forest in its existing condition. DEVELOPED SITE CONDITIONS The applicant has gained approval to subdivide 2.13 acres into 13 single-family residential lots (Project), with lot sizes ranging from approximately 3,833 to 5,717 s.f. An internal access road (SE 191st Lane) will provide access to the development and will have a temporary cul-de-sac at the east end. SE 191st Lane will have 26-feet of paving, vertical curbs, and gutters on both sides, a six foot planting strip, and a five foot sidewalk. The planting strip and sidewalk is located on the south side of the street, and parking is limited to only the south side of the street. A 20-foot paved access road will provided for lots 8 through 13. Frontage improvements will be provided along the west property line, along 120th Avenue SE. Improvements will consist of a new vertical curb and gutter 13-feet from the centerline of the right-of-way, 8-foot planting strip and a five-foot concrete sidewalk. Frontage improvements will be provided along the south property line, along S.E. 192nd Street, which is classified as a Minor Arterial with an associated 92-foot right-of-way. Improvements will consist of a new vertical curb and gutter 22-feet from the centerline of the right-of-way, 5-foot planting strip and a 7-foot concrete sidewalk. These improvements will be permitted through the City of Kent. The 13 single-family residences and their driveways combined will create approximately 34,677 s.f. of impervious area using the maximum allowable build-out rate specified in the King County Code Section 21A.12.030 (post developed maximum impervious surface percentage is 70% per lot). Post-developed onsite impervious areas including rights-of-way, sidewalks, roofs, and driveways total approximately 53,489 s.f. (not including bypass and frontage areas). The remainder of the Project will be modeled as till grass and totals approximately 34,119 s.f. (See Section IV). ©2012 D.R.STRONG Consulting Engineers Inc. Page 1 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Post developed frontage improvement areas along 120th Ave SE and SE 192nd Street total approximately 15,476 s.f. and consist of 7,688 s.f. of impervious and 7,788 s.f. of pervious areas. Small LOT BMP Requirements per Section 5.2.1.1 of the 2005 King County Surface Water Design Manual (KCSWDM) will be met with the use of a reduced impervious surface credit as outlined in Section C.2.9. A 10% reduction of the maximum impervious surface area will be applied to each the lot area, thus reducing the allowable impervious surface per lot to 60% of the total lot area. A note to the that effect will be placed on the face of the final plat. Developed runoff from the Site and a portion of the frontage improvements along 120th Ave SE and SE 192nd Street will be conveyed to a combined water quality and detention facility located onsite within Tract "B". Runoff will be treated for basic water quality and conservation flow control as outlined in Sections 5 and 6 of the 2009 KCSWDM. Developed site runoff will be conveyed to an onsite combined detention and wet pond. The site discharges runoff to Big Soos Creek though a manmade conveyance system approximately 1/4 mile downstream of the site. NATURAL DRAINAGE SYSTEM FUNCTIONS A review of the SCS soils map for the area (see Figure 4, Soils) indicates Alderwood gravelly sandy loam with 0 to 6 percent slopes (AgB). Per the Manual, this soil type is classified as SCS Hydrologic Soil Group C and KCRTS Soil Group "Till" material. The SCS Soil series descriptions follow Figure 4. In evaluating the upstream area, we reviewed the existing offsite analysis and King County IMAP aerial topography and imagery and conducted field reconnaissance and have concluded that a very minor portion of grass lawn from the adjacent residential parcels to the north (Parcel numbers #6199000140 and #6199000143) flows south onto the proposed site. ©2012 D.R.STRONG Consulting Engineers Inc. Page 2 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 1 TIR WORKSHEET King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER DESCRIPTION Project Owner: Project Name: Harbour Homes, LLC Kelsey's Crossing Address/Phone: Location: 1441 N. 34th Street, Suite 200 Township: 23 North Seattle, WA 98103 Range: 05 East Project Engineer: Section: 33 Maher Joudi, P.E. D. R. STRONG Consulting Engineers Inc. Address/Phone: 10604 NE 38th Place, Suite 232 Kirkland WA 98033 (425) 827-3063 Part 3 TYPE OF PERMIT Part 4 OTHER REVIEWS AND PERMITS APPLICATION ® Subdivision n DFW HPA ❑ Shoreline Short Subdivision Management ® Clearing and Grading COE 404 n Rockery ❑ Commercial DOE Dam Safety ❑ Structural Vault Other: FEMA Floodplain I I Other: ❑ COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community: Benson Drainage Basin Soos Creek 2012 D. R.STRONG Consulting Engineers Inc. Page 3 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Part 6 SITE CHARACTERISTICS ['River: ❑ Floodplain ❑ Wetlands ❑ Stream: ❑ Seeps/Springs ❑ Critical Stream Reach ❑ High Groundwater Table ❑ Depressions/Swales ❑ Groundwater Recharge ❑ Lake: ❑ Other: ❑ Steep Slopes Part 7 SOILS Soil Type: Slopes: Erosion Potential: Erosive Velocities: Alderwood 0-6% Slight Slow (AgB) ® Additional Sheets Attached: SCS Map and Soil Description, Figure 4 Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ® Level 1 Downstream Analysis None ® Geotechnical Engineering Study ❑ Environmentally Sensitive Areas ❑ Level 2 Off-Site Stormwater Analysis ❑ Level I Traffic Impact Analysis ❑ Structural Report ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION ▪ Sedimentation Facilities ® Stabilize Exposed Surface ® Stabilized Construction ® Remove and Restore Temporary ESC Entrance Facilities ® Perimeter Runoff Control ® Clean and Remove All Silt and Debris ® Clearing and Grading ® Ensure Operation of Permanent Facilities Restrictions ❑ Flag Limits of SAO and open space preservation ® Cover Practices areas ® Construction Sequence ❑ Other ❑ Other ©2012 D.R.STRONG Consulting Engineers Inc. Page 4 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Part 10 SURFACE WATER SYSTEM ❑ Grass Lined ❑ Tank ❑ Infiltration Method of Analysis: Channel ❑ Vault ❑ Depression KCRTS ® Pipe System ❑ Energy Dissipater ❑ Flow Dispersal Compensation/Mitigatio ❑ Open Channel ❑ Wetland ❑ Waiver n of Eliminated Site ❑ Dry Pond ❑ Stream ❑ Regional Storage ® Wet Pond Detention N/A Brief Description of System Operation: Runoff from impervious surfaces will be collected and conveyed to an onsite water quality and detention facility. From there it will be discharged to the existing piped conveyance system located near the Site's southeast property corner. Facility Related Site Limitations: Reference Facility Limitation Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS ❑ Cast in Place Vault ® Drainage Easement ® Retaining Wall ® Access Easement ❑ Rockery > 4' High ❑ Native Growth Protection Easement ❑ Structural on Steep Slope ® Tracts ❑ Other: ❑ Other: Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowle4.-,the information provided here is accurate. 6 , . , .,, Signed/Date ©2012 D.R.STRONG Consulting Engineers Inc. Page 5 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 2 VICINITY MAP r a 367.4r Qr 3.cti FL. SE 1731111)ST _ ` {? 187 _ _ [1 - fl3q /' ,( 3,78Tit CT �� _ _ C II tTaVer�nY Fa ,� t Renton ;r ��,. 77 1;T-' I sir t�-r -_� i L.,ta ;mi€3T11'ST Mi 4J ... ..,,a, � 1 `I DI 1I !I I l 71 .G_Y .2 7-- 5e v f 647TH ST �l I 1EAT1r.T Rs I1 .,,g5SHPL . BEi rMsr p' - & a SB SiTt#t f Q 2 r l 7 I! ;, oi.1Si;laiTH ST f SITE a _Tory 4 % y 1 t ..,.„-„,ii_ 1�Trfsr III, 1 p '-- 'x.--. " , re- Ili _ _ ag Tarsr,�1 _ -- __---SE viiim-st ( 5+ s6 RICH ST ' c ` I c LI O f,"--' EC 1er1t`�T :_ i SE 136TH ST > ii S 4aTft 8T , " T- r y1. '- Lt 5[isC+T►i i3, ST.,,, Q Q F S 19TTH T �c s �r,yr r i 1,,1 1 h ` r h onosT ft sz�r,4nn. Y ,1 ,1 =204r11 et. aa�rrl aT- — p� _aC- 'Tid ST— -- -* Ito .0 1 ,,,q, CI 4 - sS211TT1 l; � Kent _ .. - f� I {----. q I $ - .. SE212THST' – d R SE2>arxST sE2 4TH 1 g ` . t- _ 1 . i __ _ Sf 27fTtt S7 i y H9 ifTYr nT yy 3E<10Trr ST ?7hTI-1_ST.._' r1 rte. .�I 21 T►►s7 I 5E 217111&'T �I. z .,. RC.71 i1Tu w t- The information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. King County makes no representations or warranties,express or implied,as to accuracy, completeness,timeliness, or rights to the use of such information. King County shall not be liable for any general, special, indirect, incidental, or consequential damages including,but not limited to, lost revenues or lost profits resulting from the use or misuse of the information contained on this map.Any sale of this map or information on this map is prohibited except by written permission of King County. ©2012 D. R.STRONG Consulting Engineers Inc. Page 6 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ©2012 D.R.STRONG Consulting Engineers Inc. Page 7 of 55 Technical Information Report Kelsey's Crossing September 26,2012 � � � D.R.STRONG ('.ONSULT7NG ENGlNEERS evcv+Ea¢s r�,ua�ts suxverars +asoen�ser�rx,no�ioraawn�waaea.� 01?S.dY7.3iL&4 FI25.8272I23 urw.6��uny.pam � -i i � ,�. _. , � � / .,,�;�`�� I NOTE.• r` � I i N ' ����' I �v�5`�✓ f 6�`J: � �.e .�u r�v is,�al� P� t\L f I �gc� A� Nu�`S ., �� r : s�^a' -- ,' \l�!�C,\1 /,^P�' 6 ^�" SG _ I :?' / - , ��_ , r� �+\)�-' I I A DRAINAGE ADJUSTMENT(L08V0030) WAS OBTAlNED APPROVING THE COMBINATION � ;� / \�I' ''.. � `_E_:-'; ! vr-o re,�ce OF THE 7W0 ONSITE SUBBSINS 1N70 ON£POST DEVELOPED DRALVAGE FAClL1TY LOCATED _ ',``�_ ' ��.� •:cnr.; — ! I AT 7HE SOUTH£AST CORNER OF THE SlTE. � � �� .� ��_�_ �' //�' , � F- � -- I �� � ; �3 � -- � r , �o f I I �� .f c' �J .. I �� /. d"`, ' �_ ' I � � � ,��� . ; _� �( _ 1 . � ��t � W �I � I" ! �����. ' , �� l� � I i � a �, �; BASIN B I � I i I I ' _� ' , ` NATURAL PO/NT � �� f+ I �' P�R C�I �`, � `t . OF D/SCHAi4GE i !� � �,.., ,:, � � I� � �� � j �� �,'+�,', � � �.� j I t';.i SE! STLANE '� e, I— f j� \, —I z I U I ,� , �7 �7 O I � � � I , F. ,T� �0 g � � ' �I` � -- � � � V Z � ry� � � - - � - �I� ' 7 �% I � II � _ f`_:_N. / - rs_� � �I =1 (� � I I � � — I � ~'Q�� — — / ` ---�—c='�'�— I ` �LI � � � .� � V � � "�c�S'' / . '�� __ �c, � ���t �.+cc � � D (/� I� � ; + i " " ' � , �/ �� ` I� �/ f E ._ `�i �� y � Z � � � � � �� ��� �� � i � /� _ o z � O � l 1 s.z'� _�: ,�a, — a' #��'/ sZ�_/ �;.._ i .. �. . z G� � � Q Q � � �� � � �a� � — - ��� �� _ � O � � � � � �� i � ��� � � �- ' --- -- ' B S�N�:���,.. . _�, � �, � � OO `�` '� easiN a � �+ Q z � i I -- __ � '� � NATURAL PO/NT I 41 m � g I � � � ,' � OF D/SCHAI4GE. � � Q 1 '' i , _z;��� � � � U � � ;I � !�)� �� ��� �� I r -- c '� Z � ;� I i < r .r cu� I � I � � -- , �_�i� ��.i � a�va-o Z � i ,,- �-- �G U I " � ��� 1 I -J i� � �� � i � '�� - � � � < �. , � , , ;� :� � , �, > �,;5_� � � � � � ��� ��� � �� � ' ' �� , � �p j I ��� I I 3_�J _ , �` "I� .� - � , �Ll � I � — — — �r n�_� -- _ — a�— -�'_ �` .:_ F � i � � ./ i f_ , 49, l.:_ _ '��� '- . / R I ` _— —.- � _.. �.'' ' � . __ � � I` � � r'�f Cr T�7 C� ''� I ; . � : .. ` . \ ' / � . � , . ; — � , ri, � , " . . , �� �` ��---=---_--- _ _ _ ' , ` . ,_. ` , �, {_� BAS/NS E NEA � — — ---- ----- --------- ------- — .,_ COMB/N R _;d o .�_ — az.c7 SE 192ND STREET t3+Go urCo s5+� t5+5�.6i i� — � T — — — � — �_ — _ -- TH/S POINT o — --- , , -_ ._ . f _ ... . , , F _ . _ _ _ - — ---- ___ �� �. , � , Ii�� �� ,.'�..��..��5 .� . _ •-_. � �..r�C�. . ' ' "'.-__ �i ,�\\ I ..�_��.v'�•1� .. " ___ DRAFIEO BY.• OSM DfSIGNED BY.•OSM PR0.,ECT ENGlNEER:MAJ DA7E• 05.03.12 PROJfCT NO.:72067 FGUR£: .3 CG=�'�'RIGHT 0 2G12, D.R. STP.G•.:G C�N�CL-R.G ENGI��FERS 'dC. FIGURE 4 SOILS Sot Map—King County Area,Washington 0 a f1 IJ .1. M140 501 5U 001 5) 501 rvrw 501 W 50:00 501:10 50:20 500 55V: 5&1-50 50 AO 531:70 501:50 501.80 4'7.25 o ,.. ---.-^-rt^- __... _ 47.2351' b 1k. a SITE s .. ION 2, 0 ; 1v 7, 11 1 It 21 _ r 83 47.2546 47.254& 50 20 m,„ 501:53 55:00 50 170 501:9] 501,50 541:00 00 . 50:20 501'0 50:40 50_,50 501 80 50 70 50.52 501.20 rA aMT 8de_1.82111 palled m A sis(85•a 111 sheet b r- N Meters p o 50 20 40 Bp N Fast 0 45 00 150 270 �_ S� Natural Resaaces Web Soil Survey 8/14/2012 r� Conserv Icon Service National Cooperative Sot Survey Page 1 of 3 King County Area, Washington AgB—Alderwood gravelly sandy loam, 0 to 6 percent slopes Map Unit Setting Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 180 to 220 days Map Unit Composition Alderwood and similar soils: 75 percent Minor components: 25 percent Description of Alderwood Setting Landform: Moraines, till plains ©2012 D. R.STRONG Consulting Engineers Inc. Page 8 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Parent material: Basal till with some volcanic ash Properties and qualities Slope: 0 to 6 percent Depth to restrictive feature: 24 to 40 inches to densic material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table: About 18 to 37 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Very low (about 2.5 inches) Interpretive groups Land capability (nonirrigated): 4s Typical profile 0 to 12 inches: Gravelly ashy sandy loam 12 to 27 inches: Very gravelly sandy loam 27 to 60 inches: Very gravelly sandy loam Minor Components Buckley Percent of map unit: 10 percent Landform: Depressions Norma Percent of map unit: 4 percent Landform: Depressions Bellingham Percent of map unit: 4 percent Landform: Depressions Tukwila Percent of map unit: 4 percent Landform: Depressions Shalcar Percent of map unit: 3 percent Landform: Depressions ©2012 D.R.STRONG Consulting Engineers Inc. Page 9 of 55 Technical Information Report Kelsey's Crossing September 26,2012 SECTION II CONDITIONS AND REQUIREMENTS SUMMARY CORE REQUIREMENTS The Project must comply with the following Core and Special Requirements: • C.R. #1 — Discharge at the Natural Location: The Site currently has two onsite subbasins and discharges runoff to two natural points of discharge. The two onsite subbasins are part of one threshold discharge area (TDA) as they combine approximately 200-feet from the site. A drainage adjustment (L08V0030) was obtained approving the combination of the two onsite subbasins into one post-developed drainage facility located in the southeast corner of the site. • C.R. #2 — Offsite Analysis: A Level 1 Offsite Analysis was performed by Barghausen Consulting Engineers and was previously submitted with the Preliminary Plat. A copy of the Level 1 Offsite Analysis is included in Section III. The Analysis describes the Site's runoff patterns in detail. • C.R. #3 — Flow Control: The Project is required to provide Level 2 Conservation Flow Control to mitigate for historic flooding problems. The proposed flow control facility is a combined detention/wet pond located in Tract "B". The Level 2 Flow Control standard requires the Project to match developed discharge durations to predeveloped durations for the range of predeveloped discharge rates from 50% of the two-year peak flow up to the full 50-year peak flow, and also match developed peak discharge rates to predeveloped peak discharge rates for the 2 and 10-year return periods, assuming historic conditions as the predeveloped condition. (KCSWDM, Sec. 1.2.3.1) Furthermore, the Project must meet the Flow Control BMP requirements as specified in Section 1.2.3.3 of the Manual. The Project will utilize the reduced impervious surface credit to meet this requirement. • C.R. #4 — Conveyance System: New pipe systems and ditches/channels are required to be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. Pipe system structures and ditches/channels may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100- year runoff event does not create or aggravate a "severe flooding problem" or "severe erosion problem" as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100-year event must discharge at the natural location for the project site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. The proposed conveyance system was analyzed using the KCBW program, and is ©2012 D.R.STRONG Consulting Engineers Inc. Page 10 of 55 Technical Information Report Kelsey's Crossing September 26,2012 capable of conveying the 100-year peak storm without overtopping any structures or channels (see Section V). • C.R. #5 — Erosion and Sediment Control: The Project provides the nine minimum ESC measures. A CSWPPP is included in Appendix B. • C.R. #6 — Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and Maintenance Manual is included in Section X. • C.R. #7 — Financial Guarantees: Prior to commencing construction, the Applicant must post a drainage facilities restoration and site stabilization financial guarantee. For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 —Water Quality: Developed site runoff will be conveyed to wetpond, which will meet Basic Water Quality Requirements as outlined in Section 6.1.1 of the 2009 KCSWDM. • S.R. #1 — Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 — Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 — Flood Protection Facilities: Not applicable for this Project. • S.R. #4 — Source Control: Not applicable for this Project. • S.R. #5 — Oil Control: Not applicable for this Project. ©2012 D.R.STRONG Consulting Engineers Inc. Page 11 of 55 Technical Information Report Kelsey's Crossing September 26,2012 HEARING EXAMINER'S PRELIMINARY PLAT CONDITIONS OF APPROVAL: t ©2012 D.R.STRONG Consulting Engineers Inc. Page 12 of 55 Technical Information Report Kelsey's Crossing September 26,2012 • Denis Law Mayor . �. T. • �.' a �;' ; ' ''N: 'p;. .4. r�:-y• June 6,2012 Department of Community and Economic Development. C.E."Chip"Vincent,Interim Administrator Jamie Waltier: Harbour Homes,LLC 1441 North 34th Street,Suite 200 . REC'0 Jo 0 8 2012 Seattle,°WA 98103 RE: Kelcey's Crossing Preliminary Plat Minor Amendment Approval Clarifications NE Corner of SE 192"d.Street and 120th:Avenue SE LUA 08-069 Dear Mr.Waltier: • Thank you for meeting with me to discuss your questions on the amended conditions for the Kelsey's Crossing preliminary plat. This memo is a follow-up to our discussion to provide clarification on the project conditions. Condition#3: The reference dimensional requirements for King County R-4 zoning standards is in error. The correct reference dimensional requirements for this project are the King County R-6 zoning standards in effect at time of application. Condition#4: The reference to the 1993 KCRS is incorrect,and should be the 2007 KCRS. The proposed 20-foot wide access tracts are acceptable. Condition#5 Based upon the proposed project street design and vested King County standards,fire sprinklers are not required for any of the new homes in the plat. I hope these responses are helpful in clarifying these points. If you have additional questions regarding this approved minor amendment and associated conditions,you may contact me (425)430-7218 or Kayren Kittrick(425)430-7299. Sincerely, f(, 2 �� • Neil Watts,Director Development Services Division Cc: Chip Vincent,Interim CED Administrator kayren Kittrick,Development Engineering Supervisor • Jennifer Henning,Current Planning Manager • Renton City Hall • 1055 South Grady Way • Renton,Washington 98057 • rentonwa.gov • " . • • • • • Kelcev's Crossing Preli • minary Plat Amended.Conditions . Worksheet Summary . . 1. Compliance with all platting provisions of Title 19A of the King County Code: • . Revision: Compliance with all platting provisions of the Renton Municinal Code(RMC)4-8-110. 2. All persons:having an ownership interest in the subject property shall sign on the face of the • .final plata dedication that includes the language set forth in King County.Council Motion No.. • 5952. •Revision:.This condition is deleted: King County staff has been unable to provide any • Information on the:contentor intention of the referenced King County Council Motion No.5952. 3, The plat shall comply with the base density and minimum density requirements of the R-6 zone classification.All lots shall meetthe minimum dimensionairequirements of the R-6 zone classification or sha l be shown on the face of the approved preliminary plat,whichever is larger, • except that minor revisions.to the plat which do not result in substantial changes maybe approved et the discretion of King:County Department of Development and Environment Services(DOES). Any/all plat boundary discrepancy shall be resolved to the satisfaction of King • County DDES prior to the submittal of the final plat documents. As used in this condition, "discrepancy"is a boundary hiatus,an overlapping boundary or a physical appurtenance,which indicates en encroachment,lines of possession or a conflict of title. . Revision: The plat shall comply with the base.density and minimum density requirements of the R-4 zone classification in place in Kink County On December 11,2006.:All lots shall meet the minimum dimensional requirements of said R-4 zone classification or shall be as shown on the face of the approved preliminary plat,whichever is larger,except that minor revisions to the plat which do not result insubstantial changes may be approved at the discretion of the City of Renton Planning Division. All future houses within the plat shall substantially conform to the guidelines listed in Renton Municipal Code(RMCl.4-2-115 Residential Design and Open Space Requirements. The City shall review and approve modifications from strict adherence tithe prescribed standards provided the applicant demonstrates design alternates meeting the spirit and intent of the guidelines. pnv plat boundary discrepancies shall be resolved to the satisfaction of the Renton Planning • Division prior to.the submittal ofthe final plat documents: As used in this condition, "discrepancy"is a boundary hiatus,an overlapping boundary or a physical appurtenance which indicates an encroachment,lines of possession,or a conflict of title. • • ;4. All construction and upgrading of public and private roads shall be done in accordance:with . theKing County Road Design and Construction Standards established and adopted by County Ordinance No,11187,es amended(2007 KCRDCS). Kelcey's Crossing Preliminary 4 Amended Conditions—Worksheet Summary Page 2of8 May 17,2012 Revision: All construction and upgrading of public and private roads shall be done in accordance with the King County Road Standards established and adopted by,Ordinance No. 11187;as amended (1993 KCRS),or as otherwise modified by agreement between the City of Renton Development Services Division and the applicant per RMC.4-9-250Dt S.The applicant must obtain the approval of the King County Fire Protection Engineer for the adequacy of the fire hydrant,water main,and fire flow standards of Chapter l7 08 of the King County Code. Revision: The applicant must obtain the approval of the Renton Fire Department for the adequacy of the fire hydrant,water main,and fire flow standards of RMC 4-5-070. 6.Final plat approval shall require full compliance with the drainage provisions set forth in King County Code 9.04. Complianee:may result in reducing the number and/or location of lots as shown on the preliminary approved plat Preliminary review has identified the following conditions of approval,which represent portions of the drainage requirements. All other applicable requirements in K.C.C.9.04 and the King County Surface Water Design Manual (KCSWDM)must also be satisfied during engineering and final review: a. Drainage plans and analysis shall comply with the 2005 King County Surface Water. Design Manual and applicable updates adopted by King County: DDES approval of the drainage and roadway plans is required prior to any construction.. b. Current standard plan notes and ESC notes,as established by DDES Engineering Review, shall be shown on the engineering plans, c. The following note shall be shown on the final recorded plat; "All building downspouts,footing drains,and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on theapproved construction drawings on file.with DDES and/or the King County Department of Transportation.This plan shall be submitted With the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval.;For those lots.that are designated for. individual lot infiltration systems,.the systems shall be constructed at the time of the building permit and shall comply with plans on file:" Revisions: Condition#7 remains mostly unchanged;with minor changes in sections a, b,c,and d: Section a is revised to replace approval byODES With approval.by.City of Renton Development Services Division: Section b is revised to standard plan notes as listed in the 2005 KCSWM. Section c.is revised to the approvedconstructionplans onfile with the City:of.Renton Development Services Division:: • 7.:The drainage facilities shall meet the requirements of the 2005 King County Surface Water • Design Mandel(KCSWDM). The drainage design shall Meet at a minimum the Conservation Flow Control and Basic Water Quality requirements in the KCSWDM: • Revisions: Condition 7.is revised:to include the following requirement for full disclosure of: individual lot BMPs prior to drainage construction plans: To implement the required Best Management Practices (BMPs)for treatment of storm Water;the final engineering plans and • . Kelsey's Crossing Preliminary atAmended Conditions—Worksheet Summary I Page3of8 May 17,2012 • technical information report(TIR)shall clearly demonstrate compliance with all applicable . . design standardsThe requirements for best management practices are outlined:in Chapter.5 Of the 2005 KCSWDM. The design engineer Shall address the applicable requirements on the final . engineering plans and provide all necessary documents for implementation. The final recorded plat shall include all required covenants,easements,notes,and other to implement the required BMPsforsite development. 8. Drainage adjustment 1430030 has been approved for this project. :All conditions of • approval for this adjustment shalt be met prior to engineering plan:approval. Revision: Condition#8 remains unchanged. • 9. Th.e following road improvements are required to be constructed according to the 2007 King County Road Design and Construction Standards(KCRD(.S) a. ••The internal access Road A shall,be improved at a minimum to the urban sub:access street standard,with a temporary cul=de=sac at the east end. b. The frontage along SE 192nd Street shall be improved at a minimum to the urban • principal arterial street standard: This improvement shall also meet the Street Widening Requirements in Section 4.03 of the KCRDCS. c. Provide 12 feet of additional R/W along the frontage of SE 192nd Street with a 25 ft. . . RJW radius at the SE 192nd Street/120th Ave SE intersection(Lot 11). • d. The frontage along 120th Ave SE shall be improved at a minimum to the Urban • . neighborhood,collector standard: This improvement shall also meet the:Street Widen ng equirernenOtt Se'cr on 4.03 of the KCRDCS: • e. Tract A shall be designed to the private access tract standard per Section 2.49 of the KCRDCS . f. • Modifications to the above road conditions may be considered according to the variance provisions in Section 1.12 of the KCRDCS: . • Revision: The following road improvements are required to be:constructed in lieu of the original King County street standards : a. The internal access road(SE 1915`.Lane)shall be improved with 26 feet of paving, vertical curbs, and gutters On both sides,a six foot planting.strip and a five foot side- :walk: The planting Akin and sidewalk shall be on the south side of the Street;and parking shall be limited to onlv.the south side of the street. • b. The frontage along SE 192":4 Street must be improved per City of Kent standards( including curb;gutter and sidewalk improvements. These improvements.will require a . .. • separate constructionpermitfiom the City ofKent. • c.•• Additional right-of--way dedication alone SE 192' Street will only be required if needed • forthe.Kent required street improvementdesien. d. The frontage improvements along 120` •Ave SE shall include a new vertical curb and• . . •. putter.13 feet from centerlineof the right-of-way: An eight foot planting strip and five .• foot concrete sidewalk are also required.:The radius improvements at the.intersection . : . with SE 192nd:St must be per City of.Kent requirements,along with any associated right- of-way dedication for_the radius: • Kelcey's Crossing Preliminary sit Amended Conditions—Worksheet Summary Page 4of8 May 17,2012 e. The private access easement for Lots 8 through 13 shall be paved to a minimum width of 20 feet,with a minimum pavement depth of 4 inches ofasphalt over six inches of crushed roc L Street modifications may beapproved by.City of Renton Development Services Division .. . according to the modification procedures of Renton Municipal Code 4-9-250D: 10.All utilities within proposed rights-of-sway must be included within a franchise approved by the King County Councii prior to final plat recording. Revision:.All utilities within proposed rights-of-way.must be built and approved per RMC 4-7-: 200 prior to final plat recording: 11.The applicant or subsequent owner shall comply with King County Code 14,75,Mitigation Payment System(MPS),by paying the requiredMPS fee and administration fee as determined by the applicable fee ordinance:The applicant has the option to either (1)pay the MPS fee at the final plat recording,or(2)pay the MPS fee at the time of building permit issuance. If the first option is chosen;the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75,Mitigation Payment System(MPS),have been paid. if the second option is chosen,the fee paid shall be the amount in effect es of the date of building permit application. Revision: The applicant or subsequent owner shall comply with the.applicable City of Renton traffic mitigation fee schedule or applicable impact fee schedule in place at time offee payment. The applicant has't the option to either (1)pay the traffic mitigation or impact fee at the final plat recording,or(2)pay the mitigation or impact fee at the time of building permit issuance; if the first option is chosen,the fee paid shall be the fee in effect at the time of final plat application and a note shall be place on the face of the plat that reads;"All traffic mitigation or : impact fees required.by.Renton.Municipal Code have:been paid.".If the second option is chosen,the fee paid shall be the amount in effect as of the date of building permit application. 12.Lots within this subdivision are subject to King County Code 21A,43,which imposes impact fees to fund school system improvements needed to serve new development. As a condition of final approval,fifty.percent(50%)of the impact fees due for the plat shall be assessed and collected immediately prior to the recording,using the fee schedules in effect when the plat receives final approval. The balance of the assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to building permit issuance. Revision:'Lots within this subdivision are subject to Renton Municipal Code 4-1=160,which imposes impact fees to fund schoolsystem improvements needed to serve new development. • As a condition of final approval,fiftypercent(50%)of the impact fees due for the plat shall be assessed and collected immediately Prior:to the recording, using the fee schedules in effect when the plat receives final approval. The balanceofthe assessed fee shall be allocated evenly to the dwelling units in the plat and shall be collected prior to the building permit issuance. is Keicey'sCrossing Preliminary. JAmendedConditions=WorksheetSummary Page5of8 May 17,2012 13.Off-site school walkway; a. 120th Avenue Southeast shall be widened along the east side of the roadway,from the end of the.:subdivision frontage improvements(approximately mid-point between the. plat street and Southeast 191st Street)to the intersection of Southeast 188th Street., The improvements shallconsist of a paved walkway that provides a total width of 16 feet(11-foot northbound travel lane plus five(5)feet of walkway surface,of pavement measured from the centerline of existing roadway to the new edgeof pavement Unless previously constructed in conjunction with the preliminary plat of Wehrman(DOES File #L04P0027),a widened paved shoulder shall be provided at the northeast corner of the intersection of Southeast 188th/120th Avenue Southeast. b. If either(1)the subdivision improvements for the plat ofJessie Glen(DOES File #L05P0005)have been completed and accepted at the time of recordation of the • proposed Kelsey's Crossing subdivision;including the connection between SE • 189th Place and SE 191st in Jessie Glen,or,(2)the off-site subdivision walkway improvements for the plat of Wehrman have been completed,then no additional walkway improvements are required. If neither set of improvements have been constructed and accepted,then;in addition to the above-noted improvements to 120th Avenue SE: c. Southeast 188th Street(116th Ave SE to 120th Ave Southeast)shall be widened to provide a minimum 16-foot wide paved surface as measured from the construction centerline on either the north side Or the south side. This will provide an 11-foot wide travel lane and a five(5)-foot wide paved shoulder: The final location(north side or south side of Southeast 188th Street)will be determined during engineering plan approval. . Revision: The intention of these off-site pedestrian improvements was to provide pedestrian route from the site to the Benson Glen Elementary School approximately 2500 feet from the site. The route was to have a minimum paved shoulder for pedestrian use along the existing paved lanes. The route listed by the:conditions was north on 120th Av SE,then east on SE 188`n St to 116th Av SE..Review of the area shows that this level of pedestrian improvements already exist from the site to the school. This route is going east along SE 19ed St and then north on 116th Av SE,which is the same distance as the route listed in the original condition. Since the goal expressed for this condition already is met by existing street improvements,Condition#13 • is satisfied with the existing completion of a equivalent alternate pedestrian route from the site to the Benson Glen Elementary School: 14.Suitablerecreation space shall be provided consistent with the requirements of KCC 21A;14180 and KCC 21A:14.190(i,e.,sport court[s],children's play equipment,picnic table[s], benches,etc.).: a. A detailed recreation space plan(i.e.,location,area calculations,dimensions,landscape specs,equipment specs;etc)shall be submitted for review and approval by DOES and King County Parks prior to or concurrent with the submittal of engineering plans. b. A performance bond for recreation space improvements shall be posted prior to recording of the plat. Kelcey's Crossing Preliminar) .at Amended Conditionkm s=Worsheet Summary : r. . Page 6 of a May 17,2012 .. • Revision: The applicant may.complV with the original condition to provide suitable recreation . space:as'Dart of the plat development;or bay the Parks Mitigation or Impact fees prior to the final plat recording,using the fee schedules in effect when the plat receives final approval. If . the.applicant chooses the option to provide suitable recreation space,the detailed plan required . under section(a)shall be submitted for review and approval of the City of Renton•Community& • Economic Development Department and Parks Department instead of DDES and King County Parks. . 15.A homeowners'association or other workable organization shall be'established to the • • satisfaction of ODES,which provides for the ownership and continued maintenance of the recreation tracts. . Revision: Condition 015 is modified to replace ODES.with City of.Renton Community& • Economic Development Department. . • 16:Street trees shall be provided as follows(per KCRDCS 5.03 and•KCC 21A:16.050): • . .•a.. Trees shall be planted at a rate of one tree for every 40 feet of frontage along all roads: Spacing may be modified to accommodate sight distance requirements for driveways and intersections. . b. Trees shall be located Within the Streetright-of way and.planted in accordance with • Drawing No.5=009 of the 2007 King County Road Design'and Construction Standards, • unless King.County Department of Transportation determines that trees should not be • • located in the street right-of:way. c. If King County determines that the required street trees should not be located.within • the right-of-way,they shall be located no more than 20 feet from the street right-of-way . • linea . d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the county has adopted • . a maintenance program:Ownership and maintenance shall be noted..on the face of the final recorded plat. .. • . • e. The species of trees shall be approved by DDES if located,within the right-of-way,and shall not include poplar,cottonwood;soft maples,gum,any fruit-bearing.trees,or any • other tree or shrub whose roots are likely to obstruct sanitary or storm sewers;or that is • not compatible with overhead utility lines • f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by DDES.prior to engineering plan approval. g.• The applicant shall contact Metro Service Planning at{206)6844622 to determine if SE • •• 192nd Street is on a bus route. If so,the.street tree plan shall also be reviewed by � . Metro. h. The street trees must be installed and inspected,or a.performance bond posted prior to • recording of the plat: If a performance bond is posted,the street trees must be installed . • • and inspected within'one year of recording of the•plat. At the time of:inspection,if the • . . trees are found to be installedper the approved plan,a maintenance bond must be submitted or the performance:bond replaced with a maintenance bond,and held for one year. After one year,the maintenance bond may released after:DOES has . • . • • 7 • • • . . , . ; t li • 4.1cey's Crossing Preliminary,.at Amended ConditIons-Worksheet Summary Page 7 of 1"4 • • • • .May 17,2012 - . . . • . . . . . . • - . . • . •• . . . . • . . .• - : • • - • . . .. . . . . . . . . . . . . . . .. . . . . .• • completed a second inspection and determined that the trees have been kept healthy . . • • •• . . and thriVing. • . • - . • . •: : - • . •. : .. • . . Revision; .Street trees shall be provided is follows(per KCRS 5.03-and k:C.C:11A.I6.050)f. . • • • . . . a: . Trees shall be planted at rate of one tree for even"40 feet of frontage along all roadt.• • • .. • . .Spacing may be modified to accommodate sight distance requirements driveways :. ' . :' . . .• •• - • . .. . . - . • and interSectiOns. :-. • . • • . . • • . b. Trees shall be located within the Street rightLof-of and planted in accordance with ... . .... ... . ... ..... . . .. ... .... Drawing No,5j009 of the 1993 King County Read.Standards; UnlesiCitkinf Renton. . . . - Development Services Division determines that trees should.hert be located in the street • . right-of-way • :• '. • • : : . . -• . : • - • - •. ..r: . . . . ..... .... . . . • - c. If City of Renton Development Services Division determines that the required street - • . • . treeS.ShOi.ildnOtbe located within the rightof-WaVtheii shall-be located no more than . . • . .... ... .... 20 feet from the Street right-Of4aViine. • :• - - . . -. •• . .. . .. .• .• . . • . ... ..... .. ... . . . . .. . . . • .d. The trees shall be owned and maintained by the abutting lot owners or the homeowners • ... .. . . • . •. association Or other workable OrganizatiOn unless the city has adopted a maintenance . • Prograin. OWnerihin and maintenance shall be noted on the face Of the final recorded .• • Plat: . • . . . • • . . . • e. The of trees shall be approved b.,City of Renton Development Services Division . .. . . • if located within the right-'of-WaY,and shall not Include poplar cottonwood soft Maples, • gum,any fruit-bearing trees,or any other tree or shrub Whose rootsare likely to • • •• •.. . • •. • . •.. . • •.. . • - •. . ..•. .• -., ..•• • • •. • • • • obstruct sanitary or storm sewers,or that is not compatible with overhead utility lines. . . . . . . . . ... .... . . .... f. The applicant Shall submit a street tree plan and bond oUantiti sheet for review and . - • approval by City Renton Development Services Division prior to engineering plan ... .,. ... ... . . apPrOVal. • . ... .. . g. The applicant shall contact Metro Service Planning at(206)684-1622 to determine if SE • . - • ' 1921.1.d Sts on a bus route. •If SE1§2"c'Si is bus route,the street tree plan shall also be ... . . . . ..... . .. • reviewed by metro. . .- • . . - . • . • . . ... . h. -The street trees must be installed and inspeCte&or a performance bond posted Prior to . . ... ., .. . ... ..... ...... . . ... . . . . recording of the plat :If anerformance bond is posted,the street trees must be installed . • and iriSnetted within one year of recording of the plaL At the timeofInSbection,if the .. . . .. . .... . . . .... . . . ... . .. . . . • trees are found to be installed per the approved Wan,a maintenance bond must be • . submitted or•the performance bond eecaced With a Maintenance bond,end held for: ' • . . . • • .• . one veer: After one year, the maintenance bond maybe released after CitY Of Renton . •• ... . . .. . . . . .... . ... . . . • DevelOOMent Services Division has completed a second inspection and determined that . . the. . .. .. . . . . • • . • •. . • • • . •••• . •• • • - htrees have been kept healthy and thriving. • - :.• . • . • • ,• - • . . . • . • . is • A landscape inspection fee may also be•required prior to plat recording The Inspection - . .•• - .. • .fee is subiect to change based on the current Chi',fees at time of final Platie&irding.• • • - • . . . • • . . . - •• • •- • . . . . . . .. . . . . •• - •• .• • : 17,To implement Kcx.21Ai38, 3o,which applies to the site,a•detailed tree retention • - -- . . . .. •. ..•. .•• . .•. shall be submitted with the engineering plans fOr.the subject plat The tree retention plan(and • . .engineering PlnOsh. ilbetOniisterit With the requirements of K.:C4•OA.:0•i30,..0s Well as the . - .. .. .... . .. . . conteOtOal.tree:!!-Optiopolan.Oated February 25,2008. No clearing of the subject property is : •. . . . permitted until the final tree retention plan is approved by LUSO Flagging and temporary • : . . • . fencing of trees to be retained shall be iiroVided,consistent with K,c•C•21A.38.230.,B.41::The . . . • . . . . . . . . . . • . . • . • .. • . . . . . . . . - - • • • • • • . . • • • . . • • • • .• . . . . . . . • . . . . . . . . . • • . • . . . . . . . • • . . . • Kelcey's crossing Preliminary A Amended Conditions-Worksheet Summary Page 8 of 8 May 17,2012 placement of impervious surfaces,fill material,excavation work,or the storage of construction materialsis prohibited within the fenced areas around preserved trees,except for grading work permitted pursuant to K,C.C:21A38.230.B.4.d.(2). A note shall be placed on the final plat indicating that the trees shown to be retained on the tree retention plan shall be.maintained by the future owners of the proposed lots,consistent with K C.C.21A.38.230.B:6.(Note that the • tree retention plan shall be included as part of the final engineering plans for the subject plat.) Revision: To implement appropriate tree retention standards under RMC 4-4-130,a detailed tree retention plan shall be submitted with the.engineering plans for the sublect plat. The tree retention plan(and eneineerine plans)shall be consistent with the requirements of RMC 4-4- 130. No clearing of the subiect property is permitted until the final tree retention plan is approved bV Renton Development Services Division..Flagging and temporary fencing of trees to be retained shall be provided,'consistent with RMC 4-4-130. The placement of impervious surfaces,fill material;excavation work,or the storage ofconstruction materials is prohibited within the fenced areas around the preserved trees;except for grading work permitted pursuant to RMC 4-4-130: No clearing or grading of the site shall occur until CEO approves the detailed tree retention plan. 18.Sprinkler Requirement: a. Any future residences constructed on Lots 2 through 9 within this subdivision are required to be sprinkled NFPA 13D unless the requirement is removed by the King County Fire Marshal or his/her designee. The Fire Code requires all portions of the exterior walls of structures to be within 150 feet(as a person would walk via an approved route around the building)from a minimum 20-foot wide,unobstructed driving surface that is not over 150 feet in length if dead-ended. Vehicles parked on roadway surfaces or within the cul-de-sac are obstructions. b. To qualify for removal of the sprinkler requirement thedriving surface of Road A has to have a minimum curb-.to-curb width of 36 feet;or if classified as private,Road A will have to be marked/signed as a fire lane per requirements outlined in KCC Title 17. Revision: All future residences constructed within this subdivision are required to be sorinklered (NFPA 130)unless all portions of the exterior wails of structures will be within 150 feet(as a. . person would walk via an approved route around the building)from a minimum 20-foot wide. unobstructeddriving surface. To qualify for removal of the sprinkler renuirement,driving surfaces:between curbs mustbe a minimum of 26 feet in width when parking is allowed on one side of the roadway,and at least 32 feet in width when parking is permitted on both sides. SECTION III OFF-SITE ANALYSIS A Level One Downstream Analysis was prepared by Barghausen Consulting Engineers and is included in this section. ©2012 D.R.STRONG Consulting Engineers Inc. Page 13 of 55 Technical Information Report Kelsey's Crossing September 26,2012 LEVEL 1 OFF-SITE DRAINAGE ANALYSIS Kelsey's Crossing Preliminary Plat SEC 120th Avenue S.E. and S.E. 192nd Street King County, Washington Prepared for: 11° Bill VanEngelenburg 25302 139th Place S.E. Kent, WA 98042 July 27, 2007 s\q'• Revised February 20, 2008 Our Job No. 12542 •,1S t . .A c�NAv v.�•U Q. s rapora34/15/ ,j. =''1 'Z CIVIL ENGINEERING, LAND PLANNING,SURVEYING, ENVIRONMENTAL SERVICES 41a:4111F, 18215 72ND AVENUE SOUTH KENT,WA 98032 (425)251-6222 (425)251-8782 FAX n 1 r:- ? BRANCH OFFICES • OLYMPIA,WA • TACOMA,WA • SACRAMENTO,CA • TEMECULA,CA ` www.barghausen.com NC ENGENE TABLE OF CONTENTS TASK 1 STUDY AREA DEFINITION AND MAPS EXHIBIT A Vicinity Map EXHIBIT B Downstream Drainage Map EXHIBIT C Upstream Basin Map TASK 2 RESOURCE REVIEW EXHIBIT D FEMA Map • EXHIBIT E Sensitive Areas Folios EXHIBIT F SCS Soils Map EXHIBIT G Assessor's Map EXHIBIT H Wetland Inventory Map EXHIBIT I Basin Reconnaissance Summary Report TASK 3 FIELD INSPECTION EXHIBIT J Off-Site Analysis Drainage System Table 3.1 Conveyance System Nuisance Problems (Type 1) 3.2 Severe Erosion Problems (Type 2) 3.3 Severe Flooding Problems (Type 3) TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS EXHIBIT K Drainage Complaints TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS 12542.009.doc TASK 1 STUDY AREA DEFINITION AND MAPS The proposed Kelsey's Crossing plat is approximately 2.13 acres of land located within a portion of Section 33, Township 23 North, Range 5 East, Willamette Meridian, King County, Washington. More specifically, the site is located northeast of the intersection of S.E. 192°a Street and 120`'' Avenue S.E. Please refer to the enclosed Exhibit A -Vicinity Map for a more detailed location of the project site. The existing topography of the site is fairly flat with slopes ranging from 2 percent to 10 percent. The topography slopes to the east and south with the natural discharge point being at the southeast corner of the site. The existing single-family house and associated outbuildings have been demolished. The driveways and foundations still exist onsite and will be removed with the site development. The onsite vegetation consists of grass,brush and trees. UPSTREAM DRAINAGE ANALYSIS Based on King County topography maps, there is a very minor amount of upstream contributing basin area that the site receives from the adjacent property to the north. The existing roadway and ditch along the west side of the development capture storm water runoff prior to any runoff entering the property. The topography slopes away from the site along the south and east sides. 12542.009.doc Exhibit A Vicinity Map • • • -160111111111111' \N., PL. Cry//V. ( x sE InHD H R \�1SE 172pD a S7 to ZCb SE 173RD S<4. 1134, n tx Std 1 4, Ise N t2sov ' ` 5E lnsT . vEi 11141 1M sT S N '��� f 'p.,, 173RD '< Q¢ 5SE< 1721ti �� `d+ SE 175TH - �,m 17u I+ S r ! :J .. S E 1,7 6TH ST 5t b~s�/ SE 175,H�� "t` PET R� 1� O W„,„„0., - 4/ SE 17 sE >N Al SE 7 r` < d w @ i1 a ',g a 6i 4I'^ 6TH ST�t737,, 2v N prix 9t _ o il Fxl R % 3 .> SE -,.0 ' R a 73115 �A Iii gib; S' -. =7 ., 175TH PL _ QCT J SE 179), PL a ��`�• ti'' n %176I9GST W 3 2 SE 2:61= 7.. d R a ' -,I$150 Y 1BP E 180),5., ^ST' SE 179TH ST SE 180TH ST ( lb'SE MTh PL PQM Q a ¢ d 6 w SE 100TH PL Ade SE 161ST 4191ST ST '' 4 N^< o g >�Sf s7 $E 180TH yr r' ST SE' 18260 Q^ N W S� Y ¢ Sr NSE 182ND '< g` 5E 183RD ism Q M '¢ 1E1Sf P1 SE o fit, sE PL Sl Fx- . R< SE 182ND ST SE 1615 2 k 19314)Cl. ~ X i L2 '3 SE 153RD �+ SE ,(' SE 184TH '� Sr n • TH Si SE isgip s` 184 < . ar'^"'' 8 18471{ 134)4)1 AV SE SE 1B9rfi 1. p -- sem I Ey.`sz_.N N SO pC s7` SE 455T-/-;‘, L.s1 • a SE 186Th Pi Sr SE 186Th Sr ` . 1 sE m sslef 165TH E SE-166r/y`,,-4).,M o l`�,K`J1. 1 186tH..PL...se Q 186Th. PL.SE x { ' -''8S11f..PL .$F 1957TH 1•Wi SE 1$STH .- �. ' oo< i! d. HST 57 � SES ^l.� S DL n L., CT SE 197111 �'� JP 3^r �' �( \717/ Si , 8 4,-1. � 61 ¢leeT6 Pt bl SE 8 ST SE S' ,)4. SC Pl 4' 7117), w sE Ic 1mM vL g�r 027TH CT SE . 101`5 sr f d �tiy 't ' •'SE z to a 1. ST `� o 166), 1887}1 S7 ;yPl: SE a 42741„,"..Ern. SE Irs s PC J1 2 Ar .^..IC ~,r E,' _� ,w ,.'' it mens z- s IBM 187111 SE I\� '- 1°1 $E 1mM 57 SE 1®Tx Y 16916 F a .:• S< ^> "/y1 SE 14 al '. .' E 1901H ST imlx g�7? ST �TM 'c E SE U9111 rL 4_, n v $A P.�- i -. SE J a^9M- PL .7. /Ct. 90TH SE Air 150),PL I I S •p i`�,,,rsi��3x SITE PL .7. • SE P901N �sEYtOa T -'‘SE ( IA v1 t.�:JR HS ry R. 1St Si.o ��E ( 192Ni ST �� :> rn a 191st PL 513 II 6' 11%iri 124304 w G ,� PARK 8 J SE I9JRD Sr 1,,, W N . RIDE I F) y ,, 193 SE 194TH`p g ST��T ( 4 •_,.tt Q ^ids W� 8-, 196TH sr= alb '¢ d N 15° €N�z '� SE 196tH J SE 196TH w J <' = 1� ' eta+=�'w W ST '^ _ } SE 195tH�SE \J y SE ., `�F C. 'r ,.' �' N < SE 197TH „' �p ST -.'/ d \E 196TH 196 H pt. //I, e",7A < Q R 197TH PL riR a _ __....219711iSE 197tH SE SE 198),ST EL 51 1e •.. 199TH = x+ g.1V, a ST SE 196TH PL �!it atli' 1 SE 198TH ST PL m. 'x 61 CT Y 1967y sF '+L"Y,y d+ .1,1 sE + a� r SE 2 SE l; ' sE "13 2,21_1- M c-t 1,-;-‘,20 LST SE 201ST `rc>e ... !w'� ,y sE 20 ST ST FE v .... 1 .. 4 ,771 ^, :. : 9-C1 a x71E'. F,WTh'E' til SE 202ND PL n„ �Fa LAE �/ c SE 203RD 4 SE ST W+ NI `� �1 vtrr , Di N O Lf#kL mi sT G_`'1< ry- 2`SE 2030 ); la e P C' ST a R s'sn4 Q ,r sE IST x sE zo9ro 3 x ''T v/Ier 115/-Ni SE Nr iD1ro_``�Q S , SE 204TH PL . ;-* �`"_4 `''r. 106TH rL 64 ,/S/,/ E.•w� SE ,� K Si a$a 8w • anrw 97 sE C1 (1 x_, 3.V,, 31H / ¢ K' �SE 2mTN L `1° ST -MTN \1. { /p V / .g ST Ft {v rOfTH F'P%11) SE zo67H Si d `: 1' 1f SE 1ST 3 SE 206TH EL 206MSEST Y z n, a 's d X0(4, ST J sE S7' , 202,9 PL SE 206TH PL '/'Tr SE 207TH ST 8 �� w sT g nTTM r� y1 ST KEN7RIGLE hs m1-1sE 2D7ni < r o 5E S E 3= t <, DL i w 208T ST pi d ii:Acy I1dLt1 e�. )1_, :Y o 3 ��a �: SE 205�W I SE 209TH 3,y s<21176 12'Or1 -s" 172?_, i5-j e Jk 'W„S alien,„E C7 Q`4'- tH ,4 o `5E271), � D3 4 2116,SE 210TH s a C7 Q. .x-�a < l rs nTM�� se- 11` Q (3I/ �1� SE rtTMw 211TH 3 ST �' FS a `:s'..ai }��21r2111 v,ST C 1 005TH P1 SE 'r3 SE 21119 4/�S4 r ^��'f3' ¢*TM $ SE 21119 ' k §.'• • �' �r '< SE e�i� 212tH Sr = SE 212TH 5,> ' a3A,.H1• n ri SE 212TH PL ET SE Z 1?...!h CT 9.9 4 ce>f3-H 5T \0 7.1� 7.- �%x 1'1" '' . -SSE 212TH ST CME CF 717711 ., 1.•.t REFERENCE:Thomas Guide(2006) Scale: For: KELSEY'S CROSSING Job Number Horizontal: N.T.S. Vertical: N/A PRELIMINARY PLAT 12542 4- GHA(,s 18215 72ND AVENUE SOUTH KING COUNTY, WASHINGTON Q' N.LNA: F KENT,WA 98032 Q7` Z (425)251-6222 Title: +` , „Ili, .F (425)251-8782 VICINITY MAP <r `° CIVIL ENGINEERING,LAND PLANNING, 1'1'a eNais‘ SURVEYING,ENVIRONMENTAL SERVICES DATE:9/25/06 P:112000s1125421exhibit112542 vmap.cdr s Exhibit B Downstream Drainage Map Kelse 's Crossin - Downstream Drain� e Nia Y J � p 259769�J�20 � 2597N0150 -. . � : _ 59;b�J290 L��� � � --- � ; _ ...zs9iesotso 25y�ss�zr�� � HighJightedFeature R�-��Rur��a.ana�UAorsaeras OI22b5404� _ 259T7i�J60 '=� �ntyBour►dary �--� RA•10-RuralAma,onaBUparl4bctas _ '._ ._� __ �54J'64Q449 �� �� , zss�69a�so Gantaurs 5ft li ht uR•Urb�n aemrre.a��u 5�uas f� ` �� -- ., - $J 2597fi4J2T0 � � } p'°r u '� f�,+ 259T69�?�50- �_ , � �__ a 259)6�0�50 ��.��� R•1-Rasidmtiai,anoOU pora� � `� ; 1} " a - -. _ -. � � ' -- � 259f69U460 . R-�•Residanii�i,1DU acra 4 0422054056 -- 2597690ZYJ �� � - �� � f . - — - _ ' 25976901U0 - --asyi ' � � . `�--,__. � i� ---- 2547640�f70 Pa c9�� — r"1 Thanas&others Map Pag� R�.Ragdantcr,sou ac,� � - 25976902�0 �- . 254769U21�' �■j Hi hwa s R-�-R�idan�iaL a ou pir acre - ` 259Y690�Id0 259T6�}D22U g Y ' � Urt22D5�J5t `i -- R•1Y=Rasid«s!'r�1,12 DU paraua �1, _. ��gsrH sr Streets ,� i 1 f,.•" � , __ _ � R•1�-Rcs�nfial,l8 Dit psr acre - � _ 759T690090 � � � D4220540�t6 Z59I6�J<90 259I590J80 1���� � R•2E=ftesdanLial,24 DU pa ytra 259169050� �� � � _ � R�ib�Rasident'sal,48 DU pa arro � � . O�t22059D50 2597E90510 ; �-°� .--- � � -- NB�Haighborhaod 8usinas � � Z54T69FRC 1' ��� (� ��e5 afl�L2f�8 RtYBffi 0312459i2< � 2547640575 . � �—� � CB•Corrxnuni[y 8use�ssa '� €� � r� . -_.,. , �s9resiisoo r%�r` 5treams Q RH-Ra���u�ess - - "1597694520 fr ° .,`;. Tflf)3� �.3tlt�b � ti Q . � - __ _ y i _.`r 259T641535 _ ' � 0�OFfia � � -- �� � � . _-_� _ ' �.,' � Pareel� - �•hdu=tr� { , �� - . � . � c� �• • _- � •'� - llnincorpora�ed KC Zoning � �n« ��31A59003 � �` � Q _ �f..� 259764QSiU A.i4.ky��ur�l.one DU par t0 acres $, i � � --- r'�' � - A�}5•ltgrictiilvraE,one DU pet 35 actcs N7� • j 25976n9550 � _ � � , ' � 1 � €•Forest �. � � 25y76�J560 _ � e� '� I i� A1•M�ar�O � � 0�'1?054'.�tli � 2597640570 ' RA<2,5•Rural Arit�ona OU paf 5 a�ses ' ' � �.' �x- �` 0322054065 25976905t30.-� �COtl�y . � , � ;��-� ��j_ � ; a _ ' a � f j• +,!} - - � 259768f�f6:1_ � `� � �p ;� ' � i � t� zs9rssa2so � ' . _ � 259t6F3�J7_7o _ � ' � , � 159768J220 -_�-: - • 1 , 2sg�esosso ,'� 56352o0?rr02D0i3t� � �- �_ � . �. 25976802�0 z5416$J210 � � I Sf 196TH p� 56352d0?SU =r �� ' � 2547680250 2597fi$074D � '--�,� sS �' 254768020�J • � ' _ . 5635200�40 . y � - -- 56352b0?i0��..�� � � � '�,�5` � � 259768�J2T0 � - . � . C2 � 2597fi��30. � .- 'ti — _-- �� , �, 5635200i2q � � � 563520TRC T � ~ � � � , � , _ � � 2597fi80�20; ' , . � ; r .. � . . � . .. . ; . _ ' 04?2054065 - � � � . _ �� ; � �- _ ' Os22059158 � � I ��'' � � __ � i 03�2459266 _ � J �� __ � � � 759Y66o300 J . - `� � �� ,. � � . _ �,�ap�� �� ;� � �G}20Q5liirtq Cavnfy �, ^.. \� � - �-�. Q 1t - � The Intormatlon tnduded on this mep has been compiled by tCing Counry staft from a variery o�sources and is subJect to change without notice.�ng County makes no representatlons or warranties,e�ress or implled,as to accuracy,com�leteness,tlmellness,or rights to 1he use oi such Ir�formatlon.This documant is not irttanded for use as a survey produci FCmg Couny shall not be Ifabte lor arry genera),spedal,Indirect,incidental,or consequential damages induding,but not fimited to,lost revenuas or lost profits resutting from the use or misuse of tha in(ormaUon conffiined on thls mep.Arry sale of this map or information on this map is prohl6ited except by wrttten permisslon of Edng County. ' � King County Date:727�2007 Source:}Gng County iMAP-Proparty Infortnatlon{hripJ/www.metrokc.gov/GI�MAP) Kelse 's Crossin - Downstream Draina e Ma � _ Y g J p , 6798�26p 6�9900J0(� 61y9t1�J'J053 � 5i9401:10HrJ 6i.94!4,'�0101' �r _. � L6�IItJ . Eigo,�,;o�y Hiq6lighted Feature RA-5•R�uatAraa,anaDU parSxJns S148IrJD28U ,. ' 33?3'_�547id 4 � � � 61990r��12o `� � COttRty 80U�ddry ; . , RJt•iQ•RwalArca.oneDUp«14a�res 6t99(1J�i?6 51440G0127 � _ � -_-'.� � � �---- s19400caaas �� g asa�a�}ec.� Cantaurs(5ft figbt) uR•ur��csa,ti,w�c ou Rer 5a�rcs . I � � � agasoan��o ' 104;5W;t0�ii0 R•1•Rasdantia[.QnaDUporacrc 6t9$�OD3�0 Si9400�1i1 6199pDDit2 6!�}900�iE6 6i947a02i0 6195�!�OQ�tO � 6i951;�3?251 . �' �� R-�E-RCSidCr1lG71,a�Upat�cse � R�.a��,a�u�� sE rersrsr �`✓ j ¢� � � Thomas&att�rs Map Page � � S��Gp./'���f`��-��-yQ�,�j, � � 33�3U54�157 r 3323J54.5� 1�" � 3' 6?94a7C�2t� �C�K`f �l�' � � � � Highways R�8•R�da,t�at,�oU pa xre 3704677R-O 6�9y00t7143 t� � � Fa►2 �C�, �t� E�'�'p/`�7kfx� - � � � R•12�Residmtial.120U par xra i F�9va�c�r�a =' Streets _. �� �S� � ' R•ta•��na,taau�� � � e�s�otl2a� � � � o�asa��or�o t1� h �� � �5�� i � � � � R•2t•R�dmati�3ii D�1 psx acre bi94�Di83 f OUSQl13!17?0 �prj�� �= , 6i490001E0 6iS19;J!uJi3{ � „p� L� � R�•Resdantd�BDElparxra 6i94DQJ2i7. 61Y907U262 �� Ne•Naghb�xhaad Susnass 6i9fidUU340 ; Si990flfJZZU — i _. - `- ' siy�c�ao��z � � 4 u��scux»s.� D taEces and Large Rivers bi�9DLL71i30 fiiy9�J.'.�2i5 � � �.�..• �. � CB-£octxntlnllY$uvrl�s � �.• _ - t'1 Q � �:/ � � � ���}"'E�i . U98i0.�l40 %'� 5tr�ams R9•Ropiorsai$usutess 6Y_9?�J76? .�♦...� __ . . _ sE}�vnsr - -. ' 4� - �� D Triballands _ - — _ -: . _ _ _ � •,: � �'Offic° � zsira000�o 4� � - _ Parcels - 793200002� Z81r8h0020 28i780Ui80 ai !•ktdustrral � , � tlnincorporatecl KG Zonins� /932L�OU024 � � T9320;�00�3 ' = pq22059162 � ■ a� � - � - 3 A•io•A�ric�#ur�.�na uu per t0 aaes — C�T22!15902� + � pi�?OSyi39 0422U59�J82 2d17$0,7030 2817HCi07E0 � � ! A 3i•Aqticv4tual,an4 QU gof 15 acte3 7P�2�J0026 }� T932+J'J0.712 - � n.tZ?75d76i � � (� F�faest - __ aa»s��nou� d � !� � Z877E�J0750 �--- �•hlirsor� T932��025 � 793Z��JOJ3b T932?h:X_�35 � , zat���!v��0 181 y£+�o7 tu as2ro54oba: R�t-25•RuM+lreu,one DU pnr 5 xres 74370�?P01� � ' � �CO!}f� � 281T690130 _ • , � � , � ?8�7EGLY}80 - � 2B178JQi.0 _. i , � 28?TE1(.iNJ9� 7432P�J�1D � a.f2?U54025 � 28?78�,10 i 10 {S 287T$n7iM . < - � � � 896030�90 69603(17980 � 4�2Z054074 {�i 89603�J i 00 , . T9320C/.JOiS �r+�11 ' rJ� 896��'J70 042ZQ59i24 _ � 7432l10a04� � 89603Q9iiU 896034�JD60 � 6I22054(13� _ BIE7 S�'OS � -- •' -.T�'�".�+�+r��C`� � 79?200Pat+�J - � tf96U3�J0�50 � � OT22054UQ8 � � __ - — 79:iT�'J056 ;93?04�55 � �' ,�.. � - —- � i 89603rJ00t0 �- -�' .I� T� � ,-1,' 89603U0730 � ti +� � �' ._ 89f�030.71�0 Ty320000(T � � 8460300D3U ��22U5905i �, '� - T432000050 ' � ,� _ � � O�t22059J02 - 896Q3L�OiTO � 89603a9020 i �' , � � 74320fJ0�Pt8 74320L'�70t6 .� - � Y - _ � 84603�30iG�J E4603JOJ1� O '�22�J5�032 44QtE {C)20051Ci�y Courn ' The ln rmatlon Irx�uded on this map has been compIled by KIng County stafi from a varlety d sources and Is subje�t to change without�otice.King Counly makes no representatlons or warranties,e�ress or Emplied,fls to accuracy,com�leteness,tlmefiness,or rights lo the use of such(n!ormatlon.This doctiment Is not intended for use as a sutvey product King County shall not be Ilable for any general,spzcial,Indltect.incldental,or consequenUal damages includng,hut not flmlted to,lost revenues or last profits resulting from the use or mfsuse of the inFormation contained on thfs map.Any sale of th(s map or In(ormadon on th(s map Is prohlblted ezcepl by wrRtan permission oI(ang County. ' King�ounty Data7/2712007 So�uce:iGng Counry iMAP-Property Intormation(ht�J/www.metrokc.gwlGlSfiMAP) ' LEGAI. �ESCRI?TION - < i:/_lUT4 b195000160 5 51990D016� - CASED MGNUu;4S "?<CT a Of�IOa:1.kCSTrF:1 CaPJE�I'R�CT:.C'�17J'��iJ.5. +i,�V��u �r�_ .�,n .. c��JS �C:Gs{,y��,l,10�iE?L-1 7ME•rGr iEC�'JEJ=.':CLJ�L=.'G.- - ol_T�.?cGC 90. �F.^.°DS O?....G caVi�tt.'�.=Ho:t�"a:l. � � � � 1P� 1 ] C _ �r I v � 7 � I � � I !, I � ; i F `^ VER71CAt DAiUM I I 'Q' � � � �� � RE3a. v1/ L'�' !5 10279 ; "� w C/j � e K:::G couurv Bt��Cxw..?ic 'rs�'EtEv= a%.dI�:n�D:d � u :+ 7 bo» � o. S� 8 �'eaa;;pr,u x�ca��t r.��e w COIItFEiE+�•u�r,aa,r, I i FR 4 C:.�C CORr:Ert � � -�-� � $ " 5T<uPEO'e�rG COUiiT� vC-f-4e�97)' S PT 7. 20D5 � j ;' 9'>� i 2 i ai.��r ab '�� ;' U �S ,z-< - , .>;- o � a ! ! 4, � � , ,,, � � � a f, s- �r i � 3 ' I { E%. E' E3.�L� I O`� � < . BACIC !O? .. G N � xr � � �x. SN�o X f �r ;a Z � �' W � ' ; � A � � J � U � p� Z F R � ; ; �� �-' �. t1 NOTES � u � � � O � N oj .d � � v aF� e N p p"1 � iNt^a EU.W7 r:.i PEAiOPMc'D 81 i,�D i j „�j , .`� L^! � la:.VEASE x;TH inE�I�i�i oESVL:a _ : � MES(�:1G DP.iY.CiCC';1;.ikE'�^Ef:f j � O iRsv�;._Si_i�DsiDi C611L_�tlEO I:! � a � �� �f� �[� {t � o.x.0 5�_^ISO-CiO. i[� �v � o I ,z-;..�5 „� ��1-5 9 ��. D t C(Z�tT� � e38.65 �Jt,.p ! I^�yVL�!.rt�C rH�,;�aver n�ai[enoucica�.n�;e.;T � I '- . ` i� � Q I ��--e�- dN �-QI `^ "C� � iMF °:.�:F��Of�[l'??.Er�:TiSIE�E?afi; . � :.'�TH[R�(OR(COC's:�OT TU�FOP:10 �� �� - +(��/) (� Q :k0'n'iL i�CrJCtRS JR?:ST-iIIL:K�tI_ n '� { � �� r�f Qr o;=cco.o,r.�,.. � LOT S NW GARDEN TRACT NO 5 ;y - T /'� / c^.� �..: B9vr:Qa�v COr.;*a;:r:0 L9�C5 C•_"rtii0 0'� � Z N � 92530 SRFI i � ( � F�ys£'�,S E-�t-t/�""�('1 �. 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SCOI@ �" � JO, � � Exhibit C Upstream Basin Map � : Kelse 's Crossin - U stream Draina e Ma _ _ v g p g p 619$fi�JJZfiO — ef99wor�i � e�99�cwo5s 6i94C�OCK�59 Le�� _ - ' ; ` � HighlightedFeature H,r,•5•R,tr�1,4m�oaeoUporsaczas ----_ 6799J00120 -- - � � _ ' _I CounfyBoundary _' RA•1Q•RuralAraa.�eD{lpart0acres - - - sogaToo2ao �+ sls�ooi2e Bige�oi2� Contaurs(5R light� UR�Urban R�«re.aneoU per5ar�c3 _ (� - . - 100:504;t4�A R•1•Resdcntsa�cmDUpaaaa `ei�o�u�2s Q�'� . � RJ•R��fantiai,d DU par acn �� �f�� 1�1 Thomas Brothers Map Page R�•Rcs;don�ad,eDtl paraa. ,.' _ R�•R�sidsrii�.8 dtJ p�or acn �Slf� ��C'= D:Lt)� Highway� fi7 48{L�p30'J 6199YJO i�7 6i J�00J1 i2 ,r- R•12-Rasideniidl,l2 D{l poc�c+'e 6144.?LiDi86 619�JJJ1i0 S��B{r _-- ;� R�18•R�d�ntial,t8 OU por aua _ � NiQhway � R•24-Raadentpl,�!OU por acra Artarak � sE t9is7 ST R-4a•Rcsidantial,4Q DU par�re �� tod __ N9•Nagfibarhood Business � � Lakes and Larqe Rivers — - s�ossoa�r�� � sj9�.Muzas '� Streams � CB•C�m,uni�y8u�sss 37U9&C�O�i30 `r 6l9900�i43 r'�'� RB•R ianal$usittas 37046C)P�fiO. 3Ta960!1�•TO �7096rJWT0 l 6144900t$5 ( °Q. 370960U69J_ 31U96�J7R-D 6t99•'JOOii� � 370967.�42U 3"I�J460'JISQ � 37D96Pa380 � ` `yy � Tribal Lands � ¢ �.� E..__� _ . - i � � �.�` Parcels - _ � - - i•lndvstriai Unir►corperated KC Zoning ■ anar � 5 i 94000?0o A•10•Agrir.ulur�l ase DU per 14 afses � 7. �� � - A-]5�AgriaiMara�.ona DU per 15 arras � t�� � 6i99rYJUi$d � � p F•farast �F-�j - � 619y0�Ji33 __._. F�SrN uni� � � �.M� � - � �'s�s(p� � ^ RA-25•Rural Are�.one DU p�e►5 aaes 6?98i00360 _ _ 619[fiiQ9�il 5i9ft4003<0 (COflt� � ; � 6794000i60 � _ �, i ' � I{ I� � � �,R ' 679yPGUi81 _� � 6i99�JCvJi6i �� - - �•� � � ' 61940�Dat�J J �� --'� ' _, � _ _ _ --� '---- �-. . b � � --- __ - - -- - - .___ se-;er�o sr_-.___ �� 2> � - -- - - -- _ - _ _ -- - - - - ._ - - _- __ - � :. � , � � � _ 281780Q780 � ' 79320D�024 2Si7t300020. 2Si78000i0 � < ' ?9J700f10�7 7932001�1b 7932CVJ0010 l9320�025 T932�YJ75 - �' � - -� � 28i7800iT0 �_ 7932000026 2877600b30 287)800160 �c�aoosK.,9coanay � 0 2o9rt 2s�l8Jaoan _ The intormatlon Inciuded on lhis map has beencomp Iled by King Counry staft hom a variery of sources and is su6jed to"change wlthout notice.King Couniy makes no representations or warranties,express or implied,as to accurac.y,completeness,timeliness,or rights lo Ihe use ot such Information.This document is not intended for use as a survey product King Courity shall not be Itable for arry general,special,indlract,incidental,or cronsequential damages includng,but not IfmRed tn,lost revenues or lost profits resultirig from the use or misuse of the Information contalned on this map.My sale oi thls map or iniormation on this mep Is prohblted e�ccept try written permisslon of IGng County. ' King County Dafa 717712007 Sourca FGng County iMAP-Property InformaHon(hripJAvww.metrokc.gov/GI�MAP) L 1 TASK 2 RESOURCE REVIEW • • Adopted Basin Plans: This is not applicable. • Finalized Drainage Studies: This is not applicable. • Basin Reconnaissance Summary Report: The site is located in the Soos Creek drainage basin. This Basin Reconnaissance Summary Report is included within Exhibit I of this report. • Critical Drainage Area Maps: According to the Water Quality Application Map in the 2005 King County Surface Water Design Manual, Basic Water Quality treatment is required. According to the Flow Control Application Map, also in the 2005 King County Surface Water Design Manual,Level 2 Flow Control is required. • Floodplain and Floodway FEMA Maps: This site is located within Zone X,which means it is an area of 500-year flood or a 100-year flood with average depths of less than 1 foot. Please refer to exhibit D for this map. • Other Off-Site Analysis Reports: A review of Exhibit I—Basin Reconnaissance Summary Report and a site investigation were conducted in preparation of this Level 1 Drainage Analysis. The United States Department of Agriculture Soils Conservation Service Map is also provided within Exhibit F. • Sensitive Areas Folios: Based on a review of the King County Sensitive Area Map Folios, it was found that the subject site does not lie within any sensitive area. However, there are wetlands, seismic, and erosion areas located downstream of the project. • Road Drainage Problems: This is not applicable. • United States Department of Agriculture King County Soils Survey: Based on the Soils Map for this area, the entire site is located within Alderwood type soils, which are known to be till type soils. • Wetland Inventory Map: The Wetland Inventory Map for this area is included within Exhibit H. There are no wetlands located on this site. The entire site drains to the east and into Big Soos Creek, which is tributary 0072,. and eventually into the Green River quite a ways downstream from our site. • Migrating River Studies: This is not applicable. 12542.009.doc Exhibit D FEMA Map �'s • m 0 N-1-51 1-#1.*,,,, � SOFT EAST co il w .^`-,wa",�. MEEKER JUNIOR 0 ��'�n'� HIGH SCHOOL O t.*a p COrs " '11i1 °# by ,SITE Q aft,,,-,.1 `, 3 cn SOUTHEAST 192ND ,X1::',_ 0 a R M289 369 8O Z ,ill 36 Lu o cn *AAFt NO,41 APi -3'7:..74 ';u i;i 366 1311 o Y 9— s �' 04 iv y} SOUTHEAST 196TH STREET x r 'ili °4c :: Sa w U) �,c w co ti --I. .. v"9�• w �s p n s,R a = �, ZONE AE ��S(e� � O '. rn to SOUTHEAST SE 197TH ;4',.•_ 197TH PLACE PLACE w U THEAST 198TH STREET z as LEGEND 11.1 CU D ¢ SE 198TH ¢ N r r — SPECIAL FLOOD HAZARD AREAS INUNDATED zN BY 100-YEAR FLOOD SOUTHEAST u' COURT Cu' 2 ZONE A No base flood elevations determined. 198TH PLACE W 1997 SOUTH ZONE AE Base flood ekNatirns detemoned, n SE 199TH V �- H OTHER AREAS COURT d Q ZONE X A rex determined to be outside 500-year O IL floodplain, N SOUTHEAST 200TH STREET 7 REFERENCE: Federal Emergency Management Agency(Portion of Map 53033C0991 F, May 1995) Scale: For: KELSEY'S CROSSING Job Number Horizontal: N.T.S. Vertical: N/A PRELIMINARY PLAT 12542 42- s 18215 72ND AVENUE SOUTH KING COUNTY WASHINGTON � P, KENT,WA 98032 OOC , , Z (425)251-6222 Title: o (425)251-8782 FEMA MAP �•e. /Flli° .. <,.'4'0 r �r CIVIL ENGINEERING,LAND PLANNING, r4'0 ENGsHE SURVEYING,ENVIRONMENTAL SERVICES DATE:9/25/06 P:112000s1125421exhibitl12542 fema.cdr Exhibit E Sensitive Areas Folios -•---r ""`r"` rage i or 1. King County ICE.L Y S C ossltic, Prelimina Plat - Sensitive Areas -619840006'4-6198400065-61198400243 61 98400064-61 984000 65— I I ` ��►' 6198400060 61984002{3 6198400245 6199000100 6-98400066 I1111Tti.AVE SE 61/98400242 6198000040 ( Nit 6149000059 6199000058 1 6199000101 6198406080 6198400260 6199000041 6199000080 3 23059010 si 1 6199000120 • •,, 6198400100 6198400280 W 6199000126 to 6199000125 ( 6199000127 1 W 6148400125 6i98r�r00i20 6198400300 �Q. 6-94000-421 6�9400b2i0 6199000240 �, I �• t•--11-86 6-99000260 332\ 6198•f00i42 0 6199000165 \ I 6198400140 6198400320 f 6199000143 6/99000205 6198400141 161990001.10Wf I I ( ~ E 6198162 X6199000200 6199°00184 8•f 0.y 6199000183 •\ 6198400161 I ` 6198400180 6198100360 819040831- 6-99000215 6-990002•(-u 1 6)98•(00340 6194000160 N l 6199000220 'i1 6199000262 61198400163 I I I 6199000161 6199000180 I t. I. _------- f � 1 I J f ,..� 6199000182 !!l SE.192ND:ST I ' f w I� 128-76000-0 > 7932000010 f I 7932000024 2817800020 2817800180 Q 7932 000007 7932000014 7932000016 ) k .._w 1 I 193000043 '_ 1 ! W 7932000020 t i 1 I �l 02817800170 r co 7932000017 2817800030 -- 4475000120 •�; r 7932000026 1 rv:04�20590 02 (I ���`0.2817800160 Vlf 7932000008 - rn \ 2819800040 F•- 1 7932000042 7932000036 44T5000f00rF I r .I( ? 7932000025 N I 1 7932000035, V I I I TI( a' I \ `'2817800140 4475000060( ` 2 2817800070 1 I I 042205666 5E-193RD_PL),14}500021:1 c 82817800060, 793200004- 4•f7500Di30 7932000015 N 2817800.080 28178001301 f{75000170 4S I75000-•f0 2817800120 'i_AOK, -, l 1 114475000150 28-7800090 I 7932000040 012205 I L t 0 28-78007 i3O 7932000075 7932000055N 8960300080 7932000045 IC)2005 King County II 7932000060 012207 t 7932000056 01 158511I Legend pgSelected Parcels Clam 2sfmaid I Loxes Trntra-y8 ns j _ County Boundary f�f Class 3 i Upper Tri .t y Binns x Mountain Peaks urr'as;s-4 • Streets I] Lakes and Large Rivers die r+;sFrxsrr in.,/ Streams /✓ +rands EDSAO Wetland / SAO Landslide Parcels ;;;I SAO Coal Mine SAO Stream \ SAO Seismic XCtaa I SAO Erosion Class 2Prsasraf CAO Tributary Basins til (cat) The information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice.King C makes no representations or warranties,express or implied,as to accuracy,completeness,timeliness,or rights to the use of such information.King Cc shall not be liable for any general,special,indirect,incidental,or consequential damages including,but not limited to,lost revenues or lost profits result the use or misuse of the information contained on this map.Any sale of this map or information on this map is prohibited except by written permission c County. Date:9-22-2006 Source:King County MAP-Sensitive Areas (http://www.metrokc.gov/GIS/iMAP) http://www5.metrokc.gov/servlet/com.esri.esrimap.Esrimap?ServiceName=overview&Clie... 9/22/2006 Exhibit F SCS Soils Map CT 1J .,' 1 ar � , > iiir r ; Q ~ ±I> • wl 131 1�' • m, rt '11. +�l C" ..YSE184TH_ST. _ -^-::-.7.- - •1� I i g D �'1 i_ {SE 18 CSC w: Y f _ a ♦ >SE1: 2�*.I_ . AN., I o f •hCi Mtt rt .,�, SE 186TH ST = ' _ _ �F V if-• .• ' E1 r• 1' .msX='t-1-'mss' 'r :. ''AgC i i �T 4 " 86 • 1"' SE 186TH PL 1 =ii�� . 'AST I.b Y r: ' Qz=. it 411, dr yr' = • }_ y lig 188T 1-t STe.� r•e1�rr� , �� .• .s`Z`;• ."• `+^o ' s r F'S E 188TH PL ' s; ' 7�?>r -' ;t`.l V P•r . -.', '� r -T. �" �SITn. ,S i e 5. ' 7 rw.tirr-i ► tSE 191ST PL(7... ,� � x ts. __r ¢ ______„W,'SE 192N ___ ---- _ ....... ....1.1••••_ ,111 Lir "ISE 193RD PL1 4 >Q"'..i,,, N w 6 0 , . 41 -.---..•-- j . le 4 r EvB I. -[ • 1,t4`r uwi• •. 1 t 4,i0, fir' ? ciiii y j ti :likiini.madmisitilieC") '.. ,-,) ''''' ,„ - , 196TH ST r` I Q I ;L r ilif ' (e, k a:761r... 's ::- ;W.'i clY) { � wl SE9QISE 196TH PL i•7•.- .1:3 ,-~ 4 .e.9Tt hi" sk il,r iii. _,,.. . fl� , a, - � AQ` „ „.„ y ` Panthe Lake SE:76-0-i.-H-sT SE 200TH ST • IL '`” �r'' :�. ='' r 7 r . . rp..„••AgD N REFERENCE: Natural Resources Conservation Service LEGEND: AgB =Alderwood gravelly sandy loam 0-6%slopes Scale: For: KELSEY'S CROSSING Job Number Horizontal: N.T.S. Vertical: N/A PRELIMINARY PLAT 12542 cyHAG 72NDAVENUE SOUTH Q .r;*< ` s 1821572 DAVE KING COUNTY, WASHINGTON 98032 07` , , rZ (425)251-6222 Title: o __ (425)251-8782 KING COUNTY T��c ENGit.f'�C SURVEYING,ENVIRONMENTAL SERVICES SOIL S U CIVIL ENNEERING,LAND PLANNING, I VEY MAP DATE:9/25/06 P:112000s1125421exhibit112542 soil.cdr R° • s Exhibit G Assessor's Map 5 ' 11.1111brpyo 3 ti 9 WI KC. om2 o j of 1 16\11 �Ocg, 112006 ^ 1.07 AC I 71 m 160 02;2 m 0040 o ^+• I v - b 0 0 I N 4 z z E p N N E °90 N N 6,1, 4 2.12 A 1.06 AC 116813/ 0250 �' - 0069 .1''' 314.95 0041 618957.48 I 97.48 5.14860. 200 143 629.92 143 NO-�THWESTE GA.. DE Pp ti D m n 2 e 14600 5 z 8 T tIAC6 DIS. N Q 5 m o -2 31564 SF 1:7-90 .r. 1 6 m °° VOL ,' N h^IP ___________ 210_18_sr Z O • 2.10 A.� yj n---------��---- 30' INGRESS S EGRESS 1808, SF I 20917 SFS 0280 (4 0126 W I OQ7 343 S 89-59-20 6 143.78 630.16 143.38 120 255.08 195.08 150.57 157.54 - Rt r ° ° � N m, .63: 4,.P min 4'' ��0�p 15600 SF 25360 SF 22348 SF. iii. Q 21602 SF 0141 0142 0E6 ii 0_a 02A 2.11 AC o Q. 120 z0_ N 89-29-17 E 1O N m 0_14 89-40-5 E z 137752 m `1 15.08 7 N 157.6 - 20 N n a N °p `�\Z_2 O 9p0 a°p ,A 0_''v v In ,,,�°Jj°. I LI O oow 2 o In ni4i m E,'+qP° °� N -7Dia I c w gi aN ^ 7 -^`, ° e I¢.,N m Y 21670 SF m 22387 SF 22940 SF1' 0 0205 m 2.16 ACOHO 81� m I N 89-42-01 E 0_1 0320 093 I I 157.67 1 5 00 3 0.1 • ' - m157.69 I ' ,c z m I n LOQ°%° 11197 S- 00203 0200 S ITE .0 _ 12.9.- 89-40-54 E 30.21 N 4491. I 11 44.79 5 • NLQ2 1 p�0 m 5 0390, 200 SFo 0 ° 01.3 LOT 9' °P° 0P0 30° 22398 SR 113 E 0134 m . 9 ¢130.74 1 C 4.44 I E71C N N • O I 0O�i o p0 O 4^7 ,0 I ,90'L m N 0 8 �,ye 4 0_m; o °06� s -m vg W. 1 I 5 -Q ,, O Y o 1.02 A® 1.03 AC 10075 1.91 AC 1 21600 SF 22615SFSBOOd SF 0341 0340 011 0900160 Og 9 75 16 our 1 . 190 755 a[j( 41 150_J55 30 30 m 79 65 al Su 171 RA 9 29,29,A9-9.49-59 150 73 1!3 157.79 44 Im 192ND ST N 8 -32-54 N l0 2 3.Z*\N129-32- a n 10/.94 I3�a<1jq 54 (ROBERT MCLVILLE D. NO. 1119, EST. 2-5-17) 5 R, 0 .4 +I 95 31 .42 ' N.9-3 -098 220. _. .1 - - . •- P 1301 1`. ; Z Q.''�°j "'B ins ° c ^ o 000 ^ 24 24 ., -1S 40 m o° m `'N 114 m 1 rn ' 31 SF¢ g2P a T �,,x° m o 09,98 SFR; 5 1$0ore �p o 020 inaI0 ° i0 vp02 i 9 » N 88-21-18 8 Zpo I 11400# z HH�p�?Op 11096 - -IT.: �'l`" �°>c,2° I 0024 '',44‘4441, , 0020 a'1- z41° REFERENCE: King County Department of Assessments(1-06-2005) Scale: For: KELSEY'S CROSSING Job Number Horizontal: N.T.S. Vertical: N/A PRELIMINARY PLAT 12542 it- / S 18215 72ND AVENUE SOUTH KING COUNTY, WASHINGTON v' N ,#, •cA KENT,WA 98032 07 , , Z (425)251-6222 Title: °` _ (425)251-8782 ASSESSOR MAP -.c,r i E.� < CIVIL ENGINEERING,LAND PLANNING, '4'0 EN G1144. SURVEYING,ENVIRONMENTAL SERVICES DATE:9/25/06 P:112000s1125421exhibit112542 amap.cdr ./ i Exhibit H Wetland Inventory Map Ce 1 �$r i. Lower Cedar River N. 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'' •• : . a, .-• g5iV'"''*''..'. - .' .. •. •z-.1-1 i›..`....'•-."-.' 4...':•4---•• •-t••• •''''... -.'• - •-. • - .i.—. ' * A pprox. Photo Date: 5-80 NorthScale: 1"= 200 WETLAND: Soos Creek 6 COMMUNITY Soos Creek PLAN AREA: BASIN OR LOCATION: NE NE 4-22-5 DRAINAGE: Green River INVENTORY DATE: ACREAGE: .6 CLASSIFICATION: Fish and Wildlife Service Common Name POW Palustrine, Open Water Open Water NOTE: The wetland edge shown above is approximate, in marshes, ponds or lakes, the transition from standing water to uplands is usually dear. 1-lowever,the edges of forested or scrub/shrub wetlands are less Its n dct. There,the change from wetlandtouplandoften occurs over a broad area called the "transition zone". For a discussion,see Wetland Plants of Kng iCounty and the ptig Sound Lowlands and"Guidelines for King County Wetlands." Soos Creek 6 • OBSERVED SPECIES: (refer to list in Appendix 1) Trees: Herbs: Shrubs: Sedges/Rushes/Grass/Fern: Birds: MR, 10, BS Mammals: Fish: Other: RARE/ENDANGERED/THREATENED SPECIES: (refer to list in Appendix 2) Recorded/Observed: Potential: SIGNIFICANT HABITAT FEATURES: OUTLET: Type: None Condition: Outflow enters: POTENTIAL STORAGE: Existing Active: 1 ac. ft. Potential Active: 1 ac. ft. GENERAL OBSERVATIONS: Crazing animals adjacent to wetland. Scum on water surface. IVETLAND EVALUATION SUMMARY: Data was collected in the five categories shown below. Within each category the data was evaluated to produce numerical values. Composite values for each category were produced in order to compare each wetland to other wetlands in its sub-basin and in King County. The result of that comparison was a percentile rank. The percentile is expressed on a scale of one hundred and indicates the percent of wetlands that scored equal to or below that particular site. For example,a percentile rank of 80 under sub-basin means that the wetland scored equal to or better than 80 percent of all sites within the sub-basin for that evaluation category.NOTE: The percentile ranks are valid only within the individual evaluation category and are intended solely for reference and comparison. Rank Evaluation Category (by percentile) Sub-basin County-wide Hydrology: runoff storage potential,water quality,potential for minimizing damage 33 31 in downstream areas Biology: quality of habitat,abundance and diversity of plant and animal species 15 6 Visual: diversity and contrast of wetland and surrounding vegetation, 41 17 surrounding landforms Cultural: types of access,proximity to schools/institutions,overall 13 21 environmental quality Economic: presence of agriculture/peat extraction,anadromous or game fish, 33 12 game birds or mammals of commercial value WETLAND RATING: Each wetland was assigned one of three possible wetland ratings. The wetland ratings were determined by examining the scores of selected '-tventory tasks, specific data or percentile ranks for individual evaluation categories. The criteria used to assign the wetland ratings are scribed in the Introduction. For each rating a number of specific guidelines for new development in or adjacent to wetlands were prepared. he guidelines are intended to assist in carrying out King County's Sensitive Areas Ordinance and other wetland policies. They are included in a separate report titled"Guidelines for King County Wetlands". Wetland Rating: 3 . , . . ... _ .......... . . . . . . ...., . • .. . :4- I* •••i -. .. ......0 : . 4.-...,..-:-.• ..,t4rs-.,-t.,j:-.:,... i.• N. 9c : . . - .lc. 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Approx.Scale: "1"= 1000' WETLAND: Soos Creek 9 COMMUNITY Soos Creek PLAN AREA: • LOCATION: NW SW 3-22-5 BASIN OR Green River SE NE 4-22-5 DRAINAGE: INVENTORY DATE: 8-5--81 ACREAGE: 82 CLASSIFICATION: Fish and Wildlife Service Common Name PSS1 Palustrine, Scrub-Shrub, Broad- Scrub-Shrub leaved Deciduous (Willow, Hardhack) PFOzi Palustrine, Forested, Needle-leaved Forested Wetland Evergreen (Hemlock, Western Red Cedar) PEM5 Palustrine, Emergent, Narrow-leaved Shallow Marsh , Persistent (Juncus effusus) NOTE: The wetland edge shown above is approximate. in marshes, ponds or lakes, the transition from standing water to uplands Is usually clear. However,the edges of forested or scrub/shrub wetlands are less distinct. There,the change from wetland to upland often occurs over a broad area called the "transition zone", For a discussion,see Wetland Plants of King County and the Puget Sound Lowlands and"Guidelines for King County Wetlands." Soos Creek 9 OBSERVED SPECIES: (refer to list in Appendix 1) Trees: AR, TS, TP Herbs: LA, OS, PH, PP, RR, SN, TL, VS Shrubs: AC, CS, SX, SD Sedges/Rushes/Grass/Fern: JA, JO, SM, AF, EX, JE, LM Birds: GB, GH, BS, ST, CO, SS, YT, YW, GF Mammals: Fish: Other: RARE/ENDANGERED/THREATENED SPECIES: (refer to list in Appendix 2) Recorded/Observed: Potential: SIGNIFICANT HABITAT FEATURES: Numerous snags. OUTLET: Type: Overland Condition: Open Outflow enters: Stream POTENTIAL STORAGE: Existing Active: Not calculated. Potential Active: GENERAL OBSERVATIONS: Artificial impoundment not possible. Noise and visual impacts from adjacent pig farm. • ..ETLAND EVALUATION SUMMARY: Data was collected in the five categories_shown below. Within each category the data was evaluated to produce numerical values. Composite values for each category were produced in order to compare each wetland to other wetlands.in its sub-basin and in King County. The result of that comparison was a percentile rank. The percentile is expressed on a scale of one hundred and indicates the percent of wetlands that scored equal to or below that particular site. For example,a percentile rank of 80 under sub-basin means that the wetland scored equal to or better than 80 percent of all sites within the sub-basin for that evaluation category.NOTE: The percentile ranks are valid only within the individual evaluation category and are intended solely for reference and comparison. Rank Evaluation Category (by percentile) Sub-basin County-wide Hydrology: runoff storage potential,water quality,potential for minimizing damage 45 44 in downstream areas Biology: quality of habitat,abundance and diversity of plant and animal species 80 63 Visual: diversity and contrast of wetland and surrounding vegetation, 96 92 surrounding landforms Cultural: types of access,proximity to schools/institutions,overall 23 36 environmental quality Economic: presence of agriculture/peat extraction,anadromous or game fish, 33 15 game birds or mammals of commercial value WETLAND RATING: Each wetland was assigned one of Three possible wetland ratings. The wetland ratings were determined by examining the scores of selected •"entory tasks, specific data or percentile ranks for individual evaluation categories. The criteria used to assign the wetland ratings are cribed in the introduction. For each rating a number of specific guidelines for new development in or adjacent to wetlands were prepared. .de guidelines are intended to assist in carrying out King County's Sensitive Areas Ordinance and other wetland policies. They are included in a separate report titled"Guidelines for King County Wetlands". Wetland Rating: 2 ? •ska.r. [,:-.� v oma:r. r <.• 's.• y "°4`'`x �, � ;, •� is-•; •� •; .._ 1. • :•• .4.•m f. : •). t ::::i4:-. : 't o ,, 7 ��" •aZ- -;1' i `r .I.: . •. Fi• \fie T. ';t ;� �t ��- J� : J ����%� �s_' �k,�✓W t ,• `. • afie. - rL„�r .. -' :. tr ....... � *� >: s t `5��Y'jl} ,� j ''�y �'t�ya�•' y b•• '' _ - x,-,:.'fir L' bv.: ..jtil � '` t R: _���R;• � .�t•..;t6[v�•..• ';-,t�t :..• .4 � :3::{ ..--,;-3_,,,,-...- •F• �s :3 f -,� -4 y: t'•. ?..,:„4'c .cyrt`, u .• •.•, ,.•'4,,W.--1.14:1-4,,,,,,,..•••.- w.. ?tyti s t.•:- �y .e^a .'"ti •Z .., .•:•"x'.'•e : Soos Creek 16 OBSERVED SPECIES: (refer to list in Appendix 1) Trees: AR, FT Herbs: CM, VS Shrubs: RS, SX, SD Sedges/Rushes/Grass/Fern: SM, CX, EX, JE, JX, SX Birds: MA, RI!, VS, TS, BS, AR, CO, SS, YT, CF Lammals: Fish: Other: RARE/ENDANGERED/THREATENED SPECIES: (refer to list in Appendix 2) Recorded/Observed: Potential: SIGNIFICANT HABITAT FEATURES: Large floodplain area. OUTLET: Type: Overland, Undefined Condition: Outflow enters: Stream POTENTIAL STORAGE: Existing Active: 445 ac. ft. Potential Active: 296 ac. ft. GENERAL OBSERVATIONS: WETLAND EVALUATION SUMMARY: Data was collected in the five categories shown below. Within each category the data was evaluated to produce numerical values. Composite values for each category were produced in order to compare each wetland to other wetlands in its sub-basin and in King County. The result of that comparison was a percentile rank. The percentile is expressed on a scale of one hundred and indicates the percent of wetlands that scored equal to or below that particular site. For example,a percentile rank of 80 under sub-basin means that the wetland scored equal to or better than 80 percent of all sites within the sub-basin for that evaluation category.NOTE: The percentile ranks are valid only within the individual evaluation category and are intended solely for reference and comparison. Rank Evaluation Category (by percentile) Sub-basin County-wide Hydrology: runoff storage potential,water quality,potential for minimizing damage 96 99 in downstream areas Biology: quality of habitat,abundance and diversity of plant and animal species 76 51 Visual: diversity and contrast of wetland and surrounding vegetation, 100 99 surrounding landforms Cultural: types of access,proximity to schools/institutions,overall 13 22 environmental quality Economic: presence of agriculture/peat extraction,anadromous or game fish, 33 15 game birds or mammals of commercial value WETLAND RATING: Each wetland was assigned one of three possible wetland ratings. The wetland ratings were determined by examining the scores of selected `nventory tasks, specific data or percentile ranks for individual evaluation categories. The criteria used to assign the wetland ratings are ascribed in the Introduction. For each rating a number of specific guidelines for new development in or adjacent to wetlands were prepared. (he guidelines are intended to assist in carrying out King County's Sensitive Areas Ordinance and other wetland policies. They are included in a separate report titled"Guidelines for King County Wetlands". Wetland Rating: 2 ., z • /- .i{vim a E.., !� - til'•car. • t ..,„4„.,__,....;:._:...„.....1,,J 4.�t� _.0—,,,,4.----,,.-.. .i..:,.• • <`,7'�,RE _t'•,r ) a,, ,: kt r',,' �i•, S .1 �,r 1 :F7 T, �`�.L � : • `4 .; ,.. � k'•' T } ,r, a;�?e*.-� '4Y ,.n,f Ct,�i~t\y 5 Y•Z' �#.. f .�,jL y �y,�•sp• . f E.* �# � y t >: � y��> r���� !'cid=-t.�s'-'�y,..,5 �`'�ys� �:Y tSW'?,�L' .�1�"'t•�:;c" � Ti l "..,t‘ Y. :f" �-- .:,- .- - _ ▪i fi t` " 4t- gt.4:-_ate �kx'STi 41 .., j. ;�t�?S•C"�`, ry, >'. 1{ iv, ,Y �:�. , ei ,:: ,„,,. ..10,...,,,,f,,....• .,..1„, 't�+k ,.ph��° 3 t..,zetiv :j "` ...A _tet w_.' >y.� �k . .. • d iq S^�`�.z`•s ,�. 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L; {=i,�� k ? 3' - -4'.--ii}� , �t Z ✓��,`sY" .; t�• +3t.ue� +i., sf �. a • .. . a •fly: `r•`.�^•;▪'t..a ;y£� z ii �'c `h < �s', �'° 2i fi \G.r' +'A��,`•..y .X f . . .• s` p: ya . -,......4,4.07,..:-.4.4.....- y•}tea .. n Fq;6�['+'r X96 g,= .t* °,7,,-t'e ..l: tY '- ►' *• ��;'.y'� i . a-_`A 1 .,, ,,, gin„% .�:s r ..,+e4. `` '�i>•✓,- _4 ` , i •.. is+� i;. e. ..moo"-S t 4 •r< • ti 't; � .rw '' I' .iti>i , ...,...r.•.=' 'r � 7r-' ”b t eta-.L -y.> it -7. •;� .,`tit , , \ . . PP aii �v,..' v: `v'a't ., S .f.:%,..�` f �; sms yfy.1, , T • �jr' j.. '. ycE •N' ,mss -' .4.4.... �{''-. —8404... '. ',�L'i�,% <• '.RNat 'L" ..r Y � --V2•-7.-••*..:-.4,-e.' s +-. .4,-..1•..' Y,s 7+`i. 'sr 4 V"'R•,+j. .,, \• +� ,... . -404 L , 1• ,•G. "'+j,+J, i>t r 7- K. •'' ; ,N1i_ A�� • `se ,r0::7,_. _ '* - � -,t ._'°,'+ L,4,- r5 ,F.`'� -c3' � a Fiq ,.�'•t T,t �F,<:J., ,- �. ,Y S -s.. 1 4i t` - .'tom▪ vVi" o"1!' o '+ ay t ,Q'` `f • :.k..',:'..,. • 'r!• r • _ mr y Photo Date: 5-80 North Approx. Scale: i"= 200' WETLAND: Soos Creek 25 COMMUNITY Soos Creek PLAN AREA: LOCATION: NW NE 15-22-5 BASIN OR Green River SW NE 15-22-5 DRAINAGE: INVENTORY DATE: 8-10-81 ACREAGE: 1 CLASSIFICATION: Fish and Wildlife Service Common Name POW Palustrine, Open Water Open Water NOTE: The wetland edge shown above is approximate. in marshes, ponds or lakes,the transition from standing water to uplands is usually clear. However,the edges of forested or scrub/shrub wetlands are less distinct. There,the change from wetland to upland often occurs over a broad area called the "transition zone", For a discussion,see Wetland Plants of King County and the Puget Sound Lowlands and"Guidelines for King County Wetlands." Soos' Creek 25 OBSERVED SPECIES: (refer to list in Appendix 1) • Trees: Herbs: IP, TL Shrubs: Sedges/Rushes/Grass/Fern: Birds: MA, /3S Mammals: Fish: Other: • RARE/ENDANGERED/THREATENED SPECIES: (refer to list in Appendix 2) Recorded/Observed: Potential: SIGNIFICANT HABITAT FEATURES: OUTLET: Type: Not accessible. Condition: Outflow enters: POTENTIAL STORAGE: Existing Active: Not calculated. Potential Active: GENERAL OBSERVATIONS: Personal pond. WETLAND EVALUATION SUMMARY: Data was collected in the five categories shown below. Within each category the data was evaluated to produce numerical values, Composite values for each category were produced in order to compare each wetland to other wetlands in its sub-basin and in King County. The result of that comparison was a percentile rank. The percentile is expressed on a scale of one hundred and indicates the percent of wetlands that scored equal to or below that particular site. For example,a percentile rank of 80 under sub-basin means that the wetland scored equal to or better than 80 percent of all sites within the sub-basin for that evaluation category.NOTE: The percentile ranks are valid only within the individual evaluation category and are intended solely for reference and comparison. Rank Evaluation Category (by percentile) Sub-basin County-wide Hydrology: runoff storage potential,water quality,potential for minimizing damage 7 3 in downstream areas Biology: quality of habitat,abundance and diversity of plant and animal species 11 4 Visual: diversity and contrast of wetland and surrounding vegetation, 3 1 surrounding landforms Cultural: types of access,proximity to schools/institutions,overall 94 88 environmental quality Economic: presence of agriculture/peat extraction,anadromous or game fish, 66 12 game birds or mammals of commercial value • WETLAND RATING: Each wetland was assigned one of three possible wetland ratings, The wetland ratings were determined by examining the scores of selected inventory tasks, specific data or percentile ranks for individual evaluation categories. The criteria used to assign the wetland ratings are described in the Introduction. For each rating a number of specific guidelines for new development in or adjacent to wetlands were prepared. The guidelines are intended to assist in carrying out King County's Sensitive Areas Ordinance and other wetland policies. They are included in a separate report titled"Guidelines for King County Wetlands". • Wetland Rating: 3 44 s Exhibit Basin Reconnaissance Summary Report RECONNAISSANCE REPORT NO. 2 SOOS CREEK BASIN JANUARY 1986 Natural Resources and Parks Division and Surface Water Management Division King County, Washington King County Executive Tim Hill King County Council Audrey Gruger, District 1 Cynthia Sullivan. District 2 Bill Reams, District 3 Lois North, District 4 Ron Sims, District 5 Bruce Laing, District 6 Paul Barden, District 7 Bob Grieve, District 8 Gary Grant, District 9 Department of Public Works Parks, Planning and Resources Don LaBelle, Director Joe Nagel, Director Surface Water Management Division Natural Resources and Parks Division Joseph J. Simmler, Division Manager Russ Cahill, Division Manager Jim Kramer, Assistant Division Manager Bill Jolly, Acting Division Manager Dave Clark, Manager, River & Water Derek Poon, Chief, Resources Planning Section Resource Section Bill Eckel, Manager, Basin Planning Program Larry Gibbons, Manager, Project Management and Design Section Contributing Staff Contributing Staff • Doug Chin, Sr. Engineer Ray Heller, Project Manager & Team Leader Randall Parsons, Sr. Engineer Matthew Clark, Project Manager Andy Levesque, Sr. Engineer Robert R. Fuerstenberg. Biologist & Team Leader Bruce Barker, Engineer Matthew J. Bruengo. Geologist Amy Stonkus, Engineer Lee Benda. Geologist Ray Steiger, Engineer Derek Booth. Geologist Pete Ringen, Engineer Dvanne Sheldon. Wetlands Biologist Cindy Baker, Earth Scientist Di Johnson, Planning Support Technician Robert. Radek, Planning Support Technician Randal Bays, Planning Support Technician Fred Bentler, Planning Support Technician Consulting Staff Mark Hudson, Planning Support Technician Sharon Clausen. Planning Support Technician Don Spencer, Associate Geologist, Earth David Truax, Planning Support Technician Consultants, Inc. Brian Vanderburg, Planning Support Technician John Bethel, Soil Scientist, Earth Carolyn M. Byerly, Technical Writer Consultants, Inc. Susanna Hornig, Technical Writer Virginia Newman, Graphic Artist Marcia McNulty, Typesetter Mildred Miller, Typesetter Jaki Reed, Typesetter Lela Lira, Office Technician Marty Cox, Office Technician P:CR TABLE OF CONTENTS SUMMARY 1 II. INTRODUCTION 1 III. FINDINGS IN SOOS CREEK BASIN 2 A. Overview 2 B. Effects of Urbanization 3 C. Specific Problems 4 1. Bank failures 4 2. Channel erosion 4 3. Flooding and potential flooding 4 4. Stream habitat 4 IV. RECOMMENDATIONS 5 A. Inform appropriate governmental agencies of 5 the reconnaissance findings B. Reevaluate specific surface water management 5 policies C. Prepare a comprehensive basin plan 6 D. Construct the capital improvement projects 6 E. Maintain or enhance instream and riparian habitats 6 V. MAP APPENDICES: APPENDIX A: Estimated Costs A-1 APPENDIX B: Capital Improvement Project Ranking B-1 APPENDIX C: Detailed Findings and Recommendations C-i 1. SUMMARY The Soos Creek Basin is located north and east of the Green River in King County. While the southern and eastern portions of the basin are rural, the remainder is a rapidly expanding suburban community. This development pattern has not caused serious environmental damage or flooding, however, due to highly pervious soils, an extensive network of streams and wetlands that provide natural storage for stormwater runoff, and the fact that development has only recently accelerated in this basin. Although the overall severity of problems in the Soos Creek Basin was not great at the time of reconnaissance, several significant problems were identified and should be addressed. These include bank failures, channel erosion, flooding in some locations, and poor stream habitat. Recommendations to address these problems include efforts to 1) inform appropriate agencies of the reconnaissance findings, 2) reevaluate specific policy issues regarding the management of surface water, 3) prepare a comprehensive basin plan, 4) construct the capital improvement projects evaluated with citizen advisory committee criteria, and 5) maintain or enhance habitat throughout the basin. II. INTRODUCTION: History and Goals of the Program In 1985 the King County Council approved funding for the Planning Division (now called the Natural Resources and Parks Division), in coordination with the Surface Water Management Division, to conduct a reconnaissance of 29 major drainage basins located in King County. The effort began with an initial investigation of three basins --Evans, Soos. and Hylebos Creeks -- in order to determine existing and potential surface water problems and to recommend action to mitigate and prevent these problems. These initial investigations used available data and new field observations to examine geology, hydrology, and habitat conditions in each basin. Findings from these three basins led the King County Council to adopt Resolution 6018 in April 1986, calling for reconnaissance to be completed on the remaining 26 basins. The Basin Reconnaissance Program, which was subsequently established, is now an important element of surface water management. The goals of the program are to provide useful data with regard to 1) critical problems needing immediate solutions, 2) basin characteristics for use in the preparation of detailed basin management plans, and 3) capital costs associated with the early resolution of drainage problems. The reconnaissance reports are intended to provide an evaluation of present drainage conditions in the County in order to transmit information to policymakers to aid them in developing more detailed regulatory measures and specific capital improvement plans. They are not intended to ascribe in any conclusive manner the causes of drainage or erosion problems; instead, they are to be used as initial surveys from which choices for subsequent detailed engineering and other professional environmental analyses may be made. Due to the limited amount of time available for the field work in each basin, the reports must be viewed as descriptive environmental narratives rather than as final engineering conclusions. Recommendations contained in each report provide a description of potential mitigative measures for each particular basin; these measures might provide maximum environmental protection through capital project construction or development approval conditions. The appropriate extent of such measures will be decided on a case-by-case basis by County officials responsible for reviewing applications for permit approvals and for choosing among competing projects for public construction. Nothing in the reports is intended to substitute P:SCB 1 Soos Creek Basin (continued) for a more thorough environmental and engineering analysis possible on a site-specific basis for any proposal. III. FINDINGS IN SOOS CREEK BASIN Reconnaissance in the Soos Creek Basin was conducted in November 1985 by Ray Heller, resource planner; Randall Parsons, engineer; and Don Spencer and John Bethel, consulting soil scientists. Their findings and recommendations are presented as follows. A. Overview of Soos Creek Basin Geographic and land use features. The Soos Creek Basin is located north and east of the Green River in the eastern portion of the Soos Creek Plateau Community Planning Area. The basin is situated east of the city of Kent, northeast of Auburn, and southeast of Renton. The city of Seattle's Lake Youngs watershed is included in the Soos Creek Basin. The south and east portions of the basin are rural in character, with the north and west portions committed to a suburban development pattern that includes subdivisions and scattered single-family homes. The 1985 Kin County Comprehensive Plan shows areas east of Big Soos Creek (in the northern part of the basin) and south of Lake Youngs with "rural development" designations that specify 1-5 dwelling units (DU) per acre. The southern area to the east of Soos Creek and north of the Green River is designated "transitional." This interim designation will limit development to rural- residential densities until such time as rural/urban designations are made through updated community plans. The King County Parks Department owns more than a five-mile stretch from Southeast 192nd Street to Lake Meridian, along Big Soos Creek. These presently undeveloped park lands are mostly wetlands and lie within the 100-year floodplain. Major geologic, hydraulic, and hydrologic features. The Soos Creek drainage area is a tributary basin to the Green River basin. The area is part of the Puget Sound lowlands and is characterized by a glacial drift plain, covered by small ridges and rounded hills that were formed by continental' glaciation. While the Soos Creek Basin is moderately developed, the degree and amount of channel erosion, slope failures, and other forms of geologic and hydraulic damage are far less than might be expected. Artificial conveyances are also still functioning in this basin as they were originally designed and intended. These conditions may be explained by three main factors. First, there is a very effective natural retention and detention (R/D) system provided by an extensive network of 52 wetlands and numerous major and minor streams. Most of the wetlands are located in the northern portion of the basin in the upland areas as well as adjacent to streams. Big Soos Creek originates in the northeast corner of the plateau and flows southeast to the junction of Little Soos and Jenkins Creeks, then curves west at its confluence with Covington Creek. Big Soos Creek joins the Green River east of Auburn near State Road (SR) 13 at 160th Avenue SE. These wetlands and streams appear to be functioning well as stormwater control facilities for the current levels of development, as well as serving to prevent damage from surface water runoff. P:SCB 2 • Soos Creek Basin (continued) Second, the soils in the upland areas generally have a high infiltrative capacity, particularly in the southern portion of the basin. Stormwater is absorbed into the ground at these locations before it can cause erosion or other damage. Third, development in the basin has only just begun. Properly functioning wetlands and streams have not yet been altered, nor have well-draining soils been covered by impervious surfaces to any great extent. Maintaining these properly functioning drainage systems should be a goal in this basin and will be the focus of recommendations made later in the report. Habitat characteristics. The habitat of Soos Creek Basin is generally good and supports large populations of both native and hatchery anadromous fish. The source of the hatchery fish is a State facility near the mouth of Soos Creek. Cutthroat trout reside in stream waters, and anadromous fish spawn and travel in many of the tributaries and the main stem of Big Soos, according to field observations and reports from local residents at the time of reconnaissance. Habitat is being damaged or threatened in some places by bank erosion and degraded water quality associated with land clearing, livestock feces, and wetland filling for development. One of the more serious instances of habitat-threatening erosion originates at the parking lot of the Seattle International Raceway (SIR), which is located on the plateau in the lower portion of the basin. Drainage from the paved parking lot is increasing erosion in nearby tributaries and filling spawning gravels with sediment. Appendix C of this report identifies sites of habitat damage or potential damage. Further water quality information related to habitat in the basin can be found in the Critical Stream Inventory of Soos Creek, published by Metro. B. Effects of Urbanization Low levels of development in most parts of the Soos Creek Basin, together with a well-functioning natural drainage system, have kept serious erosion, sedimentation, and habitat damage to a minimum until now. However, the present and projected rates of development indicate that there could be increasing amounts of damage, as suggested by the types of problems observed during reconnaissance. The expansion of impervious surfaces in the basin is already beginning to accelerate the rates and volumes of stormwater flowing into (and reducing the capacities of) both natural and artificial channels. Impervious surfaces are also reducing the amount of highly pervious soils available to absorb runoff. The predictable impacts are already in evidence: erosion, mass-wasting, sedimentation, and degraded water quality and other habitat destruction. The following section provides a more detailed account of problems found during field investigation. C. Specific Problems Identified The study team examined numerous sites along the main stem of Big Soos. Little Soos, and West Soos Creeks, as well as 21 small drainages tributary to these main sterns. Several of the most significant problems found during reconnaissance are described below. P:SCB 3 Soos Creek Basin (continued) 1. Bank failures. On Tributary 0072A, river mile .30, for example, there exists a major bank failure triggered by bank undercutting. The source of the problem appears to be increased runoff from street construction. Unless flows are intercepted and redirected to storm sewers or other facilities, there will be increased bank erosion and consequential deterioration of property and stream habitat. 2. Channel Erosion. This includes both instream and bank erosion caused by large volumes of runoff emerging from storm drains and washing away highly erodible soils. This creates a new, deeply incised channel that enlarges over time. One example of this problem occurs on Tributary 0072 near the SIR in the lower part of the basin. Large expanses of pavement at this location have contributed to high volume flows and channel erosion. 3. Flooding and potential flooding. In numerous locations, development has increased the amount of runoff entering existing drainage facilities or otherwise impeded the ability of natural systems to carry the amount of runoff. When drainage systems fail to function as they were intended, flooding can occur. Increased development without concurrent increases in drainage facilities adds to the possibility that serious flooding will occur. On Tributary 0092, river mile 1.20, for example (collection point 11), the Little Soos has been contained and manicured as it passes through a developed plat. Such alteration to a natural drainage channel reduces the stream's capacity in places. The result has been the regular semi-annual flooding of some homes. Further development could aggravate these kinds of flooding problems. 4. Poor stream habitat due to: a. Lack of overhead canopy and streamside vegetation. Overhead canopy stabilizes water temperature, while streamside vegetation protects banks from erosion. b. Contamination by livestock feces. In areas of the basin where livestock have extensive access to streams, water quality has become degraded by animal feces. These cause harmful nutrients to be added to the water which can threaten fish survival c. Erosion. Streambank and channel erosion, already described above, is caused in part by livestock access. On Tributary 0073, river miles 3.60-4.70, for example, there exists poor stream habitat because livestock have trampled and denuded banks of vegetation; this has led to the sedimentation of spawning areas and caused turbidity. IV. RECOMMENDATIONS FOR A(;I'ION The following recommendations are based on findings of the field team and reflect the original goals of the Basin Reconnaissance Program, as outlined in the introduction of this report. A. Inform appropriate governmental agencies of the detailed findings from the reconnaissance of this basin. Project representatives should meet with staff from King P:SCB 4 • Soos Creek Basin (continued) County Roads Division, Surface Water Management Division, Building and Land Development, and other interested agencies to transmit relevant information. B. Reevaluate specific policy issues regarding surface water management These may include the need to: 1. improve enforcement of wetlands regulations to maintain these areas in their natural states. This will insure their continued function as surface water quality and quantity controllers, as well as preserve their habitat value. If regulation proves ineffective, the County should secure easements or consider other means to preserve wetland areas. 2. Require the establishment of undisturbed buffers and setbacks adjacent to natural drainage swales. Variations in stream morphology and geology indicate the need for stream corridor guidelines that take these into consideration. Improve enforcement of "no clearing" covenants in these sensitive areas or seek County easements or actual ownership. Fencing along streams in livestock areas would help water quality and reduce erosion and sedimentation. 3. Investigate and promote the infiltration of surface water where feasible and economical to reduce increased runoff from developed areas. Also, encourage the use of grass swales and open ditch conveyance systems to improve infiltration and water quality enhancement capacity. Areas of high filtration are identified on final display maps (for the Basin Reconnaissance Program) in the offices of Surface Water Management, Building and Land Development, and Basin Planning. 4. Require the tightlining of storm-drainage outfalls down steep or sensitive slopes using state-of-the-art facilities, including high density polyethylene pipe with energy dissipation at the outfall. 5. Reevaluate stormwater rate and volume release regulations for new developments. Current regulations may be inadequate and result in unacceptable downstream erosion that causes property damage and loss of habitat. 6. Increase current maintenance levels for King County surface water R/D and conveyance facilities. Due to the lack of funding, maintenance of existing facilities is sometimes insufficient and results in facility dysfunction and failure. These will only be aggravated by additional upstream development. P:SCB 5 Soos Creek Basin (continued) C. Prepare a comprehensive basin plan to consider, at a minimum, the need to: 1. Enhance and utilize the extensive existing wetlands as regional storm-detention facilities without jeopardizing habitat values. Prepare a schedule for the anticipated need for these hydrologic enhancements as they relate to projected development in the basin and impact the wetland ecology. 2. Examine existing storm-detention and conveyance facilities to determine whether their control orifices are properly sized to optimize the detention site and achieve the maximum benefit to the downstream systems. 3. Establish floodplains in low-lying areas of slight gradient for existing and developed runoff conditions, i.e., adjacent to wetlands, particularly for wetlands proposed as regional detention sites where inundation of adjacent properties may be significant. 4. Identify stream reaches critical to the maintenance of anadromous and trout populations. 5. Review geologic findings from this study in order to identify areas of particular soils' sensitivity and develop special analysis criteria for new developments. D. Construct the capital improvement projects according to the CTP priority selection criteria. These projects, identified in Appendix B of this report, include projects to: 1 Calibrate and retrofit existing detention-control structures and to improve existing conveyance systems. 2 Stabilize channels and slopes. 3. Provide regional detention facilities, including the utilization of wetlands, where biological assessment has determined that the natural habitat values will not be significantly altered. E. Maintain or enhance the instream and riparian habitats. 1. Maintain wetlands and buffer areas around them. These provide both valuable wildlife habitat and natural stormwater storage that helps to maintain year-round baseflows in the stream. 2. Adopt a stream-corridor policy in the Soos Creek Community Plan to protect the stream corridor from damaging types of land uses in adjacent areas. 3. Encourage the Washington State Department of Fisheries to allow use of the natural stream system for salmon spawning. Maintain a natural run of all the indigenous anadromous species. 4. Prohibit filling in the 100-year floodplain. The County should establish regulations to prevent the loss of floodplains in order to maintain their natural storage for floodwaters and guard against degradation of important fish and wildlife habitat. P:SCB 6 • �..,. by ! t Y-Ei�F oaf s[ � V t ��t;`-.\1/4 ��.. t� v-h, :,f ST. _ ...__ . . illait T •1 Ii ani yI \_ 1 i'� 1< .� �:� j rfr �s-teST �.� SOOS CREEK BASIN 1 <' # 3:, 1_; T'•. R X Fairlood.- ' � cM 1 :I � Y3� 3t ini ..,-__--t. t•-a• .1 IT. R r.�. Jf " \ 1 Basin Boundary sir.a r s. .a tj NNW. ( SE Collection Point Boundary .4 rv�! / st ^�iTs-- , .... O Collection Point �•a S rre # sr + _ 4 -'i1 ' •�/� Stream 7 IT1r -�„ ST .` .•••� SEL_T G~ 0072 Tributary Number ' l `E 'O' l• le5401 Proposed Project i� ` • •• I- ! 0 "f L'( i 645 --,.<-_-‘,./...7c' . \ - ._...f1 , 72'I-' •� z.i., ri .+;:'' -c'' `:\, 11- i; i r •• =1![ ik---- Sc le e '',t5 > ••,"'" {• `s• x _. �• 3s , •• OO i i r 1 � � Si.tlka r_, i 1111. 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L. • II _Jr mir ifi • ' i _ i i A ( •• i : 1-1 •• 1 • i>• R. • sr • • t • (EA • LsL. ••'x -. 0...1 • .a : r s[:>,t a • . ;541 -•..,p/.t.•...t,....r rt..._; .. : . 1 I, .-:; 4 Off.*' / .----,"/ • 1,„„....,1 S :? ._ .3t' \-• •_fx`^'" l Heights I o 1 r• , 1� _`—�..f•.• G EN RIVER n1 :° �' '- COMMI ITY COLLEGE • •E i^„ "•est - sUslisr c ••: Op^ 67. .K_ 7.. .t1.(� = s` N/, +'C', "'""'sem.., '- \ EAS) nr r,r.. �, 'gig• _r___ 111 GREEN !r✓O j • sE •SI I - R/VER + "' WI •• •e.7 ' • w Sr..,t �� -i\ s ss�+st 2 7 _ O E Measrom r.. /I� Si . P SE i 4 !� lkes Roark �• M .3.t ET 4 / ., C�, p t: C.1 APPENDIX A ESTIMATED COSTS: PROPOSED CAPITAL, IMPROVEMENT PROJECTS SOOS CREEK BASIN Indicates project was identified by the Surface Water Management Division prior to reconnaissance. NOTE: All projects are located on map included in this report. Project Collect. Number Point Project Description , Estimated Costs I roblem Addressed and Comments 5-101" 20 Construct low berm (approx. 2') and Mitigates increased upstream peak $153000 proportional discharge-control weir flows and runoff volumes. > at outlet to wetland. (This project (likely to be much is independently justifiable.) Wetland less due to land rating is 2 acquisition cost) # . Biological assessment is needed to assure this project does not decrease habitat values. 5402" 9 Excavate and berm to construct regional Mitigates increased upstream peak $194,000 facility at lower end of wetland, flows and runoff. 'Phis location serves (dependent on land Provide proportional weir discharge. 'I'rib. 0073 and 0076. (Good location.) costs) Wetland rating is #1. Biological assessment is needed to assure this project does not decrease habitat values. 5-103" Could not locate or verify.Y Address in basin plan. (Eliminate for now.) 5404" 17 Construct a proportional control weir Mitigates increased upstream peak flows $250,000 Wetlands 4416 at SE 2211th St. bridge. (Project should and runoff. (First site that could he justified by a future basin address flows south of Pctrovitsky.) • plan.) Wetland rating is #2. Biological assessment is needed to assure this project does not decrease habitat values. P:SCI.3.APA A-I roject Collect. Number Point Project Description Estimated Costs Prohlctn Addressed and Comments 5405" 19 Construct berm and proportional control Mitigates increased upstream peak weir in Boulevard Line Park. (Project flows and runoff. $98,000 should be justified by a basin plan.) Wetlands rating is #1 Biological assessment is needed to assure this project does not decrease habitat values. 5406" 17 Construct outlet-control structure Wetland 544-t n Mitigates increased upstream peak $17,800 at existing culvert passing flow flows and runoff. May provide under SE 256th St. (Project would extra detention to assist in be independently justifiable.) Wetland alleviating capacity problems far rating is #2. Biological assessment is downstream. needed to assure this project does not decrease habitat values. 5407 15 Construct 'a berm andro ortional Wetland 5420 p p Mitigates increased upstream peak $228,000 discharge weir at outlet of existing flows and runoff. wetland. (Project should be justi- fied by a basin plan.) Wetland rating is #2. Biological assessment is needed to assure this project does not decrease habitat values. 5408` 13 Raise the SE 240th St. roadway Mitigates increased upstream peak $70,000 approximately 2' and construct a new flows and runoff. (Good location.) bridge with proportional control weir. (Project should be justified by a basin plan.) Wetland rating is #2. Biological assessment is needed to assure this project does not decrease habitat values. P:S(:B.APA n Project Collect. Number Point Project Description I, Estimated Costs --m—` roblem Addressed and Comments 5.109" 13 Construct berm and proportional control Mitigates increased upstream peak2� Wetland 5433 - weir at outlet to Clark Lake. (Project flows and runoff volumes. May $-_ on could be independently justified.) (dependingon land provide extra detention to alleviate costs) Wetland rating is #I. Biological capacity problem downstream. assessment is needed to assure this pro- ject does not decrease habitat values. • 5410 8 Construct central manhole at outlet Wetland 5488Provides continued detention for � of existing pond. Dead storage should mobile home park plus small amount $-8,000 be maintained for aesthetics. (Project of additional area. seems of very limited value.) Wetland rating is #2. 5411* 18 Small wetland located near to f Wetland 5476 p oNo project proposed. Maintain (Eliminate for now.) subbasin; maintain condition as is. wetland in its existing state. Wetland rating is #2. Biological assessment is needed to assure this projet does not decrease habitat values. 5`112" 16 Construct berm and proportional control Mitigates increased upstream peak flows Wetland .5480 weir at outlet to wetland. Project $2e6t5on J and runoff. (dependent on land should be justified by future basin plan.) Wetland rating is #2. Biological costs) assessment is needed to assure this project does not decrease habitat values. 5.113" 3 Construct berm and proportional control Mitigates increased upstream peak Wetland 5477 weir at outlet to wetland adjacent to $1ent6o flows and runoff. (May not be as (dependent on, land SR 18. (Project should be justified by desirable as Projects 5419 and 5420.) costs) future basin plan.) Wetland rating is #2. Biological assessment is needed to assure this project does not decrease habitat values. 1':SCI3.AI'A A-3 • ).ject Collect. wnher Point Project Description ,t. Estimated . .,ts 1 ohlcm Addressed and Comments 5-114 2 Construct berm and excavate to Mitigate increased upstream peak flows $ 69,000 provide additional detention volume, and runoff. Reconstruct discharge from Construct a control manhole. (Project SE 320th St. to stable outlet. (Justifiable is independently justifiable.) immediately due to impacts on state fish hatchery.) 5415 1 Construct tighiline system in Prevents further road embankment and steep $156,000 existing stream channel. (Project cut-bank failures. (Justified immediately is independently justifable.) due to impacts on state fish hatchery.) 5416 11 Construct new landscaped berms adjacent Prevent neighborhood flooding, which to existing privately owned and main- jeopardizes 3-4 homes by containing stream tanned stream channel to increase as it passes through plat. (Justifiable capacity and prevent neighborhood immediately as situation will only worsen flooding. (Project is independently with upstream development.) justifable.) 5417 13 Raise 148th Ave. SE roadway approx. Eliminate seasonal flooding of roadway $223,000 1.5' and construct proportional control and mitigate increased upstream peak weir at SE 256th bridge. (Project is flows and runoff. (Justifiable immediately independently justifable.) due to flooding of roadway.) 5-118 18 Construct control weir at bridge on Mitigate increased upstream peak flows $88700 SE Lake Youngs Way. (Project should and runoff. ' be justified by future basin plan. 5419 10 Construct proportional weir at existing Mitigate increased upstream peak flows $138,000 bridge. (Project should be justified and runoff volumes. (Site appears more (dependent on land by future basin plan.) desirable than 5413 due to ease of use costs) access.) 5.120 II Divert excess flows from Little Soos Mitigate increased upstream peak flows $88;500 into abandoned borrow pit for infiltra- and runoff volumes. (This is a highly lion. (Project should be justified by desirable alternative due to groundwater future basin plan.) recharge and quality control.) I':SCI3.APA A-4 APPENDIX B CAPITAL IMPROVEMENT PROJECT RANKING SOOS CREEK BASIN Prior to the Soos Creek watershed field reconnaissance, 13 projects had been identified and rated using the CIP selection criteria developed by the Surface Water Management (SWM) Division and the Natural Resources and Parks Division. Following the reconnaissance, 20 projects remain proposed for this area. They include the 7 new, previously unidentified and unrated projects plus the initial 13 projects. The previous SWM capital improvements project list for the Soos Creek Basin had an estimated cost of 53,450,000, while the revised list decreases to an estimated cost of 52,622,000. This 24% reduction in estimated capital costs is due mainly to downward revised cost figures for acquiring or securing easements over wetlands. The following table summarizes the scores and costs for the CIPs proposed for the Hylebos Creek Basin. The projects were rated according to previously established SWM Program Citizen Advisory Committee criteria. The projects ranked below are those for which the first rating question, ELEMENT 1: "GO/NO-GO," could be answered affirmatively. The projects can now be considered for merging into the "live" CIP list. Any project scoring over 100 points should be considered for incorporation into the six-year CIP plans. RANK PROJECT NO. SCORE COST 1 5415 135 S 156,000 5417 127 223,000 3 5407* 113 228,000 4 5414 105 169.000 5 5409* 100 221,000 6 5416 98 68,400 7 5402" 95 194.000 8 5401' 59 153.000 9 5406* 33 17.800 TOTAL 51,430.000 Indicates project was identified by SWM prior to the reconnaisance. APPENDIX C DETAILED FINDINGS AND RECOMMENDA'T'IONS SOOS CREEK BASIN All items listed here are located on final display maps in the offices of Surface Water Management, building and Land Development, and Basin Planning. 'l'rib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj• Conditions and Problems Conditions and Problems Recommendations 0072 ! Hydrology See Item 6. Main stem will be strained to New developments in upland arca RM 2.84 • accommodate increased volume should investigate infiltration of of runoff from developing runoff as much as possible. Direct areas upstream. Bank erosion discharge to stream, after tightlining (causing increased siltation down sensitive slopes, is undesirable and habitat destruction) and "last choice" alternative. slope failures (leading to property damage) will result. 2 0072 1,3,10, I labitat Habitat of upper stream More filling of wetlands. Prohibit filling within 100-yr. RM .60 13,17, good from buffer of eaten- Sediment from adjacent devel- floodplain or in wetlands. Work with 18,19, sive wetlands and mainten- opment will fill portions of landowners to fenceg alongside stream 20 ance by County Parks Dept. wetlands and stream channel to keep farm animals out. Problems on 562 acres of due to low gradients. More wetlands include illegal debris, pollution, and flood- filling, livestock-related ing will result from additiona bank erosion, debris in development. stream. There is a greater degree of development adjacent to stream. Main stem provides important rearing habitat for • Salmonid species. P:SCIJ.AP(' 'Frib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 3 0072 1 Geology Soos Creek meanders on a Unstable soils and wet con- Future construction should receive RM .60 wide alluvial plain. Ilum- ditions on valley slopes. close study for stability and mocks on valley walls and erosion potential. "pistol butt" tree trunks suggest colluvial creep. Numerous springs with silt/ clay lithoiogy. 4 0072 I . Habitat Dam on main stem impounds Increased flows will result Develop basin plan with computer RM .60 fish for state fish in more flooding and potential simulation of stream flows to give hatchery. No problems bank erosion. complete analysis in lower portion observed. of Soos Creek. Also include Jenkins and Covington Creeks. 5 0072 1 Geology Erosional chute 6' deep Highlights severe erosional Recessional sand deposits RM 1.70 emerges from runoff of potential of this recessional in sections 2, 3, 10, 11, 14, 15, 16, Seattle International Road- sand unit and impact of un- 21, and 22 of 1'21 N, R 5 E are way (SIR) parking area. controlled runoff. highly sensitive to erosion. Require Lithograph is loose, strati- hydroloic and geotechnical reveiw fied recessional sands. for n desi adequacy, Large slide induced north g � I y, and suitability of collection and conveyance facili- of railraod right-of-way, tics for all runoff from SIR, as well as existing and planned develop- ment within boundary of collection area. Require implementation and compliance if no facilities exist. 6 0072 1 Geology Main sten of Soos Creek is None. None. RM 2.50 25' wide with well-developed gravel bars. Terraces suggest occasional flows 2" above current level. P:SCB.A PC C,-2 Trill. & Collect. Existing Item River Mile Point Category Prop. �. Anticipated ' gory I top. I toj. Conditions and Problems Conditions and Problems Recommendations 6 11072 I ('oology Main stem of Soos Creek is None. RM 2.50 None. 25' wide with well-developed gravel bars. Terraces suggest occasioanl flows 2' above current level. 7 0072 I Geology In vicinity of private foot Continued medium to large None. RM 2.60 bridge, medium to large failures into creek. bank failures occur in silt/ clay-rich colluvium. Causative mechanisms include undercutting and reduced shear strength owing to abundant springs and seepage 8 01172 1 1 tabitat Private landowner has Fill and riprap will shift Restrict filling and riprap in RM 2.60 placed riprap for 150' on stream onto opposite bank, natural meander of floodplain. If left bank. resulting in increased bank property in danger, consider pro- erosion. tective measures along•streambank such as riprap. 9 0072 I Geology 30" diameter CMP with Continued maintenance. None. RM 2.65 erosion in recessional sands. 10 0072 3 Hydrology 5413 See Item 6. Main stream will be increas- New developments in upland area RM 2 8 1 ingly strained to handle should investigate infiltation of 5.85 higher volume of runoff from runoff as much as possible. Direct- developing areas. Bank ing discharge to stream after erosion anticipated, causing tightlining down sensitive slopes habitat degradation, slope is undesirable "last choice" alter- failures, and property damage. native. P:SC.13.APC C-3 Tiib. & Collect. Existing Item River Mile Point Category Anticipated h y Prop. Proj. Conditions and Problems Conditions and Problems Recommendations I I 007? RM 4.20 3 Geology West of confluence of Creek blockage and threat to Recessional send deposits in sections Jenkins and Soos Creeks, property near edge of bank. 2, 3, 10, 11, 14, 15, 16, 21, and 22 200' of sloughing in of T 21 N, R 5 E arc highly sensitive recessional sands and to erosion. Identify discharge gravels in 40'-high bank. sources and evaluate adequacy and Cause appears to he ovcrbank suitability of collection and convey- discharge. anec facilities. Require compliance if none exists. I") 0072 3 Habitat. Stream habitat appears to None. None. RM 4.20 be in good condition on this steeper portion of the stream. Riffles common, with some pools. Stream- side vegetation and over- head canopy both abundant. 13 0072 3 Geology Near bridge, stream flows Increased future flows could Development detention for RM 5.50 through wooded wetland. overtop existing berm struc- tributaries upstream. tures and flood adjacent agricultural lands. 14 0072 10 IIydrology 5419 Slight degree of develop- RM 5.85 Area planned to develop only A basin plan should examine mens has not caused sig- moderately; significant prob- feasibility of directing flows from nificant problems. South lems will probably result Trib. 0092 at collection point 11 portion of Wetland 6430 from upstream areas tribu- into proposed R/D site at gravel and undesignated wetland lazy to this point rather pit east of 156th Pt. SE. This at this collection point than from flows generated could provide infiltration, deten- provide RID for local and by runoff. lion, and overflow discharge directly upstream tributary flows. to collection point 10. Some localized bank over- topping in portions of main reach, but innundation probably limited to adjac • - ent agricultural land. l':SC13.A PC C-4 1'rih. S Called' Existing Anticipated _ Item River Mile Point Category Prop. I'roj. Conditions and Problems Conditions and Problems Recommendations 15 0072 13 Geology At 256th crossing, wetlands Overflow between SE 148th and Perform cost-benefit analysis for RM 7.20 and slow flow characterize SE 256th. , grtdc ratsc, and improved drainage. soils. IG 0072 13 Geology At 244th (240th) overland None. None. RM 7.95 • out-of-bank flow is common; flooding. 17 0072 13 11ydrology 5417 Wetlands provide R/D for Flooding of roadways will Increase height of roadway embank- Main stem 5408 areas upstream and tribe- become more common and ments to prevent continued flooding. RM 7.20-7.4 tory to reach. 148th Ave. greater in extent as upland Monitor wetlands for illegal filling RM 7.95 SE roadway crossing wetlands areas develop. and grading. in area is overtopped during high flows due to a slight elevation of roadway. Some localized bank overtopping in nonwetland portions of main reach, but innundation limited to adjacent agri- cultural land. 18 0072 17 Geology Minor flooding in wetland Increased flooding activity Develop detention for upstream areas. RM 9.45 areas with degradation of is likely with upstream portions of SE 224th. development. 19 0072 17 Hydrology 5404 No significant problems in No upland problems antici- Monitor areas adjacent to wetland RM 9.55 upland due to low level paled as arca is planned to for illegal filling and take enforce- development. SE 224th St. develop very little more. ment action as needed for restor- road embankment is only Any developments in areas ation. approx. 2' above wetland; tributary to this subbasin may be overtopped. Periodic will exacerbate flooding of overtopping and innundation SE 224th St. of base, deteriorating road- . way where '1'rib. 0095 passes under SE 224th. P:SC:l33.APC C-5 . • Trig. & Collect. Existing Anticipated . Item River Mile Point Category Prop, Proj. Conditions and Problems Conditions and Problems Recommendations 20 0072 18 Geology Soos headwaters flow slowly None. through smooth pastureland. None. 21 0072 lit hydrology 5418 Wetland 5409 provides R/D Continued devcl ment may RM 10.78 for areas tributaryto p Monitor areas adjacent to wetland cause some localized capacity for illegal filling and take enforce- reach. Some localized bank problems in upland tributary mens action as needed for remora- overtopping in main reach areas. Flooding south of Lion. south of 204th Way, but SE 204th Way likely to become flooding currently limited more severe until upstream to adjacent agricultural regional detention sites land, development. . 22 0072 19 Hydrology 5405 Wetland 5402 provides Wetlands will continue to be Legal actions pending against illegal RM 12.20 natural RID to downstream threatened by illegal filling filling; seek to restore wetland to system, although its tune- until effective enforcement original state. Possible opportunity lions have been severely methods are developed.ed. to create multi-use facility in degraded by illegal filling Capacity problems should be existing King County Boulevard Lake • south of and adjacent to addressed by downstream anal- Park if need identified in future Petrovitsky Rd. and cast ysis for new developments. basin plan. of SE 182nd St. Some County should coordinate capacity problems exist conveyance improvements. at undcrcrossing of Petro- vitsky Rd. P:SC t3.APC C-G '1'rih. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 23 0072 20 Hydrology 5401 Tactors explaining lack of Recent installed sanitary RM 14.25 sanProtect and enhance wetland. A problems in this area; sewers make it likely that high-density multi-family development 1) this uppermost subarea area will approach its may be proposed adjacent to wetland has no other tributary anticipated density soon. due to increasing development pies- areas; 2) development is Wetland will continue to sures in area. moderate and many homes are provide adequate buffer for situated on large several- downstream system, provided acre parcels; 3) an cxten- it is not degraded by illegal sive wetland (#5401) acts filling or clearing. Channel as effective natural RID upstream of wetland is likely site, as evidenced at to experience some capacity collection point. • problems; these should be addressed by new developments as they occur, possibly with County coordinating a coopera- • live funding of conveyance improvements. 24 0072A 1 I iabitat There arc several severe More development at collet- - Repair erosion of R/D pond at RM 2.40 bank cuts, as well as debris tion point 2 and at Green upper end of tributary. in stream. Habitat for River Community College will - Remove debris from stream. fish is poor. increase flows. Increased flows will result in more bank erosion, sediment, and loss of habitat. 25 0072A 1 Geology Drain pipe undercuts to Highlights potential for Evaluate source and establish RM .25 form erosional chute. continued or increased alternate means of conveyance. Natural springs have down- erosion in loose colluvium cut 3" into soils I':SCI3.AI'C C-7 '1'rih. & Collect. Existing Anticiated Item River Mile Point Category Prop. Proj. Conditions and Problems - C onditions and Problems Recommendations 26 (1(172n I Geology hank failures of deltaic Increased erosion of banks Intercept source flows in street deposits (ancient lake) and deterioration of habitat. areas and direct to storm sewers triggered by undercutting, response to increased flows or suitable facilities. from streets above. 27 0072n 2 Ilydrology 541.4 Detention facilit for RM 2.1(3 Y If not corrected, problem Construct detention facility here Rainier Ridge single-family will deeply incise swale bank and direct runoff from SE 312th plat appeared to be and transport an unacceptable St. to this location. Analysis and functioning, although one volume of material to stream design of facility 'should calibrate section of berm had eroded below. Increased runoff from existing detention facilities and severely and needs repair area soon to be developed construct retrofitting control and armor. Pipe directing will aggravate slope failures features to allow all facilities in roadside runoff from observed. Reach is of par- the subbasin to work as a complete north side of SE 320th has ticutar concern due to adverse system. failed, and runoff has impacts on state fish hatchery cut ditch through vcge- immediately downstream. tation to east, causing significant slope failure on right bank of tributary. 2$ 0072[3 1 Habitat Culvert under railroad is Increased stream downcutting Place strict onsite controls on any RM .10 a fish blockage. Small and resulting bank erosion, future development tributary to this ephemeral stream undergoing sidecutting, and sedimenta- drainage, since no arca exists for some bank erosion due to lion downstream will occur. regional R/U. increased peak flows. 29 007213 1 Geology Silt/clay lithology exposed None. RM .75 in bank. None. P:SC13.APC c.-g 'l'rih, & Collect. Existing Anticiate Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 30 00720 1 habitat Small, class 5 stream; poor Erosion and downstream RM .10 fish habitat due to small sedimentation inevitable if Establish nonerosive stormwater ment occurs. release rates and volumes for size. Strcamside vegetation development future development. and overhead canopy in good condition. 31 00721) I I labitat Severe erosion, bank fail- There will be more movement Establish onsite control for SIR . RM .10 ores, slides, and sediment of large amounts of earth. stormwater. exist. There are ironfixing bacteria from debris. Out- fall from SIR parking lot flows into this tributary. 32 0073 I habitat Habitat in good condition. Muddy waters on rainy day show - Retain natural stream corridor. RM .30-.90 Nice pools and riffles. erosional problems upstream - Enforce erosion control require- some debris dams but no from collection point 5. ments for new development. fish blockages. Stream is fairly high, muddy and silty. Overhead trees abundant, as is strcamside vegetation. 33 0073 1 Geology 100- to 200-yr.-old debris Unstable for construction. Monitor during permit review process. RM .35 flow with recognizable fan Risky. morphology emerges from narrow draw. May have been triggered by logging before turn of century. 3-I 0073 I Geology Silt exposed in slope Continued hank recession, Evaluate total system flows and, RM RM .90 failure induced by degrading of spawning cncironment. if prudent, develop alternatives undercutting, to instream discharge of runoff from developments. • P:SCI3.APC C-9 • '!'rih. & Collect. Existing Item River Mite Point Category ,, Anticipated ' Prop. I toj. Conditions and Problems Conditions and Problems Recommendations 35 0073 RM .95P 1 Geology Silt exposed in Continued bank recession, Evaluate total system flows and, slope failure induced by degradation of spawning if prudent, develop alternatives undercutting. environment. to instream discharge of runoff from developments. 36 0073 I Geology bitter and debris blocks Periodic breakout could RM 1.00 Clean out and restore to natural stream channel. trigger flooding. condition. 37 0073 5 hydrology Accelerated bank erosion As area above Trib. 0073 Future developments above 'Tib. 007313 of main channel due to develops, erosion of swale should use infiltrative capacity of increased runoff upstream. that conveys it will experi- soils in the area as feasible to 7'rih. 007313 experiencing ence increasing capacity reduce runoff. Developments adjacent serious instability near problems. Increase erosion to main stream channel should provide confluence with main stem will occur as stream attempts adequate setbacks from slopes to due to development. (See to seek new equilibrium prevent slope failure. geologic appendix.) capacity. 33 0073 5 Geology Confluence with tributary; None. RM 1.60 None. erosional cuts suggest recent flood raised stream 3' above existing flows. 39 0073 5 habitat Habitat in good condition. Bank erosion will occur from - Plant some trees in floodplain. RM 1.60 Silt in suspension; live- presence of livestock. corridor section. stock have access to stream. - Put in some drop structures to create pools. 40 0(173 7 Geology Gentle (20%) side slopes in Slight increase in high flows None. RM 21.5 pastureland. No evidence proportional to dcvelopcmnt of erosion, but flooding upstream. reported. • P:SCB.A 1'C: C-10 '1'rib. & Collect. Existing c Anticipated Item River Mile Point Category Prop. I'roj. Conditions and Problems Conditions and Problems Recommendations 4I 0073 7 llydrology Undetermined source produc- Localized capacity problems No regional facility proposed for RM 2.15- ing substantial suspended will become more evident as this tributary due to lack of obvious 3.50 load of silt in tributary. area develops. location, but basin plan may justify Stream adequately accommo- one. dating increased runoff from upstream development. 42 0073 7 Geology Stream crossingwith runoff Slight flooding. RM 2.55 Maintain distance from 25-yr. flood- of 5-l0 cfs. Evidence of plain using 3' above existing flows short-duration flooding. as minimum guideline. 43 RMS 2.807 Geology Evidence for sideculting Widening and undercutting of None. Ci" above existing flows. banks in response to added flows. 44 0073 7 , Geology On till soils, 60'-wide None. Provides good index None. RM 2.95 flood plains 1.5' above for evaluation of system. existing flows with evidence for additional 1.5' depth. 45 0073 9 hydrology 5402 Extensive existing Wetland Filling may occur in area Monitor wetland for filling; take RM 3.15- 5450 is currently providing along north border of action to obtain restoration if 3.65 RID buffering the flow wetland to increase amount this occurs, Enforce wetland before it passes into of potential commercial real protection regulations. channel through King County estate. Subarea development Housing Authority develop- may cause localized capacity ment. problems in lower reaches. 46 0073 7 Geology In housing development, Continued erosion around Provide some armoring as bank protec- RM 3.24 erosion around culvert structure. lion (riprap). entrance 2' above existing flows. P:SC13.APC C-I I 'l'rib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 47 0073 7 Geology Peat overlies till in RM 3.55 None. None. wetland area. 48 0073 9 Ilahttai Instream habitat is poor More flooding with increased - Establish more restrictive controls RM 3.60 due to lack of overhead streamhcd and bank erosion on volumes and rates of release for 4.70 canopy and streambank will occur. developments. vegetation in some areas. - Work with landowner to provide Livestock have access to fencing and natural vegetative stream; banks have been buffer along stream. eroded in some areas. 49 0073 9 Cieology Stream occupies smile in None None. RM 4.4 rolling terrace. No erosional stress. 50 0073 12 Hydrology 5406 No significant problems. Area planned for only slight Future basin plan should consider RM 4.75 additional development. No Wetland 5444 for detention facility problems anticipated. to assist in alleviating downstream capacity problems. 5 I 007313 5 habitat Poor fish habitat. Small Increased bank erosion will Establish nonerosive stormwater RM .10-.30 stream with bank erosion occur. release rates and volumes for and associated pasture future developments. with livestock. P:SCB.APC; c-12 Trib. & Collect. Existing b llnticipatcd Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 52 0074 1,4 Hydrology 5415 Mostly undeveloped; high Future development offers Construct proposed tightline project RM .30-.50 percentage of open fields Opportunity to construct to prevent failure of road and pastures. Bank erosion regional detention facility, embankment and transportation of along west side of SE 312th as undeveloped area consists material to sensitive main creek Way threatens integrity of several large, contiguous reaches. of roadway. parcels. Bank undercutting will accelerate, causing failure of roadway along 1000' of SE 312th Way if only normal detention requirements met. Increased n►noff from suhbasin now developing will aggravate slope failures and adversely impact state fish hatchery downstream. 53 0074 1 Ilabitat Habitat downstream of SE Increased flows may cause - Clean out debris. RM .50 3.12th Way. Culvert is scour and bank erosion. - Provide RID as needed at top improved from RM .50 but of ravine. only marginally. Lots of debris in stream. 54 0074 4 Habitat hillside and road sliding Bank erosion, sedimentation Armor stream bank and RM .60 into stream at USGS stream and road failure exist. This reinforce road. gauge at RM .10. Habitat will be a big problem with poor for fish due to debris, increased flows in future. road, and erosion problems. P:S('8.A PC C-13 • '1'rib. 41 Collect. Existin [tem RiverMile [Diol C.,tcgory�, Prop,�. Proj. g Anticipated op, toj. Conditions and Problems Conditions and Problems Recommendations 55 0075 6 Hydrology Due to relativel slight RM .33- YNo problems anticipated as None. degree of development, area is planned- to develop 1.40 there do nota ear to be PP only slightly. any significant problems at this lime. 56 008 ') • habitat No majorproblems other None. - Maintain stream corridor and RM .10 than lack of overhead canopy buffer. from loss of trees, vegeta- - Encourage owner to fence stream lion. from animals. 57 008 I 9 Geology Culvert 2.5' X 2.5' passes Increased flows will have RM .62 under hydrocarbon source and under road. Irridcscent minor increase in soil test to evaluate pollutants. hydrocarbon sheen noted on erosion. Would be beneficial to isolate surface. Some minor side- livestock from sidebank areas and bank scour noted. establish vegetation on banks for erosion control and filtration. 58 0081 9 Ilabitat Stream has been ditched Bank erosion will occur. - Revegetate strcamsidcs. 1214[ .62 through pasture. Dirt - Encourage owner to fence off stream banks exposed with few or from livestock. no trees to shade stream. I':5('13.i\I'C C-14 "1'rih. & Collect. Existing c Anticipated Item River Mile Point Category Prop. Pro'. Conditions and Problems Conditions and Problems Recommendations 59 0091 `( Hydrology 541( Lake Meridian area nearly Area tributary to lake is Basin plan should consider RM 1.10 entirely developed with nearly completely developed, modification of Lake Meridian outlet single-family residences. so little change is antici- to provide considerably more dcten- Lake acts as subregional pated for system. Area south- tion with very minimal alteration receiving body is effec- east of lake has yet to fully of lake levels. This could substan- tively buffering runoff develop and potential exists tially reduce future capacity to downstream reaches. for localized conveyance problems immediately downstream. Some potential for flooding capacity problems that should of mobile home park down- be addressed by downstream stream of lake due to analysis for new developments. • possible limited capacity in pipe discharging from onsite pond. 60 009IA 13 hydrology 5409 Development is causing in- Capacity problems will Construct berm and control structure RM .17- creased capacity problems increase as upstream areas at outlet to Clark Lake to possibly 2.45 and resulting increased are developed. "detain" runoff and help reduce volume of runoff, acceler- flow downstream. If a high-density ting erosion of stream multi-family project is propsed channel in subdivisions near lake, as is likely, there near golf course. would be opportunity to develop berm and control measures. • Address capacity problems at Clark Lake by channel armoring or upsizing pipe, 61 0091A 13 habitat Altered portion of stream Future problems only likely Placement of some larger rocks to RM 20 due to road construction. to be scouring of smaller create pools and eddies. All riffles with few or no rock during peak flows, due pools. Alder shades stream to import of rock well. • P:SCB.A PC C:-15 'I'rih. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proj. Conditions and Problems Conditions and Problems Recommendations lit 0091A 13 I tabitat Stream has been ditched and More bank erosion and RM .30 most bank and shade stream by most strcamside vegetation sedimentation of channel planting native vegetation. removed through golf course. expected. Some bank erosion occurring. Very little overhead vege- • tation alongside stream. 63 0091A 13 Ilabitat Good streamside vegetative There will be additional loss - Enhance use of Clark Lake as RID RM 1.20- cover except through' of native vegetation along- facility to reduce peak flows. 2.30 shopping center. Overhead side stream. More flooding - Further restrict stormwater canopy varies by property. and erosion will occur, rate and volume realcasc rates. 6.1 0091 B 15 1 lydrology 5-107 Moderate amount of current Localized capacity problems Protect and possibly enhance wetland RM ,62 development. Wetland 5240 may occur in upland tributary as upper area develops. provides R/D, protecting as areas develop. Wetland, downstream channel from if preserved, will continue increased volume of runoff to provide R/D for increased as area develops, No sig- flow generated by new develop- nificant problems in area. ments. 65 0092 3 Geology little Soos Creek near north.lU None. RM .10 margin of Covington Channel. No reported or observed flow or erosion problems. 66 0092 3 Geology Debris and bank erosion Increased bank erosion is Reduce storm flows by use of stricter RM .30 found, expected. • stormwater controls, new RID facili- ties, and fencing of stream. increased flows. • P:SCI3.APC C-16 'I'rib. Collect. Existin,, Anticipated nlicipated Item River Mile Point Category Prop. Prot. Conditions and Problems Conditions and Problems Recommendations 67 00')2 11 hydrology 5416 Little Soos Creek tributary As development continues, No apparent suitable sites for RM .35-1.69 has been contained and mani- existingcapacity problems P' y regional detention facilities to help cured as it passes through will be further aggravated by reduce flow entering problem reaches. plats. 'Phis has reduced increased volume of runoff, Address increased runoff volumes from capacity of stream in key which previously was able to new developments with infiltration areas where resultant enter groundwater system systems where feasible. Channel channel overtopping causes directly. capacity enhancement projects (such as flooding of some homes semi- Project 5416) should be constructed yearly. to prevent further property damage. Basin plan should address potential of detaining runoff from upstream tributary area to allow for increased flows. 68 0092 I 1 I habitat Instream habitat is good. Increased flows will cause RM .65 Stream corridor mostly in flooding and erosion. bufferssh undisturbed stream good condition. Manicured lawns run down to stream in places. 69 0092 11 Ilabitat Some debris found in stream. Bank erosion, flooding, and lease RM 1.60 habitat generally good. sedimentation likely to occur. rates eand volumes shouldr control on R/D ebe established. - Maintain natural buffer along most of channel. 70 0092 14 Geology Meandering segment of Potentially unstable banks If construction were considered, RM 1.70 Little Soos; possible would affect construction. recommend evaluation of soils and colluvial creep in adjacent stability oh' sites. sidebank areas. 71 0092 14 Iiydrology Little current development. As area develops, channel Future developments should RM 1.70- No significant problems capacity problems will become utilize infiltrative capacity of 3.65 other than some localized more evident and increased soils to reduce increased runoff bank overtopping in portions erosion will occur as stream volumes. Provide adequate flooding of main reach. Innundation attemps to seek new equi- protection for future runoff con- will likely be limited to librium capacity. ditions. adjacent agricultural land. P:SC13.APC C-17 'I'rih. & Collect. Lxistinn o Anticipated ItemRiver Mile Point Category Prop, Proj. Conditions and Problems Conditions and Problems Recommendations RM 2.80 Potential for flooding in Possible flooding (minor). Consider upstream detention. low areas; very low side- slopes. 73 009') 14 I lahitat Some debris found. Bank erosion and sedimenta- - Establish stricter control on RM 2.80 tion likely. R/D release rates and volumes. - Maintain natural buffer along most 71 00`)? 16 Geology of channel. Chcrbank flows. Possible flooding (minor). Consider upstream detention. RM 3.35 75 0092 16 Ilabitat Lots of sand in bedload. More sedimentation likely, rol on RM 3.40 Streamside buffer generally as well as bank erosion and R/Dtlish release tcrates aer ndd volumes. good. flooding. - Maintain natural buffer along most of channel. 76 0092 16 Geology Resident reports trees down Some continued erosion. Some clean-out of trees and RM 3.40 in stream and sidcbank limited armoring of banks would be erosion evident. beneficial. 77 009? 16 Ilydrology 5412 Little current development, No problems anticipated p Consider Wetland 5480 for a RM 3.65- some localized bank over- as very little additional detention site, in a future basin 4.75 topping in portions of main development is planned for plan, in order to alleviate down- • reach but innundation is this area. stream capacity problems. probably limited to adjacent agricultural land. 78 0092 16 habitat Stream ditched. Little Bank erosion and flooding of - Work with land owner to fence off RM 4.00- streamside vegetation and now "improved" pasture will stream. 4'40 no overhead canopy. Some occur. . Plant native vegetation buffer. livestock-related erosion and runoff. 79 0092 16 Geology Orange iron precipitate Some localized oxygen RM 4.65 Yn Natural deposition as iron is . noted in streambed near depletion of fish habitat. exchanged for oxygen. outlet to Lake Youngs. P:SCB.AP(' C-I3 'I'rih. & Collet,. Item River Mile Point Category I-xisting Anticipated gory I rop. Prot. Conditions and Problems Conditions and Problems Recommendations fiO 0092 16 Ilahilat RM 4.65Iron fixing bacteria and None. associated odor present. None. Source unknown. Lake Youngs release rate is minimum ? cf. $1 0093 14 Ilahilat Very small tributary with Erosion and flooding from Reduce storm flows by RM .00-.87 undefined channel in places. future development likely. stormwater controls ne use of stricter Habitat value for fish is w RID low. facilities, and fencing of stream. 8? 0093 14 Cicoio�� Poorly I oorly defined stream None. RM 0.35 None. channel with no evidence of erosion. 83 0094 13 Geology Minor sidchank erosion Slight enlargement of Local armoring/riprap applied by RM 0.30 below convergence of two erosional features. culvert/creeks. owners would reduce impacts. 84 0Q`�4 13 Ilahitat Streamsidc vegetation has There is a possibilityof RM .0.30 been removed bylogging. - Provide stormwater control gg g• bank erosion due to increased - Establish stream corridor buffer. flows from development. - Improve stormwater control. $5 0094 13 Ilabitat Important: This is a salmon More bank erosion will occur. - Encourage property owners to fence RM 1.00 spawning stream. Some hank stream. erosion probably due to live- - stock. Provide stream corridor buffer. - Improve stormwater control. 86 0094 13 Ilahitat !'here is riverine wetland None. Maintain wetlands and stream corridor RM 1.5() just east of 156th Ave SE. in natural state. P:SCI3.APC C-l9 'I'rih. & Collect. Item Kivci�Mile Point Category , Listing Anticipated gory I ton. i toj. Conditions and Problems Conditions and Problems Recommendations 87 0095 17 habitat Small, ephemeral stream None. Encourage property owner to fence RM .35-.85 flowingg pasture. h �tstut•e, livestock causing bank stream. erosion. SS 0095n 18 Ilabitat Ditched area; lots of Continued filling may Maintain stream corridor. Enforce RM .00-.28 debris. occur in floodplain.P grading and filling ordinance. S`} 0095n 18 I labitat Debris exists in salmon RM .65 This will have minimal effect Maintain stream corridor in spawning area• on habitat. natural condition. 9(} 0097 18 Geology Stream flowingthrough g Continuing adjustment will The key word is "equilibrates." RM .35 development shows minor bed occur until system establishes Disturbance of the natural system and hank erosion as stream a mature, developed water- has initiated or induced readjustment equilibrates to new channel. course. in the bed as a function of new gradients, materials, and other hydraulic factors. In time, the stream will establish itself in another "natural" equilibrium, assuming no new variables such as added flows or alteration of channel geometry are introduced. 91 0097 1$ Ilabitat Debris and fill in wetland. More filling may occur. Enforce grading and filling ordinance. RM .35 1':S(:13.A PC C-20 TASK 3 FIELD INSPECTION There were no problems reported or observed during the resource review. Based on a review of the drainage complaints for this downstream drainage course, there has been one drainage complaint (Complaint#96-1550)just to the east of the site. It appears to have been a plugged culvert due to lack of maintenance. Based on our review of the King County report for this complaint, the culvert was cleaned and no further complaints have been filed. Based on our July 26,2007 field inspection of the downstream system, it appears that this same culvert may be plugged again. There was erosion in the driveway that matches the description in complaint#96-1550. 3.1 Conveyance System Nuisance Problems(Type 1) Conveyance system nuisance problems, in general, are defined as any existing or predicted flooding or erosion that does not constitute a severe flooding or erosion problem. Conveyance system nuisance problems are defined as flooding or erosion that results in the overflow of the constructed conveyance system for runoff events less than or equal to a 10-year event. Examples include inundation of a shoulder or lane of a roadway. Overflows collecting in yards or pastures, shallow flows across driveways, minor flooding in crawlspaces or unheated garages/outbuildings and minor erosion. Based on a review of the drainage complaints provided by King County,there is evidence of past conveyance system problems occurring within the downstream drainage system for this proposed project. However, it is only related to one culvert near 19121 124th Ave. S.E. There was one drainage complaint (#96-1550) for this culvert. Based on our review, this culvert was cleaned and there have been no further complaints. However, based on our field inspection, it appears that this culvert may be partially plugged again, as there is a minor amount of erosion on the gravel driveway that matches the erosion that occurred in drainage complaint #96-1550. It appears that the culvert was last cleaned in 1996. In our opinion, this is not a conveyance, capacity, or erosion problem. It appears that this culvert will just require more frequent maintenance to eliminate the problem. 3.2 Severe Erosion Problems(Type 2) Severe erosion problems are defined as downstream channels,ravines, or slopes with evidence of or potential for erosion/incision, sufficient to pose a sedimentation hazard to downstream conveyance systems or propose a landslide hazard by undercutting adjacent slopes. Severe erosion problems do not include roadway or minor ditch erosion. Based on our review of the King County drainage complaints, there have been complainants regarding erosion. However, this erosion was due to a plugged culvert, which had not been properly maintained. It is our opinion that more frequent maintenance of this culvert will eliminate the problem. 33 Severe Flooding Problems(Type 3) Severe flooding problems can be caused by conveyance system overflows or the elevated water surfaces of ponds, lakes, wetlands, or closed depressions. Severe flooding problems are defined as follows: • Flooding of the finished area of a habitable building for runoff events less than or equal to the 100-year event. Examples include flooding of finished floors of homes and I2542.009.doc • commercial or industrial buildings. Flooding in electrical/heating systems and components in the crawlspace or garage of a home. Such problems are referred to as "severe building flooding problems." • Flooding over all lanes of a roadway or severely impacting a sole access driveway for runoff events less than or equal to the 100-year event. Such problems are referred to as "severe roadway flooding problems." Based on our review of the drainage complaints,there have been no flooding problems associated with the downstream drainage system for this project. • 12542.009.doc Exhibit J Off-Site Analysis Drainage System Table OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Basin: Soos Creek , Subbasin Name: Subbasin Number: Distance Observations of Field Inspector, Drainage Component Drainage Component from Site Existing Potential Resource Reviewer,or Symbol Type,Name,and Size Description Slope Discharge Problems Problems Resident Constrictions,under capacity,ponding, Type: sheet flow,swale,stream, overtopping,flooding,habitat or organism channel,pipe,pond;size, Drainage basin,vegetation,cover, destruction,scouring,bank sloughing, Tributary area,likelihood of problem, See Map diameter,surface area depth,type of sensitive area,volume % Ft. sedimentation,incision,other erosion overflow pathways,potential impacts 1 18"Conc. Pipe Along North Side of 192nd ±5% 0— 123 None None 2 18" Conc. Pipe Along North Side of 192nd ± 8% 123 —287 None None 3 18"Conc. Pipe Along North Side of 192nd ± 10% 287—344 None None 4 18"Conc. Pipe Along North Side of 192nd ± 12% 344—410 None None 5 18"Conc. Pipe Along North Side of 192nd ± 12% 410—484 None None 6 18"Conc. Pipe Along North Side of 192nd ± 12% 484—610 None None 7 18"Conc. Pipe Along North Side of 192nd + 12% 610—774 None None 8 Channel Dense Vegetation + 6% 774—960 None None 9 18"Conc. Culvert Under Gravel Drive ±3% 960— 1007 Appears that culvert Could may be partially plug plugged, erosion again. noticed in D/W. Regular Culvert should be maintena cleaned. Same thing nee occurred with needed. drainage complaint No. 96-1550 10 Channel Dense Vegetation ±2% 1007— 1397 None None 11 ±4' Dia. CMP Flows South Under 192nd ± 1% 1397— 1439 None None 12 Channel/Big Soos Creek Dense Vegetation/Wetland ± 1% 1439 - 5439 None None 12542.012.doc TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS Runoff leaves the site near the southeast corner within a shallow ditch. The ditch appears to have been created by fill on the adjacent properties. From this point, stormwater flows south for a short distance before reaching the north edge of 192 Ave. S.E. Runoff then flows east along the edge of 192nd Ave. S.E. for a distance of approximately 120-feet ware it enters a catch basin. From here, the stormwater flows in an easterly direction for a distance of about 654-feet within an 18-inch concrete pipe. At this point, stormwater is discharged into an open channel and continues easterly for a distance of approximately 186- feet before entering an 18-inch concrete culvert. This culvert conveys the flow under an existing gravel road for a distance of approximately 47-feet. At this point stormwater is discharged into an open channel with very dense vegetation and continues easterly for a distance of approximately 390-feet before reaching what appears to be about a 4-foot diameter CMP culvert that conveys flow to the south under • 192nd Ave. S.E. From this point, the flow continues south for more than 4000-feet within what we • assume to be"Big Soos Creek" For a review of all the drainage complaints provided by King County, please refer to Exhibit K. There were two complaints concerning a plugged culvert. We assume that King County has cleaned the culverts since there have been no more drainage complaints regarding these culverts. 12542.009.doc r Exhibit K Drainage Complaints Q' CIVIL ENGINEERING,LAND PLANNING,SURVEYING,ENVIRONMENTAL SERVICES MMJ DATE: October 27, 2006 ', 4-Na TOTAL PAGES (including cover sheet): 4 FACSIMILE: (206) 296-0192 TO: Candi McKay King County Water and Land Resources FROM: Don Dawes RE: VanEngelenburg JOB NO: 12542 MESSAGE: Please fax the drainage complaints marked with an arrow on the following pages(5 total). cc: Fax No: Fax No: Fax No: Fax No: Please call(425) 251-6222 if you do not receive the Indicated number of pages. 18215 72ND AVENUE SOUTH KENT,WA 98032 (425)251-5222 (425)251-8782 FAX . SEP. 22. 2006 12: 35PM KING CSO, '�4W �� NO. 1102 P. 1 . Hca /2S-412_ VoilErydeohit Kr King County Water and Land Resources (WLR)Division 201 S Jackson St, Suite 600 Seattle,WA 98104-3855 Date: 7/o70X • Number of pages including cover sheet: FAx ... I From: Candi McKay,Brig Tech II C l WLR.Stormwater Services Section To: a?-/-gei (/0/I4 Phone: 206-296-1900 . .......„ ___ � Fax Number:206-296-0192 Fax: 1076 a(57- 7,g; IMPORTANT LEVEL 1 ANALYSIS NOTE: We do not send copies of certain complaint types that are not relevant such as BCW,F1,FIR,FIR, SUP and WQA, and we do not send CL and LS types. See key below. Type Si, S2 and S3 will not be faxed due to size constraints. The following is a list of complaint types received by the Water and Land Resources Division Drainage Services Section. Complaint numbers beginning prior to 1990-XXXX have been archived and are no longer in our possession. They can still be retrieved,if necessary,but will take additional time and may not be beneficial to your research due to their age, development which has occurred,etc. If you are interested in reviewing the actual complaints,they can be pulled(time permitting)for your review. Copies can be obtained for S.15 per page,and S2.00 per page for plans. Neys: • Type of Tnvestieation Type of Problem BCW Business'for Clean Water ACS Access C Action Request BSR Bioswale retrofit ' 'CL Claim CDT Commercial Determination E-H/R Enforcement on Hold/Review DCA Development/Construction EAI hfaintcnance Enforcement DDM Drainage-Miscellaneous FCC,FCR,FCS Facility Complaints Di.S Drainage—Eroslon/Sedfinentation FI-R/H .SWIM Fee Inquiry Review/Bold DLE Drainage—Landslide/Earth hIovement I Inquiry DTA Drainage Technical Assistance =LS Lawsuit ERQ Earthquake NDA Neighborhood Drainage Assistance GRT Grant Program RET Retrofit facility INQ General Inquiry It/RR Engineering Review/Facility Review FRG Irrigation SI,S2,SN3 Engineering Studies LSP Landscaping SUP/F Special Use Permit/Final MMA Maintenance Aesthetics WQC Water Quality Complaint Mi<lF/G/A1 Maintenance Flooding/General/Mowing WQAP/P Water Quality Audit in Progress/Permit MSQ Mosquitoes WQE/R Water Quality Enforcement/Rovicw N WDISFTD New Discounts 165-10 Discount X CCF or Response to Inquiry RFN Runoff from Neighbor REM/GRT SWM Fee Re-measurement/Grant RET Retrofit facility SGN Signs SHIi Sink hole STR Storage SWF SWM Poo Questions TRE Tree Removal WQB/D/! Water Quality—Best Management Practices/Dumping/illicit Connectiun UT1 Utility Installation YRD Yard Extension *Subject to Public Disclosure requirements I.Receipt of written request for documents 2.Review and approval by Prosecuting Attorney's office . SEP, 22. 2006 12:36PM KING CO. WLRD NO. 1102 P. 2 -11 County Water and toad Resouroa1 O1vI Ina•Brittle Woos Sectton Go i p aInt Swab Printed: 09221200811:00:08 AM camaar drit TY" Tne of Ratan] Miran 0T PNbIBQ1 Commits ibros Pie NaCuria 1975-0076 C FLOG RD WY/FWD/112TH AVE SEISE 188TH ST 686E2 -- ►1977-0072 C FLDG 12202 SE 192ND ST 688F2 1978.0080 C PONDING 19248 121ST PL SE EAST OF BENSON HWY 686F2 —1978-0081 C DRNG 19248 121ST PL SE 888F2 1979-0047 C 11403 SE 204TH ST SOIL BULLDOLEO/PANTHER LK AREA 686E2 —1982-0539 C FLOG 12600 SE 192ND ST EAST KENT AREA 686F2 1984-0298 0 FILL 18504 112TH AVE SE ILLEGAL NEAR: 17409 126TH AVE SE 885E1 1984-0313 R FLDG 13250 SE 192ND ST TO ROADS DIV.4 888F2 1984-0314 C FLOG 13250 SE 192ND ST SE 192ND ST/134TH AVE SE 888F2 1988-1168 C FLDG 11202 SE 188TH ST STORM OVERFLOW 886E2 1988-1185 C FLDG 11202 SE 188TH ST SEE:88-1166 BRYANT,BILL 888E2 1988-1190 C FLOG 11001 SE 188TH ST BASEMENT GETTING WATER 686E2 1987-0334 C DRNG 11202 SE 188TH ST CULVERTS BLOCKED 86-1166.1185 686E2 1987-0471 C FLOG 11202 SE 188TH ST SPRING GLEN 66-1166,1185 888E2 1987-0545 C DRNG 18627 109TH AVE SE INADEQUATE SYSTEM 886E2 1987-1049 C TO RD COORD 04/27/87. 886E2 1988.0238 C FLOG 18431 120TH AVE SE NEW DRIVEWAY WILL IT FLOOD 686F2 88-0238 ER PIPE 18431 120TH AVE kV SE NEED EXTENSION OF 42•CULVERT 688F2 1989-0003 C DRNG 18812 120TH AVE v SE INCREASED RUNOFF/CHANNEL 686F2 1989-0192 C DRNG 18612 120TH AVE SE X PIPE NOT WORKING 686F2 1989-0650 C DRNG 18631 111TH PL 'J SE SAN DRNG AND DAMAGE 686E2 1989-0700 X DRNG 18531 111TH PL SE WATER ON SIDEWALK/89-0850 FRITON 68662 1990-0075 C DRNG 11254 SE 186TH ST PLUGGED CULVERT/STORM 638E2 1990-0141 C FLOG 18400 112TH AVE st SE POND OVERFLOW/90.0149,235,372ISTOR 686E2 1990-0149 C FLDG 11202 SE 188TH ST R/D POND OVERFLOW/ROBERT/STORM E 688E2 1990-0231 C DRNG 18425 112TH AVE Q SE RID POND OVERFLOW/STORM 90.274,37 688E2 1990.0235 C FLDG 11202 SE 188TH ST Z WATER IN BASEMENT/STORM/00-141,149, 888E2 1990-0274 C FLDG 11022 SE 184TH PL RID POND FLOODED/STORM 688E2 1990-0342 C FLOG 11202 SE 188TH 5r R/D POND/ROBERT/STORM EVENT 688E2 1990.0372 X DRNG 11202 SE 188TH ST R/D PONDS OVERFLOW9/90-141,149,235,2 686E2 1990-0709 CL FLOG 18504 112TH AVE SE CL#12959 SEE CL#13224 DUE DECEMBE 686E2 1090-0884 C DRNC3 18427 112TH AVE SE R/D POND DRAINAGE/STORM 686E2 1990-1061 CL FLDG 11202 SE 188TH ST CL#13224 SEE CL#12969 GARAGE FLOG 688E2 1990.1186 CL FLDG 11044 SE 186TH ST MEMO/RUDDELLS STUDY TO PA 688E2 1990-1212 C DITCH 11044 SE 188TH ST RD/SIDE DITCH-FILL/90-1186 886E2 1990-1212 E FILL/DIT 11044 SE 186TH ST WILL START WORK 09!20 CHK ON 09/30/9 686E2 1990-1212 ER FILL/DM 11044 SE 186TH ST RUDELLS STUDY 686E2 Page 1 of 3 SEP. 22. 2006 12: 36PM KING CO. MLRO NO. 1102 P. 3 Not PN14LPB1- Piibit tb 199b C Iwo at Fraliiam Address of Frablam COMM Wes Papa mar Cala 1990-1228 C DRNG 18615 107TH AVE SE FLOODED BASEMENT/BAD ROADWAY 585E2 1990-1445 C DRNG 18427 112TH AVE SE RID POND OVERFLOWING TO STUDY/91.1 686E2 1990-1530 SR FLDG 18427 112TH AVE SE STORM EVENT 686E2 1990-1531 SR FLDG 18427 112TH AVE SE STORM EVENT NOT NDAP 686E2 1991-0150 C DRNG 18824 112TH AVE SE 688E2 1991-0150 SR DRNG 18624 112TH AVE SE NOT NDAP 688E2 1991-0198 C FLOG 18425 112TH AVE SE 685E2 1991.0196 SR FLOG 18425 112TH AVE SE NOT NDAP 586E2 1991-0253 0 DRNG 11254 SE 186TH ST 688E2 1991-0438 51 SPK TO FINISH 51 3/4-52 TO'92 CON 686E2 1991-0687 CL DRNG 18427 112TH AVE SE SEE 91-0438 SEE RUDDELLS 668E2 1981.0837 C DAMAGEOB 19001 116TH AVE SE CB BELOW GRADE 686E2 1991-1095 C FLOG 11200 SE 186TH ST RUDDELL POND OVERFLOW 688E2 1991-1132 C DRAINAGE 19008 116TH AVE SE INFO TO PM&D 688E2 1991-1149 X FLOG RID 11200 SE 184TH ST CCF#SWM-1031 RID POND CAPICITY 686E2 1994-0038 C PONDING 11430 SE 192ND ST POSE GRADING/FILLING VIOLATION 686E2 1994-0144 C DRNG 17925 116TH AVE SE POSS FILLING VIOL/ACT PLAT MORNING G 686E1 1995-0200 C DITCH?S 18204 116TH AVE SE LACK OF CONVEYAYNCE ON PVT PROPE 686E1 1996-0805 C DRNG 19400 120TH AVE SE DRAINGE FLOW QUESTION DEVELOP INF 686E2 —a,-1996-15.50 C DRNG 19121 124TH AVE SE PLUGGED DM CULVERT IMPACT TO PVT 686F2 •498-1564 C DRNG 18908 113TH WAY SE PRIVATE PROPERTY IMPACT TO PVT DRN 886E2 _496-2071 C FLOG 11828 SE 180TH ST INADEQUATE CONVEYANCE OFFSITE FLO 886E1 1998-2071 R FLOG 11828 SE 180TH ST INADEQUATE CONVEYANCE OFFSITE FLO 685E1 1997-1123 C GRADING 18808 113TH WAY SE PVT PROP IMPACT NO DRNG INSTALLED 686E2 1997-1123 R GRADING 18908 113TH WAY SE PVT PROP IMPACT NO DRNG INSTALLED 688E2 1997-1179 C DRAINAGE 19113 121ST PL SE INSTALLATION OF DRNG IN RNV OLD/OFF 688E2 1997-1179 NDA DRAINAGE 19113 121ST PL SE INSTALLATION OF DRNG IN RNV OLD/OFF 688E2 1997-1179 R DRAINAGE 19113 121ST Pi_ SE INSTALLATION OF DRNG IN RAV OLD/OFF 686F2 1997-1301 C DRAINAGE 19125 121ST PL SE SUBSTANDARD INSTL OF DRNG SYS PVT 686F2 1998-0019 C DRAINAGE 19018 118TH AVE SE NEW GRAVEL RD POSSIBLE PVT PROP IM 686E2 1998-0058 C DRAINAGE 18820 118TH AVE SE SFR CONST IMPACTING ADJACENT PROP 688E2 1998-0928 C DRAINAGE 19133 121ST PL SE APPARENT OBSTRUCTION IN ROAD DRN 686E2 1999-0306 C DRAINAGE 11618 SE 188TH ST ADJACENT PROP PAVED 2500 SQ FT 888E2 1999.0329 FCR BAMBOO 12317 SE 179TH PL NON NATIVE GROWTH IN R/D FACILITY 888F1 2000-0398 C DDM 12825 SE 192ND ST REQUEST TO DIVERT FLOW DISCHARGIN 888F2 2000-0572 C DDM ACROS 19029 120TH AVE SE APPARENT FILLING OF ROADSIDE DITCH. 686E2 2000-0572 R DDM ACROS 19029 120TH AVE SE APPARENT FLL.ING OF ROADSIDE DITCH. 686E2 2001-0247 FCR MMA 12317 SE 179TH FL IDENTIFIED NOXIOUS WEEDS. BLACKBER 688F1 2001-0322 WQO 11631 SE 184TH ST APPARENT GREY WATER DISCHARGE INT 688E1 2001-0322 WQC WQO 11831 SE 184TH ST APPARENT GREY WATER DISCHARGE INT 686E1 Page 2d3 '. SEP, 22. 2006 12:36PM MG("CO. WIRD NO. 1102 P. 4 C utter, Iva of Protft MMus IN Prato Commits Ztu`a3 Pstpe 2001-0389 WQC WQI SE 180T &118TH AVE SE POTENTIAL GRAY WATER DISCHARGE. C 886E1 2001-0389 WQE WQI SE 180T &118TH AVE SE POTENTIAL GRAY WATER DISCHARGE. C 686E1 2001-0389 WQR WQI SE 180T &118TH AVE SE POTENTIAL GRAY WATER DISCHARGE. C 888E1 2002-0314 C DOM 18524 114TH AVE SE SHEETFLOW ONTO PROPERTY FROM UP 886E1 2002-0381 C DDM 11825 SE 184TH ST SOGGYAREA IN YARD. MAYBE THE RES 585E1 2002-0553 C DTA 19013 114TH CT SE CONCERN REGARDING POSSIBLE SLOUG 686E2 2003-0545 WQR WQB 18801 128TH PL SE 686F2 2003-0752 WQA WQAI 19433 VASHON HWY SW BMPS ELM ALL IN PLACE 686F2 2003-0847 C DDM 19230 116T1-1 AVE SE APPARENT OBSTRUCTION OF OFFSITE C 888E2 2003.0847 NDA- DDM 19230 115TH AVE SE APPARENT OBSTRUCTION OF OFFSITE C 6813E2 2003-0847 R DDM 19230 118TH AVE SE APPARENT OBSTRUCTION OF OFFSITE C 686E2 2003-0909 WQC WQDR 18801 128TH PL SE AUTO FLUID RESIDUE ON STREET AS A R 686F2 2004-0223 FCR TRE 18004 124Th AVE SE Trees removed from Facility D92182.tnvestigat 688F1 2004-0288 E MNM 18004 124TH AVE SE Factty D92182 dispersion french filled/graded 888F1 2004-0286 FCR MNM 18004 124TH AVE SE Facility 1092182 dupers on trench fUled/greded 686F1 2004-0288 R MNM 18004 124TH AVE SE Facility 092182 dispersion trench filled/graded 688F1 2004-0745 C DTA 18418 127TH AVE SE 2 pipes from neighbor drain onto co nplahenl's 686F1 2004.0952 C DTA 12701 SE 191ST PL Referral from KG Roads.Flooding of backyard 686F2 2005-0244 C DDM 18817 128TH PL SE Wet backyard caused by broken storm the?in 686F2 2005-0316 C DTA 12503 SE 188TH PL Backup In KC Rd conveyance system.investg 686F2 "005-0401 WQC WODC 17844 120TH AVE SE Construction debris dumped on private proper[ 886F1 X05-0428 C RFN 19128 113TH WY SE Water firms across skiewaikfrom water meter. 686E2 2005-0440 WQC WQDR 11447 SE 180TH PL DUMPING FROM RV 686E1 2005-0446 WQA WQAI 12500 SE 192ND ST 666F2 2005-0488 WQC WQi 11700 SE 184T1-1 ST 686E1 2005-0491 C DCA 17830 116TH AVE SE King/re-grading on neighbor's property,Inv dl 686E1 2005-0882 FCR MNM 19133 113TH WY SE Mame from KC Health.Rats h D91898.tnv f 688E2 2006.0173 WQC WQDR 11447 SE 180TH PL RV leaving trail of sewage. 688E1 2006-0173 WQR WQDR 11447 SE 180TH PL RV laming troll of sewage. 886E1 2006-0299 C RFN 18821 116TH AVE SE Broken dralnege pipe @ Benson HMI Elem Soh 686E2 2008-0404 WQA WOO 12317 SE 179TH PL Trucking/consbuctlan business 886F1 2006-0404 WQC WOO 12317 SE 179TH PL Trucking/construction business 686F1 2008-0450 C DTA 18621 116TH AVE SE School const dieing water seepage into yard 886E2 Page 3of3 , Map Output Page 1 of 1 ® King County VanEngelenburg Drainer a Complaints Map ,./9323_92401w.w=0-1 7 ,928f_92$? 911J 1 1 1 f t e-1-1 9039 ‘ /i +" 0183 02810280 0281 0310; 07: 0301I. f �� ' `• lJ — �0150 _i 9119 0'179 0318--31 0130—Cif{0160 0180 90/3 0350�a �1„ 01rN 0183 rw--1 03r0� I.0321 �� 0??T01'sy 0�5'0 4J420T 1 __ T __. .. � ysE1ai3TllaT.�; 038..7-T,741( 04 r D223 02{11 -Mal-• 1900; u 9,43 9015 rn j 1 ¢ , j 0 2 0020 0073-I 1 00991 j ill- Y ��� 1 08201 / iii 0021 2--0218 5E-166TH:PL,� — W�/ 0770,•( gm.' r----070i ++ L n0810�.�i S 9t1d 't p.....471 (- j 022 0 10560�U580''m. �, -j ,;R089b •� �1-0061_0065. - 0245 Ill 0059- -� .. d6�001_ a 0930 09,0 > to. . ,t0063--L----.2-6243-1_ I v� Ii 06, .jZ I� 0 0260 > 905T r { cG60�07oD'-- 1 on. 0280 Q I 0 l ti--I x-0630. `r-'- , • _._� _ j t>91119 9.:X L C2/ sn I 0125 t 0300 -N _� W 0210 0210 /1 9051 f ►_- 71_0!) 4'0 5/0'-, _�I. '-• r42 1 Nom. // t 0550x /: t~ 113 -.0205 t t ! r ---rt-'0590, 903G 1 1----.--._ __- a,__01333^;! ur - 182 t . i •(0200err Q91899 y, 93(8 161 0360 .0311 N 1 0 0720 ' °190.903/ 092819 0-- ..._.-N IG77D' ' '.0267 l 0/3Dik' ■• ---ill* 1 • 01100 780-lull / • aaos Doul :�2i— \!� - 0013 (-`W�a610. I —, {oDt6+ 2 UD1 In - 9021 9139' 9D�_ . 9cw2 w=0^ MI o0 ('�'�� 00zG� ,) 00161 0042 w• -,›0710- C r--"— t -0025 - ✓m 0035 >' `a �5 9230 SE-193RD -`'-. . . •tS � 0W1 Q' _\ } , I W/ 11--� f ! I 0040 q 9025 ���-.. t,� D�088J1 IL ! I I71— .�f 907_{-\ iii ` '. f ,.� 'VN> 001 . 9320 9065 • tI 00/9 0076 . 1 0060 ��0055 xa - 9018 1- i� I 0075 t r O 9031 ' �) D08l1 l 00110012,0066 I 0,70 t r• ODSD ----- —i—_SE.196TH:ST. �_--- _i-t in 0046 9032 ( 9723-4.-f: 9216 �-Tf- dJ.1 T,.13" __ -r_tl- _ i 0092-0091 �. „ - -'+1 .- ;Trill I • IC)2035 King Courtly 9005 9099, 9110( 0088 009011 0095 .I 010 !U 105,1_0o 10 Met t 0121 0120 I J 9003 \ s _ U I 9:75 t-doss—I c_909133 f.( I 1-11.�._�af' .. Itt2pn : Legend al Selected Parcels Streets /. County Boundary r4401 tr,Ti, aThomas Brothers Map Page lti,' k» s A Drainage Studies xf ' • Neighborhood Drainage Projects rl Parcels • Regional Stomr atom Faeitios n Lakes and Large Rivers • Residential Stormwater Facades t:,/ Streams Commercial Slommvater Facities ED Drainage Complaints The information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice.King C makes no representations or warranties,express or implied,as to accuracy,completeness,timeliness,or rights to the use of such information.King Cc shall not be liable for any general,special,indirect,incidental,or consequential damages Including,but not limited to,lost revenues or lost profits result the use or misuse of the information contained on this map.Any sale of this map or information on this map is prohibited except by written permission c County. Date:9-22-2006 Source:King County iMAP-Stormwater (hltp://www.rnetrokc.gov/GIS1iMAP) http://www5.metrokc.gov/servlet/coin.esri.esrimap,Esrimap?ServiceName=overview&Clie... 9/22/2006 OCT. 3c:. 2006— 3:27PM KING CO. WL,RD NO. 1697 Y. • I25L-z King County Water and Land Resources (WLR)Division Copy 201 S Jackson St, Suite 600 ` Seattle,WA 93104-3555 Date: /0 30FAx Number ofpages including cover sheet: 9,5 From: Candi McKay, Eng Tech 11 WLR Stonnwater Services Section To: ‘2(997ijiaje0Phone: 206-296-1900 Fax Number: 206-296-0192 Fax: lob`v� a51-67cf -' - IMPORTANT LEVEL 1 ANALYSIS NOTE: We do not send copies of certain complaint types that are not relevant such as BCW,FI,FIR,FM, SUP and WQA, and we do not send CL and LS types. See key below, Type'S1,S2 and S3 will not be faxed due to size constraints, The following is a list of complaint types received by the Water and Land Resources Division Drainage Services Section. Complaint numbers beginning prior to 1990-XXXX have been archived and are no longer in our possession. They can still be retrieved,if necessary,but will take additional time and may not be beneficial to your research due to their age, development which has occurred,etc. If you are interested in reviewing the actual complaints,they can be pulled(time permitting)for your review. Copies can be obtained for S.15 per page,and S2.00 per page for plans. Ke1's r Type of Investigation Type or Problem BCW Business'for Clean 1Yator ACS Aeceu C Action Request BSR Bloswale retrofit frCL Claim CDT Comtnercial Determination E-l:IiR Enforcement on Hold/Review DCA Development/Canstructlon EM Maintenance Enforcement DDM Drainage-Miscellaneous. FCC,FCR,FCS Facility Complaints DES Drainage—Eroslon/Sedtmentation FI-II/FI SWM Fee Inquiry Review/Hold DLE Drainage-Landslide/Earth Movement %11 I Inquiry DTA Drainage Technical Assistance *LS Lawsuit ERQ Earthquake NDA Neighborhood Drainage Assistance GRT Grant Program RET Retrofit facility INQ General Inquiry RIRIt Engineering Review/Facility Ruview I12G Irrigation S1,S2,SN3 Engineering Studies ISP Landscaping SUP/F Special Usa Permit/Final MBIA Maintenance Aesthetics WQC Water Quality Complaint MMF/G/<ti1 Maintenance Flooding/General/Mowing WQAP/P Water Quality Audit In Progress/Permit MSQ Mosquitoes WQE/R Water Quality Enforcement/Review MVD/SFTD New Discounts/65-10 Discount X CCF or Response to Inquiry RFN Runoff from Neighbor //,,// fin/0�9�is , ,ode /P9/ REPGRT SWRetrofit f t f Ro-rncility surement/Grxnt Lll� RET Retrofit facility th27 SGN Signs n^N� W / SiCIt Sink Hole STRStorage P /3 a neJ /a5� v ‘S VD' &WM Fee Quutlons TRE 'Prep Removal '!e W J C� Te571 are _L''r, /;a70# WQBID/I Water Quality—best Management Practices/DutnpingQillclt Connection UTI Utility Installation YRD Yard Extension *Subject to Public Disclosure requirements 1.Receipt of written request for documents 2.Review and approval by Prosecuting Attorney's office u1,1, iU. Lvv j:L/rM— _..K1NU W. WLKU ..........7......_ NU. 1695 �. 1 KING COUNTY SURFACE WATER MANAGEMENT DIVISION NI I A DRAINAGE INVESTIGATION REPORT Pagel: INVESTIGATION'REQUEST . Type (1,. Thceived by: �� _ Date: 6/26/1 OK'd by: D p4,4 Fife-No, 5r,,, ..___/.5.1./ Received from: ' ' (Plass°print plainly for scannlnB). (Day)) • (Eye) �•�— NAME; /� l/G . cJ r� PHONE g59 7_3F7 ADDRESS: 1 q 12'/ .' /2 y iF S - Clty fl rb4,/ . State ZippgO 58 Location of problem, if different; � y /5 @ a/--- • /.�Ls E I T2 nd 74--.. 12 4Y s Reparfed Problem: // / pass/',b /e, NO Lc f 2 0,4' S'1.0 278113 • Plat name: A/44A%JD S n Ca,ro{cyt Tis 17i V Lot No: 13 block No: Other agencies involved: No Field Investigation Needed ?Mg*:,R Z. ... 7:-ai ".:iS v drtP ,'�• '@ I , �? `Y?',.. w •r' }i 1�) u•.. (In�Uals) ..1.. ro d,Yi � YsNe,Jjrtll�-.., !• 'ip!'�-�,,,,,5, ''r••�, '• ` ', Z ?1 �' �fI Parcel No. 6/9 90o 0 262 Kroll Th,Bros: New(0j J2, : 1/4 S I R Basin�!L-A ) Council Dist 9 Charge No: 7 Old di RESPONSE; Citizen notified on f.-?2-9 4 b "- - Y ,phone�.. letter in person q/?-9G •eel-e-i r-a 1ztr,44'4::s5,94 4' or44Lc/9 67,nZ17:�v —• sHL-" 5-f1iv / Di� S •`J/9 D L1.044 C (�L 9T.294/- yl eLG'75t-t/6C,eDSS el,ft-�/�"R�, 7 /�� :��Wo4GO nnO,SG o 4,- i�s0P40i /. .- DISPOSITION: Turned to on., by OR: No further action recommended because: Lead agency has been notified: 7 Problem has been corrected. Na problem has been identified, Prior investigation addresses problem: Private problem-NDAP will not consider because: See Filo - Water originates onsite and/or on neighboring parcel Location is outside SWM Service Area. Other (Specify): ' DATE CLOSED;-�/ '274(. �r' ' by' p f Y , _71 ' /tea ci-rb UGI. H. 200b • 3:28PM KING CO. WLRD NO. 1695 P. 3 TO 'i'ONY •LEDBETTER, SUPERVISOR \\� \ FROM LARRY GETTLE, SENtoq 'ENION''`" ROADS DIVISION 4 \ .` �\ SURFACE WATER MANAGEMENT \\ KEM ON :\\ ��• LOCAL DRAINAGE SERVICES UNIT MAIL STOP 9A Ktng County MAIL STOP 022 Surface Water Management Brea7044% 111,01 dewhe.a .....-. to�.........ti. ......wui�.....................y.,. ........ ...��� ..... MESSAGE DATE 9-27-96 • FOR YOUR RESPONCE. DRAINAGE PIPE AT 19121 - 124TH AVE SE APPEARS TO I3E WITHIN THE 120' RIGHT-OF--WAY AS SHOWN ON THE ACCESSORS MAP. PIPE APPEARS TO 8E PLUGGED, PLEASE REPLY IF ROADS WILL CORRECT. IF NOT POSSIBLE NDA. ,9„7 • 1 • ► A 1 IA 192ND ter 1 r SIGNED REPLY DATE • ,at„ ?1C-)) .11 • Litv _ �L IA 0 • SIGNED OCT, 30. 2006 3: 23PM KING CO, WIRD - --'I I� �-Nt O3 rNO. 1695 P. 4 King County .P91.13 NO. 96-1550 Surface Water • \�\ \\� Management NAME JEANtVIE RILEY Management :........, s,.eizme creorastreas ADDRESS 18121 - 124TH AVE SE PHONE 854-9397 TB PAGE 646-F2 DRAINAGE INVESTIGATION REPORT KROLL PAGE 605W DAV3 9-13-96 FIELD INVESTIGATION MAINT, DIVISION 4 INITIALS- MAM DETAILS OF INVESTIGATION: /\ SITE Vlslrt ON e•os-;e. PLUGGED DRAINAGE CROSS CULVERT • INVESTIGATION FOUND SIGNS OF DRIVEWAY BEING WASHED OUT AT 1;121 -124TH AVE SE. AN 1e CONCRETE DRIVEWAY CULVERT WAs FOUNb TO BE FULL OF SEDIMENT AND GRAVEL WHICH IS RESTRICTING FLOWS. DURING INVESTIGATION ONLY A SMALL AMOUNT ON WATER WAS PASSING THROUGH THE PIPE. II PHOTOS TAKEN *1 LOOKING AT DRIVEWAY AND SIGNS OP WASHING OUT CAUSED BY PLUGGED CULVERT. 0 2 LOOKING AT UPSTREAM END OF CULVERT IMPACTED WITH • ti c. SKETCH: HOUSE .....`... 10121 :. GRAVEL DRIVEWAY • AREA BEING WASIM OUT • • POWER POLE O '�P CRDSS CULVERT �"" 10'CONC PIPE FLAW DIRECTION . ROADSIDE DRAINAGE . . . . . SE 192ND ST w Cl? w N FEB. 20. 2008 3:54RING 41(I NG CO. WLR DrERAND LAND RESOURCES DIvISIN°. 9141 P. 2/6�-a. DRAINAGE INVESTIGATION REPORT M Page 1: INVESTIGATION REQUEST Type PROBLEM:' Dom'/n/v44 _ / 11��,A� RECEIVED BY: 2- ( E776•& Date: ���/ 9 7 OK'd by: ✓1— FILE No. R"7- 13 b. I Received from: 11 (Day) ( ) (Eve) ( _ NAME; +'� N 61J el..;5 PHONE ADDRESS: City State vi Zip ?Po Se Location of problem, if different: 9 (Z 5 (2-4 S T ‘p(- ..c '. (D a,v;cL C. Cq i b miq Reported Problem: CALL FIRST d (Would Lake To Be present) Re_n-t-brt 9 Bn$g?Z37 �QaP T� A-12_ X2/s 7- 7i /l 2 /mac Co c -r Yom/t/L'7,v4A T �s/L{/� Tf' �'f s O /Y6.0 9-e-,S' �e7 %'/? - �o'7��i!l�.fiAnr� �f j / i 4,•••":4t7 Plat natne: iv. 1,3 e�f e.Yki 4a.r-e!•e,4 V.-5- Lot No: q Block No: Other agencies involved: 97—c2( 9 r9 r No field investigation required , ,. (initials) . M . y, •K � �� t � s� ^ T - X7YoI, . • 1 %a S T R Parcel No, f //ef 65D —004- Kroll 6e251.1)Th.Bros: New 6z F Z q Old 4z }36 Basin 5 DD Council District ( Charge No. RESPONSE: Citizen notified on by; phone letter in person Co►wpLA)m-r L° Lo fo 47 - 1 (I/ ZNvtr srfG .S►>—ioAJ /?E 151), DISPOSITION: Turned to on / / by OR: No further action recommended because: Lead agency has been notified: _ Problem has been corrected. No problem has been identified. Prior investi ation addresses problem: saz ru,s# 7—/1z/ Private problem-NDAP will riot consider because: Water originates onsite and/or on neighboring parcel. Location is outside WLRDSe ' Other(Specify): DATE CLOSED: 7 / / 7 7 By: , S�L� 27//77 _FEB. 20. 2008 3:54PM _ KING CO. WLRD NO. 9141 P. 3/6 KING COUNTY vrca rro. 97-1301 • Department of Natural Resources NAME ANONYMOUS Water and Land Resource Division ADDRESS 19125 - 121ST PL SE PHONE TB PAGE 686-F2 DRAINAGE INVESTIGATION REPORT IazoT.T,PAGE sosw DATE 7-25-97 FIELD INVESTIGATION MAIM'.DIVISION 4 INITIALS- MAM DETAILS OF INYESTIC:ATION: • /\ SITE VISIT ON 7.24.97. PROPERTY OWNER AT 1G12s - 121ST PL SE FILLING IN DRAINAGE DITCH WITH s•PERF. INVESTIGATION FOUND 121ST PL sr= Is A PRIVATE ROAD WITH AN OPEN DITCH ON THE WEST SIDE OF THE STREET. NW THE PROPERTY OWNER AT 19126 is IN THE PROCESS OF INSTALLING A 6"PERF PIPE WITH DRAIN BOXES 1N THE DITCH IN FRONT OF THEIR PROPERTY.THE EXISTING DRIVEWAY CULVERTS ARE 12'CONCRETE. FURTHER INVESTIGATION FOUND A CONTROL STRUCTURE WHICH SERVICES THE DRAINAGE DITCH. IT APPEARS THE PROPERTY OWNER AT 19139 -121ST PL SE HAS FILLED IN HIS PORTION OF DITCH WITH 6•PERF PIPE. PROPERTY OWNERS MAY BE REDUCING THE STORAGE VOLUME WITHIN THE DITCH BY FILLING. COMPLAINT CLOSED TO 97-1179 •SKETCH: HOvss 1 S11 12 DOW A TT HOUSE ` ...:::...:::: •,,Y COHG 19125 • • V PERF LU DRAIN DO _] I- 1r ADS r HOUSE 19133 16•PERF 0•C P CONTROL STRUCTURE LI • SE 192ND ST FEB. 20. 2008 3:55PM KING CO. NERD NO. 9141 P. 4/6 KING COUNTY WATER AND LAND RESOURCES DIVISION i DRAINAGE INVESTIGATION REPORT y /9 Page l: 1'NVBSTIGA`f ION REQUEST. Type ( . .PROBiE;'vl: P /n/ • RECEIVED BY: (- G Ti -t Date: /$�/7? OK'd by: RR-444—'1;11x Received from: / (Day) (.'-53 (Eve) ( NAME: r/9/Z Y 149/V V f// C) PHONE PS-4- 2 4 ADDREss: '_..../ 9/3 5• /2/s-- /76 "----;3 City c'2( 1-7VAI State (.J4 Zip 9PO58 Location of problem, if different: / 'pg Reported Problem: CALL FIRST tEl (Would Lice To Be Present) 4-5 c Cf-4- L./fa DttJS/To PRg/,✓Act' S 7's�' -�-� ��'r�`` `' t [sem Pe- . s / /�S Ga/Ff cn� Gfl s �2 /� 4•tei / /i-f 57�TcY» ��t/ �J'Zti �� Qa 1 0 ^/d s'Ta�✓7 l SJiS TG�I. - ciT c/R 9 2 rn t,c4c -e ec r 21 p Sq' Ye..&f ckPA..— Ate, erAN° 5''n Plat name: /t/Cclovie,1.27j2%z..0.6_,77 . zoo c '- q Lot No: 1 Block No: Other agencies involved: No field investigation required initials r:' ii !7 W t '-�y� y+ :.•1 s..7",=r t•_r�,::� tF•-e•:�?:+�ry} �,' �:1 r�=.s:�r•s. r I�.�,.. ,:..:_ • % S T R Parcel No.6/c 6'/ff 2 Kroll as4) Tb.Bros: New ),,g6 J jEPR, Old Basin S� Council District / Charge No. RESPONSE: Citizen notified on /—/ 2'9 9 by: phone letter >< in person LdT 0, cA, SL/vr- 6, t-41 .Snyv asF,O 19N.0 % - 1F041)s P/v/1/o.0 ro 0/4/6Ck' vr./ S"c' /7t, 5/' 7; DTSPOSXTION: Turned to on p / / by OR: No further action recommended because: _,X2:_ _ Lead agency has been notified: h c)1I� 3 ��fi/L-17- 2) ti 4' Problem has been corrected, No problem has been identified. Prior investigation addresses problem: SE$FT# Private problem-NDAP will not consider because: Water originates onsite and/or on neighboring parcel. Location is outside WLRD Servi - - Other(Specify): DATE CLOSED: / �/ By: FEB, 20, 2008 3: 55PM KING CO, WLRDNO. 9141 P. 5/6 • KING COUNTY FILE NO. 98-0926 Department of Natural Resources NAME GARY VANGO Water and Land Resource Division ADDRESS 19133 - 121ST PL SE PHONE (253)854-2649 TB PAGE 886-F2 DRAINAGE INVESTIGATION REPORT DROLL PAGE 605W DATE 1-22-99 FIELD INVESTIGATION MAI'T DIVISION 4 INITIALS-MAM DETAILS OF INVESTIGATION: /N SITE VISIT ON 1-12-99, STREET DRAINAGE DLOCKED CAUSING DRAINAGE SYSTEM oN PRIVATE ROAD To SACK UR INVEsT{GATION FOUND THE DRAINAGE SYSTEM oN 121sT PL SE HAS A CONTROL STRUCTURE WHIcH DRAINS TO A CATCH BASIN IN THE ROAD RIGHT-op-WAY. THE SLIDE GATE FOR THE SYSTEM WAS OPEN WHICH ALLOWS FOR WATER© TO FLOW INTO SYSTEM FROM STREET CATCH BASIN. CLOSED SLIDE GATE AT THIS TIME. INSPECTED STREET NTS DRAINAGE ON SE 182ND ST JUST EAST OF 121ST PL SE FOR ANY BLOCKAGE. WHEN LINE WAS CANDLED LIGHT REFLECTED BACK. THERE APPEARS TO BE A METAL OBJECT ABOUT SO' DOWN THE UNE. TALKED TO COMPLAINANT IT WAS SUGGESTED SLIDE GATE BE KEPT CLOSED TO PREVENT A SACK WASH INTO PRIVATE SYSTEM. MENTIONED A MEMO WOULD BE SENT TO ROADS TO HAVE THEM INVESTIGATE OBJECT IN PIPE. NO PHoTO2 TAKEN SKETCH: HOUSF lU 18133 N a H- 0 T N (3 1r / ":1 ❑ 0 CANDLED PIPE NOTED SOME TYLE OF 9LOGKAGE SE 192ND ST LIGHT AEFLECT2B BACK FEB. 20. 2008 3:55PM KING CO, WLRD NO, 9141 P. 6/5 To:Tony Ledbetter,Supervisor I �, �� g�G Corcrr From:Larry Gettle,Senior Engineer __ © Department of Transportation Water and Land Resources Division Roads Maintenance Division 4 Oepulment Nalurel Ae>reweae Water end land aeeeuree DMelc� Local Drainage Services Unit Mail Stop 9A Renton -o+. Mail Stop G22 MESSAGE: DATE 1-28-99 INITIALS MAMVI • For your information: Investigation of drainage complaint 98-0926 found the drainage system east of 121a P1 SE may have a blockage.The drainage system on 121'l PI SE had a t-section with the slide gate left open allowing water to backup onto 12151 P1 SE. at time of investigation closed slide gate. See attached copy of investigation form for more information. • SIGNED REPLY: DATE • • • SIGNED Task 5 TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS Based on our inspection of the downstream system for the Kelsey's Crossing project, there does not appear to be any current conveyance capacity, erosion, or flooding issues. With that in mind, we do not see a need for any additional mitigation or analysis. We have also reviewed the previous drainage complaints which are included in Task 4 of this report. Complaint#96-1550 consisted of a plugged 18-inch concrete culvert. There was no information available to confirm that the culvert was cleaned. However, we can only assume that it was, since there have been no further complaints regarding this culvert. Complaint#97-1301 is not part of the downstream system for this project,but has been included at the request of the King County reviewer. Complaint#98-926 is part of the downstream and based on the available information; it consisted of a blockage in one of the downstream conveyance pipes. As with the previous complaint, there is no available information to confirm that the blockage was removed. However, we can only assume that it was since there have been no further complaints regarding this culvert. Based on our review of these drainage complaints for the downstream system, we do not see any conveyance capacity, erosion, or flooding problems that would warrant additional mitigation or analysis. The proposed project will provide Conservation Flow Control (Level 2)based on the 2005 King County Surface Water Design Manual. This will maintain pre-developed flows to the downstream system. Also, to meet individual lot BMP requirements, we are proposing "Reduced Impervious Surface Credit" per section 5.2.1.1 of the 2005 KCSWDM for each of the 13 lots. A Level 2 or Level 3 Off-Site Analysis should not be required for this project site as there is no evidence of potential problems identified in this Level 1 analysis. 12542.009.doc SECTION IV FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the soil type is modeled as "Till" for the Alderwood Gravelly Sandy Loam SCS classification as shown in Figure 4. Soils. The entire Site is modeled as "Forest." Results of the KCRTS analysis are included in this section. 2012 D. R.STRONG Consulting Engineers Inc. Page 14 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Pre-developed Hourly Time Step Modeling Input: 40 Land Use Summary , � -Area ?� # Till Forest 2.37 acres Till Pasture 0.00 acres Till Grass 0.00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres Total 2.37 acres Scale Factor : 1.00 Hourly Reduced Time Series: predevi ») Compute Time Series Modify User Input File for computed Time Series [.TSF] Pre-developed Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.149 2 2/09/01 18:00 0. 191 1 100.00 0.990 0.041 7 1/06/02 3:00 0. 149 2 25. 00 0. 960 0. 111 4 2/28/03 3:00 0. 115 3 10. 00 0.900 0.004 8 3/24/04 20:00 0. 111 4 5.00 0.800 0.066 6 1/05/05 8:00 0.097 5 3.00 0.667 0.115 3 1/18/06 20: 00 0.066 6 2.00 0.500 0.097 5 11/24/06 4:00 0.041 7 1.30 0.231 0. 191 1 1/09/08 9:00 0.004 8 1.10 0.091 Computed Peaks 0. 177 50. 00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 15 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 5 PREDEVELOPMENT AREA MAP ©2012 D.R.STRONG Consulting Engineers Inc. Page 16 of 55 Technical Information Report Kelsey's Crossing September 26,2012 �. I ` ' .� �� _,_ _ D � � � , , ^ _ ____ _ � � . � , �� �,� � , ,���� ,�� � � �� � � D.R.STRONG i � __ - . .-.- .- s.`� „ `--- CONSULTIIVG ENGlNEERS I ; � �_� ` _.- ' '� ' ''� , a° �vcx�irs Prrma�ns s�w�rars ' �. ( � �^v ,. .' � V`. . ;. ' ' �1 '` �� / 1M01 Ot2T.l27.�30.0 FXIRlO.MH),�GE039 a.F � / _ . �i:EM.'OF �`� f`L;'rla'iil�':E.:G.9—! �� amp m,�"' I i � ' � �`�"`'"'�'E"'E-' PREDEVE'LOPED ONSl7E AREA TO POND OFFSITE FRONTAG� i �°`''"-u � � / � � i � g�T� nweRwous(na�.�ivr� PERNOVS(FQ4EST) /MPROVEMENTS i � __� i � TO POND I �� ' � � zor�c o.oa ec I zcr ac � ' t I � ' � � TRA�T 8 + � , � r' i .; : Pf-,RC_` A � i �"�- ' � �, � -? `'`"^\�\� PREDEVfLOPED FRONTAGE IMPROVEMENTS TO POND � i �,`,+ r,�e:,� ov-z�'- ., J� r� �or�c Sl7E aPEA /A�ERYH7llS(PAYfMIX� acawous(r-or�s�) I � , �', '' . HOQ N1dE. _ . Q7J AC 0.00 AC Q1J AC . I -u�3'"� + i � . 4 C✓.':I I .. � � �I ill'8 .__ � ONSITEAREA � _ , :.•� � �i �i TO POND , `' '' -� � �/ � �� ``� PREDEVELOPED BYPASS AREA ; ' �'l��`f ��• i ' - -------� roru I / � � �-•. nS .�.,`Ir�t'EtECE • 571F ARFA Il/PERNOUS(PAYflVfNI) PFRNOl15(fOP£57) _.s=`'" F ; ry � ,� /, + � - __ `=i . `:I . I . - ' � � �� ` -< < 0.12 O.00AC O.iTAC v � I.�� / ! (� C�..a. FE'tf BrPASSAREA �_ _ ;� �; r _ �-��� � �� o-�r.1c � �- ��- !/ � pci �� �� \ �"-�.� ' � Q I ' 'x-�--µy--� �Ir °� °' �'�`� ; I� N — ----� � ' f `= � _ tj // �` � (� � O o � I / � r � Q � o � � ' � � _ � � W � �� ,�, I � ; , - � Q � �=(I Fl 7 2G� �il� �'� � I . � _ - G �Jf W N ..ne.Era,2.iO �'I ( ' .:a[J7 � - . ._. ,: �l.'—'y �I � � p I_�8'M=-i. .2J � 1 ' �, O M _<�,.�� -, - ; � Q � � �I �,_y5 R91.67 , .;.�� I I 1 � � ��_ I i\ }�c � -5-}' � � � ^ � � C���'r� I ' � / I ' ' '� •�w � E _,_Za .'_ I.. I ..� � -- - i -_ r,, _ � 3 �..!�:�-�..,_ ,' .I ''y . _..! ' _ i .._, s ��.:. � � � � . � . I a L�. :, O 2 ___.. _ I 1..� '` -I ': •' ',:' . < o ------ 4 �J I' � ._ . . . : � � � , , � �e�rr�i.��c_ � J J �, , :� �� :---.. ,' , � � , : . ,. .. , : � y � U � i '� � � � �� � � � � s� � � - o � OZ � � � U o� - - - I- FF RaNTAG - - - � - - - � .x IMPROVEMENTS W _ _ � i —=- TO POND _ , : . -_-_ _____ - - - - --- , ---- ---_ �- - ---- ---- -_ ------ ,..- �-' _." .. G.Y'J 4Ck.M�.,R / --... _:/ i , F. uV�.J 3L:�...P.: 7.i�7J9 - , _'_ .._ .- .-_ _ _. '__ / _�.:��/I —�—' /! . ,.7:� � � � 6 C l� .-N� O K .�-. c � � u 0 0 / h � 0 i 0 � 0 i c� DRAFIEO BY.• OSM DES/GN£D HY•DSM PROJECT ENGfN£ER:MAJ DATE' 09.21.72 PRO,.i�C7 h'0.:1200"1 FlGUP,£: S CCP`(BIGyT OO ZQ�2, D.R. STRONG CCNSUL7ING ENGWEERS INC. DEVELOPED SITE HYDROLOGY (PART B) Developed Site Area Hydrology KCRTS was used to model the developed peak runoff from the Site. The soil types are unchanged from the pre-developed conditions. The portions of the Site within the proposed clearing limits tributary to the proposed combination detention and water quality pond were modeled as "Till Grass" and Impervious as appropriate. Results of the KCRTS analysis are included in this section. Rdin (to flow control facility): Portions of offsite frontage improvements are being routed to the onsite combined detention and water quality pond, along with the developed onsite areas. Bypass: A portion of onsite area is not being collected and routed to the onsite flow control and water quality facility. This area is being treated as bypass, and the proposed combination detention and water quality pond is both over detaining and over treating for the bypassed areas. See Figure 6 Post Development Area Map for onsite, offsite, and bypass area locations. ©2012 D.R.STRONG Consulting Engineers Inc. Page 17 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Developed rdin (to flow control facility) Hourly Time Step Modeling Input: Land Use Summa -Area i Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.89 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.35 acres -Total 2.21 acres Scale Factor : 1.00 Hourly Reduced Time Series: rdinl »I Compute Time Series I Modify User Input I File for computed Time Series [.TSF] Developed rdin (to flow control facility) Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:rdin.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.407 6 2/09/01 2: 00 0.826 1 100.00 0.990 0.329 8 1/05/02 16:00 0. 513 2 25.00 0.960 0.490 3 2/27/03 7:00 0. 490 3 10.00 0. 900 0.353 7 8/26/04 2:00 0. 431 4 5.00 0.800 0.426 5 10/28/04 16:00 0. 426 5 3. 00 0. 667 0.431 4 1/18/06 16:00 0.407 6 2.00 0.500 0.513 2 10/26/06 0:00 0.353 7 1.30 0.231 0.826 1 1/09/08 6:00 0.329 8 1. 10 0.091 Computed Peaks 0.722 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 18 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Developed Bypass Hourly Time Step Modeling Input: land Use Summary • -Area .1 Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.07 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.06 acres -Total 0.13 acres Scale Factor : 1.00 Hourly Reduced Time Series: bypass Compute Time Series Modify User Input File for computed Time Series [.TSF] Developed Bypass Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:bypass.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.021 5 2/09/01 2:00 0.043 1 100.00 0.990 0.016 8 1/05/02 16:00 0.025 2 25. 00 0.960 0.025 2 2/27/03 7:00 0.023 3 10.00 0.900 0.016 7 8/26/04 2: 00 0.022 4 5.00 0.800 0.020 6 10/28/04 16:00 0.021 5 3.00 0. 667 0.022 4 1/18/06 16:00 0.020 6 2.00 0.500 0.023 3 10/26/06 0:00 0. 016 7 1.30 0.231 0.043 1 1/09/08 6:00 0. 016 8 1.10 0.091 Computed Peaks 0.037 50.00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 19 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 6 POST DEVELOPMENT AREA MAP ©2012 D.R.STRONG Consulting Engineers Inc. Page 20 of 55 Technical Information Report Kelsey's Crossing September 26,2012 i ; �. . . . , - . _ . , � _ , . . ; ;< , . - , , . : , ; _ -- _ _ ;- .- - , � , . ,- , _ - � ;. - , , ,� - : . ; - ,_r� i, �. : ,� _, .�.. " , -- I I - .. �. - -- s - _ai__; i � � �, ` � � � � ' i� k' � '' F `- MAXIMUM /MPERI?OUS TABLE D.R.STRONG CONSULTlNG ENGINEEAS �$1 '� F.: ;�� V I , ";• ; ( NAXNA/N ALLOWABLE RE57RIC1E0 � I I lYPERNOUS A4E1 P[R LY)DE lMPE/tN0U5 FOOTPRWT h I � I .' a l-'� ,� . ' ,) LOTNQ LOTAREA r��NE3&hAtPbO KWKLA�AIDV Ao�3 I �� •:1.,? ��". I 1547 71fl3 2728 O<25.B2�.JOG1 F12i8�]21Z3 OFFSITEFKONTAGff � ��, � .= i�E� I " ' � �� s szes svas zsss »,„„,,,,,,g�,,,, IMPROVEMENTS W �� � Z 3`' � 4! 5 6 t 7. ' ''�" �68' Z'oo ��� I W� r- -- I �359 30S1 T6/5 TO POND I � i �� 1 '� s „09 .ro� 7645 t .W I C Y`"' C. �� 6 �3I9 301J 159I CJ � I � �- '? I '� ,,.>� � � 4,ui .w�s sc.0 I Q 1. ' .�!� ..��L ��� � B IIN 297f 25f6 : r � �, . r '•. Z � . : i � F �• , , . ` `� �', T ! y,'\ 9 J960 1772 1376 � � � ' � ' ----t-- ' � '' L-- ---- _,.� ro *aw aass zeas I - n s3�e .ses.� .u�i SE 1 ST LANE �„ 1S �500 3f50 2700 � . �� . 1J I666 J266 7800 0 ''.�� :� o � .. - ,_ ONSlTE AREA. i ^� � • .. .. _ . TO POND`� � ` � �� - - - - ` . � � 93�a � � ;� �� ��+;��� � I ! 8'� > + � POST DEVELOPED ONSlTE AREA TO POND BYPASS AREA I I �1'_ ___ P7� - _ TRACT`6� S7ETAREA '��NOUS(PAlfll/EN� PERNWS(1HL GRASS) — I f � - �'_ ���- � � - _ _ GaArNAGEFACIUT.'ES f2asf xq R ^ � � � � I 207 AC I.?J AC Q78 � � -.-- � �� ,� %rnacr a- _ _ : . , .. '. ,''''/2 � j � PR.vA10.37rW�macr +a� J. p; .,:.,. _ � �. ' ��I � _.�, .. -. /.� * ,'` / -......_—� ' '-- __ ,� ;. � / . � , � 8 . G �� 9' � POST DEVFLOPED FRONTAGE IMPROVEMENTS TO POND � � � o � , � I � � �T�. Q O � WPfRNIX15(PA4E)/EN� Perrweus[rni canss) � � C !F*`�PD I :1. . — I � _f [1 AIE AREA � � f1 � ��.CJp '� � � . '-� `� � � ' ;CLCY � � 0.23AC 0./2AC 0.tlAC \ R Wf1� N i �'1 Y � � ,I, J t. JJJi � � IO .18T � �^�r(� � �/y �L p � I I . _�Fl 3..< /77.: � +- 'A rl � N � � � V� \ . I I -�",� - n i; � � � Q 0 � - \ - ,1� �- � { i I I �ea �� 0 � f� � / � � � . , ,; � � � POS DEVfLOPEO BYPASS AREA Q 2 N 4 L12 l ��� I �.-� ' _ / ��,_- TOTAL T � W � + :C!18 r�..�,ai_�2 1 :I � . I .r, , t' � ..a ' ..T 97F AREA PO7NCU5 PA NOYIS(TRC '` CIu �-_t c nr ( �tuav� vtx raauJ � � a, _ . � i � y"-. ,-. . . . - .i � 0.l2 Q06AC a07AC 3 � � � t ._�� ',�_I : .. '�_ ' / ��E�'N C�i f':;__�r . .._-"._--.___ ' , " 49.� 7 �A O O o — -�, � . . . . .._ = _ —• _ — 1,, W Z ♦I �. ° , � � - I ��-�- ��--�\-��-�- _�_� - ,"i A ] �.I v_ ,1 � V � �+� <f*Cc� I7+G7 SE f92N0 STREET 43rCG BYPASS AREA ��,,,�, as.Lh7 � �i � U � �I — ��� ��H�i G - . — — � . � . —r — I — — � — � � � o , MENTS � � � W v � ` TOPPOND I-- _ -- _ _ : --- ---- - v .... - - �. -- _ _ - ----- � ---- - - o , , ___ _ _-- -- -- � — .—.—•—•—- - � � i `o a c C s c m � � u 0 0 � % N / O / G N / DRAF7E0 BY.� DSM �, D£SICNED BN OSlA �' PROJECT ENClNEER:MAJ DA7E:09.21J2 ' PROJECT NO.:12051 �rcuRe 6 CCPY?GHT OO ����, D.R. S�0'dG CG'<SCLTING EfJGiNEERS INC. PERFORMANCE STANDARDS (PART C) The Project is required to meet the Level 2 Flow Control and Basic Water Quality Treatment requirements. The Level 2 performance requires the developed condition discharge rates to match the predeveloped rates ranging from 50% of the two-year peak up to the 50-year peak. Also match developed peak discharge rates to predeveloped peak discharge rates for the 2 and 10-year return periods. The Project is located in the Basic Water Quality Treatment area. The treatment goal is removal of 80% of Total Suspended Solids for flows including the WQ design flow or volume defined in Section 6.2.1 of the 2005 KCSWDM. Conveyance criteria for the Project require that all new pipes be designed to convey and contain (at minimum) the 25-year peak flow. The conveyance system as designed will convey the 100-year peak storm with overtopping of the most upstream structures. FLOW CONTROL SYSTEM (PART D) The Site will utilize a detention pond meeting the Level 2 Flow Control Criteria. The King County Runoff Time Series (KCRTS) software was used to size the detention facility. The detention pond design information is included in this section. Flow Control BMP Selection Subdivision projects are required to mitigate for impervious surface equal to a minimum of 10% of each lot area by use of Flow Control Best Management Practices (BMP's). Projects are required to first analyze the feasibility of dispersal and infiltration before choosing another method. The Site's location and surrounding urban environment, together with the size of the proposed lots are not conducive to stormwater dispersal. The site contains till soils, and therefore indicates that the Site is not highly suitable for infiltration. Therefore, the Reduced Impervious Surface Credit BMP as described in Appendix C, Section C.2.9 of the KCSWDM will be utilized for the Project. The maximum impervious surface allowed per zoning code for the total lot area (1.34 acres) is 0.94 acres using the maximum allowable build-out rate of 70%. All lots shall be restricted to a maximum impervious coverage equal to 60% of each lot area (0.81 acres). A restricted footprint covenant shall be recorded on the face of the final plat map. This satisfies the flow control BMP requirements in Section 1.2.3.3 and 5.2 of the KCSWDM. ©2012 D.R.STRONG Consulting Engineers Inc. Page 21 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Flow Control Facility Design Output Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 3.00 H:1V Pond Bottom Length: 55.50 ft Pond Bottom Width: 55.50 ft Pond Bottom Area: 3080. sq. ft Top Area at 1 ft. FB: 8482. sq. ft 0. 195 acres Effective Storage Depth: 5. 10 ft Stage 0 Elevation: 0.00 ft Storage Volume: 25962. cu. ft 0.596 ac-ft Riser Head: 5.10 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.76 0.035 2 3.68 1.60 0.083 4 .0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 0.00 0. 0. 000 0.000 0.00 3080. 0.01 0.01 31. 0.001 0.001 0.00 3087 . 0.02 0. 02 62. 0.001 0.002 0.00 3094. 0. 03 0. 03 93. 0. 002 0.003 0.00 3100. 0.04 0.04 124. 0.003 0.003 0.00 3107 . 0. 05 0.05 155. 0.004 0.003 0.00 3114. 0. 06 0.06 186. 0.004 0. 004 0. 00 3120. 0. 16 0. 16 501. 0.012 0.006 0.00 3188. 0.26 0.26 824. 0.019 0.008 0.00 3256. ©2012 D.R.STRONG Consulting Engineers Inc. Page 22 of 55 Technical Information Report Kelsey's Crossing September 26,2012 0.36 0. 36 1153. 0 . 026 0. 009 0. 00 3325. 0. 46 0. 46 1489. 0. 034 0.011 0. 00 3394 . 0. 56 0. 56 1832. 0.042 0. 012 0. 00 3464 . 0. 66 0. 66 2182 . 0. 050 0. 013 0. 00 3535 . 0. 76 0.76 2539. 0.058 0. 014 0. 00 3607 . 0. 86 0. 86 2903. 0. 067 0. 015 0. 00 3680. 0. 96 0. 96 3275 . 0 . 075 0. 015 0. 00 3753. 1. 06 1. 06 3654 . 0 . 084 0.016 0. 00 3827 . 1. 16 1. 16 4040. 0.093 0. 017 0. 00 3901. 1.26 1 .26 4434 . 0. 102 0. 018 0. 00 3977 . 1.36 1. 36 4835 . 0 . 111 0. 018 0. 00 4053. 1. 46 1. 46 5244 . 0. 120 0. 019 0. 00 4129. 1.56 1 . 56 5661. 0. 130 0. 020 0. 00 4207 . 1. 66 1. 66 6086. 0. 140 0. 020 0. 00 4285 . 1.76 1. 76 6518 . 0. 150 0. 021 0. 00 4364 . 1. 86 1 . 86 6959. 0. 160 0. 021 0. 00 4444 . 1. 96 1. 96 7407 . 0. 170 0. 022 0. 00 4524 . 2 . 06 2 . 06 7863 . 0. 181 0. 023 0. 00 4605 . 2. 16 2 . 16 8328 . 0. 191 0.023 0. 00 4687 . 2.26 2 .26 8801. 0.202 0. 024 0. 00 4769. 2.36 2 . 36 9282 . 0.213 0. 024 0. 00 4853 . 2. 46 2 . 46 9771 . 0.224 0. 025 0. 00 4936. 2. 56 2 .56 10269. 0. 236 0. 025 0. 00 5021. 2. 66 2 . 66 10775. 0.247 0. 026 0. 00 5107. 2 .76 2.76 11290. 0.259 0. 026 0. 00 5193. 2.86 2 . 86 11814 . 0.271 0. 027 0. 00 5279. 2. 96 2 . 96 12346. 0.283 0.027 0. 00 5367 . ©2012 D. R.STRONG Consulting Engineers Inc. Page 23 of 55 Technical Information Report Kelsey's Crossing September 26,2012 3.06 3.06 12887. 0.296 0.027 0. 00 5455. 3. 16 3. 16 13437. 0.308 0.028 0. 00 5544 . • 3.26 3.26 13996. 0.321 0.028 0.00 5634 . 3.36 3.36 14564 . 0.334 0. 029 0.00 5724 . 3.46 3.46 15141. 0.348 0. 029 0.00 5816. 3.56 3.56 15727. 0.361 0.030 0. 00 5907 . 3. 66 3. 66 16323. 0.375 0.030 0. 00 6000. 3. 68 3. 68 16443. 0.377 0. 030 0. 00 6019. 3.70 3.70 16564 . 0.380 0. 031 0. 00 6037. 3.71 3.71 16624. 0.382 0.032 0. 00 6047 . 3.73 3.73 16745. 0.384 0.035 0. 00 6065 . 3.75 3.75 16867. 0.387 0.039 0. 00 6084 . 3.76 3.76 16927 . 0.389 0. 044 0.00 6093. 3.78 3.78 17050. 0.391 0.049 0. 00 6112 . 3.80 3.80 17172 . 0.394 0.054 0. 00 6131. 3.81 3.81 17233. 0.396 0. 056 0.00 6140. 3.83 3.83 17356. 0.398 0.058 0. 00 6159. 3. 93 3. 93 17977 . 0.413 0.066 0. 00 6254 . 4.03 4 .03 18607 . 0. 427 0.073 0. 00 6349. 4. 13 4. 13 19247 . 0. 442 0. 078 0.00 6445 . 4.23 4.23 19896. 0.457 0.084 0. 00 6542 . 4.33 4 .33 20555. 0.472 0.089 0. 00 6639. 4. 43 4 . 43 21224 . 0.487 0.093 0. 00 6737 . 4.53 4.53 21903. 0.503 0.097 0.00 6836. 4. 63 4. 63 22591. 0.519 0. 101 0.00 6936. 4.73 4.73 23290. 0.535 0. 105 0.00 7036. 4.83 4.83 23998 . 0.551 0. 109 0.00 7137 . ©2012 D. R.STRONG Consulting Engineers Inc. Page 24 of 55 Technical Information Report Kelsey's Crossing September 26,2012 4. 93 4. 93 24717. 0.567 0. 112 0. 00 7239. 5. 03 5.03 25446. 0.584 0. 116 0.00 7341. 5. 10 5. 10 25962. 0.596 0. 118 0.00 7413. 5.20 5.20 26709. 0. 613 0. 429 0.00 7517. 5.30 5.30 27466. 0. 631 0. 996 0.00 7621. 5. 40 5.40 28233. 0. 648 1.730 0. 00 7726. 5. 50 5. 50 29011. 0. 666 2.520 0. 00 7832. 5. 60 5. 60 29800. 0. 684 2.810 0. 00 7939. 5.70 5.70 30599. 0.702 3. 070 0. 00 8046. 5.80 5.80 31409. 0.721 3.300 0.00 8154 . 5. 90 5. 90 32230. 0.740 3.520 . 0. 00 8263. 6. 00 6. 00 33062. 0.759 3.730 0. 00 8372. 6. 10 6. 10 33904. 0.778 3. 930 0.00 8482. 6.20 6.20 34758. 0.798 4. 120 0. 00 8593. 6.30 6.30 35623. 0.818 4.290 0. 00 8705. 6. 40 6.40 36499. 0.838 4. 470 0.00 8817. 6.50 6.50 37386. 0.858 4. 630 0. 00 8930. 6. 60 6. 60 38285. 0.879 4.790 0.00 9044. 6.70 6.70 39195. 0. 900 4 . 950 0.00 9158. 6.80 6.80 40117. 0. 921 5. 090 0.00 9274 . 6. 90 6. 90 41050. 0. 942 5.240 0. 00 9390. 7. 00 7.00 41995. 0. 964 5.380 0.00 9506. 7. 10 7. 10 42951. 0. 986 5.520 0.00 9624 . Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.83 0.53 5.22 5.22 26843. 0.616 2 0.41 0.12 5.10 5. 10 25949. 0.596 3 0.49 0.10 4 . 61 4. 61 22480. 0.516 4 0.51 0.10 4.59 4.59 22303. 0.512 5 0.43 0.07 4.01 4. 01 18483. 0.424 ©2012 D.R.STRONG Consulting Engineers Inc. Page 25 of 55 Technical Information Report Kelsey's Crossing September 26,2012 6 0.33 0.03 3.37 3.37 14647. 0.336 7 0.28 0.03 3.72 3.72 16693. 0.383 8 0.35 0. 02 2. 46 2.46 9755. 0.224 Hyd RID Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.53 0.04 ******** ******* 0. 54 2 0. 12 0.02 ******** ******* 0. 13 3 0. 10 0.03 ******** 0. 12 0. 11 4 0.10 0.02 ******** ******* 0. 11 5 0.07 0.02 ******** ******* 0.08 6 0.03 0.02 ******** 0. 07 0.04 7 0.03 0.01 ******** ******* 0.04 8 0.02 0.02 ******** ******* 0.04 Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0.826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0.616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0. 118 2 2/09/01 21:00 0.530 5.22 1 100.00 0.990 0.029 7 1/07/02 4 : 00 0. 118 5. 10 2 25.00 0.960 0. 100 3 3/06/03 22: 00 0.100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7: 00 0.099 4.59 4 5.00 0.800 0.034 6 1/08/05 5: 00 0.072 4. 01 5 3. 00 0.667 0.072 5 1/19/06 0: 00 0.034 3.72 6 2.00 0.500 0.099 4 11/24/06 8: 00 0.029 3.37 7 1.30 0.231 0.530 1 1/09/08 10: 00 0.025 2. 46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50.00 0.980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob ©2012 D.R.STRONG Consulting Engineers Inc. Page 26 of 55 Technical Information Report Kelsey's Crossing September 26,2012 (CFS) (CFS) Period 0. 129 2 2/09/01 18:00 0.545 1 100. 00 0.990 0.041 6 1/05/02 16:00 0. 129 2 25. 00 0. 960 0.109 3 3/06/03 19: 00 0. 109 3 10.00 0. 900 0.039 8 8/26/04 2: 00 0. 108 4 5.00 0.800 0.040 7 1/05/05 8: 00 0.077 5 3.00 0. 667 0.077 5 1/18/06 23: 00 0.041 6 2.00 0.500 0.108 4 11/24/06 6:00 0.040 7 1.30 0.231 0.545 1 1/09/08 10:00 0.039 8 1.10 0.091 Computed Peaks 0.407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability O O CFS % - O 0.002 31965 52.128 52.128 47.872 0.479E+00 0.005 5080 8.284 60. 413 39.587 0.396E+00 0.008 4953 8.077 68.490 31.510 0.315E+00 0.012 4101 6. 688 75. 178 24.822 0.248E+00 0.015 3880 6.327 81.505 18.495 0.185E+00 0.018 4671 7. 617 89.123 10.877 0. 109E+00 0.022 2302 3.754 92 .877 7. 123 0.712E-01 0.025 1505 2. 454 95 .331 4. 669 0. 467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1.187 99.410 0.590 0.590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0.486E-02 0.045 6 0.010 99.524 0.476 0. 476E-02 0.048 17 0.028 99.552 0.448 0. 448E-02 0.051 11 0.018 99.569 0.431 0.431E-02 0.054 11 0.018 99.587 0.413 0.413E-02 0.058 16 0.026 99. 614 0.386 0.386E-02 0.061 24 0.039 99. 653 0.347 0.347E-02 0.064 28 0.046 99.698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0. 024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0.181 0. 181E-02 0.081 8 0.013 99.832 0.168 0.168E-02 0.084 10 0.016 99.848 0.152 0.152E-02 0.087 10 0.016 99.865 0. 135 0.135E-02 0.091 13 0.021 99.886 0.114 0.114E-02 0.094 10 0.016 99. 902 0.098 0. 978E-03 0.097 12 0.020 99. 922 0.078 0.783E-03 0. 101 14 0.023 99. 945 0.055 0.554E-03 0.104 8 0.013 99. 958 0.042 0.424E-03 0.107 9 0. 015 99. 972 0.028 0.277E-03 0.110 4 0.007 99. 979 0.021 0.212E-03 0.114 4 0.007 99.985 0.015 0. 147E-03 0.117 5 0.008 99.993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % ° 0 ©2012 D.R.STRONG Consulting Engineers Inc. Page 27 of 55 Technical Information Report Kelsey's Crossing September 26,2012 0.002 31997 52.180 52. 180 47.820 0.478E+00 0.005 5419 8.837 61.018 38. 982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 0.013 4075 6. 645 76.370 23. 630 0.236E+00 0.016 4635 7.559 83. 929 16.071 0. 161E+00 0.020 3523 5.745 89. 674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0.380E-01 0.031 1383 2.255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0.145 99.403 0.597 0.597E-02 0.042 41 0.067 99. 470 0.530 0.530E-02 0.045 24 0.039 99.509 0. 491 0. 491E-02 0.049 16 0.026 99.535 0. 465 0. 465E-02 0.052 16 0.026 99.561 0. 439 0. 439E-02 0.056 10 0.016 99.578 0.422 0. 422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0.184 0. 184E-02 0.085 9 0.015 99.830 0.170 0. 170E-02 0.088 9 0.015 99.845 0. 155 0. 155E-02 0.092 12 0.020 99.865 0. 135 0. 135E-02 0.096 12 0.020 99.884 0. 116 0. 116E-02 0.099 13 0.021 99.905 0.095 0. 946E-03 0.103 7 0.011 99. 917 0.083 0.832E-03 0.107 14 0.023 99. 940 0.060 0. 603E-03 0.110 12 0.020 99. 959 0.041 0. 408E-03 0.114 7 0.011 99. 971 0.029 0.294E-03 0. 117 4 0.007 99. 977 0.023 0.228E-03 0. 121 4 0.007 99. 984 0.016 0.163E-03 0.125 7 0.011 99. 995 0.005 0. 489E-04 0.128 2 0.003 99. 998 0.002 0. 163E-04 Duration Comparison Anaylsis Base File: predev.tsf New File: dsout.tsf Cutoff Units: Discharge in CFS Fraction of Time Check of Tolerance Cutoff Base New %Change Probability Base New %Change 0.033 I 0. 95E-02 0. 90E-02 -4.8 I 0. 95E-02 0.033 0.032 -1. 1 0.042 I 0. 63E-02 0.53E-02 -15.9 I 0. 63E-02 0. 042 0.037 -12. 1 0.051 0.49E-02 0.45E-02 -8.6 0.49E-02 0. 051 0.045 -11. 6 0.060 I 0.37E-02 0.39E-02 6.2 I 0.37E-02 0. 060 0.062 4 .2 0.069 I 0.28E-02 0.29E-02 2. 9 I 0.28E-02 0. 069 0.070 1.4 0.078 I 0.22E-02 0.21E-02 -5. 9 I 0.22E-02 0. 078 0.076 -1.8 0.086 I 0. 15E-02 0.16E-02 11.0 I 0.15E-02 0. 086 0.090 3. 6 0.095 I 0. 10E-02 0. 12E-02 14.5 I 0.10E-02 0.095 0.099 3.2 0.104 I 0. 62E-03 0.75E-03 21.1 I 0. 62E-03 0. 104 0. 106 1. 9 0.113 I 0.34E-03 0.29E-03 -14.3 I 0.34E-03 0. 113 0. 112 -1.2 0. 122 I 0.23E-03 0. 11E-03 -50.0 I 0.23E-03 0. 122 0.117 -4 . 1 ©2012 D.R.STRONG Consulting Engineers Inc. Page 28 of 55 Technical Information Report Kelsey's Crossing September 26,2012 0.131 I 0. 16E-03 0.00E+00 -100.0 I 0.16E-03 0. 131 0.121 -7. 9 0. 140 I 0. 11E-03 0.00E+00 -100.0 I 0. 11E-03 0. 140 0.123 -12.2 0.149 I 0. 16E-04 0.00E+00 -100.0 I 0.16E-04 0. 149 0.129 -13.5 Maximum positive excursion = 0.003 cfs ( 5.0%) occurring at 0.061 cfs on the Base Data:predev.tsf and at 0.064 cfs on the New Data:dsout.tsf Maximum negative excursion = 0. 007 cfs (-14. 1%) occurring at 0.048 cfs on the Base Data:predev.tsf and at 0. 041 cfs on the New Data:dsout.tsf Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0. 826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year. 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21: 00 0.530 5.22 1 100.00 0.990 0.029 7 1/07/02 4:00 0. 118 5. 10 2 25.00 0.960 0. 100 3 3/06/03 22:00 0. 100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7:00 0.099 4.59 4 5.00 0.800 0.034 6 1/08/05 5:00 0.072 4.01 5 3.00 0. 667 0.072 5 1/19/06 0:00 0.034 3.72 6 2.00 0.500 0.099 4 11/24/06 8: 00 0. 029 3.37 7 1.30 0.231 0.530 1 1/09/08 10:00 0.025 2. 46 8 1.10 0.091 Computed Peaks 0.393 5. 19 50.00 0.980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.129 2 2/09/01 18:00 0.545 1 100.00 0. 990 0.041 6 1/05/02 16:00 0. 129 2 25.00 0. 960 ©2012 D.R.STRONGConsulting Engineers ineers Inc. Pae 29 of 55 9 Technical Information Report Kelsey's Crossing September 26,2012 0.109 3 3/06/03 19:00 0. 109 3 10.00 0.900 0.039 8 8/26/04 2:00 0. 108 4 5.00 0.800 0.040 7 1/05/05 8:00 0.077 5 3.00 0.667 0.077 5 1/18/06 23: 00 0.041 6 2.00 0.500 0. 108 4 11/24/06 6: 00 0.040 7 1.30 0.231 0.545 1 1/09/08 10: 00 0.039 8 1.10 0.091 Computed Peaks 0.407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability - % 0 CFS % % 0.002 31965 52.128 52.128 47 .872 0. 479E+00 0.005 5080 8.284 60. 413 39.587 0.396E+00 0.008 4953 8.077 68.490 31.510 0.315E+00 0.012 4101 6. 688 75.178 24 .822 0.248E+00 0.015 3880 6.327 81.505 18.495 0. 185E+00 0.018 4671 7. 617 89. 123 10.877 0. 109E+00 0.022 2302 3.754 92.877 7.123 0.712E-01 0.025 1505 2. 454 95.331 4 . 669 0. 467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1. 187 99.410 0.590 0.590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0. 486E-02 0.045 6 0.010 99.524 0.476 0.476E-02 0.048 17 0.028 99.552 0.448 0. 448E-02 0.051 11 0.018 99.569 0.431 0. 431E-02 0.054 11 0.018 99.587 0.413 0. 413E-02 0.058 16 0.026 99. 614 0.386 0.386E-02 0.061 24 0.039 99. 653 0.347 0.347E-02 0.064 28 0.046 99. 698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0.181 0. 181E-02 0.081 8 0.013 99.832 0.168 0. 168E-02 0.084 10 0.016 99.848 0.152 0. 152E-02 0.087 10 0.016 99.865 0.135 0. 135E-02 0.091 13 0.021 99.886 0.114 0. 114E-02 0.094 10 0.016 99.902 0.098 0. 978E-03 0.097 12 0.020 99.922 0.078 0.783E-03 0.101 14 0.023 99. 945 0.055 0.554E-03 0.104 8 0.013 99.958 0.042 0.424E-03 0.107 9 0.015 99.972 0.028 0.277E-03 0. 110 4 0.007 99. 979 0.021 0.212E-03 0. 114 4 0.007 99. 985 0.015 0. 147E-03 0. 117 5 0.008 99. 993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence Probability % O % CFS Exceedence_ O O 0.002 31997 52.180 52.180 47 .820 0. 478E+00 0.005 5419 8.837 61.018 38 .982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 30 of 55 Technical Information Report Kelsey's Crossing September 26,2012 0.013 4075 6.645 76.370 23. 630 0.236E+00 0.016 4635 7.559 83. 929 16.071 0. 161E+00 0.020 3523 5.745 89. 674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0.380E-01 0.031 1383 2.255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0. 145 99.403 0.597 0. 597E-02 0.042 41 0.067 99. 470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0. 491E-02 0.049 16 0.026 99.535 0.465 0. 465E-02 0.052 16 0.026 99.561 0.439 0. 439E-02 0.056 10 0.016 99.578 0.422 0. 422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0.184 0. 184E-02 0.085 9 0.015 99.830 0.170 0. 170E-02 0.088 9 0.015 99.845 0.155 0. 155E-02 0.092 12 0.020 99.865 0. 135 0. 135E-02 0.096 12 0.020 99.884 0.116 0. 116E-02 0.099 13 0.021 99.905 0.095 0. 946E-03 0.103 7 0.011 99. 917 0.083 0.832E-03 0.107 14 0.023 99. 940 0.060 0. 603E-03 0. 110 12 0.020 99. 959 0.041 0.408E-03 0.114 7 0.011 99. 971 0.029 0.294E-03 0.117 4 0.007 99. 977 0.023 0.228E-03 0.121 4 0.007 99. 984 0.016 0. 163E-03 0.125 7 0.011 99. 995 0.005 0.489E-04 0.128 2 0.003 99.998 0.002 0. 163E-04 ©2012 D.R.STRONG Consulting Engineers Inc. Page 31 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Flow Frequency Analysis Ea Pauud-Flow Frequen y-KCRTS Return Period 2 5 10 20 50 100 =o rdoutpks in Sea-Tac • dsout.pks -0 predev.pks • 0 R o - 0 L U • 0 • oeO 00 m O 0 N 10 2_ 0 103 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Cumulative Probability Duration Analysis Paused-Duration Analysis-KCHTS' '. 1 0, x-`- rdoutdur o dsout.dur • target.dur o o • eN R • Nil..„441\ 4. m o y 00 o. c, 0 I I I 1 1 1 1 1 1 I I I 1 1 1 1 1 1 I I 1 1 1 1 1 1 1 I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 10 10 10 3 10 2 10 1 10° Probability Exceedence ©2012 D. R.STRONG Consulting Engineers Inc. Page 32 of 55 Technical Information Report Kelsey's Crossing September 26,2012 WATER QUALITY TREATMENT SYSTEM (PART E) The Project is located in the Basic Water Quality Treatment area. The treatment goal is for removal of 80% of Total Suspended Solids for flows including the WQ design flow or volume defined in Section 6.2.1 of the 2005 KCSWDM. Wetpond Rainfall (R) of the mean annual storm = 0.47 in. From KCSWDM Fig. 6.4.1.A Area of impervious surface(Ai) = 61,177 s.f. Area of till soil covered with till grass(Atg) = 41,907 s.f. Area of till soil covered with till forest(Atf) = 0 s.f. Area of outwash soil covered with grass or forest(Ao) = 0 s.f. Volume factor(f) = 3 N/A From KCSWDM Sec. 6.4.1.1 Calculations Units Notes Volume of runoff from mean annual storm (Vr) = 2,567 c.f. =(0.9Ai+0.25Atg +0.10Atf+0.01Ao)*R/12 Minimum Wetpool volume required (Vb) = 7,700 c.f. =f*Vr The calculation shown above is based on 60% lot coverage. The provided wetpool volume is 8,278 c.f. with a minimum of a 4:1 length to width ratio. ©2012 D.R.STRONG Consulting Engineers Inc. Page 33 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FIGURE 7 DETENTION & WATER QUALITY FACILITY DETAILS ©2012 D.R.STRONG Consulting Engineers Inc. 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'2''"`'`E"'°E DETENTION SUMMARY SHEET FRCM POND I Df9GN W.S a 489.80 /E=481.70 ?' ����s �`R/P RAP PAD SPEClFICA7lONS FENCING SPECIF/CA770NS ���6 �!� RlPRAP SHALL BE REASO,NABLY N£iL GRAOED M11H GRADAiION AS Fr]JCMC SURRIX/NDIHG TRACT'B'SNAll BE w5D0T STANDARO M1. FOLLOWS' 1-20.70-OI TYPE J.6'MCH BULK NNTL GA7F SHALL BE BL7GC �'' NN11 DpJBLf GATE PER WSDOT STANOFRD L-JO.fo-01.LOLYC SHALL N, 6� MAJOMUAI STUNE 9ZE: 1f INGfES(NOMMlAL DlANE7ER) B£WRCNASEO A7 p7Y Cl�SAAMIAMSH. �3��� MEZNAN S70NE SYZE I6 lNCHES a�vnce�=r.eo' Mfw�*uv sror�s�zE• s u+ar�s POND LINER NOTE R!➢RAP.9ZlNG GOVERNED BY SIDE SLCl°ES ON CUIL£T CHhNN£L IS NO PONO LINER IS REIX/IRfD PER C£O7FCHNfCAL ENLYNEERINC SRXIY �•a. MEMORANWM DA7E0 NAY J,2012. ASSUNED TO BE APPROX7MAIELY 3:1 12'/R6ER I 12�G OU7LET PIPE 1.5 s OlA i E=484.70 - z,M� ,�ry�y REkOVAEttE WA7ERTICHT CWPLMC OR FLANGE ., iz•uaer wae �z•ouncr v�re PLAN V1EW � w��a�iav�s- -�vuN�s+.ro ��/�7�-� scacE r'a s=o' � p z.� I2'I CNP RISFF ].U�NANUM OF A Sf'IXA!/EfER 7YPE 7NYI CATCH BAS/N. � i � 2 W71Ef CAPAGTY: 100-177 OE4E20PED PEAK FLOW 3.NETAL PARTS CORR09ON RE457ANT. NON-GALYANlZED PARTS � 7'�CTION OF PIpE A77A!?�O BY p/zEFEqRE0. GALViWIZm PIPE PAA75 TO HA4£ASPHACT 7REAINENT 1. vl I GASKE7ID BAND TD ALLOW RENOVAL <.fAAME AND LAOOER OR S1FPS CKFSfT Stk •1Z L SNEAR GATE W/CONTROL RLO FOR � CLEANOU7 ORAlN(ROD BENi AS 2'M1N RfSTRlLTOR PLATE W/0.76'/ A IXEANIXIT GA 7E/S NSIBL£FRON 7DP. m`� rrEo'o Far t�Rncu a�vu�r w/ oRo-1cE s�soort�tvt� B.CYIMB-OON?I.S�ACE IS G.FAIt OF RfgR AND LYFi1N0UT Cr�JE RECOMMENDED FOR APPOVAL COIER)SEE KLRS ONG 53 �p.7p 5.1F AlETAL PUT1E7 PoPE CdYMFC75 TO fEMINT GnNCRETE P1PE , ,,. I� - IXlA£T P1PE TO HA4E SNOO7N O.R£QUAL 7D[X7NCREIE P1PE I.0. 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RECOMME DED FOR AP � vommu�i-ae�eq sR�cvurcn�(cxccrramm r�usr���na.cr ro xo.�nw�r omoss-axwris�ni rocrr BY: Date: 4. 7}45 OEBPoS BARRMFR/S FGR L6E W1SDE Q'"ROAO MCMT-QF-MAY 0'¢Y, f01Y QFHRIS G23 Nf7HW RWO � wwr-o�-w�r,stE aru�wc s-oze KCRs BY: Date: s BY: Date: � BIROCAGE EMERGENCY OVFRFLOW BY: Date: N � D.R.STRONG � �tis ►�nrED ""x"''"e"' : ,� CITY OF KELSEY'S CROSSING o6—is—i2 8 D p � CONSUCTING ENGINEERS c� Y � FIGURE 7:STORM DRAINAGE D=TAILS � D E,�,.���,��„5 �.,,�� R EN TON � � roaw�.aernae.rro�Kmiee.wo.w�asev �� d17UY oasan..x�ttv�zs.m�zav � =lannirg/Bu'IC"�ng/Puhlic ribrks DepL 2 pp y •�="=^*��sxn N�. REVIS�ON BY DATE APPR � 'r"'�"�""" �'�� � A-NNNN A SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN GENERAL PARAMETERS Per C.R. #4 of the KCSWDM, the conveyance system must be analyzed and designed for existing tributary and developed onsite runoff from the proposed project. Pipe systems shall be designed to convey the 100-year design storm. The Rational Method was used to calculate the Q-Ratio for each pipe node. A conveyance system consisting primarily of pipes and catch basins has been designed for the Project. Onsite runoff will be collected by the multiple catch basins. Pipes are typically twelve and eighteen-inch diameter LCPE material. The pipes will have a minimum slope of 1.00%. The pond primary overflow riser and jailhouse is designed to convey the 100-year peak storm (design storm), based on the KCRTS 15-minute time series for developed, undetained conditions on site. This is calculated at 2.04 cfs. A secondary emergencey overflow birdcage structure will also be provided. The results of the 15-minute KCRTS time series, overflow riser analysis, and KCBW Calculations are included in this Section. Pond Outfall The proposed combination detention and water quality pond will outfall to an existing 18-inch storm line which flows east along SE 192n Place. The proposed point of connection will be a 48-inch manhole with an invert elevation of 483.32. The water quality elevation of the proposed pond is 484.70. No tailwater effects are anticipated at the outfall during large storm events. 2012 D.R.STRONG Consulting Engineers Inc. Page 35 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Developed 15-Minute Time Step Modeling Input: nd Use'Surin a I I 4 a -Area Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.89 acres L: 11.50 S: 0.02 Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.35 acres L: 300.00 5: 0.02 -Total 2.24 acres Scale Factor : 1.00 15-Min Reduced Edit Flow Paths I Time Series: 15min_dev »I Compute Time Series I Modify User Input I Retrieve runoff files and compute Time Series Developed 15-Minute Time Step Modeling output: Flow Frequency Analysis Time Series. File: 15mindev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.736 6 8/27/01 18: 00 2 .04 1 100. 00 0.990 0.571 8 1/06/02 1:00 1. 60 2 25. 00 0.960 1. 60 2 12/08/02 17: 15 1.11 3 10. 00 0.900 0.617 7 8/26/04 1:00 1.00 4 5.00 0.800 1.11 3 11/17/04 5:00 0. 780 5 3.00 0.667 0.780 5 10/22/05 10:00 0.736 6 2.00 0.500 1.00 4 10/25/06 22:45 0. 617 7 1.30 0.231 2.04 1 1/09/08 6:30 0. 571 8 1. 10 0.091 Computed Peaks 1.89 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 36 of 55 Technical Information Report Kelsey's Crossing September 26,2012 BACKWATER ANALYSIS BACKWATER TABLE Storm Water Runoff Variables: A= Total of Subasin and Tributary Areas C= Runoff Coefficient(the anticipated proportion of rainfall volume that runs off the area)see 2009 KCSWM Table 3.2.1A Cc= Composite Runoff Coefficient Cc= S(Cn"An)/Arota Tc= Time of Concentration(Typically 6.3 minutes which is the minimum value used in calculations) R= design return frequency iR= Unit peak rainfall intensity factor 1R- (aR)(Tc)^(-bR) aR,bR= coefficients from 2009 KCSWM Table 3.2.1.6 used to adjust the equation for the design storm IR= Peak rainfall intensity factor for a storm of return frequency'R' IR= PR*jR PR= total precipitation(inches)for the 24-hour storm event for the given frequency. See Isopluvial Maps in 2005 KCSWM Figures 3.2.1.A-D QR= peak flow(cfs)for a storm of return frequency'R' QR= Cc*IR*A The Q-Ratio describes the ratio of the tributary flow to the main upstream flow. R= -year storm aR= 2.61 bR= 0.63 PR= inches Conveyance System Variables: d= pipe diameter n= Manning's Number I= length of pipe ©2012 D.R.STRONG Consulting Engineers Inc. Page 37 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Pipe Structures Subasins A A C CC Tc iR IR OR SOR C- d Material n I Slope invert invert over- C V Bend CB Tributaries subasiri Ratio in out flow Full Full Dia elev. Flow Flow FROM CB To CB sf Ac Ac Min. cfs cfs in ft % ft ft ft cfs fps CB#5 TO INLET 5 5 4 5 1617 0.04 0.90 6.3 0.82 3.19 0.11 0.11 0.00 12 N-12 0.012 24 3.62 49522 494.34 498.73 7.36 9.37 0 2 4 4 3 4 8462 0.19 0.76 6.3 0.82 3.19 0.47 0.58 4.42 12 N-12 0.012 70 3.62 494.34 491.79 493.73 7.37 9.38 90 2 3 3 2 3 13412 0.31 0.66 6.3 0.82 3.19 0.65 1.23 1.12 12 N-12 0.012 25 3.76 491.79 490.86 496.28 7.51 9.56 100.59 2 RNN201-2 r 29705 F.0.68 0.66 2 2 1 2 1632 0.04 0.90 2 2 1 2 31337 0.72 0.67 6.3 0.82 3.19 1.54 2.77 1.26 12 N-12 0.012 157 2.72 490.86 486.6 496.43 6.38 8.13 100.59 4 RUN'IO2-1 19333 r 0A4 0.72 1 1 INLET 1 1 3681 0.08 0.90 1 1 INLET 1 1 23015 0.53 0.75 6.3 0.82 3.19 1.27 4.03 0.48 18 N-12 0.012 78 4.98 486.10 482.2 490.99 25.45 14.40 90 2 CB#102 TO CB#1 102 102 101 102 16071 0.37 0.69 6.3 0.82 3.19 0.81 0.81 0.00 18 N-12 0.012 24 0.99 486.81 486.57 490.31 11.33 6.41 0 2 101 101 1 101 3262 0.07 0.90 6.3 0.82 3.19 0.22 1.03 0.27 18 N-12 0.012 37 1.29 486.57 486.1 490.31 12.95 7.33 90 2 19333 0.44 0.72 CB#201 TO CB#2 201 201 2 201 29705 0.68 0.66 6.3 0.82 3.19 1.43 1.43 0.09 12 N-12 0.012 104 1.00 491.90 490.86 494.90 3.88 4.93 0 2 CB#400 TO INLET 2 400 400 INLET2 400 13077 0.30 0.90 6.3 0.82 3.19 0.86 0.86 0.00 12 N-12 0.012 36 14.83 487.60 482.2 490.50 14.90 18.98 0 2 ©2012 D.R.STRONG Consulting Engineers Inc. Page 38 of 55 Technical Information Report Kelsey's Crossing September 26,2012 BACKWATER ANALYSIS MAP ©2012 D.R.STRONG Consulting Engineers Inc. Page 39 of 55 Technical Information Report Kelsey's Crossing September 26,2012 _ � i�;i'�! �'�_ I� �:' � �� �,\ - -- '; {= ,' ' ` � j�ii' a —____ _— .._ ��72)5Q7.f6 I ,� �� ��.� _ ` _ _ .... - t'l l ,'� ` <L1 �= �T�t=s;-�' . ;.�t . ,���f_ � .. -�-`--"a - -L- i -- - - 33f17.71.f2lY R� i 1 I � � � y �.f ' r 1 7 � I �, - � Reu sou� � i '` P � � ��J �t�I'i .� ` 'i/. ` f I I n`�� � . ;I_ � D.R.STRONG ��qgg� ' � �_ F = � � r � `- CONSULTlNGENGINEEAS ;r B3LOT i � � �^' �� CB 4 LOT i � �" �r v �i� � i. ' � � r �,. �csa r�seca a�.n+or K�Rlaa�ao,�wa sResms � ��2,4 5 8 S F ,� � C B�0 2 L O T f 4,547 SF l �•e-es.;= I ( ( ' ���' � ' _ . , o<z�az�ao�3 s<ss.az�xzr I i � ; i (, i ; � 13,�79 SF ,''i� ,�:. l i 2 ,.�..��.�,r �, i � ._, f CB 3�ROADi '�� ` ` ; i;?t ` I I u � CB 4 ROA� � � �� I i , i�� 954,SF , h '� '� � i ; a; f`` �n 39l6SF � i ; i .� �� ��: w ��/.� � , .� CB 70��iOAD �+ ��c ' '^ro+eao2 r2rrt uisas aztrt � I ` � ; �sa» I �sea� + � 952 SF ��� / i rs+oz�ti rvr e I ` ' I I �N raw�so.eo i I . :- i , s.w..0 ; ; wrn,l �� � _ �� � --- I �tee.ro y , . ---- � l� i - -�r I --;- ti__ ,:� { i � � �ii i �I ��t23`'; I ' ��'• �. -- -C -- _� � r ; � � � t ( T,_=_ - ' _ rs+.is.2�.�zfr i �� , �,_ - — L� ' �, - � ' , ' _t - -T �/, __ � ; , ,�:..��,.. -�r��_ .� � L __ I -- '�- � �� ,�.��, �:�• I _.� �F ��. _ � _ — ° , _�.-- _._ ,_�3f3t(k.; , �` . �' -.=�t . � L6 101 7YPF iL � . � � � 73+J924 12/ R � _ 1 .,.�� ' PoI!i�RJI � �-._ I . . � _ lE fB&37 `�^ `•.. � . . . � � . �''' �' � I -- - �_ �' � � � � CB5 ROAD , I � � 1 : � �� . .;: ;~ - - ' ;=C6 10!ROAD_ `!,6l�SF � i I , � ._ .' _ ,, ." - _ ; , _ r- -: I -- � � . i/i' - -- { rn�z-u �'-� --3,262_SF-s� r,�^�— ca soi rrae_r b _ ` : . r++aza7z�r s cw--- 1- � ? D .n+n.eZ iztY R � �ca �rac r i �as.0 i ��.uea `� �, ' f:��iar F � re Aso.as_,, r __ � �. - �E.: �._ � f-'� � \ (Ji n: -i � ��iEI.q5.22 (�� r� I �\` ^Hr �na'.. � i a � I t � !!-— CB 2 ROAD , i � . ' B �JQOAD{,' i i , \\ . ' , r°N,,h't r .� � � :c I a �, I : �__ _ 1�532 SF F-�' �-{ _ �68LSE � � ou�nwceFacx�r�s � , ^. ' , _�� z D � I I j : �' CB201 ROAD } , - --' -— __� { \�� *�_ � } i � �: CB 400 ROAD � €,' �� ' � 1 �raacT A - ' �-= _ - o � ' � Z�O3$SF._, � I 1 vg�vnrenccEssrancr ' i� i =' +e� ' (;'� f- c� 73�07T SF I I � �� . . ' i �% � zc3asa.g. ;� i I, I �`� � � h' �� � � � � , � , ,; � I �F� ' i �;� � I �,-�--_" } � i �' I I� `� I ; �C6 20.!LOT-1 `� h ' r I � ' � , , _ I-, M „ � i : � _27,672 SF !' _ l- - �I - _ � I � �__ - 1 � _�� a g0 � � � __ � ' - , c� , -� I I : > -/�- - -.. . _ _ � _�p -- ,_ y , ,,.. �_s. „uQ I � � ' - � � � y _ __ �I j/I✓ — i � I � :^ � ��a7 f����,S�, I � � � � 1 - I�' I I " _ � - �� re m �r - , � , J � ,: . r,� ' �:�-` �i`x,-s r^ \ . ,_. �•, 2f+S.AO 6.7Y,1 --�182-' / �i i - � � � v, Z � �`� � I - ���' , z ��,% � � r.so � ; � � � � � '� _ r-� ; � �re�.�a � ' ,��_° �� � � Q °' 2�w�a'ss�z� :e _ I ,_'S ( l isr�aa�zi.�r c i ,�— — _�as '�\i �, ce.wr rne 2�s- �_a,; -�a � . ` ;- �. .. ��sz ' ,' 1 - � �� ��— �,� ,� , ���"� � ,;, , .: �, 3 , I ' i ' - -— ,,_ _ ' — -' —! l — -- . .,..�+z�•� � 3 '� 1 >- � � �- , ;_ a ;��� � -—- � �` I ,. aau,a�zz . . I � f i. ♦ . i �/ 'O c, .. - IXC81 AIWNO� - _ - f _ 1 � � "lE18l7lF� .....: ,' � C 1 � _-_�.,,. �.. - ' ' .. . _ � � .w+zr..n.�a rr I 1 �. � . i - � s��rsrt s,�Er ai i� •� o raw+a�sz < _ , " � �� __ ` �� ss�. � �� � f`. . � - - __- ' "9F -_ ='� E_ ,. _ � ��- _ � _ , , , � - : � ; �(�sx��r.zz , , �- -, .-.�c . : . _. . . _ - _ _ — — — — - - � . �--� f _ . .-. , � _. ,: . _._. . . , . _ . . . . - -� , _ ,, . . `'. - � . . . . . . . . . . . . � , , o:' ' � ; r �/ i T ',, . � �\ . _ _._ . ... . .. ._ . .. . .. . _- .', _ .- .. . ._.. . . ..-.. .- . .�� . . . � • �� �'�� SpJOL0U7NGW - — ��'�U' _ . � � � `___-_ .. . . � p � . . ._ ,,, ____.__'____________________________ - --_- _--___ _ � ... . ..___4i+47.H,lflf}F'L - . :.�_ -� �LI Q � � ,u�r 4e��s � ' --�� � � U a _ • �saza - � rar�,�cr�+cr o�cow srrructuee 11, � — — — � � _ �sa�alt ..r� — — — �� — �1 Q � �or -r �t�r�t�cH aKc s�auu • � m O � � . � � � 43+7S.A721.}YL. � lE!%Ol � � ' U 3 . � � � � RN 4Ba.R7 . . . . . � � ..-. ._' , : . . . ... ... . . . .. . _ - __ �/ , - ,- ____. . -. .� � - I£C725)�48 � .___'_ , �, � ' ..._.__ __/E�12?/).487.Q7 _.._ ."—' ___ --_'_ '__ -___ � ` -- � 7.OJ __. -. .__._..._ _._-.__ ___—_ . _ m " _ .... � i ' - . - � ' _.___ I_ / � F- 0 c % � 0 n v � m � E � V i � I � I / r7 / � 0 % I 0 N O N / � ORAF7ED BY.• O�'A DES1C1Jf0 BY.•OS'd PROJECT£NGlNEER:MAJ OA7F.•09.27.12 PROJECT NO.:72G57 FIGJRE: . CCPY?�HT C 2��2, D.R. STRC�:V� CG\SULTING EN�'�,"JEERS IVC. ' BACKWATER COMPUTER PROGRAM FOR PIPES BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#5 TO INLET 1.bwp Surcharge condition at intermediate junctions Tailwater Elevation:489.92 feet Discharge Range:0.392 to 4.03 Step of 0.392 [cfs] Overflow Elevation:498.73 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 78 LF - 18"CP @ 4.98% OUTLET: 482.20 INLET: 486.10 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 490.99 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.46 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.39 3.83 489.93 * 0.012 0.24 0.13 7.72 7.72 3.83 3.83 0.28 0.78 3.83 489.93 * 0.012 0.33 0.19 7.72 7.72 3.82 3.83 0.41 1.18 3.85 489.95 * 0.012 0.41 0.22 7.72 7.72 3.83 3.85 0.53 1.57 3.87 489.97 * 0.012 0.48 0.26 7.72 7.72 3.83 3.87 0.63 1.96 3.90 490.00 * 0.012 0.53 0.29 7.72 7.72 3.84 3.90 0.73 2.35 3.94 490.04 * 0.012 0.59 0.31 7.72 7.72 3.85 3.94 0.82 2.74 3.98 490.08 * 0.012 0.63 0.34 7.72 7.72 3.87 3.98 0.91 3.14 4.03 490.13 * 0.012 0.68 0.36 7.72 7.72 3.88 4.03 1.00 3.53 4.08 490.18 * 0.012 0.72 0.38 7.72 7.72 3.90 4.08 1.09 3.92 4.14 490.24 * 0.012 0.76 0.40 7.72 7.72 3.91 4.14 1.18 4.31 4.21 490.31 * 0.012 0.80 0.42 7.72 7.72 3.93 4.21 1.27 PIPE NO. 2: 156 LF - 12"CP @ 2.72% OUTLET: 486.60 INLET: 490.86 INTYP: 5 JUNC NO. 2: OVERFLOW-EL: 496.43 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.26 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.27 0.28 491.14 * 0.012 0.22 0.15 3.33 3.33 0.22 ***** 0.28 0.54 0.41 491.27 * 0.012 0.31 0.20 3.33 3.33 0.31 ***** 0.41 0.81 0.51 491.37 * 0.012 0.38 0.25 3.35 3.35 0.38 ***** 0.51 1.08 0.61 491.47 * 0.012 0.44 0.28 3.37 3.37 0.44 ***** 0. 61 1.34 0.71 491.57 * 0.012 0.50 0.32 3.40 3.40 0.50 ***** 0.71 1.61 0.80 491.66 * 0.012 0.54 0.35 3.44 3.44 0.54 ***** 0.80 1.88 0.89 491.75 * 0.012 0.59 0.38 3.48 3.48 0.59 ***** 0.89 2.15 0.98 491.84 * 0.012 0.63 0.41 3.53 3.53 0.63 ***** 0.98 2.42 1.07 491.93 * 0.012 0.67 0.43 3.58 3.58 0.67 ***** 1.07 2.69 1.16 492.02 * 0.012 0.71 0.46 3.64 3.64 0.71 ***** 1.16 2.96 1.26 492.12 * 0.012 0.74 0.48 3.71 3.71 0.74 ***** 1.26 PIPE NO. 3: 24 LF - 12"CP @ 3.76% OUTLET: 490.86 INLET: 491.79 INTYP: 5 JUNC NO. 3: OVERFLOW-EL: 496.28 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 1.12 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.12 0.17 491.96 * 0.012 0.15 0.09 0.28 0.28 0.15 ***** 0.17 0.24 0.25 492.04 * 0.012 0.21 0.13 0.41 0.41 0.21 ***** 0.25 0.36 0.32 492.11 * 0.012 0.25 0.15 0.51 0.51 0.25 ***** 0.32 0.48 0.37 492.16 * 0.012 0.29 0.18 0.61 0.61 0.29 ***** 0.37 ©2012 D.R.STRONG Consulting Engineers Inc. Page 40 of 55 Technical Information Report Kelsey's Crossing September 26,2012 0.60 0.43 492.22 * 0.012 0.33 0.20 0.71 0.71 0.33 ***** 0.43 0.71 0.47 492.26 * 0.012 0.36 0.21 0.80 0.80 0.36 ***** 0.47 0.83 0.52 492.31 * 0.012 0.39 0.23 0.89 0.89 0.39 ***** 0.52 0.95 0.56 492.35 * 0.012 0.41 0.25 0.98 0.98 0.41 ***** 0.56 1.07 0.61 492.40 * 0.012 0.44 0.26 1.07 1.07 0.44 ***** 0.61 1.19 0.65 492.44 * 0.012 0.47 0.27 1.16 1.16 0.47 ***** 0.65 1.31 0.69 492.48 * 0.012 0.49 0.29 1.26 1.26 0.49 ***** 0.69 PIPE NO. 4: 70 LF - 12"CP @ 3.62% OUTLET: 491.79 INLET: 494.34 INTYP: 5 JUNC NO. 4: OVERFLOW-EL: 498.73 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 4.42 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.06 0.11 494.45 * 0.012 0.10 0.07 0.17 0.17 0.10 ***** 0.11 0.11 0.17 494.51 * 0.012 0.14 0.09 0.25 0.25 0.14 ***** 0.17 0.17 0.21 494.55 * 0.012 0.17 0.11 0.32 0.32 0.17 ***** 0.21 0.22 0.25 494.59 * 0.012 0.20 0.13 0.37 0.37 0.20 ***** 0.25 0.28 0.28 494.62 * 0.012 0.22 0.14 0.43 0.43 0.22 ***** 0.28 0.34 0.31 494.65 * 0.012 0.24 0.15 0.47 0.47 0.24 ***** 0.31 0.39 0.34 494.68 * 0.012 0.26 0.16 0.52 0.52 0.26 ***** 0.34 0.45 0.36 494.70 * 0.012 0.28 0.17 0.56 0.56 0.28 ***** 0.36 0.51 0.39 494.73 * 0.012 0.30 0.18 0.61 0.61 0.30 ***** 0.39 0.56 0.41 494.75 * 0.012 0.32 0.19 0.65 0.65 0.32 ***** 0.41 0.62 0.43 494.77 * 0.012 0.33 0.20 0.69 0.69 0.33 ***** 0.43 PIPE NO. 5: 24 LF - 12"CP @ 3.62% OUTLET: 494.34 INLET: 495.22 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.01 0.05 495.27 * 0.012 0.05 0.03 0.11 0.11 0.05 ***** 0.04 0.02 0.06 495.28 * 0.012 0.06 0.04 0.17 0.17 0.06 ***** 0.06 0.03 0.08 495.30 * 0.012 0.08 0.05 0.21 0.21 0.08 ***** 0.08 0.04 0.09 495.31 * 0.012 0.09 0.06 0.25 0.25 0.09 ***** 0.09 0.05 0.11 495.33 * 0.012 0.10 0.06 0.28 0.28 0.10 ***** 0.11 0.06 0.12 495.34 * 0.012 0.11 0.07 0.31 0.31 0.11 ***** 0.12 0.07 0.13 495.35 * 0.012 0.11 0.08 0.34 0.34 0.11 ***** 0.13 0.08 0.14 495.36 * 0.012 0.12 0.08 0.36 0.36 0.12 ***** 0.14 0.09 0.15 495.37 * 0.012 0.13 0.08 0.39 0.39 0.13 ***** 0.15 0.10 0.16 495.38 * 0.012 0.14 0.09 0.41 0.41 0.14 ***** 0.16 0.11 0.17 495.39 * 0.012 0.14 0.09 0.43 0.43 0.14 ***** 0.17 ©2012 D.R.STRONG Consulting Engineers Inc. Page 41 of 55 Technical Information Report Kelsey's Crossing September 26,2012 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#102 TO CB#1.bwp Surcharge condition at intermediate junctions Tailwater Elevation:490.26 feet Discharge Range:0.81 to 1.03 Step of 0.022 [cfs] Overflow Elevation:490.31 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 36 LF - 18"CP @ 1.29% OUTLET: 486.10 INLET: 486.57 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 490.31 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.27 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.81 3.71 490.28 * 0.012 0.34 0.26 4.16 4.16 3.70 3.71 0.45 0.83 3.70 490.27 * 0.012 0.34 0.26 4.16 4.16 3.69 3.70 0.45 0.85 3.70 490.27 * 0.012 0.35 0.27 4.16 4.16 3.69 3.70 0.46 0.88 3.70 490.27 * 0.012 0.35 0.27 4.16 4.16 3.69 3.70 0.47 0.90 3.70 490.27 * 0.012 0.36 0.27 4.16 4.16 3.69 3.70 0.47 0.92 3.70 490.27 * 0.012 0.36 0.28 4.16 4.16 3.69 3.70 0.48 0.94 3.70 490.27 * 0.012 0.37 0.28 4.16 4.16 3.69 3.70 0.48 0.96 3.70 490.27 * 0.012 0.37 0.28 4.16 4.16 3.69 3.70 0.49 0.99 3.70 490.27 * 0.012 0.38 0.29 4.16 4.16 3.69 3.70 0.50 1.01 3.70 490.27 * 0.012 0.38 0.29 4.16 4.16 3.69 3.70 0.50 1.03 3.70 490.27 * 0.012 0.38 0.29 4.16 4.16 3.69 3.70 0.51 PIPE NO. 2: 24 LF - 18"CP @ 0.99% OUTLET: 486.57 INLET: 486.81 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.64 3.47 490.28 * 0.012 0.30 0.25 3.71 3.71 3.47 3.47 0.39 0.66 3.46 490.27 * 0.012 0.31 0.25 3.70 3.70 3.46 3.46 0.40 0.67 3.46 490.27 * 0.012 0.31 0.25 3.70 3.70 3.46 3.46 0.41 0.69 3.46 490.27 * 0.012 0.31 0.26 3.70 3.70 3.46 3.46 0.41 0.71 3.46 490.27 * 0.012 0.32 0.26 3.70 3.70 3.46 3.46 0.42 0.73 3.47 490.28 * 0.012 0.32 0.26 3.70 3.70 3.46 3.47 0.42 0.74 3.47 490.28 * 0.012 0.33 0.27 3.70 3.70 3.46 3.47 0.43 0.76 3.47 490.28 * 0.012 0.33 0.27 3.70 3.70 3.46 3.47 0.43 0.78 3.47 490.28 * 0.012 0.33 0.27 3.70 3.70 3.46 3.47 0.44 0.80 3.47 490.28 * 0.012 0.34 0.27 3.70 3.70 3.46 3.47 0.44 0.81 3.47 490.28 * 0.012 0.34 0.28 3.70 3.70 3.46 3.47 0.45 ©2012 D.R.STRONG Consulting Engineers Inc. Page 42 of 55 Technical Information Report Kelsey's Crossing September 26,2012 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#201 TO CB#2.bwp Surcharge condition at intermediate junctions Tailwater Elevation:492.05 feet Discharge Range:1.43 to 1.43 Step of 1. [cfs] Overflow Elevation:494.9 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 103 LF - 12"CP @ 1.00% OUTLET: 490.86 INLET: 491.90 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.43 0.73 492.63 * 0.012 0.51 0.43 1.19 1.19 0.51 ***** 0.73 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#400 TO INLET 2.bwp Surcharge condition at intermediate junctions Tailwater Elevation:489.92 feet Discharge Range:0.86 to 0.86 Step of 1. [cfs] Overflow Elevation:490.6 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 36 LF - 12"CP @ 14.83% OUTLET: 482.20 INLET: 487.60 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.86 2.37 489.97 * 0.012 0.39 0.17 7.72 7.72 2.34 2.37 0.47 ©2012 D.R.STRONG Consulting Engineers Inc. Page 43 of 55 Technical Information Report Kelsey's Crossing September 26,2012 KCRTS Analysis for Sediment Trap Developed 15-Minute Time Step Modeling Input: FirrUWii I -Area ?� Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.89 acres L: 11.50 5: 0.02 Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.35 acres L: 300.00 S: 0.02 Total 2.24 acres Scale Factor : 1.00 15-Min Reduced Edit Flow Paths I Time Series: 15min_dev I») Compute Time Series Modify User Input I Retrieve runoff files and compute Time Series Developed 15-Minute Time Step Modeling output: Flow Frequency Analysis Time Series File: l5min_dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.736 6 8/27/01 18:00 2.04 1 100.00 0.990 0.571 8 1/06/02 1:00 1. 60 2 25.00 0.960 1. 60 2 12/08/02 17: 15 1.11 3 10.00 0.900 0. 617 7 8/26/04 1:00 1.00 4 5.00 0.800 1. 11 3 11/17/04 5:00 0.780 5 3.00 0.667 0.780 5 10/22/05 10:00 0.736 6 2.00 0.500 1.00 4 10/25/06 22:45 0. 617 7 1.30 0.231 ©2012 D.R.STRONG Consulting Engineers Inc. Page 47 of 55 Technical Information Report Kelsey's Crossing September 26,2012 2.04 1 1/09/08 6:30 0.571 8 1. 10 0.091 Computed Peaks 1.89 50.00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 48 of 55 Technical Information Report Kelsey's Crossing September 26,2012 SWPPS PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP's listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSD) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. The complete CSWPPP can be found in Appendix B of this report. The site plans can be found in the engineering plan set. ©2012 D.R.STRONG Consulting Engineers Inc. Page 49 of 55 Technical Information Report Kelsey's Crossing September 26,2012 SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT BOND QUANTITY WORKSHEET Bond Quantity Worksheet—to be submitted prior to final plat recording. 1. The Stormwater Facility Summary Sheet is included in this section. See Figure 7 for facility sketch. 2. A draft Declaration of Covenant for reduced impervious surface BMP is included in this section. ©2012 D.R.STRONG Consulting Engineers Inc. Page 50 of 55 Technical Information Report Kelsey's Crossing September 26,2012 FLOW CONTROL AND WATER QUALITY FACILITY SUMMARY SHEET AND SKETCH Stormwater Facility Summary Sheet Development Kelsey's Crossing Date September 21, 2012 Location NE corner of SE 192nd Street and 120th Avenue SE ENGINEER DEVELOPER Name Maher Joudi, P.E. Name Firm D. R. STRONG Consulting Firm Harbour Homes, LLC Engineers, Inc. Address 10604 NE 38th Place, #232 Address 1441 N. 34th Street Suite 200 Kirkland, WA 98033 Seattle, WA 98103 Phone (425) 827-3063 Phone (206) 315-8130 Developed Site: 2.13 acres Number of lots 13 Number of detention facilities on site: Number of infiltration facilities on site: 1 ponds ponds vaults vaults tanks tanks Flow control provided in regional facility (give location) No flow control required Exemption number Downstream Drainage Basins Immediate Basin Major Basin Soos Creek Green/Duwamish River ©2012 D.R.STRONG Consulting Engineers Inc. Page 51 of 55 Technical Information Report Kelsey's Crossing September 26,2012 Water Quality Summary Sheet See Figure 7 for facility sketch. Number & type of water quality facilities on site: biofiltration swale (regular/wet/ or continuous inflow?) sand filter (basic or large?) sand filter, linear (basic or large?) Stormfilter 1 combined detention/WQ pond sand filter vault (basic or large?) combined detention/wetvault stormwater wetland compost filter wetpond (basic or large?) filter strip wetvault flow dispersion pre-settling pond farm management plan flow-splitter catchbasin landscape management plan oil/water separator (baffle or coalescing plate?) catch basin inserts: Manufacturer pre-settling structure: Manufacturer DESIGN INFORMATION INDIVIDUAL BASIN Water Quality design flow Water Quality treated volume Drainage basin(s) Onsite area (inlcudes frontage) (ac) 2.13 Offsite area (ac) 0.24 Type of Storage Facility Pond Live Storage Volume (required) (cfs) 25,962 Predev Runoff Rate (cfs) 2-year 0.066 10-year 0.115 100-year 0.191 Developed Runoff Rate (cfs) 2-year 0.407 10-year 0.490 100-year 0.826 Type of Restrictor Frop-Tee Size of orifice/restriction (in) No. 1 0.76 No. 2 1.60 No. 3 ©2012 D.R.STRONG Consulting Engineers Inc. Page 52 of 55 Technical Information Report Kelsey's Crossing September 26,2012 SECTION X OPERATIONS AND MAINTENANCE MANUAL See excerpts from the 2005 KCSWDM included in this section. ©2012 D.R.STRONG Consulting Engineers Inc. Page 53 of 55 Technical Information Report Kelsey's Crossing September 26,2012 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 1 -DETENTION PONDS Maintenance Defect or Problem Conditions When Maintenance Is Needed Results Expected When Component Maintenance Is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Top or Side Slopes Rodent holes Any evidence of rodent holes if facility is acting Rodents removed or destroyed and of Dam,Berm or as a dam or berm,or any evidence of water dam or berm repaired. Embankment piping through dam or berm via rodent holes. Tree growth Tree growth threatens integrity of slopes,does Trees do not hinder facility not allow maintenance access,or interferes with performance or maintenance maintenance activity. If trees are not a threat or activities. not interfering with access or maintenance,they do not need to be removed. Erosion Eroded damage over 2 inches deep where cause Slopes stabilized using appropriate of damage is still present or where there is erosion control measures. If erosion potential for continued erosion. Any erosion is occurring on compacted slope,a observed on a compacted slope. licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam,berm or embankment that has Top or side slope restored to design settled 4 inches lower than the design elevation. dimensions. If settlement is significant,a licensed civil engineer should be consulted to determine the cause of the settlement. Storage Area Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed accumulation designed pond depth. pond shape and depth;pond reseeded if necessary to control erosion. Liner damaged Liner is visible or pond does not hold water as Liner repaired or replaced. (If Applicable) designed. Inlet/Outlet Pipe. Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than''%-inch at the joint of the No cracks more than'/4-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. Emergency Tree growth Tree growth impedes flow or threatens stability of Trees removed. Overflow/Spillway spillway. Rock missing Only one layer of rock exists above native soil in Spillway restored to design area five square feet or larger or any exposure of standards. native soil on the spillway. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-2 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Trash and debris Trash or debris of more than''/cubic foot which No Trash or debris blocking or is located immediately in front of the structure potentially blocking entrance to opening or is blocking capacity of the structure by structure. more than 10%. Trash or debris in the structure that exceeds 1/3 No trash or debris in the structure. the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60%of the depth from the Sump of structure contains no bottom of the structure to the invert of the lowest sediment. pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Damage to frame Corner of frame extends more than 3/,inch past Frame is even with curb. and/or top slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than'/,inch. Frame not sitting flush on top slab,i.e., Frame is sitting flush on top slab. separation of more than 3/4 inch of the frame from the top slab. Cracks in walls or Cracks wider than 1/2 inch and longer than 3 feet, Structure is sealed and structurally bottom any evidence of soil particles entering structure sound. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe. of soil particles entering structure through cracks. Settlement/ Structure has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than''/-inch at the joint of the No cracks more than 1/4-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the structure at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing Ladder is unsafe due to missing rungs, Ladder meets design standards and or unsafe misalignment,rust,cracks,or sharp edges. allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure T section securely attached to wall wall and outlet pipe structure should support at and outlet pipe. least 1,000 lbs of up or down pressure. Structure is not in upright position(allow up to Structure in correct position. 10%from plumb). Connections to outlet pipe are not watertight or Connections to outlet pipe are water show signs of deteriorated grout. tight;structure repaired or replaced and works as designed. Any holes—other than designed holes—in the Structure has no holes other than structure. designed holes. Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-7 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily and maintenance person. is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to Plate is in place and works as missing,out of place,or bent orifice plate. designed. Obstructions Any trash,debris,sediment,or vegetation Plate is free of all obstructions and blocking the plate. works as designed. Overflow Pipe Obstructions Any trash or debris blocking(or having the Pipe is free of all obstructions and potential of blocking)the overflow pipe. works as designed. Deformed or damaged Lip of overflow pipe is bent or deformed. Overflow pipe does not allow lip overflow at an elevation lower than design Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than'%-inch at the joint of the No cracks more than'h-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. Metal Grates Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s)of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs.of lift. reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Sediment Sediment exceeds 60%of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of more than'A cubic foot which No Trash or debris blocking or is located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capacity of the catch basin catch basin. by more than 10%. Trash or debris in the catch basin that exceeds No trash or debris in the catch basin. 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Damage to frame Corner of frame extends more than 3/4 inch past Frame is even with curb. and/or top slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than'A inch. Frame not sitting flush on top slab,i.e., Frame is sitting flush on top slab. separation of more than 3/4 inch of the frame from the top slab. Cracks in walls or Cracks wider than 1/2 inch and longer than 3 feet, Catch basin is sealed and bottom any evidence of soil particles entering catch structurally sound. basin through cracks,or maintenance person judges that catch basin is unsound. Cracks wider than'A inch and longer than 1 foot No cracks more than 1/4 inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe. of soil particles entering catch basin through cracks. Settlement/ Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than'A-inch at the joint of the No cracks more than''1A-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the catch basin at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than 1/2-inch at the joint of the No cracks more than''/4-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design (Catch Basins) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s)of the grate. Grate is in place and meets design Any open structure requires urgent standards. maintenance. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs.of lift. reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 6-CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20%of the diameter of the pipe. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged;rust or corrosion Pipe repaired or replaced. coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%or is determined to have weakened structural integrity of the pipe. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all sediment accumulation design depth. and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion observed on a ditch slope. Slopes are not eroding. slopes Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. place or missing(If area 5 square feet or more,any exposed native Applicable) soil. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 9-FENCING Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Erosion or holes Erosion or holes more than 4 inches high and 12- No access under the fence. under fence 18 inches wide permitting access through an opening under a fence. Wood Posts,Boards Missing or damaged Missing or broken boards,post out of plumb by No gaps on fence due to missing or and Cross Members parts more than 6 inches or cross members broken broken boards,post plumb to within 11/2 inches,cross members sound. Weakened by rotting Any part showing structural deterioration due to All parts of fence are structurally or insects rotting or insect damage sound. Damaged or failed Concrete or metal attachments deteriorated or Post foundation capable of post foundation unable to support posts. supporting posts even in strong wind. Metal Posts,Rails Damaged parts Post out of plumb more than 6 inches. Post plumb to within 11/2 inches. and Fabric Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence(including post,top rails,and Fence is aligned and meets design fabric)more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or Part or parts that have a rusting or scaling Structurally adequate posts or parts protective coating condition that has affected structural adequacy. with a uniform protective coating. Openings in fabric Openings in fabric are such that an 8-inch Fabric mesh openings within 50%of diameter ball could fit through. grid size. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-14 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 12-ACCESS ROADS Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway drivable by maintenance square feet(i.e.,trash and debris would fill up vehicles. one standards size garbage can). Debris which could damage vehicle tires or Roadway drivable by maintenance prohibit use of road. vehicles. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Blocked roadway Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restricting the access to a 10-to At least 12-foot of width on access 12 foot width for a distance of more than 12 feet road. or any point restricting access to less than a 10 foot width. Road Surface Erosion,settlement, Any surface defect which hinders or prevents Road drivable by maintenance potholes,soft spots, maintenance access. vehicles. ruts Vegetation on road Trees or other vegetation prevent access to Maintenance vehicles can access surface facility by maintenance vehicles. facility. Shoulders and Erosion Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches in hinder maintenance access. height or cleared in such a way as to allow maintenance access. Modular Grid Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of Pavement pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damaged or missing Access surface compacted because of broken on Access road surface restored so missing modular block. road infiltrates. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-17 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 16-WETPOND Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance Is Performed Site Trash and debris Any trash and debris accumulated on the Wetpond site free of any trash or wetpond site. debris. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Side Slopes of Dam, Rodent holes Any evidence of rodent holes if facility is acting Rodents removed or destroyed and Berm,internal berm as a dam or berm,or any evidence of water dam or berm repaired. or Embankment piping through dam or berm via rodent holes. Tree growth Tree growth threatens integrity of dams,berms or Trees do not hinder facility slopes,does not allow maintenance access,or performance or maintenance interferes with maintenance activity. If trees are activities. not a threat to dam,berm or embankment integrity,are not interfering with access or maintenance or leaves do not cause a plugging problem they do not need to be removed. Erosion Eroded damage over 2 inches deep where cause Slopes stabilized using appropriate of damage is still present or where there is erosion control measures. If erosion potential for continued erosion. Any erosion is occurring on compacted slope,a observed on a compacted slope. licensed civil engineer should be consulted to resolve source of erosion. Top or Side Slopes Settlement Any part of a dam,berm or embankment that has Top or side slope restored to design of Dam,Berm, settled 4 inches lower than the design elevation. dimensions. If settlement is internal berm or significant,a licensed civil engineer Embankment should be consulted to determine the cause of the settlement. Irregular surface on Top of berm not uniform and level. Top of berm graded to design internal berm elevation. Pond Areas Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed accumulation(except designed pond depth. pond shape and depth. first wetpool cell) Sediment Sediment accumulations in pond bottom that Sediment storage contains no accumulation(first exceeds the depth of sediment storage(1 foot) sediment. wetpool cell) plus 6 inches. Liner damaged(If Liner is visible or pond does not hold water as Liner repaired or replaced. Applicable) designed. Water level(first First cell empty,doesn't hold water. Water retained in first cell for most of wetpool cell) the year. Algae mats(first Algae mats develop over more than 10%of the Algae mats removed(usually in the wetpool cell) water surface should be removed. late summer before Fall rains, especially in Sensitive Lake Protection Areas.) Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won't seal Valve does not seal completely. Valve completely seals closed. Emergency Overflow Tree growth Tree growth impedes flow or threatens stability of Trees removed. Spillway spillway. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-21 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 16-WETPOND Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance Is Performed Rock missing Only one layer of rock exists above native soil in Spillway restored to design area five square feet or larger,or any exposure of standards. native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than'''A-inch at the joint of the No cracks more than'h-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-22 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 24-CATCH BASIN INSERT Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance Is Performed Media Insert Visible Oil Visible oil sheen passing through media Media inset replaced. Insert does not fit Flow gets into catch basin without going through All flow goes through media. catch basin properly media. Filter media plugged Filter media plugged. Flow through filter media is normal. Oil absorbent media Media oil saturated. Oil absorbent media replaced. saturated Water saturated Catch basin insert is saturated with water,which Insert replaced. no longer has the capacity to absorb. Service life exceeded Regular interval replacement due to typical Media replaced at manufacturer's average life of media insert product,typically one recommended interval. month. Seasonal When storms occur and during the wet season. Remove,clean and replace or install maintenance new insert after major storms, monthly during the wet season or at manufacturer's recommended interval. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-35 APPENDIX A BOND QUANTITY WORKSHEET Bond Quantity Worksheet—to be submitted prior to final plat recording. ©2012 D.R.STRONG Consulting Engineers Inc. Page 54 of 55 Technical Information Report Kelsey's Crossing September 26,2012 APPENDIX B CSWPPP ©2012 D.R.STRONG Consulting Engineers Inc. Page 55 of 55 Technical Information Report Kelsey's Crossing September 26,2012 STORMWATER POLLUTION PREVENTION PLAN For KELSEY'S CROSSING Prepared For Harbour Homes, LLC 1441 N. 34th Street, Suite 200 Seattle, Washington 98103 (206) 315-8130 Owner Developer Operator/Contractor Harbour Homes, LLC Harbour Homes, LLC Maher A. Joudi, P.E. 1441 N. 34th Street, Suite 200 1441 N. 34th Street, Suite 200 10604 NE 38th Place, Suite 232 Seattle, Washington 98103 Seattle, Washington 98103 Kirkland, Washington 98033 Project Site Location NE corner of intersection of SE 192nd Street and 120th Avenue SE Renton; Washington Certified Erosion and Sediment Control Lead TBD SWPPP Prepared By D.R. Strong Consulting Engineers, Inc. 10604 NE 38th Place, Suite 232 Kirkland, Washington 98033 Maher A. Joudi, P.E., Senior Project Engineer SWPPP Preparation Date September 5, 2012 Approximate Project Construction Dates TBD ©2012 D.R.STRONG Consulting Engineers Inc. STORMWATER POLLUTION PREVENTION PLAN TABLE OF CONTENTS 1.0 INTRODUCTION 1 2.0 SITE DESCRIPTION 3 2.1 Existing Conditions 3 2.2 Proposed Construction Activities 3 3.0 CONSTRUCTION STORMWATER BMPS 6 3.1 The 12 BMP Elements 6 3.1.1 Element#1 — Mark Clearing Limits 6 3.1.2 Element#2 — Establish Construction Access 6 3.1.3 Element#3 — Control Flow Rates 7 3.1.4 Element#4 — Install Sediment Controls 7 3.1.5 Element#5 — Stabilize Soils 9 3.1.6 Element#6 - Protect Slopes 9 3.1.7 Element#7 — Protect Drain Inlets 10 3.1.8 Element#8 — Stabilize Channels and Outlets 10 3.1.9 Element#9 — Control Pollutants 11 3.1.10 Element#10 — Control Dewatering 12 3.1.11 Element#11 — Maintain BMPs 12 3.1.12 Element#12 — Manage the Project 12 3.2 Site Specific BMPs 15 3.3 Additional Advanced BMPs 15 4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION 16 5.0 POLLUTION PREVENTION TEAM 17 5.1 Roles and Responsibilities 17 5.2 Team Members 17 6.0 SITE INSPECTIONS AND MONITORING 18 6.1 Site Inspection 18 6.1.1 Site Inspection Frequency 18 6.1.2 Site Inspection Documentation 18 6.2 Stormwater Quality Monitoring 19 6.2.1 Turbidity Sampling 19 6.2.2 pH Sampling 19 6.2.3 Temperature Monitoring 20 7.0 REPORTING AND RECORDKEEPING 21 7.1 Recordkeeping 21 7.1.1 Site Log Book 21 7.1.2 Records Retention 21 ©2012 D.R.STRONG Consulting Engineers Inc. Page i of ii Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 7.1.3 Access to Plans and Records 21 7.1.4 Updating the SWPPP 21 7.2 Reporting 22 7.2.1 Discharge Monitoring Reports 22 7.2.2 Notification of Noncompliance 22 7.2.3 Permit Application and Changes 22 Appendices Appendix A— Site Plans 23 Appendix B — Construction BMPs 24 Appendix C —Alternative BMPs 25 Appendix D — General Permit 26 Appendix E — Site Inspection Forms (And Site Log) 27 Appendix F — Engineering Calculations 35 Appendix A Site Plans • Vicinity map (with all discharge points) • Site plan with TESC measures Appendix B Construction BMPs • Possibly reference in BMPs, but likely it will be a consolidated list so that the applicant can photocopy from the list from the SWMM. Appendix C Alternative Construction BMP list • List of BMPs not selected, but can be referenced if needed in each of the 12 elements Appendix D General Permit Appendix E Site Log and Inspection Forms Appendix F Engineering Calculations ©2012 D.R.STRONG Consulting Engineers Inc. Page ii of ii Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 1 .0 INTRODUCTION This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the Kelsey's Crossing residential project located in Renton, Washington. The site is located at the NE corner of intersection of SE 192nd Street and 120th Avenue SE in Renton Washington. The proposed development consists of the construction of 13 single family dwelling units, frontage and roadway improvements, stormwater detention facilities, and landscaping on 2.13 acres. Construction activities will include, grading, roadway construction, utility installation and home construction. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on July 2, 2005. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2005) and in the Stormwater Management Manual for Eastern Washington (SWMMEW 2004). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: • Section 1 — INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. • Section 2 — SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post— construction conditions. • Section 3 — CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP (SWMMEW 2004). ©2012 D.R.STRONG Consulting Engineers Inc. Page 1 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan • Section 4 — CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. • Section 5 — POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector • Section 6 — INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. • Section 7 — RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A— Site plans Appendix B — Construction BMPs Appendix C —Alternative Construction BMP list Appendix D — General Permit Appendix E — Site Log and Inspection Forms Appendix F — Engineering Calculations ©2012 D.R.STRONG Consulting Engineers Inc. Page 2 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 2.0 SITE DESCRIPTION 2.1 Existing Conditions Total parcel (Site) area is approximately 92,657.35 s.f. (2.13 ac.), and includes 5,049.18 s.f. (0.12 ac.) of right-of-way dedication. The Site's developable area is approximately 103,083.69 s.f. (2.37 ac.), which includes 10,036.50 s.f. (0.23 ac) of offsite right-of-way improvements, and includes the 5,049.18 s.f. (0.12 ac.) of right-of-way dedication. A portion of the offsite frontage improvement areas will bypass the onsite combination detention and water quality pond, and will be accounted for with additional detention and water quality volume. The site previously contained a single family residence that has since been demolished. A driveway and foundation still remain onsite, and will be removed with the site development. The onsite vegetation consists of grass, brush and trees. In general, the majority of the property has slopes ranging from 2-10%. Generally, the land slopes to the easterly across the site. The predeveloped Site has one Natural Discharge Areas (NDA); located along the east property line. The entire site is contained within one Threshold Discharge Area (TDA). For purposes of flow control analysis and design, the Site will be considered till forest in its existing condition. 2.2 Proposed Construction Activities The applicant has gained approval to subdivide 2.13 acres into 13 single-family residential lots (Project), with lot sizes ranging from approximately 3,833 to 5,717 s.f. An internal access road (SE 191st Lane) will provide access to the development and will have a temporary cul-de-sac at the east end. SE 191st Lane will have 26-feet of paving, vertical curbs, and gutters on both sides, a six foot planting strip, and a five foot sidewalk. The planting strip and sidewalk is located on the south side of the street, and parking is limited to only the south side of the street. A 20-foot paved access road will provided for lots 8 through 13. Frontage improvements will be provided along the west property line, along 120th Avenue SE. Improvements will consist of a new vertical curb and gutter 13-feet from the centerline of the right-of-way, 8-foot planting strip and a five-foot concrete sidewalk. Frontage improvements will be provided along the south property line, along S.E. 192nd Street, which is classified as a Minor Arterial with an associated 92-foot right-of-way. Improvements will consist of a new vertical curb and gutter 22-feet from the centerline of the right-of-way, 5-foot planting strip and a 7-foot concrete sidewalk. These improvements will be permitted through the City of Kent. ©2012 D.R.STRONG Consulting Engineers Inc. Page 3 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan The 13 single-family residences and their driveways combined will create approximately 34,677 s.f. of impervious area using the maximum allowable build-out rate specified in the King County Code Section 21A.12.030 (post developed maximum impervious surface percentage is 70% per lot). Post-developed onsite impervious areas including rights-of-way, sidewalks, roofs, and driveways total approximately 53,489 s.f. (not including bypass and frontage areas). The remainder of the Project will be modeled as till grass and totals approximately 34,119 s.f. (See Section IV). Post developed frontage improvement areas along 120th Ave SE and SE 192nd Street total approximately 15,476 s.f. and consist of 7,688 s.f. of impervious and 7,788 s.f. of pervious areas. Small LOT BMP Requirements per Section 5.2.1.1 of the 2005 King County Surface Water Design Manual (KCSWDM) will be met with the use of a reduced impervious surface credit as outlined in Section C.2.9. A 10% reduction of the maximum impervious surface area will be applied to each the lot area, thus reducing the allowable impervious surface per lot to 60% of the total lot area. A note to the that effect will be placed on the face of the final plat. Developed runoff from the Site and a portion of the frontage improvements along 120th Ave SE and SE 192nd Street will be conveyed to a combined water quality and detention facility located onsite within Tract "B". Runoff will be treated for basic water quality and conservation flow control as outlined in Sections 5 and 6 of the 2009 KCSWDM. Developed site runoff will be conveyed to an onsite combined detention and wet pond. The site discharges runoff to Big Soos Creek though a manmade conveyance system approximately 1/4 mile downstream of the site. • Total site area: 2.37 acres • Percent impervious area before construction: 4.91 % • Percent impervious area after construction: 59.35 % • Disturbed area during construction: 2.37 acres • Disturbed area that is characterized as impervious (i.e., access roads, staging, parking): 1.40 acres • 2-year stormwater runoff peak flow prior to construction (existing): 0.130 cfs • 10-year stormwater runoff peak flow prior to construction (existing): 0.237 cfs • 2-year stormwater runoff peak flow during construction: 0.407 cfs • 10-year stormwater runoff peak flow during construction: 0.490 cfs ©2012 D.R.STRONG Consulting Engineers Inc. Page 4 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan • 2-year stormwater runoff peak flow after construction: 0.041 cfs • 10-year stormwater runoff peak flow after construction: 0.109 cfs All stormwater flow calculations are provided in Appendix F. ©2012 D.R.STRONG Consulting Engineers Inc. Page 5 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 3.0 CONSTRUCTION STORMWATER BMPS 3.1 The 12 BMP Elements 3.1.1 Element #1 — Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: • High Visibility Plastic or Metal Fence (BMP C103) The plastic fence will be placed around the perimeter of the developable area of the Site. BMP will be implemented at the start of construction. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element #2 — Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C105) • Construction Road/Parking Area Stabilization (BMP C107) A Stabilized Construction Entrance will be placed at the entrance of the Site on SE 2nd Street. This BMP will be implemented at the start of construction. Construction Road and Parking Area Stabilization will occur along the road into the site and in staging areas where parking of equipment will occur. This will occur as the project goes along. Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General 2012 D. R.STRONG Consulting Engineers Inc. Page 6 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element#3 — Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: • Detention Pond and Vault A detention/water quality pond will be installed in Tract B. A detention/water quality vault will be installed in Tract D. Both the pond and vault will be constructed and used as a sedimentation device during construction. Construction flow rates Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, the project must comply with Minimum Requirement 7 (Ecology 2005). In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element#4— Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence (BMP C233) • Storm Drain Inlet Protection (BMP C220) • Interceptor Swale (BMP C200) • Sediment Trap • Detention Pond Silt fence will be installed around the perimeter of the Site in areas where runoff could sheet-flow offsite. This BMP will be installed at the start of construction. ©2012 D.R.STRONG Consulting Engineers Inc. Page 7 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan Storm Drain Inlet Protection will be installed on all newly constructed catch basins throughout the site as well as the tie in catch basin offsite. The tie in catch basin protection will be installed at the start of construction, and protection for the newly constructed catch basins will occur as they are installed. The interceptor swale and sediment trap will be installed during the time of grading. The detention pond and vault will be installed and used for sedimentation during construction. Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. The following BMPs will be implemented as end-of-pipe sediment controls as required to meet permitted turbidity limits in the site discharge(s). Prior to the implementation of these technologies, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sedimentation controls. • Construction Stormwater Filtration (BMP C251) • Construction Stormwater Chemical Treatment (BMP C 250) (implemented only with prior written approval from Ecology). ©2012 D.R.STRONG Consulting Engineers Inc. Page 8 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 3.1.5 Element#5 — Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: • Temporary and Permanent Seeding (BMP C120) • Plastic Covering (BMP C123) • Dust Control (BMP C140) Permanent Seeding will occur as grading is completed. All stabilized sections will be seeded and vegetated. Plastic Covering will occur throughout the site as deemed necessary by the contractor and CESCL. Dust Control will occur throughout the site as deemed necessary by the contractor and CESCL. Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element#6 — Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes erosion. The following specific BMPs will be used to protect slopes for this project: • Temporary and Permanent Seeding (BMP C120) • Pipe Slope Drains (BMP C204) • Check Dams (BMP C207) Permanent Seeding will occur throughout the site as slopes are stabilized. ©2012 D.R.STRONG Consulting Engineers Inc. Page 9 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan Pipe Slope Drains will be installed to convey runoff across 2:1 slopes. These will be installed throughout the grading process as slopes are constructed and stabilized. Checks Dams will be installed every 50' as shown on the plan. Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element#7 — Protect Drain Inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: Drop Inlet Protection • Catch Basin Filters There is one which will require protection of an existing catch basin. The outlet catch basin in Tract B will require a catch basin filter be installed while the outfall system is being constructed for the detention pond. If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element#8 — Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: • No BMPs to be implemented The project will not discharge to any outlets or channels; therefore no BMP's are required. Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment ©2012 D.R.STRONG Consulting Engineers Inc. Page 10 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a Type 1A, 10-year, 24- hour recurrence interval storm for the developed condition. Alternatively, the 10-year, 1- hour peak flow rate indicated by an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems. 3.1.9 Element#9 — Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. Vehicles, construction equipment, and/or petroleum product storage/dispensing: • All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. • On-site fueling tanks and petroleum product storage containers shall include secondary containment. • Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. • In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. • Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Demolition: • Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (BMP C140). • Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C220 as described above for Element 7). • Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C152). ©2012 D.R.STRONG Consulting Engineers Inc. Page 11 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan • Concrete and grout: • Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151). Sanitary wastewater: • Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: • Solid waste will be stored in secure, clearly marked containers. Other: • Other BMPs will be administered as necessary to address any additional pollutant sources on site. The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act (CWA). 3.1.10 Element#10 — Control Dewatering There will be no dewatering as part of this construction project. 3.1.11 Element#11 — Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications (attached). Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element#12 — Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: • Design the project to fit the existing topography, soils, and drainage patterns. • Emphasize erosion control rather than sediment control. • Minimize the extent and duration of the area exposed. • Keep runoff velocities low. • Retain sediment on site. ©2012 D.R. STRONG Consulting Engineers Inc. Page 12 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan • Thoroughly monitor site and maintain all ESC measures. • Schedule major earthwork during the dry season. In addition, project management will incorporate the key components listed below: (West Response) As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction • The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. • Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations • From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: o Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and o Limitations on activities and the extent of disturbed areas; and o Proposed erosion and sediment control measures. • Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. • The following activities are exempt from the seasonal clearing and grading limitations: o Routine maintenance and necessary repair of erosion and sediment control BMPs; o Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and o Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions • Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. ©2012 D.R.STRONG Consulting Engineers Inc. Page 13 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan Inspection and Monitoring • All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: o Assess the site conditions and construction activities that could impact the quality of stormwater, and o Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. • A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. • Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP • This SWPPP shall be retained on-site or within reasonable access to the site. • The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. • The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. If the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. ©2012 D.R.STRONG Consulting Engineers Inc. Page 14 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 3.3 Additional Advanced BMPs ©2012 D.R.STRONG Consulting Engineers Inc. Page 15 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION The BMP implementation schedule will be driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. • Estimate of Construction start date: TBD • Estimate of Construction finish date: TBD • Mobilize equipment on site: TBD • Mobilize and store all ESC and soil stabilization products: TBD • Install ESC measures: TBD • Install stabilized construction entrance: TBD • Begin clearing and grubbing: TBD • Demolish existing buildings: TBD • Begin Site Grading: TBD • Begin implementing soil stabilization and sediment control BMPs throughout the site: TBD • End Site Grading TBD • Begin Utility Construction TBD • End Utility Construction TBD • Begin Paving and Sidewalk Installation: TBD • Permanent erosion control measures (hydroseeding): TBD • End Paving and Sidewalk Installation: TBD • Final landscaping and planting begins: TBD ©2012 D.R.STRONG Consulting Engineers Inc. Page 16 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 5.0 POLLUTION PREVENTION TEAM 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: • Certified Erosion and Sediment Control Lead (CESCL) — primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. • Resident Engineer — For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative • Emergency Ecology Contact — individual to be contacted at Ecology in case of emergency • Emergency Owner Contact — individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. • Non-Emergency Ecology Contact — individual that is the site owner or representative of the site owner than can be contacted if required. • Monitoring Personnel — personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control TBD Lead(CESCL) Resident Engineer Emergency Ecology Contact TBD Emergency Owner Contact Non-Emergency Ecology Contact TBD Monitoring Personnel TBD ©2012 D.R.STRONG Consulting Engineers Inc. Page 17 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 6.0 SITE INSPECTIONS AND MONITORING Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements; • Site inspections; and, • Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL) per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month. 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. ©2012 D.R.STRONG Consulting Engineers Inc. Page 18 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 6.2 Stormwater Quality Monitoring The site discharges into existing storm drainage systems. Before project discharge leaves the Site, it enters a combination detention and water quality pond. This will be sufficient in accommodating detention and water quality requirements for the developed site. Testing at the outlet will still occur as necessary. 6.2.1 Turbidity Sampling Sampling and monitoring will be conducted during the entire construction phase of the project. Samples will be collected daily at the downstream catch basin for the. If there is no flow in this catch basin, the attempt to sample will be recorded in the site log book and reported to Ecology in the monthly Discharge Monitoring Report (DMR) as "No Discharge". Samples will be analyzed for turbidity using the EPA 180.1 analytical method. The key benchmark turbidity value is 25 nephelometric turbidity units (NTU) for the downstream receiving water body. If the 25 NTU benchmark is exceeded in any sample collected from the tested catch basins, the following steps will be conducted: 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document modified BMPs in the SWPPP as necessary. 3. Sample discharge daily until the discharge is 25 NTU or lower. If the turbidity exceeds 250 NTU at any time, the following steps will be conducted: 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue sampling daily until the discharge is 25 NTU or lower Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours, and implement those additional treatment BMPs as soon as possible, but within a minimum of 7 days. 3. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling Sampling and monitoring for pH will occur during the phase of construction when concrete pouring will be conducted until fully cured (3 weeks from last pour) and discharges are documented to be below pH 8.5. Samples will be collected weekly at the sedimentation pond prior to discharge to surface water. Samples will be analyzed for pH using a calibrated pH meter and recorded in the site log book. The key benchmark pH value for stormwater is a maximum of 8.5. If a pH greater than 8.5 is measured in the sedimentation trap/pond(s) that has the potential to discharge to surface water, the following steps will be conducted: ©2012 D. R.STRONG Consulting Engineers Inc. Page 19 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 1. Prevent (detain) all discharges from leaving the site and entering surface waters or storm drains if the pH is greater than 8.5 2. Implement CO2 sparging or dry ice treatment in accordance with Ecology BMP C252. Describe inspection results and remedial actions that are taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.3 Temperature Monitoring No temperature monitoring is required for this construction site. ©2012 D.R.STRONG Consulting Engineers Inc. Page 20 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 7.0 REPORTING AND RECORDKEEPING 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements; • Site inspections; and, • Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. 7.1.2 Records Retention Records of all monitoring information (site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s) that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. ©2012 D.R.STRONG Consulting Engineers Inc. Page 21 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan 7.2 Reporting 7.2.1 Discharge Monitoring Reports Water quality sampling results will be submitted to Ecology monthly on Discharge Monitoring Report (DMR) forms in accordance with permit condition S5.B. If there was no discharge during a given monitoring period, the form will be submitted with the words "no discharge" entered in place of the monitoring results. If a benchmark was exceeded, a brief summary of inspection results and remedial actions taken will be included. If sampling could not be performed during a monitoring period, a DMR will be submitted with an explanation of why sampling could not be performed. 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: 1. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Any time turbidity sampling indicates turbidity is 250 nephelometric turbidity units (NTU) or greater or water transparency is 6 centimeters or less, the Ecology regional office will be notified by phone within 24 hours of analysis as required by permit condition S5.A (see Section 5.0 of this SWPPP for contact information). In accordance with permit condition S4.F.6.b, the Ecology regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water (see Section 5.0 of this SWPPP for contact information). 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit. ©2012 D. R.STRONG Consulting Engineers Inc. Page 22 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan APPENDIX A - SITE PLANS ©2012 D.R.STRONG Consulting Engineers Inc. Page 23 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 APPENDIX B - CONSTRUCTION BMPS High Visibility Plastic or Metal Fence (BMP C103) Stabilized Construction Entrance (BMP C105) Construction Road/Parking Area Stabilization (BMP C107) Detention Pond Silt Fence (BMP C233) Storm Drain Inlet Protection (BMP C220) Temporary and Permanent Seeding (BMP C120) Plastic Covering (BMP C123) Dust Control (BMP C140) Temporary and Permanent Seeding (BMP C120) Pipe Slope Drains (BMP C204) Check Dams (BMP C207) Grass-Lined Channels (BMP C201) Materials on Hand (BMP C150) • ©2012 D.R.STRONG Consulting Engineers Inc. Page 24 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan APPENDIX C - ALTERNATIVE BMPS The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. ©2012 D.R.STRONG Consulting Engineers Inc. Page 25 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 APPENDIX D - GENERAL PERMIT ©2012 D.R.STRONG Consulting Engineers Inc. Page 26 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Stormwater Pollution Prevention Plan APPENDIX E - SITE INSPECTION FORMS (AND SITE LOG) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. c. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief". ©2012 D. R.STRONG Consulting Engineers Inc. 27 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. ©2012 D.R.STRONG Consulting Engineers Inc. 28 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan SITE INSPECTION FORM General Information Project Name: Inspector Name: Title: CESCL# : Date: Time: Inspection Type: ❑ After a rain event ❑ Weekly ❑ Turbidity/transparency benchmark exceedance ❑ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 2: Establish Construction Access BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 3: Control Flow Rates BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. 29 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 4: Install Sediment Controls BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 5: Stabilize Soils BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D. R.STRONG Consulting Engineers Inc. 30 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 6: Protect Slopes BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 7: Protect Drain Inlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. 31 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan Element 8: Stabilize Channels and Outlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 9: Control Pollutants BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 10: Control Dewatering BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. 32 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Discharges From the Site Observed? Y N Problem/Corrective Action Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen Water Quality Monitoring Was any water quality monitoring conducted? ❑ Yes ❑ No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? ❑ Yes ❑ No If Ecology was notified, indicate the date, time, contact name and phone number below: Date: Time: Contact Name: Phone* General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? ❑ Yes ❑ No If photos taken, describe photos below: ©2012 D.R.STRONG Consulting Engineers Inc. 33 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan ©2012 D.R.STRONG Consulting Engineers Inc. 34 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan APPENDIX F - ENGINEERING CALCULATIONS ©2012 D.R.STRONG Consulting Engineers Inc. 35 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the soil type is modeled as "Till" for the Alderwood Gravelly Sandy Loam SCS classification as shown in Figure 4. Soils. The entire Site is modeled as "Forest." Results of the KCRTS analysis are included in this section. Pre-developed Hourly Time Step Modeling Input: Land Use Summary a -Area ?� Till Forest 2.37 acres Till Pasture 0.00 acres Till Grass 0.00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres -Total 2.37 acres Scale Factor : 1.00 Hourly Reduced Time Series: predevl >> Compute Time Series I Modify User Input i File for computed Time Series [.TSF] Pre-developed Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.149 2 2/09/01 18:00 0.191 1 100.00 0.990 0.041 7 1/06/02 3:00 0.149 2 25.00 0.960 ©2012 D.R.STRONG Consulting Engineers Inc. 36 Brauejwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan 0.111 4 2/28/03 3:00 0.115 3 10.00 0.900 0.004 8 3/24/04 20:00 0.111 4 5.00 0.800 0.066 6 1/05/05 8:00 0.097 5 3.00 0.667 0.115 3 1/18/06 20:00 0.066 6 2.00 0.500 0.097 5 11/24/06 4:00 0.041 7 1.30 0.231 0.191 1 1/09/08 9:00 0.004 8 1.10 0.091 Computed Peaks 0.177 50.00 0.980 DEVELOPED SITE HYDROLOGY Developed Site Area Hydrology KCRTS was used to model the developed peak runoff from the Site. The soil types are unchanged from the pre-developed conditions. The portions of the Site within the proposed clearing limits tributary to the proposed combination detention and water quality pond were modeled as "Till Grass" and Impervious as appropriate. Results of the KCRTS analysis are included in this section. Rdin (to flow control facility): Portions of offsite frontage improvements are being routed to the onsite combined detention and water quality pond, along with the developed onsite areas. Bypass: A portion of onsite area is not being collected and routed to the onsite flow control and water quality facility. This area is being treated as bypass, and the proposed combination detention and water quality pond is both over detaining and over treating for the bypassed areas. ©2012 D.R.STRONG Consulting Engineers Inc. 37 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan Developed rdin (to flow control facility) Hourly Time Step Modeling Input: Land Use Summary £; -Area ? Till Forest 0.00 acres i Till Pasture 0.00 acres Till Grass 0.89 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.35 acres -Total 2.24 acres Scale Factor : 1.00 Hourly Reduced Time Series: rdinl »I Compute Time Series I Modify User Input I File for computed Time Series [.TSF] Developed rdin (to flow control facility) Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:rdin.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.407 6 2/09/01 2:00 0.826 1 100.00 0.990 0.329 8 1/05/02 16:00 0.513 2 25.00 0.960 0.490 3 2/27/03 7:00 0.490 3 10.00 0.900 0.353 7 8/26/04 2:00 0. 431 4 5.00 0.800 0.426 5 10/28/04 16:00 0.426 5 3.00 0.667 0.431 4 1/18/06 16:00 0. 407 6 2.00 0.500 0.513 2 10/26/06 0:00 0.353 7 1.30 0.231 0.826 1 1/09/08 6:00 0.329 8 1.10 0.091 Computed Peaks 0.722 50. 00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. 38 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan Developed Bypass Hourly Time Step Modeling Input: t Land Use Summar;74 d __ 1 ,1-Area ?� Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.07 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.06 acres -Total 0.13 acres Scale Factor : 1.00 Hourly Reduced Time Series: bypass »I Compute Time Series I Modify User Input I File for computed Time Series [.TSF] Developed Bypass Hourly Time Step Modeling Output: Flow Frequency Analysis Time Series File:bypass.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.021 5 2/09/01 2: 00 0.043 1 100.00 0. 990 0.016 8 1/05/02 16: 00 0.025 2 25.00 0. 960 0.025 2 2/27/03 7: 00 0.023 3 10.00 0.900 0.016 7 8/26/04 2: 00 0.022 4 5.00 0.800 0.020 6 10/28/04 16:00 0. 021 5 3.00 0. 667 0.022 4 1/18/06 16:00 0. 020 6 2. 00 0.500 0.023 3 10/26/06 0: 00 0. 016 7 1.30 0.231 0.043 1 1/09/08 6: 00 0.016 8 1. 10 0.091 Computed Peaks 0.037 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. 39 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan The on-site bypass areas satisfy all the requirements set forth in the Manual, Section 1.2. Runoff from the bypass areas and the flow control facilities converge within a quarter-mile. The flow control facility is designed to compensate for uncontrolled bypass. The 100-year discharges from the bypass areas are 0.043 cfs which is less than the 0.4 cfs threshold. There should be no adverse downstream impacts to the downstream drainage system created by the runoff from the bypass. ©2012 D.R.STRONG Consulting Engineers Inc. 40 Brauerwood Estates Technical Information Report Sammamish,Washington Stormwater Pollution Prevention Plan PERFORMANCE STANDARDS The Project is required to meet the Level 2 Flow Control and Basic Water Quality Treatment requirements. The Level 2 performance requires the developed condition discharge rates to match the predeveloped rates ranging from 50% of the two-year peak up to the 50-year peak. Also match developed peak discharge rates to predeveloped peak discharge rates for the 2 and 10-year return periods. The Project is located in the Basic Water Quality Treatment area. The treatment goal is removal of 80% of Total Suspended Solids for flows including the WQ design flow or volume defined in Section 6.2.1 of the 2005 KCSWDM. Conveyance criteria for the Project require that all new pipes be designed to convey and contain (at minimum) the 25-year peak flow. The conveyance system as designed will convey the 100-year peak storm with overtopping of the most upstream structures. FLOW CONTROL SYSTEM (PART D) The Site will utilize a detention pond meeting the Level 2 Flow Control Criteria. The King County Runoff Time Series (KCRTS) software was used to size the detention facility. The detention pond design information is included in this section. Below is a summary of the pre and post development runoff rates. Detailed flow control and water quality treatment calculations can be found on the following pages. PREDEVELOPED (PREDEV.pks) POST DEVELOPED (dsout.pks) 0.191 1 100.00 0.990 0.545 1 100.00 0.990 0.149 2 25.00 0.960 0. 129 2 25. 00 0.960 0.115 3 10.00 0.900 0. 109 3 10.00 0.900 0.111 4 5.00 0.800 0. 108 4 5.00 0.800 0.097 5 3.00 0.667 0.077 5 3.00 0.667 0.066 6 2.00 0.500 0. 041 6 2.00 0.500 0.041 7 1.30 0.231 0. 040 7 1.30 0.231 0.004 8 1.10 0.091 0. 039 8 1. 10 0.091 0.117 50.00 0. 980 0. 407 50.00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. 41 Brauerwood Estates Technical Information Report Sammamish,Washington FLOW CONTROL SYSTEM The Project will utilize a combination detention and water quality pond to meet level 2 flow control and basic water quality. The King County KCRTS software was used to size the detention facilities. Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 3.00 H:1V Pond Bottom Length: 55.50 ft Pond Bottom Width: 55.50 ft Pond Bottom Area: 3080. sq. ft Top Area at 1 ft. FB: 8482. sq. ft 0. 195 acres Effective Storage Depth: 5. 10 ft Stage 0 Elevation: 0.00 ft Storage Volume: 25962. cu. ft 0.596 ac-ft Riser Head: 5. 10 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.76 0.035 2 3. 68 1.60 0.083 4.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 0.00 0. 0.000 0.000 0.00 3080. 0.01 0.01 31. 0.001 0.001 0. 00 3087. 0.02 0.02 62. 0.001 0.002 0. 00 3094. 0.03 0.03 93. 0.002 0.003 0. 00 3100. 0.04 0.04 124. 0.003 0.003 0.00 3107. 0.05 0.05 155. 0.004 0.003 0.00 3114. 0.06 0.06 186. 0.004 0.004 0. 00 3120. 0.16 0.16 501. 0.012 0.006 0. 00 3188. ©2012 D.R.STRONG Consulting Engineers Inc. Page 42 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.26 0.26 824 . 0.019 0.008 0. 00 3256. 0.36 0. 36 1153. 0.026 0.009 0.00 3325. 0. 46 0. 46 1489. 0.034 0.011 0.00 3394. 0.56 0.56 1832. 0.042 0.012 0.00 3464. 0. 66 0. 66 2182. 0.050 0.013 0.00 3535. 0.76 0.76 2539. 0.058 0.014 0.00 3607. 0.86 0.86 2903. 0.067 0.015 0.00 3680. 0. 96 0. 96 3275. 0.075 0. 015 0.00 3753. 1.06 1.06 3654. 0. 084 0.016 0.00 3827. 1. 16 1. 16 4040. 0.093 0.017 0.00 3901. 1.26 1.26 4434. 0.102 0.018 0.00 3977. 1.36 1.36 4835. 0. 111 0.018 0.00 4053. 1.46 1.46 5244 . 0. 120 0.019 0.00 4129. 1.56 1.56 5661. 0.130 0. 020 0.00 4207. 1. 66 1. 66 6086. 0. 140 0.020 0.00 4285. 1.76 1.76 6518 . 0.150 0. 021 0. 00 4364 . 1.86 1.86 6959. 0.160 0.021 0.00 4444. 1. 96 1. 96 7407. 0. 170 0.022 0.00 4524 . 2.06 2. 06 7863. 0.181 0.023 0.00 4605. 2. 16 2. 16 8328. 0. 191 0. 023 0.00 4687. 2.26 2.26 8801. 0.202 0.024 0.00 4769. 2.36 2.36 9282. 0.213 0.024 0.00 4853. 2.46 2. 46 9771. 0.224 0. 025 0.00 4936. 2.56 2.56 10269. 0.236 0.025 0.00 5021. 2. 66 2. 66 10775. 0.247 0.026 0.00 5107. 2.76 2.76 11290. 0.259 0.026 0.00 5193. 2.86 2. 86 11814. 0.271 0.027 0.00 5279. ©2012 D.R.STRONG Consulting Engineers Inc. Page 43 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 i 2. 96 2. 96 12346. 0.283 0.027 0.00 5367. 3.06 3.06 12887. 0.296 0.027 0.00 5455. 3. 16 3.16 13437. 0.308 0.028 0. 00 5544. 3.26 3.26 13996. 0.321 0.028 0.00 5634. 3.36 3.36 14564. 0.334 0.029 0.00 5724. 3.46 3.46 15141. 0.348 0. 029 0.00 5816. 3.56 3.56 15727. 0.361 0.030 0.00 5907. 3. 66 3. 66 16323. 0.375 0.030 0. 00 6000. 3. 68 3. 68 16443. 0.377 0.030 0. 00 6019. 3.70 3.70 16564. 0.380 0.031 0.00 6037. 3.71 3.71 16624. 0.382 0.032 0.00 6047. 3.73 3.73 16745. 0.384 0. 035 0.00 6065. 3.75 3.75 16867. 0.387 0.039 0. 00 6084 . 3.76 3.76 16927. 0.389 0.044 0. 00 6093. 3.78 3.78 17050. 0.391 0.049 0.00 6112. 3.80 3.80 17172. 0.394 0.054 0.00 6131. 3.81 3.81 17233. 0.396 0. 056 0.00 6140. 3.83 3.83 17356. 0.398 0. 058 0. 00 6159. 3. 93 3. 93 17977. 0.413 0.066 0. 00 6254. 4. 03 4.03 18607. 0. 427 0.073 0. 00 6349. 4. 13 4. 13 19247. 0. 442 0.078 0. 00 6445. 4.23 4.23 19896. 0. 457 0.084 0. 00 6542 . 4.33 4 .33 20555. 0. 472 0.089 0. 00 6639. 4.43 4.43 21224 . 0. 487 0.093 0.00 6737. 4.53 4.53 21903. 0.503 0.097 0.00 6836. 4. 63 4. 63 22591. 0.519 0. 101 0.00 6936. 4.73 4.73 23290. 0.535 0. 105 0.00 7036. ©2012 D.R.STRONG Consulting Engineers Inc. Page 44 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 4.83 4.83 23998. 0.551 0. 109 0. 00 7137. 4. 93 4. 93 24717. 0.567 0.112 0. 00 7239. 5.03 5.03 25446. 0.584 0. 116 0.00 7341. 5. 10 5. 10 25962. 0.596 0. 118 0.00 7413. 5.20 5.20 26709. 0. 613 0.429 0. 00 7517. 5.30 5.30 27466. 0. 631 0. 996 0. 00 7621. 5.40 5. 40 28233. 0. 648 1.730 0.00 7726. 5.50 5.50 29011. 0. 666 2.520 0. 00 7832. 5. 60 5. 60 29800. 0. 684 2.810 0. 00 7939. 5.70 5.70 30599. 0.702 3. 070 0.00 8046. 5.80 5. 80 31409. 0.721 3.300 0.00 8154 . 5. 90 5. 90 32230. 0.740 3.520 0. 00 8263. 6.00 6. 00 33062. 0.759 3.730 0. 00 8372. 6.10 6. 10 33904. 0.778 3. 930 0. 00 8482. 6.20 6.20 34758. 0.798 4. 120 0. 00 8593. 6.30 6. 30 35623. 0.818 4.290 0. 00 8705. 6.40 6. 40 36499. 0.838 4.470 0. 00 8817. 6.50 6.50 37386. 0.858 4. 630 0. 00 8930. 6. 60 6. 60 38285. 0. 879 4.790 0. 00 9044. 6.70 6.70 39195. 0. 900 4. 950 0. 00 9158. 6.80 6. 80 40117. 0. 921 5.090 0. 00 9274. 6. 90 6. 90 41050. 0. 942 5.240 0. 00 9390. 7.00 7. 00 41995. 0. 964 5.380 0. 00 9506. 7.10 7. 10 42951. 0. 986 5.520 0.00 9624. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 0.83 0.53 5.22 5.22 26843. 0. 616 2 0.41 0. 12 5. 10 5. 10 25949. 0.596 3 0.49 0. 10 4. 61 4. 61 22480. 0.516 ©2012 D.R.STRONG Consulting Engineers Inc. Page 45 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 4 0.51 0.10 4.59 4.59 22303. 0.512 5 0.43 0. 07 4.01 4.01 18483. 0.424 6 0.33 0.03 3.37 3.37 14647. 0.336 7 0.28 0.03 3.72 3.72 16693. 0.383 8 0.35 0.02 2.46 2. 46 9755. 0.224 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.53 0.04 ******** ******* 0.54 2 0. 12 0.02 ******** ******* 0. 13 3 0.10 0.03 ******** 0. 12 0. 11 4 0. 10 0.02 ******** ******* 0. 11 5 0.07 0.02 ******** ******* 0.08 6 0.03 0.02 ******** 0.07 0.04 7 0.03 0.01 ******** ******* 0.04 8 0.02 0.02 ******** ******* 0.04 Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0. 826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21:00 0.530 5.22 1 100.00 0.990 0.029 7 1/07/02 4:00 0. 118 5. 10 2 25.00 0. 960 0.100 3 3/06/03 22: 00 0. 100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7: 00 0.099 4.59 4 5. 00 0.800 0.034 6 1/08/05 5: 00 0. 072 4. 01 5 3. 00 0. 667 0.072 5 1/19/06 0:00 0.034 3.72 6 2.00 0.500 0.099 4 11/24/06 8:00 0.029 3.37 7 1.30 0.231 0.530 1 1/09/08 10:00 0.025 2. 46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50.00 0. 980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ©2012 D.R.STRONG Consulting Engineers Inc. Page 46 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.129 2 2/09/01 18: 00 0.545 1 100.00 0.990 0.041 6 1/05/02 16: 00 0. 129 2 25.00 0.960 0.109 3 3/06/03 19:00 0. 109 3 10. 00 0.900 0.039 8 8/26/04 2:00 0. 108 4 5.00 0.800 0.040 7 1/05/05 8:00 0. 077 5 3. 00 0. 667 0.077 5 1/18/06 23:00 0. 041 6 2.00 0.500 0.108 4 11/24/06 6: 00 0.040 7 1.30 0.231 0.545 1 1/09/08 10: 00 0.039 8 1. 10 0.091 Computed Peaks 0.407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS 9,5 ?o- 0.002 % 0 0.002 31965 52.128 52. 128 47 .872 0. 479E+00 0.005 5080 8.284 60.413 39.587 0.396E+00 0.008 4953 8.077 68.490 31.510 0.315E+00 0.012 4101 6. 688 75.178 24.822 0.248E+00 0.015 3880 6.327 81.505 18.495 0. 185E+00 0.018 4671 7. 617 89.123 10.877 0. 109E+00 0.022 2302 3.754 92.877 7.123 0.712E-01 0.025 1505 2. 454 95.331 4 . 669 0.467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1. 187 99.410 0.590 0. 590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0. 486E-02 0.045 6 0.010 99.524 0.476 0. 476E-02 0.048 17 0.028 99.552 0.448 0. 448E-02 0.051 11 0.018 99.569 0.431 0. 431E-02 0.054 11 0.018 99.587 0.413 0. 413E-02 0.058 16 0.026 99. 614 0.386 0.386E-02 0.061 24 0.039 99.653 0.347 0.347E-02 0.064 28 0. 046 99. 698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0.181 0. 181E-02 0.081 8 0.013 99.832 0. 168 0. 168E-02 0.084 10 0.016 99.848 0. 152 0. 152E-02 0.087 10 0.016 99.865 0. 135 0. 135E-02 0.091 13 0.021 99.886 0. 114 0. 114E-02 0.094 10 0.016 99. 902 0.098 0. 978E-03 0.097 12 0.020 99.922 0.078 0.783E-03 0.101 14 0.023 99.945 0.055 0.554E-03 0.104 8 0.013 99. 958 0.042 0. 424E-03 0.107 9 0.015 99.972 0.028 0.277E-03 0.110 4 0.007 99.979 0.021 0.212E-03 0.114 4 0.007 99.985 0.015 0.147E-03 0.117 5 0.008 99.993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf ©2012 D.R.STRONG Consulting Engineers Inc. Page 47 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.002 31997 52 .180 52.180 47.820 0. 478E+00 0.005 5419 8 .837 61.018 38. 982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 0.013 4075 6. 645 76.370 23. 630 0.236E+00 0.016 4635 7.559 83.929 16.071 0. 161E+00 0.020 3523 5.745 89.674 10.326 0. 103E+00 0.023 2260 3.686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0.380E-01 0.031 1383 2.255 98.459 1.541 0.154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0.145 99.403 0.597 0.597E-02 0.042 41 0.067 99.470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0. 491E-02 0.049 16 0.026 99.535 0. 465 0.465E-02 0.052 16 0.026 99.561 0.439 0.439E-02 0.056 10 0.016 99.578 0.422 0.422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0. 184 0. 184E-02 0.085 9 0.015 99.830 0. 170 0. 170E-02 0.088 9 0.015 99.845 0. 155 0. 155E-02 0.092 12 0.020 99.865 0.135 0.135E-02 0.096 12 0.020 99.884 0.116 0.116E-02 0.099 13 0.021 99.905 0.095 0.946E-03 0. 103 7 0.011 99.917 0.083 0.832E-03 0. 107 14 0.023 99.940 0.060 0.603E-03 0. 110 12 0.020 99.959 0.041 0.408E-03 0. 114 7 0.011 99.971 0.029 0.294E-03 0.117 4 0.007 99.977 0.023 0.228E-03 0.121 4 0.007 99. 984 0.016 0. 163E-03 0.125 7 0.011 99.995 0.005 0.489E-04 0.128 2 0.003 99. 998 0.002 0. 163E-04 Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0.826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf ©2012 D.R.STRONG Consulting Engineers Inc. Page 48 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21:00 0.530 5.22 1 100.00 0.990 0.029 7 1/07/02 4:00 0. 118 5. 10 2 25.00 0. 960 0. 100 3 3/06/03 22:00 0. 100 4 . 61 3 10.00 0.900 0.025 8 8/26/04 7:00 0. 099 4 . 59 4 5. 00 0.800 0.034 6 1/08/05 5: 00 0. 072 4. 01 5 3.00 0.667 0.072 5 1/19/06 0: 00 0.034 3.72 6 2.00 0.500 0.099 4 11/24/06 8:00 0.029 3.37 7 1.30 0.231 0.530 1 1/09/08 10:00 0.025 2. 46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50.00 0. 980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.129 2 2/09/01 18:00 0.545 1 100.00 0.990 0.041 6 1/05/02 16:00 0. 129 2 25.00 0.960 0.109 3 3/06/03 19:00 0. 109 3 10.00 0.900 0.039 8 8/26/04 2:00 0. 108 4 5.00 0.800 0.040 7 1/05/05 8:00 0.077 5 3.00 0. 667 0.077 5 1/18/06 23:00 0.041 6 2.00 0.500 0.108 4 11/24/06 6:00 0. 040 7 1.30 0.231 0.545 1 1/09/08 10:00 0. 039 8 1. 10 0.091 Computed Peaks 0. 407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS0 0° % 0.002 31965 52.128 52.128 47.872 0. 479E+00 0.005 5080 8.284 60.413 39.587 0.396E+00 0.008 4953 8.077 68.490 31.510 0. 315E+00 0.012 4101 6. 688 75.178 24 .822 0.248E+00 0.015 3880 6.327 81.505 18.495 0. 185E+00 0.018 4671 7. 617 89.123 10.877 0. 109E+00 0.022 2302 3.754 92.877 7 .123 0.712E-01 0.025 1505 2 .454 95.331 4 . 669 0. 467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1.187 99.410 0.590 0. 590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0. 486E-02 0.045 6 0.010 99.524 0. 476 0. 476E-02 0.048 17 0.028 99.552 0. 448 0. 448E-02 0.051 11 0.018 99.569 0.431 0. 431E-02 ©2012 D.R.STRONG Consulting Engineers Inc. Page 49 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.054 11 0.018 99.587 0.413 0. 413E-02 0.058 16 0.026 99. 614 0.386 0.386E-02 0.061 24 0.039 99. 653 0.347 0.347E-02 0.064 28 0.046 99. 698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0. 181 0. 181E-02 0.081 8 0.013 99.832 0.168 0. 168E-02 0.084 10 0.016 99.848 0.152 0. 152E-02 0.087 10 0.016 99.865 0.135 0. 135E-02 0.091 13 0.021 99.886 0. 114 0.114E-02 0.094 10 0.016 99.902 0.098 0. 978E-03 0.097 12 0.020 99.922 0.078 0.783E-03 0.101 14 0.023 99. 945 0.055 0.554E-03 0.104 8 0.013 99. 958 0.042 0. 424E-03 0.107 9 0.015 99. 972 0.028 0.277E-03 0. 110 4 0.007 99.979 0.021 0.212E-03 0. 114 4 0.007 99.985 0.015 0. 147E-03 0.117 5 0.008 99. 993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS 0 0 0 0 0 0.002 31997 52. 180 52.180 47.820 0.478E+00 0.005 5419 8.837 61.018 38. 982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 0.013 4075 6.645 76.370 23. 630 0.236E+00 0.016 4635 7.559 83. 929 16.071 0. 161E+00 0.020 3523 5.745 89.674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0.380E-01 0.031 1383 2.255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0.145 99.403 0.597 0.597E-02 0.042 41 0.067 99.470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0.491E-02 0.049 16 0.026 99.535 0.465 0.465E-02 0.052 16 0.026 99.561 0.439 0.439E-02 0.056 10 0.016 99.578 0.422 0.422E-02 0.060 18 0.029 99.607 0.393 0.393E-02 0.063 23 0.038 99.644 0.356 0.356E-02 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0.184 0. 184E-02 0.085 9 0.015 99.830 0.170 0. 170E-02 0.088 9 0.015 99.845 0. 155 0. 155E-02 0.092 12 0.020 99.865 0. 135 0. 135E-02 0.096 12 0.020 99.884 0. 116 0. 116E-02 0.099 13 0.021 99.905 0.095 0. 946E-03 0.103 7 0.011 99.917 0.083 0.832E-03 0.107 14 0.023 99.940 0.060 0. 603E-03 ©2012 D.R.STRONG Consulting Engineers Inc. Page 50 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.110 12 0. 020 99.959 0.041 0. 408E-03 0. 114 7 0.011 99.971 0.029 0.294E-03 0. 117 4 0.007 99. 977 0.023 0.228E-03 0.121 4 0.007 99. 984 0. 016 0. 163E-03 0.125 7 0.011 99.995 0.005 0. 489E-04 0. 128 2 0. 003 99.998 0.002 0. 163E-04 Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0. 826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21: 00 0.530 5.22 1 100. 00 0.990 0.029 7 1/07/02 4:00 0. 118 5. 10 2 25.00 0.960 0.100 3 3/06/03 22:00 0. 100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7:00 0.099 4.59 4 5.00 0.800 0.034 6 1/08/05 5:00 0.072 4.01 5 3.00 0. 667 0.072 5 1/19/06 0:00 0. 034 3.72 6 2.00 0.500 0.099 4 11/24/06 8:00 0.029 3.37 7 1.30 0.231 0.530 1 1/09/08 10:00 0.025 2. 46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50.00 0.980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0. 129 2 2/09/01 18:00 0.545 1 100.00 0.990 0.041 6 1/05/02 16:00 0. 129 2 25.00 0.960 0. 109 3 3/06/03 19:00 0. 109 3 10.00 0.900 0.039 8 8/26/04 2:00 0.108 4 5.00 0.800 0.040 7 1/05/05 8:00 0. 077 5 3.00 0.667 0.077 5 1/18/06 23:00 0.041 6 2.00 0.500 0.108 4 11/24/06 6:00 0.040 7 1.30 0.231 ©2012 D.R.STRONG Consulting Engineers Inc. Page 51 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.545 1 1/09/08 10:00 0. 039 8 1. 10 0.091 Computed Peaks 0.407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS O O O 0.002 31965 52.128 52 .128 47.872 0. 479E+00 0.005 5080 8.284 60.413 39.587 0.396E+00 0.008 4953 8.077 68.490 31.510 0.315E+00 0.012 4101 6. 688 75.178 24.822 0.248E+00 0.015 3880 6.327 81.505 18.495 0. 185E+00 0.018 4671 7. 617 89.123 10.877 0.109E+00 0.022 2302 3.754 92.877 7.123 0.712E-01 0.025 1505 2.454 95.331 4 . 669 0.467E-01 0.028 1773 2.891 98 .222 1.778 0. 178E-01 0.031 728 1.187 99.410 0.590 0.590E-02 0.035 33 0. 054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0.486E-02 0.045 6 0.010 99.524 0.476 0.476E-02 0.048 17 0.028 99.552 0.448 0.448E-02 0.051 11 0.018 99.569 0.431 0.431E-02 0.054 11 0.018 99.587 0.413 0.413E-02 0.058 16 0.026 99.614 0.386 0.386E-02 0.061 24 0.039 99.653 0.347 0.347E-02 0.064 28 0.046 99.698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0.181 0.181E-02 0.081 8 0.013 99.832 0.168 0.168E-02 0.084 10 0.016 99.848 0.152 0.152E-02 0.087 10 0.016 99.865 0.135 0.135E-02 0.091 13 0.021 99.886 0. 114 0. 114E-02 0.094 10 0.016 99. 902 0.098 0. 978E-03 0.097 12 0.020 99. 922 0.078 0.783E-03 0.101 14 0.023 99. 945 0.055 0.554E-03 0.104 8 0.013 99.958 0.042 0.424E-03 0. 107 9 0.015 99. 972 0.028 0.277E-03 0.110 4 0.007 99.979 0.021 0.212E-03 0. 114 4 0.007 99. 985 0.015 0.147E-03 0.117 5 0.008 99. 993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence Probability 0 CFS % - o o 0.002 31997 52.180 52.180 47.820 0.478E+00 0.005 5419 8.837 61.018 38. 982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 0.013 4075 6. 645 76.370 23. 630 0.236E+00 0.016 4635 7.559 83.929 16.071 0.161E+00 0.020 3523 5.745 89.674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0.380E-01 ©2012 D.R.STRONG Consulting Engineers Inc. Page 52 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.031 1383 2.255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0.145 99.403 0.597 0.597E-02 0.042 41 0.067 99. 470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0.491E-02 0.049 16 0.026 99.535 0.465 0.465E-02 0.052 16 0.026 99.561 0.439 0.439E-02 0.056 10 0.016 99.578 0.422 0. 422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0. 184 0.184E-02 0.085 9 0.015 99.830 0. 170 0.170E-02 0.088 9 0.015 99.845 0. 155 0. 155E-02 0.092 12 0.020 99.865 0.135 0. 135E-02 0.096 12 0.020 99.884 0. 116 0. 116E-02 0.099 13 0.021 99. 905 0.095 0. 946E-03 0.103 7 0.011 99. 917 0.083 0.832E-03 0.107 14 0.023 99. 940 0.060 0. 603E-03 0. 110 12 0.020 99. 959 0.041 0.408E-03 0.114 7 0.011 99. 971 0.029 0.294E-03 0.117 4 0.007 99. 977 0.023 0.228E-03 0.121 4 0.007 99. 984 0.016 0. 163E-03 0.125 7 0.011 99. 995 0.005 0.489E-04 0.128 2 0.003 99. 998 0.002 0.163E-04 Route Time Series through Facility Inflow Time Series File:rdin.tsf Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0.826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21:00 0.530 5.22 1 100.00 0.990 ©2012 D.R.STRONG Consulting Engineers Inc. Page 53 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.029 7 1/07/02 4:00 0. 118 5. 10 2 25.00 0.960 0.100 3 3/06/03 22:00 0. 100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7: 00 0. 099 4.59 4 5.00 0.800 0.034 6 1/08/05 5:00 0. 072 4. 01 5 3.00 0.667 0.072 5 1/19/06 0:00 0. 034 3.72 6 2.00 0.500 0.099 4 11/24/06 8:00 0. 029 3.37 7 1.30 0.231 0.530 1 1/09/08 10:00 0. 025 2. 46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50.00 0.980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0. 129 2 2/09/01 18: 00 0.545 1 100. 00 0. 990 0.041 6 1/05/02 16: 00 0. 129 2 25. 00 0.960 0. 109 3 3/06/03 19: 00 0. 109 3 10. 00 0.900 0.039 8 8/26/04 2: 00 0.108 4 5. 00 0.800 0.040 7 1/05/05 8: 00 0.077 5 3. 00 0. 667 0.077 5 1/18/06 23: 00 0. 041 6 2. 00 0.500 0.108 4 11/24/06 6: 00 0. 040 7 1.30 0.231 0.545 1 1/09/08 10: 00 0.039 8 1. 10 0.091 Computed Peaks 0. 407 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability - CFS % % 0.002 31965 52.128 52 . 128 47.872 0. 479E+00 0.005 5080 8.284 60.413 39.587 0.396E+00 0.008 4953 8. 077 68.490 31.510 0.315E+00 0.012 4101 6. 688 75.178 24.822 0.248E+00 0.015 3880 6.327 81.505 18.495 0.185E+00 0.018 4671 7. 617 89.123 10.877 0. 109E+00 0.022 2302 3.754 92.877 7.123 0.712E-01 0.025 1505 2.454 95.331 4. 669 0. 467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1.187 99.410 0.590 0.590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0.486E-02 0.045 6 0.010 99.524 0.476 0.476E-02 0.048 17 0.028 99.552 0.448 0.448E-02 0.051 11 0.018 99.569 0.431 0.431E-02 0.054 11 0.018 99.587 0.413 0. 413E-02 0.058 16 0.026 99.614 0.386 0.386E-02 0.061 24 0.039 99.653 0.347 0.347E-02 0.064 28 0.046 99.698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0. 181 0. 181E-02 0.081 8 0.013 99.832 0. 168 0. 168E-02 0.084 10 0.016 99.848 0. 152 0. 152E-02 ©2012 D.R.STRONG Consulting Engineers Inc. Page 54 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.087 10 0.016 99.865 0.135 0. 135E-02 0.091 13 0.021 99.886 0.114 0. 114E-02 0.094 10 0.016 99.902 0.098 0. 978E-03 0.097 12 0.020 99.922 0.078 0.783E-03 0.101 14 0.023 99.945 0.055 0.554E-03 0. 104 8 0.013 99. 958 0.042 0. 424E-03 0. 107 9 0.015 99. 972 0.028 0.277E-03 0.110 4 0.007 99. 979 0.021 0.212E-03 0.114 4 0.007 99. 985 0.015 0. 147E-03 0.117 5 0.008 99. 993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS 0 0 0.002 31997 52. 180 52.180 47.820 0. 478E+00 0.005 5419 8.837 61.018 38.982 0.390E+00 0.009 5339 8.707 69.724 30.276 0.303E+00 0.013 4075 6. 645 76.370 23.630 0.236E+00 0.016 4635 7.559 83.929 16.071 0. 161E+00 0.020 3523 5.745 89.674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6. 641 0. 664E-01 0.027 1744 2.844 96.204 3.796 0. 380E-01 0.031 1383 2 .255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0. 145 99.403 0.597 0.597E-02 0.042 41 0.067 99.470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0. 491E-02 0.049 16 0.026 99.535 0.465 0. 465E-02 0.052 16 0.026 99.561 0.439 0.439E-02 0.056 10 0.016 99.578 0.422 0. 422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 0.067 26 0.042 99.687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0.184 0. 184E-02 0.085 9 0.015 99.830 0.170 0. 170E-02 0.088 9 0.015 99.845 0.155 0. 155E-02 0.092 12 0.020 99.865 0. 135 0. 135E-02 0.096 12 0.020 99.884 0.116 0. 116E-02 0.099 13 0.021 99. 905 0.095 0. 946E-03 0.103 7 0.011 99. 917 0.083 0.832E-03 0.107 14 0.023 99. 940 0.060 0. 603E-03 0.110 12 0.020 99. 959 0.041 0. 408E-03 0.114 7 0.011 99. 971 0.029 0.294E-03 0.117 4 0.007 99. 977 0.023 0.228E-03 0.121 4 0.007 99.984 0.016 0. 163E-03 0.125 7 0.011 99.995 0.005 0. 489E-04 0.128 2 0.003 99.998 0.002 0. 163E-04 Route Time Series through Facility Inflow Time Series File:rdin.tsf ©2012 D.R.STRONG Consulting Engineers Inc. Page 55 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Outflow Time Series File:rdout POC Time Series File:dsout Inflow/Outflow Analysis Peak Inflow Discharge: 0. 826 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0. 530 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.22 Ft Peak Reservoir Elev: 5.22 Ft Peak Reservoir Storage: 26843. Cu-Ft 0. 616 Ac-Ft Add Time Series:bypass.tsf Peak Summed Discharge: 0.545 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:dsout.tsf Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.118 2 2/09/01 21: 00 0.530 5.22 1 100. 00 0.990 0.029 7 1/07/02 4: 00 0.118 5. 10 2 25.00 0.960 0.100 3 3/06/03 22: 00 0.100 4. 61 3 10.00 0.900 0.025 8 8/26/04 7:00 0.099 4.59 4 5.00 0.800 0.034 6 1/08/05 5:00 0.072 4.01 5 3.00 0. 667 0.072 5 1/19/06 0:00 0.034 3.72 6 2.00 0.500 0.099 4 11/24/06 8:00 0.029 3.37 7 1.30 0.231 0.530 1 1/09/08 10: 00 0.025 2.46 8 1. 10 0.091 Computed Peaks 0.393 5. 19 50. 00 0.980 Flow Frequency Analysis Time Series File:dsout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.129 2 2/09/01 18: 00 0.545 1 100.00 0.990 0.041 6 1/05/02 16: 00 0. 129 2 25.00 0.960 0.109 3 3/06/03 19: 00 0. 109 3 10.00 0.900 0.039 8 8/26/04 2:00 0. 108 4 5.00 0.800 0.040 7 1/05/05 8: 00 0.077 5 3.00 0.667 0.077 5 1/18/06 23:00 0. 041 6 2.00 0.500 0.108 4 11/24/06 6: 00 0.040 7 1.30 0.231 0.545 1 1/09/08 10:00 0.039 8 1.10 0.091 Computed Peaks 0. 407 50. 00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence Probability CFS % - 0.002 31965 52.128 52. 128 47.872 0.479E+00 0.005 5080 8.284 60. 413 39.587 0.396E+00 0.008 4953 8.077 68. 490 31.510 0.315E+00 0.012 4101 6.688 75.178 24.822 0.248E+00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 56 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.015 3880 6.327 81.505 18.495 0. 185E+00 0.018 4671 7. 617 89.123 10.877 0. 109E+00 0.022 2302 3.754 92.877 7.123 0.712E-01 0.025 1505 2.454 95.331 4 . 669 0. 467E-01 0.028 1773 2.891 98.222 1.778 0. 178E-01 0.031 728 1.187 99.410 0.590 0.590E-02 0.035 33 0.054 99.463 0.537 0.537E-02 0.038 21 0.034 99.498 0.502 0.502E-02 0.041 10 0.016 99.514 0.486 0.486E-02 0.045 6 0.010 99.524 0. 476 0.476E-02 0.048 17 0.028 99.552 0.448 0.448E-02 0.051 11 0.018 99.569 0.431 0.431E-02 0.054 11 0.018 99.587 0.413 0.413E-02 0.058 16 0.026 99. 614 0.386 0.386E-02 0.061 24 0.039 99. 653 0.347 0.347E-02 0.064 28 0.046 99. 698 0.302 0.302E-02 0.068 21 0.034 99.733 0.267 0.267E-02 0.071 23 0.038 99.770 0.230 0.230E-02 0.074 15 0.024 99.795 0.205 0.205E-02 0.077 15 0.024 99.819 0. 181 0.181E-02 0.081 8 0.013 99.832 0.168 0. 168E-02 0.084 10 0.016 99.848 0. 152 0. 152E-02 0.087 10 0.016 99.865 0.135 0.135E-02 0.091 13 0.021 99.886 0. 114 0. 114E-02 0.094 10 0.016 99. 902 0.098 0. 978E-03 0.097 12 0.020 99. 922 0.078 0.783E-03 0.101 14 0.023 99.945 0.055 0.554E-03 0.104 8 0.013 99.958 0.042 0. 424E-03 0.107 9 0.015 99.972 0.028 0.277E-03 0.110 4 0.007 99.979 0.021 0.212E-03 0.114 4 0.007 99.985 0.015 0. 147E-03 0.117 5 0.008 99.993 0.007 0. 652E-04 Flow Duration from Time Series File:dsout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS ° o ° o 0.002 31997 52 .180 52. 180 47.820 0.478E+00 0.005 5419 8 .837 61.018 38.982 0.390E+00 0.009 5339 8 .707 69.724 30.276 0.303E+00 0.013 4075 6. 645 76.370 23.630 0.236E+00 0.016 4635 7 .559 83. 929 16.071 0. 161E+00 0.020 3523 5.745 89.674 10.326 0. 103E+00 0.023 2260 3. 686 93.359 6.641 0. 664E-01 0.027 1744 2 .844 96.204 3.796 0.380E-01 0.031 1383 2 .255 98.459 1.541 0. 154E-01 0.034 490 0.799 99.258 0.742 0.742E-02 0.038 89 0.145 99.403 0.597 0.597E-02 0.042 41 0.067 99.470 0.530 0.530E-02 0.045 24 0.039 99.509 0.491 0. 491E-02 0.049 16 0.026 99.535 0.465 0.465E-02 0.052 16 0.026 99.561 0.439 0.439E-02 0.056 10 0.016 99.578 0.422 0. 422E-02 0.060 18 0.029 99. 607 0.393 0.393E-02 0.063 23 0.038 99. 644 0.356 0.356E-02 ©2012 D.R.STRONG Consulting Engineers Inc. Page 57 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 0.067 26 0.042 99. 687 0.313 0.313E-02 0.070 21 0.034 99.721 0.279 0.279E-02 0.074 21 0.034 99.755 0.245 0.245E-02 0.078 23 0.038 99.793 0.207 0.207E-02 0.081 14 0.023 99.816 0. 184 0.184E-02 0.085 9 0.015 99.830 0.170 0. 170E-02 0.088 9 0.015 99.845 0.155 0. 155E-02 0.092 12 0.020 99.865 0.135 0. 135E-02 0.096 12 0.020 99.884 0. 116 0.116E-02 0.099 13 0.021 99. 905 0.095 0. 946E-03 0.103 7 0.011 99.917 0.083 0.832E-03 0.107 14 0.023 99.940 0.060 0. 603E-03 0. 110 12 0.020 99. 959 0.041 0.408E-03 0.114 7 0.011 99. 971 0.029 0.294E-03 0.117 4 0.007 99. 977 0.023 0.228E-03 0.121 4 0.007 99.984 0.016 0. 163E-03 0.125 7 0.011 99.995 0.005 0. 489E-04 0.128 2 0.003 99.998 0.002 0. 163E-04 Peaks Plot 7auud-Fbw Frequency- Y +,lydL'GI�:' Return Period 2 5 10 20 50 100 :o rdout.pks in Sea-Tac -• dsout.pks ,,,-O predev.pks • - 0 0 R a 10-1_ eC 0 _ o a u_ U - - • 0 • o l0 O L N O 107 .- 0 103 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Cumulative Probability ©2012 D.R.STRONG Consulting Engineers Inc. Page 58 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 DurationpCurve N Paus<d-Duration Analysis-KCRT, Ii ,p tssi-R i`f rdout dur o dsoutdur • target.dur o N R rnC ��. LL • m o En. o 0 CD oo • - • O � 1 1 1 1 1 1 I I I 1 1 1 1 1 1 I I I 1 1 1 1 1 1 I I I 1 1 1 1 1 1 I I 1 1 1 1 1 1 1 105 10 ° 103 10.2 10-1 100 Probability Exceedence FLOW CONTROL PRIMARY OVERFLOW RISER Using standard orifice equation to determine stand pipe diameter in control structure Q100 = Developed 100-Year, Hourly Peak Storm calculated using KCRTS 0100 = 2.04 cfs HMAX= Maximum available head in feet measured from crest of weir HM,(= 0.5 ft. D = Riser Diameter D = (Q100/(3.782 * HMAX .5))0.5 D = 0.87 ft. (min. diameter) use D = 12 in. or 1 ft. Calculate actual height above the weir expected during the 100-year, 24-hour peak storm H = Actual head above weir achieved with Q100 H = (Q100/(9.739* D))^0.67 H = 0.35 ft. ©2012 D.R.STRONG Consulting Engineers Inc. Page 59 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 JAILHOUSE EMERGENCY OVERFLOW Using standard orifice equation to determine stand pipe diameter in control structure D= Control structure diameter D= 54 in. Q100= 100-Year, 24-Hour Peak Storm calculated using KCRTS 0100= 2.04 cfs HMAx= Head above weir achieved with 0100 HMAX= 0.35 ft. P= Height of overflow above outlet invert elevation P= 5.22 ft. c= Constant per Figure c= 3.27+0.4*HMAx/P C= 3.30 ft. L= Arc length of the jailhouse window as necessary but not to exceed 50% of the control structure's internal circumference L= (Q100/(C*HMAX1 5))+0.2*HMAX L= 3.06 ft. (min. arc length) C= Control Structure Circumference C= 14 ft. Calculate corrected L due to vertical bars in window. Lad1= adjusted arc length of the jail-house window Lad1= L+0.083*(L/0.33) Ladi= 3.83 ft. SECONDARY EMERGENCY OVERFLOW STRUCTURE - BIRDCAGE Using sharp crested weir equation to determine stand pipe diameter in control structure Ref. KCSWDM '98 Figure 5.3.4.E Q100=!100-Year Peak Storm calculated using KCRTS 15-Minute Time Steps 0100= 2.04 cfs P= Height of primary overflow above outlet invert elevation P= 5.45 ft. D= Control structure diameter D= 54 in. L= Control structure circumference L i 14.14 ft. C= 3.27+0.4H/P (ft) use... 0100= 3.27+0.4H/P(L-0.2H)H"1.5 H= Emergency overflow water surface elevation H=1 0.12 ft. ©2012 D.R.STRONG Consulting Engineers Inc. Page 60 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012 Water Quality Treatment The Project is located in the Basic Water Quality Treatment area. The treatment goal is for removal of 80% of Total Suspended Solids for flows including the WQ design flow or volume defined in Section 6.2.1 of the 2005 KCSWDM. Wetpond Rainfall(R) of the mean annual storm = 0.47 in. From KCSWDM Fig. 6.4.1.A Area of impervious surface (Ai) = 61,177 s.f. Area of till soil covered with till grass(Atg)= 41,907 s.f. Area of till soil covered with till forest(Atf)= 0 s.f. Area of outwash soil covered with grass or forest(Ao) = 0 s.f. Volume factor(f)= 3 N/A From KCSWDM Sec. 6.4.1.1 Calculations Units Notes Volume of runoff from mean annual storm (Vr) = 2,567 c.f. =(0.9Ai+0.25Atg +0.10Atf+0.01Ao)* R/12 Minimum Wetpool volume required(Vb) = 7,700 c.f. =f*Vr The calculation shown above is based on 60% lot coverage. The provided wetpool volume is 8,278 c.f. with a minimum of a 4:1 length to width ratio. ©2012 D.R.STRONG Consulting Engineers Inc. Page 61 of 61 Stormwater Pollution Prevention Plan kelsey's crossing September 5,2012