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Home My WebLink About03613 - Technical Information Report t . � � �� PRELIMINARY .__� � - _ � � � �y k� ` TECHNICA� I�FORMATION REPORT 9 m � Proposed Plat of Cavalla East Side of 162nd Avenue S.E. South of S.E. 137th Place King County, Washington Prepared for: KBS II1, LLC 12320 N.E. 8th Street, Suite 100 Bellevue, WA 98005 F� �=,.:"�:r� December 21 , 2005 - � ��-�� Our Job No_ 11778 � <4 ` /L� L� -�7 .,� �RY JACp9 ��;,� ��04 wasr��s r� �� ' C ��';� �'�' o �L �_ .., � y Z iD � JAN 1 2 2G06 t k ? 9 O„ -� K.C. �.�.�.5. c, �S �;G � GHAU L�C�Paoo EY.PIftES �o,�o, � � S 1 m T��j,z CIVIL ENGINEERING, LAND PLANNING, SURVEY�NG, ENVIRONMENTAL SERVICES � 15215 72ND AVENUE SOUTH KENT, WA 98032 (425)251-6222 (425) 25i-8782 Fa,x °y i BRANCH OFFICES ♦ OLYMPIA, WA ♦ TEMECULA, CA ♦ WALNUT CREEK, CA . s� � : y- www.barghausen.com `r�~G ENG�� 3 �i3 TABLE OF CONTENTS 1.0 PROJECT OVERVIEW Figure 1 —Technical Information Report(TII2)Worksheet Figvre 2—Vicinity Map Figure 3—Drainage Basins, Subbasins, and Site Characteristics Figure 4—Soi1s Map 2.0 CONDITIONS AND REQUIRENLENTS SiJ1�1MARY 2.I Analysis of Core Requirements 22 Analysis of Special Requirement No. 1 3.0 OFF-STTE ANALYSIS 4.0 FLOW CONTROL AND WATER QUALITY FACILITY AN.4LYSIS AND DESIGN A. Existing Site Hydrology B. Developed Site Hydrology � C. Performance Standards D. Flow Control System E. Water Quality System 1177&.00�.doc[JPJ/tepl � w � � x w � 0 � � w � 0 x a 0 � 1.0 PROJECT OVERVIEVV The proposed plat of Cavalla is approximately a 9.4-acre site located within a portion of the Southeast quarter of Section 14, Township 23 North, Range 5 East, Willamette Meridian, King County, Washington. More specifically, the site is located on the eastern side of 162nd Avenue . S.E. and 200 feet south of S.E. 137th Place and is fairly rectangular in shape. The enclosed Figure 2—Vicinity Map,depicts the approximate location of the proposed site. The existing topography is such that it is undeveloped and consists of forested areas over the entire site. The site tends to slope at an approximately grade of 8 percent in a north to southwesterly dircction. There is one existing single-family residence located in the northwest corner of the project site. This residence will be demolished with the construction of ihis plat. The storm drainage facility is proposed to be located in the southwest corner of the project site such that the site will discharge in the same location it does under existing conditions. There are no wetlands located on this project site and road improvements are proposed for haIf-street �videning of 162nd Avenue S.E. This is why the flow control calculations uti}ized 9.91 acres of development rather than 9.4 acres, since there are road improvements along the western property line of the site. The western boundary of the project site is formed by 162nd Avenue S.E. The plat of Liberty Lane forms the project site's northem boundary. Unplatted land, which may be a park area, forms the eastern boundary of the project site. There is a proposed development located sonth of the project site that will probably be developed concurrently with this project since it has been previously submitted to King County for plat approvaL The proposal for this development is to subdivide the property into 34 separate lots with a separate tract for access to some of the lots, and another tract for starmwater quaiity and a flow control facility. In addition, road improvements will be constructed throughout the project to provide access to the project's lots. Elevations on the site range from 480 along the northern property line do��rn to 432 along the southern property line at the south��est corner of the project site. There is an approximate S.4-acre upstream basin contributing runoff to the northern property line of the project site. This runoff is channeled along the perimeter of the property line of the site and discharges at the northwest corner of the site near a ditch onto the road improvements proposed for this development. This ditch «�ill be collected by a ca[ch basin and pipe conveyance system at the northwest corner of the site and routed, in a separate system bypassing the on-site pipe conveyance system, discharging to the detention pond. This upstream basin ��ill be routed through the road improvements and will discharge further do�unstream, much as it does under existing conditions, at the southwest corner of the property site. 11778.005-doe[JPJ/tepl FIGURE 1 TECHNICAL INFORMATION REPORT (TIR) WORKSHEET King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner KBS Ill,LLC Project Name Address 1232Q N.E. 8th Street, Suite 100 Pro osed Plat of Cavalla Bellevue, WA 98005 �ocation Phone Township 23 North Project Engineer Ali Sadr, P.E. Range 5 East Company Bar hausen Consulting Engineers, Inc. Section 14 Address/Phone 18215—72nd Avenue South Kent, WA 98032/(425) 251-6222 Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS � Subdivision HPA ❑ DFW HPA ❑ Shoreline Management ❑ Short Subdivision ❑ COE 404 ❑ Rockery � Grading ❑ DOE Dam Safety ❑ Structural Vaults ❑ Commercial ❑ FEMA Floodplain ❑ Other_ ❑ Other ❑ COE Wetlands Part 5 SITE COMMUNITY AND DRAtNAGE BASIN Community Renton Highlands Drainage Basin Cedar River Part 6 SITE CHARACTERISTICS ❑ River ❑ Floodplain ❑ Stream ❑ Wetlands ❑ Critical Stream Reach ❑ SeepsJSprings ❑ Depressions/Swales ❑ High Groundwater Table ❑ Lake ❑ Groundwater Recharge ❑ Steep Slopes ❑ Other 11778.00�.dce[1PJ/tepl � Part 7 SOlLS Soil Type Slopes Erosion Potential Erosive Velocities Alderwood ❑ Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT D � � ❑ ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION � Sedimentation Facilities � Stabilize Exposed Surtace � Stabifized Construction Entrance � Remove and Restore Temporary ESC Facilities � Perimeter Runoff Control � Clean and Remove All Silt and Debris ' ❑ Ctearing and Grading Restriclions � Ensure Operation of Permanent Facilities � Cover Practices ❑ Flag Limits of SAO and Open Space Preservation Areas � Construction Sequence ❑ Other ❑ Other Part 10 SURFACE WATER SYSTEM ❑ Grass Lined Channel ❑ Tank ❑ Infiltration Method of Analysis � Pipe System ❑ Vault ❑ Depression KCRTS ❑ Open Channel ❑ Energy Dissipater ❑ Flow Dispersal Compensation/Mitigation � Dry Pond ❑ Wetland ❑ Waiver of Eliminated Site Storage � Wet Pond ❑ Stream ❑ Regional Detention Level 2 Flow Control Brief Description ot System Operation Catch basin collection ro pi conveyance to�;�et/detention pond ihen dispersed. Facility Related Site Limitations Reference Facifity Limitation 117;�i-(k15 d��1P1hcE>j Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS �'� ❑ Cast in Place Vault ❑ Drainage Easement ' ❑ Retaining Wal� ❑ Access Easement ❑ Rockery>4'High ❑ Native Growth Protection Easement ❑ Structural on Steep Slope � Tract ❑ Other ❑ Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER f,or a civil engineer under my supervision,have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. 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'�� . . . . . � a I a � . � .... . . ..... . � � :e . , � 3 � , __::.� , �,. � . . . � w �59.9 �M1[�5[CnON 0! 6 �\ ..PVl SfA - 14+01 w�.00 S�, ♦ .07 . . S7A 1�sW. VJI F1fV��59.20 � � � No. poU gy Cyy. App�. RMNen Jop Nump�r kyh; �G A(�� o..�a�.e.re_ K BA<M FOf° TIU� 18215 72N0 AVENUE SOUTH ��' w�s F 11778 P , t� KeNT, WA 98032 Dnwn _4GW Mmli0�t01 0��°� "'�`- KBS DEVELOPMENT CORP, PRELIMINARY ROAD AND PROFILES m "' Z �azs�zs,—szzz � 12320 N.E. 8TH STREET, STE.100 AND DRAINAC3E PLAN .'� cn.cww .ws_ i'-so' ! ` 5„„, � �°� • (425)251-8782 FAX BELLEVUE, WA 98005 FOR o �...�m.. i� �,q, A x5e'12 0 � �. :. MO�wN DIfB_ VMkal `� fGisi(ut, a4, s, �, ay� CML ENGINEENINC, IAND PIµNING, H�� 'ssipN�� H�,� C � ,N�EN�\HFE SURVEYINC, ENHIRONMENTAI SERVILES po�• t2�o7/OS CAVALLA 2 0l �J %I 9 7J U/ �� ._�,. '_, .... ,.,....e . _..� •r v,,..,r,: , s . 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' � �n .... .,;• ahX,�. f . �, ' j� � � � � � �:� � � Z �� ' s�� a `�- „ i _—'____—_.�:�r:---- --'------ —��.`�_"ti�. _`; —= —_ � I g�N �`� � J Z �. � �i �bba ��o�`� i I I � 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of Core Requirements Core Reguirement No. 1: Discharge at the Natural Location. Response: This project site will discharge after flow control in the water quality pond at the same location it does under existing conditions. Core Requirement No. 2: Off-Site Analysis. Response: This project has prepared an off-site analysis that is located in Section 3.0 of this Preliminary Technical Information Report. Please refer to that document for the off-site analysis. Core Requirement No. �: Flow Control. Response: This project will provide flow control in the form of a wet/detention pond located in the southwest corner of the project site discharging to the same location as i[ does under existing conditions. In addition, Flow Control BMPs will be applied to all lots by the developer and the contractor at the time of construction. For the initial sizing of the flow controi pond prepared for this development, the flow control BMPs were not included in the calculations. Therefore, a pond targer than what will actually be required «�as determined for this project site. This is a conservative design. Core Requirement No. 4: Conveyance System. Response: The conveyance system for this project site will be sized according to the 2005 King County, Washington Surface Water Design Manuat (KCSWDM). Since the project site is tess than 10 acres in size, the pipe conveyance system will be sized based on the Rational method as delineated in the 1990 KCSWDM utilizing an initial time of concentration of 6.3 minutes and a Manning's "n" value of O.Q14. In addition,the 25-year precipitation will be utilized, which is a requirement of the 2005 KCSWDM. The 100-year event will be analyzed for overtopping as long as it dces not impact any downstream development. Core Requirement No. S: Temporan'Erosion and Sedintent Control. Response: This project site will follow the erosion and sediment control measures as delineated in Appendix D of the 2005 KCS�'VDM such that clearing limits will be specified, cover measures will be instituted, perimeter protection will be installed in the form of silt fences, a rock construction entrance will be installed, and the streets will be swept clean of sediment after construciion at the end of each day. On-site sediment retention will be maintained in the form of a sediment pond. Surface water collection will be maintained by collecting runoff from the project site through temporary V-ditches and routing them to the sediment pond, sized according to Appendix D of [he 2005 KCSWDM. Core Reguirement No. 6: Maintenance and Operatio�zs. Response: This project will concur with all maintenance and operations requirements as � delineated in the 2005 KCS�'�'DM for projects of lhis nature. �� ri cN�s d�x�n��i��p] Core Requirement No. 7: Financial Guarantees and Liability. Response: This project will concur with all financial guarantees and liability requirements of ihe 2005 KCSWDM as delineated for projects of this nature. Core Reguirement No. 8: Water Quality. Response: The Water QuaIity Men❑ followed for this projeci site requires that the Basic �'Vater Quality R�enu be followed for this developmeni. One of the options of the Basic Water Qoality Menu allows the provision of a wet pond. This project is proposing a wet pond located below the live storage in the wet/detention pond soch that three timcs the mean annual storm will be provided as dead storage below the live storage in the wetldetention pond. 2.2 Analysis of Special Requirement No. 1 Special Requirentent No. 1: Other Adopted Area-Specific Requirements. Response: To the best of our knowledge, the site is not located in an Other Adopted Area-Specific Requirement area; therefore, Special Requirement No. 1 does not apply. 11778.00S.doc[JPl/tepl � M� � � � � � � w � � � � � � � O M LEVEL 'I OFF-SITE DRAINAGE ANALYSIS Proposed Plat of Cavalla East Side of 162nd Avenue S.E. South of S.E. 137th Place King County, Washington Prepared for: KBS III, LLC 12320 N.E. 8th Street, Suite 100 Bellevue, WA 98005 November 14, 2005 Our Job No. 11778 �RRY JA��es ��7'� � �OF WAShrr�C O Z 1 `' �"� I6 �'� (� :, :�AL�`•u \ W.. �NA� ` er.F��_s 1+?/IO/D�P ! m� rT�j Z CIV�L ENGfNEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES ��, - 1 H215 72ND AVENUE SOUTH KENT,WA 98032 (425) 251-6222 (425) 251-8782 FAx ° i BRANCH OFFICES ♦ OLYMPIA,WA ♦ TEMECUTA, CA ♦ WALNUT CREEK, CA Z �I ,� � , 11� �� www.barghausen.com �E...G�'.1�- TABLE OF CONTENTS TASK 1 STUDY AREA DEFINI'TION AND MAPS EXHIBIT A Vicinity Map EXHIBTT B Downstream Drainage Map EXI-IIBIT C Upstream Basin Map TASK 2 RESOURCE REVIEW EXHIBI'F D FEMA Map EXHIBIT E Sensitive Areas Folios EXHIBIT F SCS Soils Map EXHIBIT G Assessor's Map EXHIBTT H Wetland Inventory Map EXHIBIT I Basin Reconnaissance Summary Report TASK 3 FIELD INSPECTION EXHIBI'T J Off-Site Analysis Drainage System Tab}e 3.1 Conveyance System Nuisance Problems (Type 1) 3.2 Severe Erosion Problems (Ty�pe 2) 33 Severe Flooding Problems (Type 3) TASK � DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS EXHIBIT K Drainage Complaints 1 1778.003.doc TASK 1 STUDY AREA DEFINITION AND MAPS TASK 1 STUDY AREA DEFIIVITION AND MAPS The proposed plat of Cavalla is approximately a 9.4-acre site located within a portion of the Southeast quarter of Section 14, Township 23 North, Range 5 East, Willamette Meridian, King County, Washington. More specifically the site is located on the eastern side of 162nd Avenue S.E. and 200 feet south of S.E. 137th Place and is fairly rectangular in shape. The enclosed Exhibit A — Vicinity Map depicts the approximate location of the proposed site. The existing topography of the site is such tha[ it is undeveloped and consists of forested areas over tI�e entire site. The site tends to slope at an approximate grade of 8 percent in a north-to-south westerly direction. There is one existing single-family residence located in the northwest corner of the project site. This residence will be demolished with the construction of this plat. The storm drainage facility is proposed to be located in the south��est corner of the project site such that the site will discharge in the same location it does under existing conditions. There are no wetlands located on this project site and road improvements are proposed for half-street widening of 162nd Avenue S.E. The western boundary of the project site is formed by 162nd Avenue S.E. The pIat of Liberty Lane forms the project site's northern boundary. Unpiatted land, which may be a park area, forms the project's western boundary. There is a proposed development located south of the project site, which will probably � be developed concurrently with this project site since it has been previously submitted to King County for � plat approval. �, The proposal for this development is to subdivide the property in 34 separate lots with a separate tract for II access to some of the lots and another tract for stormwater quality and flow control facilities. In addition, � road improvements will be constructed throughout the project to provide access to the project site's lots. , Elevations on the site range from 480 along the northern property line, down to 432 along the southern � property line at the southwest corner of the project site. � UPSTREAI�I DRr1INAGE ANaLI'SIS Based on revie�� of the topo�raphic map, the site improvement plans prepared for the Liberty Lane plat loc;ated north of the project site, and our site visit it appears there is upstream ftow onto and through the site. This upstream flow is all routed to the northwest corner of the property and is conveyed in a ditch along the future right-of-way of 162nd Avenue S.E., where it finally disperses after coursing apgroximately half way south along the project site's western property line. This upstream basin in approximately 5.4 acres in size, consists of a portion of the developed area known as Liberty Lane plat, and the remainder is undeveloped land. The runoff from the upstream basi� will he collected and canveyed separate[y around the project site by being conveyed in the right-of-��-ay of i62nd Avenue S.E. 1]778_003.dcw EXHIBIT A Vicinity Map i � o �,,,,, e � � q� m � -' � '1� A 2 m � e ��C 0 �"fc h w 149TF1 PL �--SE `�� „`ti..;,�� ;5`�„ v��NE�NILE AV �.x' AV NE AV Sf _ �., N �„ _ . ° �SpM ' in in ' � o r� w��Eoyw[ O � a � " � �" ,V S� I 150iM _Fl,��$E m �I qS �,l'�� A=M (MIIE Dl��:NfIF PL NE�1 rr7 ^'151ND AV � SlST k � .�� `' g .'� � + I� �INF$ �� 1d97N�V SE m „« H r�^i �, � � i /�y 'p P � i�� C �� SE ; h �:I �, xY L SE J`p rl�r~ 3aHii��III�y ^T � �. un Hc F -{ ,Z� I =�� - x '' a S fij� i�'. 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' � � ' � � �. r � EXHIBIT C Upstream Basin Map _ - - _ . -- . .. _ __ - -_ � � :-„-,- __ -��.h r ".___.--__�__ .___"'__.'-___'_"'__"_ 5_E.t36TH_5T '"_' S.E.1367MSTr•��— -.—______'____'-_"__'_ � � „ `n _' ___i- ' �n_. -T�r._'^.,. .-.. . . ..- _ _ ,� a t � , ' <»ia '.. - � ,_ . - -- '_ �� Y' C N3.!i � ,�1�: ,�M ! �t' ppg) . _ - . � � � wf�v ' QPJ u 1 0� � I � � g � � ' - - � . ` � I I ,�•�' �� .. a , , _ � �,, �, �r �� _ = i � -�. .,. �`:;��,..- -- __ _ _ ; 1 �A�S t N _ �.. - � , - -v.,, -� � ;�, - - _ � Y: .�. .r:: u� �.: �:�,v � � �� v �M �y :�_. �. _ ; ...: ,.�: � = � ` � � .�.,.,: ,-�sseea-- ----- - �,,,----— " _�' (Q 's S.E.137-MYl '�.�.� _ , �_ •• '�LI B RfiY A E " °°° . .f, �,.;;_,,. �o �� a �� _ � e i - - = `;;�� °°°�� °" �' �',` °�°° �:,- ��" �� . _ ; ..,,,,. � I i �` ; - � " ,..., ,,,,�. - - t _ - ' � I _ _ =I [[E1=f131!)75 =i0'v4��;�r4!L<f _ . ��LF � -I -- .- .�.r - �:. � .,�.. °w` .,,; _ �� ni�i-��—— �oog, i .,,,�., oas � .s��-., j '�—��—,--- — - __ — tas�sC CEDAR PARK _ I FIVE ACRE TRACTS I _ • .,�,., i ' � ' °°'„ � _ - �;_ - ' - S � �"E' - _ =�� - ; I � � � �� 0�0•� I ��•. Ph�� I . . . . t��.1: ''� /� ' I I � 1 ' � I � I � � u� . _ ,,.. ; , ,. �y � � � ; i f --- -� � v(�� i�'� �'�'S I I� � r /� /�'p l •I ,.� � j'�V I `� «� � w � � N � �i w � � � � � � � L/1 � TASK 2 RESOURCE REVIEW • Adopted Basin Plans: The site is part of the Lower Cedar River drainage basin. • Finalized Drainage Studies: This is not applicable. • Basin Reconnaissance Summary Report: Once again, the site is located in the Lower Cedar River drainage basin and drains to an area that has no mapped tributary (which would have been mentioned in the basin reconnaissance summary report if it had its own drainage basin). • Critical Drainage Area Maps: According to the ��ater quality applications map in the 2005 King County, Washington Surface Water Desigr► Manual (KCSWDM), Basic Water Quality treatment is required. According to the flow control appIications map, also in the 2005 KCSWDM, Conservation Flow Control (kno�vn as Level 2 F1ow Control) is required as a minimum. • Floodplain and Floo�ivay FEMA Maps: Please the enclosed Exhibit D—FEMA Map utilized far this analysis. Panel No. 1,001 of 1,725,Map No. 53033C1001 F,revised May 16, 1995> indicates that the proposed project site does not Iie within a floodplain or floodway of a stream. • Other Off-Site Analysis Reports: A review of Exhibit I—Basin Reconnaissance Summary Report and the site investigation work conducted in the preparation of this LeveI 1 Drainage Analysis. The U.S. Department of Agriculture Soils Conservation Service (SCS) soils map is also provided (see Exhibit F — SCS Soils Map). In addition, the off-site analysis prepared for the project site Iocated immediately south of this site was reviewed for conformance with the findings from the off-site analysis performed for ihis project. • Sensitive Areas Folios: Based on a revie�� of the King County sensitive areas map folios, it was found that the subject site does not lie within a sensitive area. However, it does drain to a landslide hazard area further downstream from the project site and, ultimately, into the Cedar River, ��.�hich is a satmon-bearing river. There are no wetlands or coal mine hazards, etc., associated with this project site or the downstream drainage course_ • Road Drainage Problems: This is not applicahle. • United States Department of Agriculture King Couniy Soils Survey: Based on our review of the soils map for this area,the entire site lies within Alderwood type soils. • Wetla�ad Inventor}� Map: The wetland inventory map for this area was reviewed and it was II de[ermined that there are no wetlands on the site or in the downstream drainage course of the site. ', • Migrating River Studies: This is not applicable. I �i�;s ou_;.�� A � � � � � � � � W W w -- — . . - - - -... . ..�.. ..,�.a,r �v �rno raJVGL: � Revised May 16.1995 to update map format. I To determine if flood 'msurance is available,corNact an insurance agent or caN U�e National Flood k�su2nce Program at(8001636-6620. I � APPROXIMATF SC1�LE IN FEET 500 0 500 NATIONAL FLOOD INSURANCE PR06RAM � FlRM f100D INSURANCE RATE MAP KING COUNTY, WASHINGTON AND INCORPORATED AREAS PANEL 10010F 1TZ5 (SEE MAP INDEX FOR PANELS NOT PRWTED) CONIAINS: COMMUNITY NUMBER PANEI SUFFU( KING CWNTY, UMNCORPORATED AREAS 5.30071 7001 F MAP NUMBER 53033C1001 F �, MAP REYISED: �e�o�•• 44G� ��' MAY 16, 1995 .. � , � °�. o� Federal Emergency Management Agency - - - - � - .^ _.. _. _ _., ,s°"�� e'9,QC `�S 3(1N31�'d cn 1SI.9� m �'cn � m y N °� m g ^' q � 8 �, '1� �� N x� A � � � �P �O�N�., N��C � � �s �' z c R' ,�• � m tG?ND � m n <qc� � � � � ' _ N � �m � 164TH PLACE SOUTHEAST ��TH AVENWE SOUTHEAST -•- N � � m v� cbi � N m -� 85TH AVENUE � m � Z 168TH AVE � Sp m H�AST m SE � � x D 88TH PLACE SOUTHEAST � 168TH PLACE SE � I � D D � � o 187TH PLAGE SOU7HEAST � � N m 169TH AVENUE SOUTHEAST � � 170TH AVENUE � � � � � 171ST AVENUE SOUTHFAST �, � Z � 172ND AVENUE � r'r m 2 �y�'p`� � � � �'�� o W . EXHIBIT E Sensitive Areas Folios i -�' � --- �'�-�--� ��. ��L �� ' � � � � , --,,i "�� ,� �� k�t ;` ��`��r� �.�.��"1 — , _`tl \,� �� o,� �� `��T�4� i < }:1� ~1 'i �� 1 Z � i:'t t• �ti '�` -°`�y��' i {��"-i. .: �,. y _ ` 1 '�� _: i� �`✓ ';:r.s�� I�1," --a i f' l �� ,s � � � �� _ .,� -� �` — � t , � ; � � fi �� . � �� < <` � < < �,r �� ,��, ''�� ;� E L'_ _ w��"z �\``—.`��r �'t:t" � f =tt - t �`,y ` !-'t .o�� `. .:-��}�� ' 'f V - 4 �_ .- �_:, __'y� - �� -`� �-� 4 2 # ' f �� t (i �*� ��'1`�--y --� ��t l: I � � �,, ' \� ; - � , y `-r �t ` � � �. A�` � `�' � �z�-�_� �-� ��-L _�r . . -.-_ ,��;� . . . - t �� _- �: � � - ��. � . . 't�� y - . -. ' <' ' � t ,� �. �.Y = i _, .,i.� - •- \ - �1 `t i s ^��' 1 - �y ' < - ��j-.`�:� ', • � .yxy- � �Qsk�.^ � /�--{\ � \ ,�' t ��, � � � , I j � � - �, "4 • � ,� �+ ' �'�.�.� F � .�i. -,I � � � ;` li '.— n� .� - �.�-�C.LL� �l` -�,t � r _, `. � � li � .� .d��.:��'s-�,�i-` 1 � . :� t \ � : r ��: " ��y T��a--� �... ?�, c cti�_: ��F i�. _ � ,.: II � Jt�.�\ I.�'� '.��_� . �YY�"\ �k� x � �,M z..'�•�_ � r- �-za- �o K: . L �;`�, , r'° . M1 — � _,. ' ` � �� ' :� �j,f�tT -�- -- 'r .. � �k l� ` ��'��6{�� -__---�--\� }� 3, i r �y �, �� -� �t. • -- s-/`i^� r"�"�. � �� - _�� ` � � —�� \. _ _ �y��+ `� _ � Q Y j.� ;1 S -��}� i � ;a�` � `-� �''� - �.. � -, i� � '�� ( I � • \`1�� .a � - • `� �� :�_ c � - ��. � ;`��, t _ _ —�-,; 1 u2 o t MLE mP¢GHALS�2 o � = COAL MINE HAZARD AREAS ��,��°' NORTH SOURCE 1990 KING COUNTY SENStTIVE AREAS FOLIO �-�'- - �' � �L��'C:y-�� ` �} `�!_ �� 4�}� �— -� �,� \-�` ��\ P � \\�✓� l��l f ,,�� ,� � �e\'Ri. 4 �;l'� ��->E �� .��,`•�t' �� _"f. �-t � i �1 z.,+> \� f`1-n � �' \'� �� , ? 1J? � } r \ a- r �\� � t �� ; ;� _ � >� , 1� �I� �i�'�.: • � �'i�` : � . �l �_.` (, � \\`Sl�f ��/ .7�y�'� � 1 r -' �� t, �� _,�� \ � �A� .\�3,,��- � '.��.�� 1� �� _ � � V �_ A�„-. � �� - F i \ � �1 \ �_ �1 � �� - ; =� . ,� , .� ;\'�� , � -- �,� \ � �. � 4�J� � � ' :-y �\ �' y�rt�' �� {� . �?t-� � \ / �� .�� a � � .�. - E �`•1 J� - � �� ' \ �'� '� } } � w a � ��,-,.. � ' � � i ;a _ - . ' !3 \, - - �� r 1f`�'} ,' � \ \* i ,�'Y � i _ -_ \-k�S . �{ '�` � \ _ � _ 19�-. . ��f��,� ,��J / � . \ \ � • _ 1 ,/ f� \ 'f }qi'�,f� ��`T��'`LL-��' •�� s_ - ). _ �_ � ��: I � j � . l . � :��< ' �-':�-� � r L . a� �� :� � ��, _ � �, �� $�—��... � __ ."� x ��, T -�__ — i � 1'- ` — j� �i v�� .� }?� '�..i� �} � " _ __ f _ lE �. � '� '�`` ��ylk`' . --�_'�� I��£j�l�d � ��`��Y — - ��}.� . ... ',`. �l� �'—�F�� f .�� y. �\' �V\ � ` `.� ��l '.. �y r J �� ` �. \�� ~\ � ;. K� .. �{;.: � S' �,� " .J�_ -- _T � �, i.f� r'�`�' : �{ p � � .; { A `� � ��"� y� _ ` � � �! � � �/ � ry �� .-� �t� �:•rn.� -- P -.. . . '-C%i r . -_ -.' .:-� . != .. - . . � �/Z � � MLE mP¢�Ha�s�2 SEISMIC HAZARD AREAS , o t u �+� e NORTH �� SOURCE: 1990 KIMG COUNTY SENSITIVE AREAS FOLIO i � � v . . a _ -� -�-,fi-�� ,` �, 1� � � t j '--; r �— �;. �` 4 • _ � , F`Y \��_ � �� i \,�� .. \� � � \ , / r� —� �1��.5 i �- � � �� -`i \�� ;�(�. ' ■ � � I z�.. < l� �� .� i/ � ,�t �� "- �^}` `,.�r f :x� 1 � _ ,� `�J �`\�h��. � '� � :;�"� , � , �,• �� : , Y`� � � ; � �� t _ � `` ` �'�Il (f; '� ��,� ' , �r �-� C :�__ 1 �� t.;�tr " i�,��- � i � . �_ _ _�� 4� � � � . _ „ � s� ` � �` \�i oi`,—t i , � ti R v . � � 1 � i '..'��r� -- ��i ' � '- ��: j•.� '�� : � � ,� �� , , 1' , .� - � u5 1 ' 'V, � r � - j �t ` - . "" � �� < — �� — .t �<' . �.� r�,� —:-' -'�,1 � \* " � l i . •ti-��!S, l� .. t�. is� . ��'� u + �� .\�� ;� � :'t ,/'1 1 r.: Q +' i'fi'` �'- �_3� \ � .i �� . � - ' ` � , � •�l - � _ ` - � ��. �_ �� Y, � �- , # ; � i=� -.� �,� �-,� .ti -�;� ,� .� _ , -;` - , : ,,� , �� ;.: , � .; , ��rt r �., . � �� ." _� s 3 � � �{[ �.5.- FJ Y , r . t/ _ .. 6 ^�;'• __ � ll , --�\' - - __ .'a-'�L � __, � � _� , � * L- '�:•� _ � I �j� jYF�' .., �� Y. T � 1r �}ti:. `� v� ' � �. �f• S \1. � / �� — . 1 i , � �� n' � C ��` � � � � ... � , � .':I �� I i ,rz o � tv9LE mP¢CyHAC'S�2 o � � LANDSLIDE HAZARD AREAS �4� �°� NORTH � SOURCE: 199d KING COtINTY SENSITNE AREAS FOLIO w = g F' Q 0 Z ��1� I.�'i�r��s � ...�J` _ ,-�^""�,�.` -.;'� 'a �„�` ..;�` �., o y � �� y�r��i i/ � r4., .ly��' ��1��\��T�`� /•�, ii��} -.;~ , ._. �^" �, �: � �� — � �� - ' � � � �� i�s` "r� � r'r ��, ',✓ i � i, � �� 1�� : � � ��C 1,� " � � `�?-�� `�`iPo ��.�1��d . �� ... � � ' ��'� ' '� / - � � ��v� _ � � �� . �,I i !� .'� �l �l �` �Y�i �'.�� r��. `. c-S� �� ,��._. � ,�� -_ i, :. ' " �---�� --- s��,--,� � �/� _ti��l�� j�� - � t �, 1 �� i� ° ti V/ l . �l � l '!�� ` 1 �� , � �� ' � 1 Q � r i i i �. ' t ' ��t-./_C� �� 'S� /1� t ,�'�`rr""� W �:��9/ 'r � /I .1 �.- '. �� .�� '��/ �'�.�! � / � { � ' x�ll. '✓� �� i�! �>_"�(7 '''�`, . � /6�'� '�( J ,i �� ,L i ,r,�� l� _ . 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' �._ ;�',� .. , iiz w a I � � i �r'� ;ti' „�� ,� I • •« •• II�-•M%"�,.., . ... t� � �L¶: n �� • � � , •• �' •'tt1 .u 4 ,+'� •�� ' :..0 T � �a a V .. �... k�� li .�.. • . �,5v H�,�d � y 1 �v � a a � . �Q\ Q . .�. . g�•• � "^ o��s=:' x+� �' � ��f .� '' �.. �� ' ,°il ..�� . u �- (� ...� � � . .. •, r1 ` 1 � il JaM � ''r�.�� •„ �y� I � � � � �'W � � 'r�� r �: o�� w ' :' � i • Q � r i i: � . , i �r: :p � �,; ,� _ , � . �,-, : � � '�'., r; � �� z I 1 ' Q� ' � �� ii � � . , � , � �• � . • � � •� ��• • .. . � . ' I .Y �r��__�r�..._.___��`�.��r�..�- �l� .�.�. .r.� _: � �� I g�N '''w. J o� x k � � � � �' s� b9 ��o,+� EXHIBIT G Assessor's Map -. ,.,,-�,. --------=R-,,..: ,,:,�. ,,:,. � — -_. .. --__- - --_.. _._- - � _ ------ ---- �----- te.�wni_sT _ ' - �u�E-- ---------------- --- i - - -- sc,3arrsc —_-- � . H ` _� .�_. T... � '„ .....`.'.�:- - .. •�- - ' . - i ; ._. "_' �- .._ - — i . � _`` ' J 1.1.. :u' . . 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' �t.t. .�_ �` . ,n' 745750 ---a-4=�-��— CEDAR PARK � FIVE ACRE TRACTS I - r.,,., - i �4 � > -. _�_- ; S I �E _ -� � e ; ; � _ j , :. �,;: �°� ,.� -�. � � �-%� �� _�' . i f : � - � � _ _ � : - � f ; - ,� t i . nw s_ '- •. � i ppy oC6 , ..�. � � - e_ _ � � Q¢GHqGSF m � ? ASSESSOR'S MAP � �'�,,,� �°' NORTH � EXHIBIT H Wetland Inventory Map EXHIBIT I Basin Reconnaissance Summary Report RECONNAISSANCE REPORT NO. 13 LOWER CEDAR CREEK BASIN JUNE 1��7 Natural Kcsources and Parks Uivisior�� and Surface Water Manapement Division Kinb County, Washinhton � King County F�ecutive Tim Hill '�, King County Coun�it i Audrey Gruger, District 1 Cynthia Sullivan, Disirict 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 Worl�s P�rks, Plannin� and Resources Don LaBelle, Director Jce Naoel, Director SurCace Water Maoagement Division Natural Resources and Parks Divi.sion Joseph J_ Simmler, Division Manaber Russ Cahill, Division Manaber Jim Kramer, Assistant Division Manager Bill Jotly, Acting Division Manaber Dave Clark, Manaper, River & Water Derek Poon, Chief, Resources Planninb Sertion Resource Section Bilt Eckel, Mana�er, Basin Plannina Program Larry Gibbons, Manager, Project 1�lanagement and Design Section ('.ontributing Staff Coatnbuting Staff Doua Chin, Sr. Engineer Ray Heller, Project Manager & Team Leader Randall Parsons, Sr_ Enbineer Matthew Clark Project Manaber Andy Levesyue, Sr. Engineer Robert R. Fuerstenberg, Biolo�st .� Team Leader Bruce Barker, Enbineer Matthew J. Bruengo, Geolooist Arny Stonkus, Engineer Lee Benda, Geologist Ray Stei�er, Engineer Derek Booth, Geoloaist Pete Ringen. Engineer Dyanne Sheldon, Wetlands Biolo�st Cindy Baker, Earth Scientist Di Johnson Planninp Support Technician Robert Radek, Planninb Support Technician Randat Bays, Planninb Support Technician f�red Bentler, Plannino Support Technician ('onsulting Staff Mark Hudson, Planninb Support Technician Sharon Clausen, Planning Support Technician Don Spencer, Associate Geolobist, Earth David Truax, Planning Support Technician Consultants, Inc. Brian Vandert�ur�, Planning Support Technician John E3ethel, Soil Scientist, Earth Carolyn M. Byerly, Technical Writer Consultants, tnc. Susanna Hornib, Technical Writer Vi ainia Newman, Graphic Artist Mamia McNulty; Typesetter Mildred Miller, Typesetter Jaki Reed, Typesetter Lela L�ra, OfCee Technician Mam Cos, Officc Technician P:CR TABLE OF CONTENTS I. SUMMARY 1 II. INTRODUCTION 1 iII. FINDINGS IN LOWER CEDAR RIVER BASIN 2 A. Overview of Basin 2 B_ Effects of Urbanization 4 G Specific Problems 5 1. Drainage and floodinb problems 5 ?. Damabe to properiy r, I)��iru�ri��+� �,i h.,l�it:,+, Iv. izLco�1�1�N��riotvs ��ox ,aci�i�rr � A. Reduce landslide hazards 7 B. Reduce erosion and floodinb 7 C. Prevent future erosion and floodinb with appropriate analysis, 3 planning, and policy development D. Stop present (and prevent future) damabe to habitat 8 by addressina specific problems in stream systems V. MAP 11 APPENDIC�S: APPENDIX A: Fstimated Costs A-1 APPENDIX B: Capital [mprovement Project RankinD B-1 APPEDDIX C: Detaited Findings and Recommendations C-1 I. SIIIu�NARY The Lower Cedar River Basin, in southwest King County, is unique in its development pat- terns and the associated envimnmental problems that appear t6roughout the basin. Eacept for the city of Renton and areas on the Cedar River Valiey floor, most of the deveiopment in the basin has occurred on the upland plateaus. Most of this development is recent and primarily residentia(_ In addition, the plateau is the site of numemus sand and gravel mining operations and, in the southern upiands, an abandoned coai mine_ Peat is also being mined north of Otter Lake. In some areas livestock are being raised on small farms; there are no major crop-related agricuitura( activities in the basin_ The effects of development are most apparent where storm drainage is routed over the valley walls Impervious surfaoes on the plateau 6ave increased the rate and vdume of storm runoff, resutting in substantial erosioq siltatioq and flooding bebw. In addi- tion, emsioa and siltaqon hav�e damaged or desiroyed habitat in many tn�butaries, threatening the survival of fish. Habitat aad water quality throughout the basin are also threatened by the filling of wetlands and the presence of large amounts of dom�stic trash in some streams. The reconnaissance team noted that the Peterson Creek system has so far remained in its natural, nearly pristine condition. Maintaining this quality should be a high priority in future basin planning capitat project prob ams. Recommendations in the Low�er Cedar River Basin include 1) desi�ing and ooastructing appropriately sized R/D and other drainage facilities; 2) establishing stricter land use policies rebardinb floodplains, wedands, and gravet mining; 3) conducting more detailed and compreheasive hydraulic/hydrologic analyses of proposed developments; and 4) pneveating damage to the natural drainage system_ The field team also recommends 5) restoring the habitat of several tributaries (e.g., cleaning b avels, revegetating stream banks, and diversifyinb streambeds for spawnin� and rearing) as well as 6) protecting the neariy pristine quality of Peterson Creel� Q. aV"IRODUCI'ION: History and ('�oaLs of the Program In 1985 the King County Counci} approved funding for the Planning Division (now calied 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 et'fort began with an initial investigation of three basins -- Evans, Soos, and Hytebos Creeks -- in order to determine existing and potentiat surface water problems and to recommend action to mitigate and prevent these problems. These initial investiga- tions used available data and new fie{d observations to examine geoloby, hydrology, and habitat conditions in each basin. Findings from these three basins ied the King County Council to adopt Resolution 6013 in Aprit 1986, calling for reconnaissance to be completed on the remainin� 26 basins_ The Basin Reconnaissance Program, which was subsequently established, is now an important ele- ment of surface water management_ The goals of the program are to provide useful data with regard to 1) critical problems needing immediate solutions, ?) basin characteristics for use in the preparation of detailed basin management plans, and 3) capitai costs associated w-ith the eariy reso{ution of drainage and problems_ The reconnaissance reports are intended to provide an evaluation of present drainage con- ditions in the County in order to transmit information to policyroakers to aid them in developing more detaited reb larory measures and specific capital improvement plans. They are not intended to ascribe in any conclusive manner the causes of drainabe or erosion P:LC 1 L,ower Cedar River Basin (continued) probiems; instead, they are to be used as initial surveys fmm which choices for subsequent - detailed eno neerinb 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 environmentaf narratives rather than as finai engineerinb conclusions_ Recommendations contained in each report provide a description of potential mitibative measures for each particular basin; these measures miDht provide maximum environmental protection through capital project construction or development approval conditions. The appropriate extcnt of such measures w•ili be decided on a case-by-case basis by County offi- cials responsibie for reviewin� applications for permit appmvals and for choosing amona competinD projects for publie construction_ Nothing in the reports is intended to substitute for a more thoroubh em�ironmental and engineering analysis possible on a site-specific basis for any proposal. �. I�IND(NGS IN I,OWER C,'E:DAR RIVER BASIN "I'he Cicld reconnai�.k�nce of Louer ('e�iar River Basin was conducted in Janu<1rv 1957 bv Robert R. Fuerstenberg, biologist; E3ruce L. Barker, en�ineer; and Lee Benda; beolooist. Their findinas and recommendations are presented here. a Overview oC Lower (',eciar River I3asin The iower Cedar River Basin is located in southw�est King Count� and is 27 square n�iles in area. It extends southeast from the mouth of the Cedar River on Lake Washington to approximatelv river mile 14.0. T'he boundarv ro the northeast is marked by a rid�etop connecting the city of Renton to Wehster and Franklin I �jkc>,_ the boundarv to the southwest runs alonb Petrovitsky Road to Lake Younbs. Renton is the only incorporated area in the basin. Other population eenters inclueie Fainyood, Maplewood Heiphts, and Maple Vattev_ Except for the city of Renton, most of the residential concentrations are located on the upland plateaus overlookinb the Cedar River �'alley. The.se upland developments are recent compared to the smaller I established communities on the valley floor_ The basin lies within portions of three Kin� Countv planninr areas: Newcastle in the northeast (which includes Renton), Tahoma-Raven Heiohts in the east, and Soos Creek (the largest of the three) in the west_ Rural areas eaist on the valley floor on bot1� sides of the Low-er Cedar River, from appro�imatelv river mile 5.50 to 13.�0. These are limited to pastureland for horses, co�s, and some sheep and several small "u-pick" fruit and ��e�etai�le farms. Similar areas are located oo the southern uplands abo��e the reach from river mile S.SQ to 7.00 and in the Lake Desire-0tter Lake area. The plateau is also the site of s��nd and cravel mininb operations and, in the southern uplands, of the abandoned Fire Kino Coal Mine. Peat deposits exist west of Lake Desire and north anci south of Otter lake, and peat mininp is beinb carried out north oE Otter Lake. Present ZORIII� allows for urban and subufian densities throu�hout much of the basin, particularly on the vpland plateaus and in the Cedar River Valley from its mouth to appo�imately river mile 6.50. Population projections for the year ?000 in the three plannibn areas containinb the Lower Cedar Basin are over 311,000; an increase of =17 P:LC ? Lower Cedar River Basin (continued) percent from the present. Most of this orowth will occur in the Soos Creek Plannino Area. Dominant goological and geomorphic featura. The geolooy of the Lower Cedar River Basin is diverse. Geologicai formations exposed along the valley include sedimentary rocks, undifferentiated older glacial drift, extensive ground moraine deposits, recent alluvium along the Cedar River, and landslide deposits alonr the river and its tribu- taries_ The sedimentary rocks, composed of moderately dipping sandstones, con- rlomerates, mudstones, and shales, are exposed localty along the cliffs of the Cedar River Vallev near the mouth of the Cedar River. In addition, the Renton forn�ation. composed oC sandstones, mudstones, and shales with periodic deposits of coal, is also exposed along the lower portion of the Lower Cedar River Valley. Undifferentiated glaciat deposits found here are composed of three or more titl sheets, gtacio-fluvial sand and gravel, glacio-lacustrine clay, and sand, and non-�lacial s��nd, clav and thin peat_ These lie rner the sedimentary rock formations and are best exposed in cross-section along the cliffs of the main vailey and major trihutaries. The morpholoD of the Lower Cedar River Basin is dominated by the valle�• formed bv the Cedar River. Valley walls are steep cliffs formed by landslides in glacial sedi- ments. A once extensive and meanderin� River, which created a wide vallev ffoor as i[ cut its way w-estw-ard, the Cedar today is diked for most of its length through the lower valle�_ A narrow but extensive band of Iandslide deposits eaists alonc the steep cliffs of the main river and its major tributaries. The landslide deposits consist of defonned blocks of �lacial sediments and colluvium derived from slides or mass flowage, such as landslides and debris flow-s. Recent alluvial deposits fill the vallev and major tributaries. Small, composiie, alluvial debris fans exist at the mouths of the lar�est tributaries. Closed depressions, principally in the uplands, have lacustrine and peat deposits. I � The Lower Cedar River Valley has a high potential for erosion due to steep slopes I and the eaistence of a day layer that promotes soil failures. In addition, the confned nature of tributary channels between steep hillslopes promotes bank erosion darin� hibh ffow-s. Numerous recent landslides are evident alonp cliffs of many of the steep tributaries and alona the main siem of the Cedar River_ These have been accelerated by the remo��al of vecetation and the routinc of concentrated storm flows over steep slopes in areas where deveiopment has occvrred. Hydrologic and hydraulic c6aracteristies The Cedar River Basin is composed of a comp)ex drainare network consistinb of the Cedar River and 17 tributaries_ The lar�er tributaries begin in lakes or wettands on t6e bluffs and flow throu�h relativelv flat, stable channels to the edce of the Cedar River Valley, then plun�e down to the ��allev fioor throuoh steep, erodible ravines. Tributaries of this type such as Tributarv 0�04 (with headw-aters at Wetland 3111} and Tributary 0323 (which beains at L.ake Desire), are found on the south side of the Cedar River. Another tvpe of tributary collects surfare runoff from uri�anized area�. pastureland. and woocied areas_ Tributaries 030?, 0307, and 0312 are e3:ampfes of this type of tnhutarv. The�� are intermittent (dependinD on rainfatl), shorter in lenb h, flow throu�h shallow•er channels that are steeper at the bluffs and transport more material durinb times of P:LC ; Lower Cedar River &�sin (continued) high flows. Some of the worst problems located during field investib tion (see Appendix C for a full tisting) occur on this type of tributary. Catchmenis 5, 6, and 12 have very infiltrative soi[s. Urban developments hvae utilized R/D poinds to effectively infiltrate all urban runoff before it reaches the valiey hillslopes_ The infiltrated runoff then reappears as springs. Two large lakes (Desire and Otter), together with four smaller ones (Shady, Peterson, Webster, and Francis} lie in the southeast third of the basin_ Numerous large wetland areas exist in this section as weH. The field team identified 10 potential wedand sites that had not been previously ideniified in the Sensitive Areas Map Folio (SAMF). The system of lakes and wetlands in this area effectively buffers the high flows draining to these tributaries. Habitat c6aracteristic� With few exceptions, usable Eish habitat exists only i� peren- I� nial streams (i.e., Trib. o302, d30=t, 0305, 0323, and possibly 0303). In other streams (e.b., Trib. 0�03 and 0310), steep gradients preclude fish use. Steep gradients also reduce fish u.se in the perennia3 systems (except for Trib. 032�t). Habitat is in various sta�es of debradation in these systems; pools are being fitled and bravels and debris shift reb larlv. In Tributary 0323 (Peterson Creek), however, habitat diversity is , eatensive, and the channel is not seriousiy degraded. At this location the field team observed at least three species of salmonoids. In Deneral, the most diverse and least disturbed habitat in a tributary system occurs in the targe w�etland areas in the southeast third of the basin. Usable habitat for anadromous fish is found in the low-gradient portions of streams where channels cross the Cedar River Valley floor. In these reaches, however, only spawnino habitat is likely to be available, as the pools and woody debris necessarv for successful rearinb either do not exist or are quite limited. Eacellent spawning and rearing areas e�:ist u�here pools and riEfles are extensive, instream cover and bank vebetation are intact, and diversity of habitat types is abundant. Q_ Gtfects of Uifiani•ratioo ia the Basin I-loodin�, erosion, and the decradation of habitat associated with developmeni in the Low•er Cedar River Basin are most apparent where development has eliminated vege- tation alon� the edbes of the valley and w•here stormw•ater has been rotited down channeis and s�ales. The removal of veretation, such as trees, above and below the edces of valley walls, as well as Ihe dischar�inb o[ stormwater over the valley wall, has resulted in tension cracks and landslides that are endangering some houses. The secii- ments from these failures are depositinb in streams and on valley floors and damazinp fish habitat and private property. Discharpin� stormwater from increased impervious areas into steep tributary channels and swales is seriously destabilizing channels and valley walls; this in turR results in channel downcutting, bank erosion, and lands}ides_ The sediments from these problems often debrade fish habitat and settle out on pri- vate property alonp the valley Eloor. Two serious instances of development-related erosion occurred durin� the November 1936 stonn: 1) culverts reroutinb the stream were plu�ed, causino the formation of a new� channel that destroyed portions of roads on Tributarv 0314; and 2) new, uncom- P:LC �7 Low�er Cedar River Basir► (continued) pacted fip adjacent to new residences near collection point 5 was washed partty aw•ay during the storm, causing landstiding and b llying. Future problems will be simiiar to these, as commercial and residential developments increase flow rates and volumes by decreasing natural storage and infittration. This is expected to occur if wetlands on the upper plateau are encroached upon or lost (e.b., on Trib. 0304 at RM 230 and on Trib. 030�A at Rm 1.6Q). The preservation oC wetlands and streambank vebetation and the attenuation of storm flows are essential in this basin. G SpeciC�c Probiems Identified The steep valley sideslopes through which streams pass and the often dense upland I development result in a number of similar problems that repeat themselves throu�hout the Lower Cedar River Basin. The most significant oC these are outlined and I discu.ssed belov�-. 1. Drainage aod flooding problems are often the result of several conditioas_ � a Undersized cu[verts and inadequate entrance structures. The most notahle area is on Tributary 0306 at river mile .i0, where a culvert here was blocked bv debris carried downstream bv the stream and caused erosion and floodinb of Fainvood Golf Course. The blockage was compounded by the fact that the culvert was undersized; the problem will w•orsen as flows increase from upstream development. b. Serious iastream erosion and subsequeot down.Stream sedimentatioo. These have been caused by three main factors: 1) runoff from residential developments on the b(uffs above the vatlev, ?) compacted pastureland due to livestock, and 3) runoff from impervious areas originatinp at gra��el pits. These problems wili continue and worsen until mitioative measures are �aken. (See Appendix C for speciEic examples.) c_ Undersized rechaanelized streams. Tnbutaries on the vallev floor are roo smal! to cam ihe inrreased flows oribinatinc in developed residentia! areas along the top of the bluffs. f�or example, Tributary 0�02 at river mile .25, the channel alonb Maplewood Ciolf Course, overrops and floods during storms. d_ ('.00structioo in wetlaod and Cloodplain areas, Many of the w�etlands on the south side of the Cedar River are peat bo�s, and roads buiit throu�h them continue ro settle each year, increasing the amount of floaiinb on the road. For eaample, the road crossinb w�ith Tributary 0324Q oorth of I.ake Desire will experience more severe floodinb as the road settles. c. DiSc6arging of stormwater at the top of sieep banks. At river mile 2.?0 on the Cedar River, a trailer park (constructed on the edge of the cliff) dischar�es its drainabe down the valley wa!!. Inrreased flows erode the steep valley, depositinD sediments on the valley floor, blockinb channels and causinc floodinr. These problems will e.�en�uallv stabilize, but only after a lar^e yuantitv of soil has hren erode�i. P:1_C 5 Lower Cedar River Basin (continued) 2 Darnage to property is being caused by three factors: a. Candstidcs and potentiai land.siides. Landslides are accelerated by the I removal of vegetation on steep slopes in preparation for residential construction and/or by the routing of storm flows over hillslopes_ For example, a large landslide has already occurred in the front yard of a resi- dence on the Cedar River at river mile 7.80. b. Sedimentation (from landslides). Sedimentation and channel and bank ero- sion are dama�ng private property alonc the valley fioor (Trib_ 0299 and 0310). c Flooding during storms. Flooding has been brou�ht on by the effects of i development and associated chanbes to the natural drainabe systems in the basin. (See "B" above.) I 3_ Destnfction of habitat is being cau.Sed by four moditioos: � a_ Sedimeotatioa of pools and riffles and cemeotiog of gravels. These �' problems, the resutt of severe erosion and the transport of bedload • material, have been caused bv upland developments in the basin and the presence o[ associated impervious surfaces, w-hich increase the rate and yuantity of surface runoff. Sedimentation and cementin� of �ravels in streambeds destroy natural spawnin� and rearinb habitat. On Tributary 0307 at river mile .40 and Tributary 0305 at river n�iles 95, 1.?0, and 1.70, recent hi�h flow•s have eroeied the streambed at least one foot, contributina to a serious siltation problem downstream. Heaw bedload transport is evi- dent in alf systems of the basin except 'I�ributary 032�t_ In Tributarv 0.03 at river mile .25, fine sediments are accumulatin� in gravels that may be used bv resident fsh. In Tributaiy 0�04 betw�een river rniles .95 and 1.20. pools are beina filled by sands and gravels and rearinD habitat is beinb rapidlv lost. b. Channelization of stream beds. Loss of habitat thronch channelization has occurred in all the major streams of the basin, but most noticeably in tho.se reaches that cross the vallev floor. These reaches lack hahitat diversitv. reducin� fish use for spawninb and rearino. Channelization has dama�ed or �iestroved habitat in several reaches that were once heavilv used bv fish: these include Tributarv 030? betw-een civer mile .3Q and 40. Tributarv 0�0� hetw•een river miles .OS and .]R. Tributarv 0305 between river mile .20 and .7S_ and Tributarv 0323 from river mile 1_10 to 1_-�0_ T'hese svstems cannot afford a further reduction of habitat and still remain viable fisherv resour- ces. c_ 'I'he accumulation of trash in stream beds. This problem occurs in ciose proximity to residential areas. Trash de�rades water yuality and is visuall� unpleasant. Tires, appliartces, furniture, and other trash have heen throw�n into Tnbutarv 0302 at river miles 1.00 and 1.10 and in Z�riht�tarv 0�0� at ri<<er mile .35. P:LC 6 Lowec Cedar River Basin (continued) d_ Wetlaad encroachmeot_ Encroachment destrovs habitat and eliminates naturat water filtration and storage for surface runoff. Eaamples of this problem were observed on Tributary 030� at river mile ?30, Tnbutary 0�03 at .3Q, and Tributary 030�3A at river mile 1.30. Many wetlands have already been completely lost tfirou�h filling, for example on Tributary 0306A at river mile .55. Suspected violations were fonsarded to Buildin� and Land Development for enforcement. IV. RGCOMMENDATIONS FOR ACTION The primary recommendations for action in the Low-er Cedar River 8asin addresses current severe problems related to erosion, habitat destrucdon, and flooding. Prevention of tfiese problems will be accomplished by controltinb locations and densities of new� development and providing adequate R/D facilities for stormwater. A Reduce landslidc ha7ards by_ L Including seesitive areas not previously mapped oa the Seositive Arcas Map t�olio (SA11�II�)_ See Appendi� C Cor a fult listing of sensitive areas. 2 Establishing building setbacks along ciiffs and native grow�th protection easements along steep ravines. 3_ Discouraging or eliminating the routing of stoimwater over c(iffs, unless adequate ti�htline svstems can be constructed to convey flows in a safe, nonerosive manner to the bottom of cliffs_ 4. Decr+ea.sing peak flvw+s by constructinb faraer R/D faci(ities to lessen Ule landslide and erosion occurrence alonb tributary slopes_ I3. Reduoe erosion and flooding in the basin by improving surface water management: 1. Direct the Facilities Management Section of the Surface Water Maoagemeot Divi.tion to evaluate e�isting storm�detentioo and 000veyanoe facilities to deter- mine whether they are properly sized to meet current standards. Evaluation should berin w-ith all single-orifice R/D facilities. 2 Consider areas other than wetlands as regionaf storm�eteotion facilities_ Tributary 0300 at river mile .42 is the site for a proposed dam, for eaample_ 3. Utilize existing lower quaGty wetlands (t6ose rated ot6er than �1) as regional storm�etention facilities. Wetlands 3103 and 3142 could provide more live stora�e, for example. 4_ Rev�ew+ channel and culvert capacity [or rooveying eAsting and future runoff, and establish floociplain areas in regions of sli�ht bradient for existina and future runoff conditions. S. Promote the inCdtration oC sudace water through the use of retention facilities aod open channels instead of pipes where the soil and slope conditions permit. Collertion points 5, 6, and 12 on plateaus have such soi! conditions. P:LC 7 I.ower Cedar River Basin (continued) C. Prev�ent future problems of erosion and flooding with appropriate analysis, planning, and policy development �+etated to surface water management� 1_ Condud a detailed, mmprehensiv�e hydrduGc/hydrologic aoalysis of aoy propose.d dcxebpmenLs to determine impacts on the draina�e courses downstream. This is especially critical for areas on the upper biuffs and ptateau, which drain over steep, sensitive banks above the Cedar River. 2. Coaduct a study o[ the impact of locating infdtration ponds utilized near the edge of the bluffs to determine their effect on seepabe faces on the lower face of the bluffs. This might be accompGshed w�ith a computer-based numerical model of the gmundwater flow. 3_ Requere the tig�tlining of storm drainage ciown steep or seositive slopes when they cannot be directed away from the slopes. This is done bv piping the flo.� down the s)ope and discharginc it at the bottom ��ith adequate ener�� di�.sipatinn. Many of the intermittent tributaries flowin�; ��.��n rl,�� i� ,��._�� . ��'..1 !�: u�.�l��I-��,��_i as urban development increases flow to then� 4_ ('.oa5truct new R/D ponds with fdter berms to improve water quality and m,�iucc fine sediment loads. New R/D ponds shou(d have tw-o cells with gravel-berm filters and ve�etated sua(es at the inlet and outlet. Consider Tributaries 0304, 030=1.A ,-,-,,, � ,,,,.. . , .,- � .- � ; .. r �_ _ _ . qualin �I 5_ Maint��.; k,.,�v»� .;,b��s::��: �,�, :a.;,.,.��.�:.ti:. .:,�� ,.��.n,.:,;�.<<<::.. . ... , � �_� �I important for relatively flat channels flowin� on the plateau before thev rea� ! S[Ct,'� f1�UfE5 bCCBUSC 1�16Se �'f',. ,,,��1.- ��ni_i tl��.j. fln�� '!��; � _j!I ��ti- �. �� f�i��,� �I durinr times of heavy runc ' 6. Maintain buFfer amas arou�, , w, <. . . . I'' of the Cedar River headu�at�r �,t «��tl,in�i.,. 1 h��c ti��i<<n�� ,ict ,i� natui.�l st��r��c areas durin� storms. 7. Reevaluate King County policy regarciing pe:rntitting for grdvel mining c�n ste�i�. sensitive slopes. 8_ [nclude the city of Reation in future intertocat agreements for plannin� and capi- ' tal improvement projects where city and countv interests over(ap. D. Eliminate pcesent damage to habitat and prevent future damage by addressing specific problcros in the strcam systems. The folEowino activities shoufd he coordinated amon� Kin� County, the Muckleshoot [ndian "I'ribe, and State Departments of Fisheries and Game: 1_ Reduee damaging storm flovvs with breater detention volume and lower release rates at upstream developments. 2 Implement c�esioration projects on Tributaries 0304 (river mile .00-.20), Tributary 030$ (river mile 20-.30), Tributarv 0303 (river mile .25-35). and Tributary 03��5 (river mile 110 -1.40): P:LC 3 Lawer Cedar River Basin (continued) a On Tnbutary 0304: Clean sireambed gravels, add habitat and bed-control weirs, and plant bank vegetation for shade. b_ On Tnbutacy 0305: Construct a new channel and mrne stream fram road- side channe[ to its new location on adjacent lands. Implement a full restoration project to provide channel meanders, habitat structures, pool/riffle enhancement, streambed gravel replacement, and revegetation. c. Oa Tn�butary 0303: Move stream from present channel to a location further north, away from the roadside. [f relocation is not possibie, these minimum steps should be taken: Add habitat structure ro existing channel with root masses, deflectors, boulder ciusters, and other features; revegetate channel banks with shrubs and small trees; enhance stream crossinD with bottomless pipe arches. d. On Tn�butary 0328 (Peterson Creek): Add habitat structure by replacing the straight, shortened channel with a more natural, meandering one; place habitat structures (such as root masses, deflectors, cover lo�s, and boulder clusters} throughout the channel; and revegetate banks with shrubs common ' to adjacent riparian zones (salmonberry, ninebark, or dop•ood, for example). 3. Protect the Peterson Creek system (Tnb. 0328) in its present, near-pristinc state_ , This will include not only the restoration outlined in section A above, but also !, the adoption of land use management rea lations to prevent future habitat destruction: a. Protect all existing wetlands within the subcatchments of Peterson Cree� Employ wetland bufCers at least 100 feet wide without exception_ b. Restrict devebpment in the critical headwater area (drainage, 6abitat, water quality) bounded by Iake Desire, Otter Lake, and Petersoo Iake to rural deosities. c Designate and protect stream.side management zones of at least 10(} feet from the ordinary high-water mark (OHWM) along the main stem of the creek. Use 25 feet from the OHWM on tributaries. d. Preserve floodplains and t6eir forests for dynamic retention of sediments and water. e_ Restrict vegetation remaral in �reamside/w�ettand managemeot zones. f. Size R/D facitities to store the 100-year storm at a two-to-five-year release rate. Use the two-eell tyge of pond with a forebav, a gravel filter, and a vegetated swale outflaw where feasible. g_ Reg�late more c{osely ail septic tank and drain-Cield installations, as welf as maintenance schedules, particularty in the i.ake Desire, Otter Lake, and Peterson Lake drainage areas. P:LC 9 I.ower Cedar River Basin (continued) h_ Work with the State Department of Emiogy to establish miaimum stream- flow requirements for Peterson Creek and Lake Desire tributary. 4. Devebp and pmmote public education and involvement pro�ams for basin awareness. 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I �--- _ � �T�� \ t�\ APPENDIX A � ES'CIMATEU COSTS: PROPOSED CAPITAL iM1'R(�VEMENT PROJCCTS LOWER CEDAR CRE1:K BAS[N �� Indicates proJect was identified by Surface Water Management olfice prior to reconnalssance. NOTE: All projects are located on map includeG in ihis report, Project Collect. Estimated Costs Numher Point Proi�c:t De�ription Prohlem Addre�.5ed and Comments 3105' 10 Cnh�nce 2300' of Trih. 030.5 from Miti��itcs floadin� of King $115,000 Cedar River to Elliot Bridge, County park land. (NOTE: This project w�s proposed hy Surface W�ter M�n�gement, is in the design phase, and will be constru�ted by 1939.) 3109'° 10 Sccuce easements to wetland located Better utilizcs wetl�nd's stor�ge $136,000 in Casc:�ide P�rk and construct a berm c�pacity to �ddress peak flows from at the oullct. Rcpl�ce existing surrounding i�rhan area. catch h��sins with control stnictw•es, Pr�ject should he ,justified hy � , h:�sin studv. Wetli�nd r�ted #2. ("Chis wetl�nd will requirc furthcr biolo�ical �valu��tion before R/D dusirn and construction.) P:LC,nP� A-1 Pro.jcct Collect. Estimate�i Costs Number Point Pi•ojeet Dexription Prohlem ileidre�.sed and Commcnts 3111 Secure casements to outlet to Francis Will provide additional storage $175,000 (Wetland L�ike �nd 11�0' oF channel from I��ke to miticatc anticiputc�l future 313G) to SE 184th St. Construct a weir to increased flows. r��isc I�ke level 1', an�i enhance 1100' of Trih. 0317. Should hc justified hy a l��sin pl�n. Wctland ratcd #1. (This wctland will rcqtiire furthcr hioloriral cvaluation hefoi•e R/D �icsign :in�i const��uction.) 3112 19 Sccurc cascmcnt for outict to wctland Will pcovidc �idclitional storage $117,000 (Wctl�ind an�i rcplace existinb weir witli � for antie:ipatcd future peak flows. 3142) concrete-slotted wuir. Should be juttified hy a basin plan. Wetland rated #2. (This wetl�nd will requirc further l�iological evaluation hefore R/D desi�n and constivction, 3114"' Sccurc: casemcnt to Wetland 3150 an�i Addres.s�s �nticip�►ted inereases in $134,000 (Wetl��nd consti��ct a containnient berm and flow cause�i hy development. 3150) control struc:ture �t thc outict. Pro,ject should be justified l�y � hasin pl�n. Wetl�nd rated #2. ('I'his wetland will require further I�iologict�l cv�►lualion hcfOrc: R/U design �nd const�l�citon.) 3115 1�4 Inst111 detention pond �nd 1,000' Mitigltes severe erosion and $3G1,000 of tightlinc. Project is indcpen- flooding during times of high dcntly ,justiEiable. flow:s. I':LC.AP/� A.2 Projc;ct Collcct. Estimated Costs Numher Point Projcct Dcsc:ription Prohlem n�idres.sed and Comments :�I]h 21 Raisc ezisting ro<�d emhankment Miti��tes seasonal flooding of 1..��ke $73,000 2-4', I'rojcet should be indepen- Uesire Ur. SL caused by road bed dently ,justifiahle. (Refer to sett(ing in the peat bog. i Roa�is Uivision.) � 3117 16 Install 1,400' of tightline, a Mitig��tes severe erosion, sediments $501,000 scdimcnt trap, and 700' of channcl depositcd on County roads, and from Jones Rd, to CcJar River. floodin� durinr times of high Project is indepcndcntly justi- flows. Fiablc. 3114 10 Inst�ll 300' of 36" eulvert, a new Will prevent blockage of culvert $37,000 inlet stn�cture, m�nhole, �nd c�tch and the ac�ompanying flooding and h��tiin. Project is indepcndently erosion of l�ai�wood Golf Course �nd justifiable. mobile home p�irk below. 3119 4 Constnict a detention dam and Pro.ject loc�tion is ide11 l�ecause $159,000 control structure in � deep it addres.s�:s flows from � I�rge ch�nnelized section of 'I'rih. residentill area t�cfore they r�nch 03(�. Pro.ject is indepenciently the steep, sensitive area next to justifi�hle. the Cedar River. �120 15 Consti-�ict a x:�iimcnt�ition pond an� Miti�atcs floo�iing of residcnce and $1G3,000 1,b00' of ch�nne:l from Jones Rd. to sediment deposition on Jones Rd. Cud�ir Itivcr. I'ro,jcct is indcpen- �icntly justifiablc. P:I,C:.nPn q.3 Project Collect. Estimated Costs N�imher Point Proicct Description Problem Ad�irc�.sed and Comments 3121 7 Sceure easement to wetl�nd and c;on- Addre�.Ses incre�sed flows in Ti•ib. $371,000 (Wctland struct a containmcnt herm and concrcte 0304 �n�i 0�04A from residenti�l :�102) wcir <it outlet. Project shouW be developments. ,justificd by �� l��sin plan. Wctl��n� ' ratcd #2. 13iological 1�.se�.smcnt is needed to ��ssure that this projcct does not decre�se habit�t v�lues. 31?2 ]1 Purchase exiStinfi ponds on Fairwood Mitigates flaoding �nd erosian $342,000 Ciolf Coursc and expand to provide downstre��m. �re��ter flow �ctention. 1'ro,jcct is independently justifiahle. � I':LC,APn n-4 APPENDIX B CAPITAL IMPROVEM£NT PROJECT RANKING LOWER CEDAR RIVER BASIN Prior to the Lower Cedar River Basin fietd reconnaissance, 12 projects had been identified and _ ' rated usinb the CIP selection criteria develaped by the Surface Water Management (SWM) and . Natural Resources and Parks Divisions. Followina the reconnaissance, 13 projects remain proposed for this area_ They inrlude eight new, previously unidentified and unrated projects_ These disptace seven previously selected projects, which were eliminated based on the consensus of the recon- naissance team. Projects were eliminated for several reasons: two sites were annexed by the city of Renton, tw-o projects w•ere found to be unnecessary, two sites were categorized as #1 wetiands (and are�ineli�ible), and one project was determined to be infeasible. The previous SWM capital improvement project list for the Lawer Cedar River Basin had an esEi- mated cost of $2.710,000, while the revised list increases ro an estimated ��ost of ��,734,000. This 3 percent increase in estimated capital costs is due to the addition of pro}ects after the reconnaissance_ The followinp table summarizes the scores and costs for the CIPs proposed for the Lower Cedar River Basin. These projects were rated according to previously establis6ed SWM Pro�am Citizen Advisory Committee criteria. The projects ranked below are tho.se for which the first rating question, ELEh1ENT 1: "GO/NO GO," could be answered aEfirmati�ely Projects w-ith scores of 100 or higher can be considered now for merb n� into [he "live" CIP list. RANK PROJECT NO. SCORE COST 1 3I?2 103 $342.�00 2 3118 90 57.000 3 3120 75 163,000 4 3109$ 67 136.000 5 3121 65 371.000 6 3 i 17 60 501.000 ' 7 3115 60 361.000 3 3116 55 73.000 9 3114` 23 1;4.000 10 3111' 25 175.000 ' lI 3112" 17 117.000 ' 1? 3ll9° 15 I59.000 13 3105 12 115.000 TOTAL $2.784.000 I� ' Projects propcued prior to the Reconnaissance Probram Ili I P:LC.APB B-1 APPENDIX C DETAIt.ED FINDINGS AND RECOMMENDATIONS LUWER C�DAR RIVER BASIN ' " All itema listed here are located on final display maps in the offices of Surface Water Management, Building and Land Development, and 8asin Planning. Trih. � Collect. Existing Anticipated Item' River Mile Point C�te o Prop. Proi• Conditions and Prohlems Conditions and Problems Recommendations 1 -- 5 Geology Gullying and landslides in Continued erosion. Recompact fill, revegetate, uncomp�cted fill in new and drain Adequately. � development near edge of steep hillslope. 2 -- 13 Geology Small landslide h�s formed None (natural failure). None. debris flow (11/36), Sedimentation in yard of residence. 3 0299 4 Geology Landslides in sedimentary Natur�l f�ilure. None. RM 2.6 rock in �uthanks adjacent to railroad, 4 0299 16 Geology Drainage from residentiaf Incre�sing erosion. Provide adequate R/D to RM 9.65 area is resulting in attenuate flows. gullying in �vale. P: LC.APC G1 _ _ _ __ Trib. S Collect, Existing Anticipatcd Item River Mile Point Cate�ory Prop. Proj. Conditions �nd Problems Conditions and Problems Recommendations 5 0299 1$ Geology Horse farm in uplands has Continued high erosion and Develop R/D at horse farm RM 12.1 created extensive imper- sedimentation. to attenuate peak flows. vious surfaces, resultinb See Project 3115. in channel scour, bank erosion, landslides, and sc:dimentation at mouth of basin. Residence overcome ' with sediment. 6 -- 13 Geology L,andslide terrain for sale Site of future mass erosion. Prohibit development here. by realtors. High risk for Notify Building and Land landslides, floodins (from Development. Add area to springs). SAMF. 7 -- 7 Geology Large-scale landsides Natural process. None. adjacent to Cedar River due to springs and cutting of toeslopes by stre�ms, Appears to be natural. 4 •- 2 Geology Gullying in valley wall, Unknown. None. possibly from natural springs. 9 -- 14 Geolagy Landslide debris flow from Existin; tension cracks Revegetate hillslope with residence on SE 147th Pl., indicate fi►ture instability. trees and shrubs. Renton. P: LC.APC G2 Trib. �� Collect. Existing Anticipated Item River Mile Point Cate�or� Prop. Prol• Conditions and Problems Conditions and Problems Recommendations I 10 0299.1A 21 Hydrology 3116 Frequent flooding of Road located on top of peat Elevate the road 3-4' by RM .08 county road caused by low bog and will continue to filling on top of the road embankment. settle, a�;ravating flooding present road embankment. problem. Also stabilize embankment, 11 0300 4 Geology Extensive channel and Problems will continue. Provide adequate R/D in RM .00-,40 bank erosion and numerous uplands. (See Project landslides due to 3119.) development-related stormwater. 12 0300 4 Hydrology 3119 Development-related peak Increased erosion on Construct detention dam in flows have caused sig- hillslopes below. deep, channelized reach of nificant bank erosion. Trib. 0300. I 13 0300 4 Hydrology 3109 Collection point 4 has Degradation of Trib. 0300 Construct berm and standprd RM 1.40 been nearly completely from RM .42 downstream. This control structure at outlet urbanized. section is very�steep and to WetlAnd 3120 in CAscade sus�eptible to erosion. Park. 14 0302 6 Geology Channel downcutting and Will continue at same level Control storm flows from RM .50 bank erosion. or inerease. uplands. 15 0302 6 Geology Bank erosion (medium den- Increasing erosion with Provide adequate R/D in RM .80-1.00 sity) at meanders and increasing flow from devel- uplands as area develops. - obstructions, opments. P: LC.APC C-3 Trib. Rc Collcct. Existing Anticipated Item River Mile Point Cate�ory Prop, Proj. Conditions and Problems Conditions and Problems Recommendations 16 0:�02 6 Geology Gully erosion from broken None. Culvert has Ue�n None. culverts, repaired. 17 0302 6 Geolo�y Severe gully erosion Continued erosion. Tightline flows to RM .60•.80 cr�ating small valleys main stem. from daylight culverts. I 18 0302 b Iiabitat Stream channeled along While fish now use this Add habitat diversity RM.35 �olf course road. No reach, lack of habitat will (e.g., structures, overhead overhead cover. No habi- eventually reducc popula- vegetation). Gain tat diversity. tions. easement to restore mean- ders, if possible. 19 0302 6 I-iydrology Tributary drains down Problem will worsen as Construct detention dam RM .45 steep bluffs on north development upstream upstream of golf course. side of Ced�r River, continues. carrying debris and flooding Maplewood Golf Course. 20 0302 6 Habitat Water supply dam. Full As impoundment fitls, storm- Dredge pond and m�intain RM .50 barier to upstre�m water will flood over bank. it as sediment catch. mi�ration. Impoundment Stn�cture may fail. is filling with sediment. 21 0302 6 Habitat Severe gullying from ribht Wi(I continuc to erode until - Tightline downslope. RM .90 bank corregated metal reaches till layer. - Add velocity attenuator at pipe. Heavy sediment stream. delivery to stream. r; t.c.nrc c_a Trib. c�c Collect. Existing Anticipated Item River Mile Point C�te�orv Prop. Proj. Conditions and Problems Conditions �nd Problems Recommendations 2? 0302 6 Habitat Trash in stream (auto, Area adj�cent to corridor, - Remove trash. RM 1.00 tires, appliances), will continue to collect - Distribute educational trash and debris. Further materials to streamside worsening of water yuality, residents. sediment�tion, erosion. - Cite violators, if problem persists. 23 0302 6 Habitat Trash in stream. Water Area adjacent to corridor, - Remove trash. RM 1.10 qu�lity problem, will continue to collect - Distribute educational unsightly. trash and debris. Further materials to streamside worsening of water quality. residents. • Cite violators, if problem persists. 24 0303 G Geology Extensive bank erosion in Nonc. Increase R/D volumes, slow release upper portions of tribu- rate to nonerosive Icvels. tary. 2S 0303 6 Habitat H�bitat suit�ble for resi- Scdiments will eventually - Control stormwater volumes RM .25 dent fish. Sediment accu- cover grayels. E�abitat and discharge rates from mulating. will become unsuitable for developments. fish use. - Manually clean gravets when necess�ry. 26 0303 6 Hal�itat Trash and litter in Further decreases in water - Remove trash and litter. RM .35 channel affecting water quality. � Distribute educational materials quality, causing erosion. to streamside residents. - Cite violators, if problem persists. P: LC.APC GS Trib. R Colle�t. Existing Anticip�ted item River Mile Point Cate�orv Prop. Proi. Conditions �nd Problems Conditions and Problems Recommendations 27 0304 7 Habitat L.andslides contributing Sediment will continue to Maintain riparian corridor RM ,40 sediment to channel, Heavy enter system until landslide with setbacks at least 50' deposition in pools, at stabilizes. from tops of banks. obstructions, even in riffles. 24 O:iO4 8 Habitat Horses h�ve access to Further decreases in water - �ncourage residents to fence RM ?.10 stre�m, c�using some bank quality, bank erosion likely. chnnnel back 15' from ordinary deterioration �nd possibly high-water mark. affecting w�ter quality. - Limit access to livestack to one or two points �long strc�m. 29 0304 8 �iydrology Flooding cAused by failing Problem will continue until • Problem referred to Mnin- RM 3.30 R/D �t 17Gth St. �C 14Gth outlet structure is tenance section of Surfae;e Ave SE. modified. Water Management Division. �0 Q304 4 Hahitat Encroachment occurring Wetland likely to be - Require encroaching fills RM 2.40 along all boundaries of reduced slowly until it is to be removed. this headwater wetland. �ompletely destroyed. L.oss - Establish specific buffer of storage, filtration, around this wetland. organic production, and - Enforce sensitive areas wildlifc liabitat. ordinances and regula- tions. 31 0304 7 C'reology Several �ullies due to Problem will continue. • Tightline drainage. RM .�0 d�ylight culverts; a few h�ve recent landslidcs. P: I�C.APC C-6 Trib. � Collect. Existing Anticipated Item River Mile Point Cate�orv Prop. Proi, Conditions and Problems Conditions �nd Problems Recommendations 32 0304 7 I-I�l�itat Extensive riffle (ro RM Gravels risk hecoming - Enhance habitat by addi- 1tM .00 .15, Creek cl�anneled. No cemented. Few resting are�s tion of woody debris in woody debris, little bank for upstream migrating fish. stream. vegetation. Stcelhead, - Revegetate bank, co��o spawners here. - Cnhance pool/riffle ratio, 33 0304 7 Habitat Debris jam may he a Debris will continue to - Selectively remove debris RM .20 parti�l migr�ition barrier. accumtilate. Channel will to allow fish pas.s��ge. likely divert or jam will - Stabilize large woody fail, releasing accumulated debris. sediment. 34 0304 7 Habit�t Debris jam. Bed drops 3' Debris will continue to - Selectively remove debris RM .62 over jam and sediment, accumulate. Channel will to allow fish passage. forming Anadromous likely divert or jam will - Stabilize large woody barrier. fail, releasing accumulated debris. sediment. 3<i 0304 7 I-Iabitat W�ter turbid; oily sheen W�ter yuality will continue • Educate residents about RM .80 and odor prescnt. Storm to decline �s runoff and how to maintain wt�ter quality, drains empty directly into waste enter stream. • Mark storm drains with stre�m. "Dump no oil" signs. • Emphasize recycling of oil. 37 0304A 7 I iydrology 3102 Eaistine forested wetland Additional storage could be Construct a proportional weir RM 1.30 providcs detention for utilized by constructing and berm at wetlAnd outlet. Trib. 0304A and 0304 in berm and weir at outlet. Project could be used instead heavily developed area. This could be done to atten- of Project 3107 to rpeserve the uate increased peak flows #1 rated wetland (where project �s upstre�m are� develops. would be built). P: LC.APC C-7 Trih. �C Coliect. Existing Anticipated Ctem River Mile Point Categorv Prop. Proj. Conditions and Problems Conditions and Problems Recommendations 3�t 0304A 14 F�Iydrolo�y 3115 Rtmoff generated on top of Flooding will continue as - Construct detention pond RM .40 bluffs on southwest side long �s land use remains the at top of bluffs. of Cedar River is causing same on top of bluffs or - Tightline drainage down severe bank erosion, until mitigating measures bluffs, then channelize it floodin� and debris flows are taken. Runoff origin- to an existing ditch onto several residences ates from highly compacted alongside SR 169. of v�lley floor. pastureland on uplands. - Prevent similar problbms elsewhere with land use regulations, including provisions for prescrvation of vegetation buffers near tops of cliffs. 39 0305 10 Geology Extensive bnnk erosion, Susceptible to inerease;s Attenuate high flows. partly due to subsurface with increasing storm flow. clay layer and landslide topography. 40 0;�05 10 Geology Local severe bank Problem will continue. Existing rock•filled RM 1.10 erosion. gabions are deflecting flow. 4l 0305 l0 C'reology Extensive channel down- Continued erosion. Attenuate high flows with RM 2.10- cutting �nd b�nk erosion. adequate R/D. (R/D 1.75 currently exists.) 42 0305 10 Geology Several gullies and �sso- Erosion will continue. Tightline culverts. RM 2.15- ciated landslides due to 1.75 daylight culverts on steep slopes adjacent to ehan- nels. � , P: LC.APC C-8 Trih. �� Collcct. Existino Anticipated Item River Miie Point C�te^orv Prop. Proj. Conditions and Prol�lems Conditions and Problems Recommendations 4� 0305 1� i labitat M�dsen Creek in ditch along Potential for fuei entry in- Acquire 30' e�sement away RM .20 SE Jones Rd. I ieavy silt; to creek. I�urther decreases from roadside. Construct road runoff; water yuality in water quality can be ex- new stream channel. advetsely affected. pected. 44 0305 10 II�►bitat Creek in ditch along south Further decreases in water Acquire 30' easement away RM .35 side of SR 169. F�leavy qua(ity can be expected. from roadside. Construct inputs of oils, anti- Potenti�l for autos to enter new stream channel. freezes, heavy metals, channel. L,ack of habitat. organic pollut�nts likely. i Sand, silt from ro�dside (of SR 169) enters also. 45 0305 ItM .00• 10 }iydrology 3105 Section of Trib. 0305, Plooding will continue. Construct and enhance 2200' of ! .40 RM .00-.40 is experiencing (Sce Appendix A, Proje�t channel through undeveloped extensivc floodinp. 3105,) King County Park Lnnd. 4G 0305 ]0 Habitat Channclized along dri- Further siltation, water Acquire easement; move KM .50 veway; lacks h�bitat quality degradation can be creek from driveway divcrsity. Driveway scdi- anticipated. Lack of habitat 10-15'. Add meanders and ments enter channel, and precludes optimum salmonid habitat structures to oil placed on driveway use. inerease diversity. enten stream. 47 0305 10 1-iabitat Channelized tributary Little s��lmonid use Add structures to incre�se RM .(5 lacks habitat diversity, anticipated. Spawning and diversity in stream. cover for s��lmonids. rearin; succes.s limited Manually clean gravels by Gravels compacted. (unles.s reach is restored), churning them. I': LC,APC C-9 Trib, & Collect. Cxisting Anticip�ted Item River Mile Point Cate�orv Prop. Proj. Conditions and Problems Condirions �nd Problems Recommendations 44 0305 10 Hahitat Good spawnang riffles occur Increased flows may cause Control flows into system RM ,90 here. �h-3" gr�vels, few grlvcl bar movement. from developed areas fines, not compact. High St�itable �r�vels m�y be upstream. If necessary, [lows �re moving matcrial, transported downstream to add Ued controls to hold however, unus��hle are�s for spawning gravels or "vee" struc- salmonids. tures to recruit them. 49 0305 10 Habitat Severe b�nk cuttin� �nd Ftirther erosion/scouring can Control high flows by RM .95 erosion occurs here. Bed be expected. Channel inereasing upper basin R/D scourin� evident. Reach deterioration will continue. facilities, lowering suhject to hi;h, r�pid Flows �ppear to bc gener�itcd discharge rates to stream. flows. at developments. $0 0305 10 Iiabitat Much woody debris Debris jams will occur with Control upstream flows RM 1,20 movement and numerous greater frequency as flows with greater R/D volume, dcbris j�ms. Reach is incre�se. Sedimcnts will lower discharge rates, subject to hi�h, rapid bt�ild up and channel will Sctectively remove dcbris. f lows. d ive rt. 51 0305 10 Hahitat Channel erosion, bank Further channel deteriora- - Increase R/D capacity. RM 1.70 failures, downcutting oc- tion may be expected. Silt, - Decrease dischar�e rates. curring. Re�ch subject to sand transport to m�instem high, rapid flows. will incre�se. 5? 030b 10 Geolo�y Failure of manhole during Not �pplicahle. Repair manhole. RM .40 11/3( storm has resulted in gully crosion. P: LC.APC C-10 Trih. �C Collect. Existin� Anticipated item River Mile Point C�te�ory Prop• Proj. Conditions and Prohlems Conditions and Problems Recommendations S3 0:�06 10 Geology Channel downcuttin;, b�nk Erosion will increase. Clay Further increase in runoff RM .20 erosion and several layer in valley makes area should be attenuated; this landslides, due both from scnsitive to landslides. is a sensitive channel. increased storm flows and development along edge. 54 0306 10 Geology Undersized culvert in arti- Possible fill failure: Lake Enlarge the corregated RM .3U ficial fill in golf course ponded bel�ind culvert in metal pipe �nd/or threatens to build lake and in 1931 and threatened construct adequate trash possibly overtop bank. the fill. rack. Breach flood possible. I SS 030�i 11 IInbitat Channel subject to hirh, Further ch�nnel damage can Increase R/D capacity, RM .25 d��m�ging flows. Erosion be expected. Sediment decrease discharge rate. evident. transport downstream will continue. S�i 030�i 10 Geology Downcutting, bank erosion Will continue or increase in Attenuate storm flows. RM .:�0-.45 �nd landslides. future. 57 O�Of Ilydrology 3113 Trib. 0306 connccts with Problem will worsen as • Replace existing pipes RM .30 large trihutary at manhole development upstream with larger diameter pipes here, Dcbris from 030C continucs. (if downstream analysis clogs this manhole, c�i�sing allows for inereased flows). severe erosion of Fainvood • Install new inlet struc- � Golf Course. tures with trash racks. 5� 030GA 11 I-Iydrolo;y 3123 Existing small ponds on Arca upstream is developing - Acquirc easements for ponds RM 1.3Q 030bA are overtopped and quickly, thiis worsening the and additional area around ponds receive considcrable silt problem. and construct detention pond. durinr high flows. Tlie • Location is ideal for addressomg ponds are located on peak flows before they reach }�airwood Golf Course. the sensitive Cedar Reiver bluffs. P: LC.APC C-]1 Trib. �C Collect. Existing Anticipated Item River Mile Point Cate orv Prop. Proj. Conditions and Prohlems Conditions and Problems Recommend�tions 59 030GA 11 I-I�ibittit Some usable habitat exists Further habitat deterioration - Increase R/D capacities. I RM .2S for resident s��lmonids, likely. Cl��nnel erosion will - Decrease discharge rates. Water yuality is poor. increase. - Encourage use of 2-cell Channel subject to high detention ponds, swales. flows. • Prohibit filling of eaisting wetlands, ponds in upper basin, 60 0307 12 Geolocy Extensive bank erosion at Increased erosion will - Miti�ate development- RM .10-.40 all meanders and ohstruc- result witl� increased flows. related high flows. tions (trees, cars) due • Provide adequate R/D. I to increased flows from development. I 61 0307 12 Geology Stream eroding toes of Increasin� erosion with - Mitigate development RM ,10-.GO slopes resultinF in increasin; flows. related high flows. landslide failures. - Provide adequate R/D. 62 0307 12 I[abit�t Stream channcl pushed to Erosion will worsen as - Incrcase R/D capacity at RM .30 one side of ravine for stream flows increase. all delivery points. roadway. I-li;l� encr�y May threaten road bank at - Reduce release rate below system. Much b�nk cuttinr, toe of slope. channel scour level. scdimcnt transport, dcbris movcment. h3 0307 13 Hydrolory Area on top of I�luffs ne�r Infiltration sites should Construct retention faci- RM .GO Trib. 0307 h�s excellent be used whenever possible, lities for new develop- infiltrative cap�city. These would provide ground- ments in area at these sites. water recharge. P: I�C.APC G12 Trib. fi Collect. Existing Anticipatcd Item River Mile Point C�terorv Prop. Proj. Conditions and Prohiems Conditions and Problems Recommendations f,4 03Q9 15 Habitat Subject to heavy, rapid Erosion, deposition wiil - Control storm flows RM .10 flows, Channel erosion, increase. Sediments will upstream. deposition bars migration. migrate downstream, creating - Control volume and discharge a water quality problem. rates, 65 0310 15 Geology Sedimentation upstream from Continued sedimentation. - See "Hydrologic and hydraulic RM .60 culvert due to debris and characteristics" section in tindenized culvert. New this report. corregated metal pipe con- tinues to pass water through. 6G 0310 15 Geology Severe erosion below Continued erosion and - Install energy dissipator RM .OS culvert, severe sedimen- scdimentation. below corregated metal pipe. tation in residencc yard. - Excavate channel through yard where originAl chAnnel was located. Ci7 0:�10 1S Geology Road drainage forming gully Continued erosion. Reroute drainage. Refer problem RM 1.50 �dj�cent to roAd; road bed to Roads Maintenance. in danger, 6�4 0310 1S I�Iabitat 3120 Corre;ated met�l pipe is Problem will continue. Reinstall corregated metal RM ,2S anadromous b�rrier. pipe at or below bed level. P: I�C.APC G 13 Trib. �C Collect, Cxistinb Anticipated ttem River Mile Point C�te�arv Prop. Proi. Conditions and Problems Conditions �nd Problems Recommendations 69 0310 15 Hydroloby 3120 Existin� chlnnel draining Frequency and severity of Construct detention pond RM .40 off bluffs on noi•tl� side problem will worsen as on upstream side of Jones of Cedar River, causing development on Uluffs Rd. to trap sediments, and flooding of residences and increases. enhance 1,000' of creek dehris flows onto .lones Rd. from Jones Rd. to Cedar during peak flows. River. �0 0310 15 Habitat Corregated metal pipe Problems will continue and Remove new and old pipes; RM .60 outlet approximately wonen as outfall velocities replace at lower level 9' �bove bcd levcl. will scour bcd and banks. with oversized pipe with Complete b�rrier to fish. Upstre�m has recent (11/46) trash rack. Old culverts at bed Icvel deposition up to 4' deep. are plugged. 71 0311 13 Geolocy Gully erosion in dr�inage Continued accelerated ero• If possible, enlarge R/D RM 1.70 swale due to outflow of sion. prior to its outlet in the wetland that partly seems wetland, to act as an R/D facility. 72 0314A 1G Ilydrology 3117 Severe erosion, flooding, Problem will be aggravated • Tightline drainage between RM .20 damage to County �nd as �rea above develops. detention ponds in gravel pit. private ro�ds from - Constn►et detention pond increased runoff from next to Jones Rd, to cr�p gravel pit operations on sediments. I�iIlSide. • Constnict channel from Jones Rd. to Cedar River. 73 0314n/ 16 C;eolopy In�dequate R/D, plugged Not applic�ble. See hydrology comment 0314B culvert caused by exten- above. RM .10-.40 sive channel and bank erosion and landslides. W�ter has cut n new channel. I': LC.APC G14 Tril�. �C Collect. Existing Anticipated Item River Mile Point Cate^ory Prop. Proj. Conditions and Problems Conditions and ProUlems Recommend�tions �4 0317 Hydrology 3111 Francis L.ake is only Trib. 0317 flows througlt - Constnict proportionll I RM 1.G0 hYdr��ulic control for steep lrea downstream of weir at outlet. I Trib. 0317. lake. If area around Francis - Enhance 1,100' from I��ke develops, incre�sed Francis Lake to SE 134th St. peak flows could cause severe �I dam�oe to Trib. 0317 in the steep re�ion. 7S 0:�30 Hydrolo�ry 3114 Existin; forested wetland if si�rroundin; area urb�n- Constn�ct containment berm RM 2.40 with larbe amotmt of un- izes, this would be a good and control structure at utilize�i St01'B�C, Wctland site to attenuate peak outlec of wetland (if bio- currently detains flows on flows. lo�ical an�lysis permits). Trib. 03?0. 7G 031g 19 Iiabit��t Salmonid parr in m�ny Decrease in water quality Establish and maintain RM .10 pools, t,arge pools up to with increasin� develop- adequate buffers, 100' 1.75' deep. Some deposi- ment. Loss of habitat, from ordinary high-water tion in pools, bchind Decrease in [ish use. mark or 25' from top fo ohstnictions. . slope break, whichever is greater. 77 0342 19 F�abit�t Salmonid use apparcnt from System is mostly in natural - Maintain adequate stream RM .3S c�rcasses. Sockeye, condition. As development corridor buffers. Chinook spawners. Some increases, hibher flows and - Reduce discharge rates to sedimentation occurrinc. worse water quality ean be pre-development levels. expected, Prevent clearing, grading within buffers. P: LC.APC G15 . . i Trib. .� Collect. Existine Anticipatcd Item River Milc Point Cate�ory Prop. Proj. Conditions and Prohlems Conditions and Problems Recommendations 73 0323 19 Geology Medium-density landslides None. Limit development in the RM ,50 and higlt-density bank basin, erosion occurring due to natural causes. This indi- cates channel and valley sensitive to effects of development. (Sensitivity due to clay layer, Basin hosts some of best fish habitat in upper reaches.) 79 0324 19 IIabit:�t Significant s��lmonid use Scdiment�tion from upstream Maintain leave strips RM .70 throughout. Sockeye reach possible. Adjacent adjacent to stream at spawners, c�rca�.5es present. development will likely least 100' from ordinary Coho, steelhe�jd parr in reduce diversity and quality high•water mark. Restrict pools. Bxcellent h�►bitat of habitat. use/development within this for spawning and rearing streAmside management zone. (a redd site). Much ciiversity •- most exemplary in basin, Channelized reach, Uniform May cause thermal problems Restore stream habitat SO 0324 19 Hahitat channel, no habitat diver- as w�ter temperatures rise, throughout: add structure, RM 1.10 sity. Heavy s��nd deposition. No useful hahit�t. diversity, Uank vegetation, 1.40 l,ittle overhe�d canopy or and canopy. Cost should be hank vegctation. borne by paCty(ies) who channelized this reach. 81 0328 19 �[y�iroloby 3112 [.ake Peterson is small, I.ake provides good peak flow Replace weir at outlet RM 1.d0 open-water weUanci with a attenuation and will hecome with a higher weir in weir at outict. more important as upstream order to gain additional tributary area dcvclops. srorage. I': LC./1I'C C•1G TASK 3 FIELD INSPECTION EXHIBIT J Off-Site Analysis Drainage System Table OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 $asin: Cedar River Subbasin Name: Subbasin Number: Distance Observations of Fietd 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: lheet(7ow,swale,stream, over[opping,flooding,habita[or organism channel,pipe,pond;size, Drainage basin,vegetation,cover, destruction,scouring,bank sloughing, Tributa�y area,likelihuod of prohlem, See Map diameter,surface cven depth,type of sensitive arca,volume °lo Ft. sedimentation,incision,other erosian overflow pathways,potential impacts 1. Sheetflow off south Discharges to seasonal stream 5.15 0 -660 None Noted None Noted property line through forested area 2. Seasonal stream 2-foot bottom, 2 feet deep, l:l 1-2 660 - 1,060 None Noted None Noted side slopes 3. Dispersed flow through Courses south 2 1,060 - 1,260 None Noted None Noted thick brush and ' blackberries 4. Rockery wall Covered by blackberries — 1,260 - 1,265 None Noted None Noted 5. Broad channel may be Grass lined,4U-by 170-feet 1 1,265 - 1,435 None Noted None Noted detention pond 6. 18-inch CMP Flows south from channel to 1 1,435 - 1,450 None Noted None Noted catch basin 7. 18-inch CMP Flows south from catch basin 1 1,450- 1,490 None Noted None Noted to catch basin on south side of S.E. 144th Street 8. 18-inch CMP Flows west from catch basin to 1 1,490 - 1,612 None Noted None Noted catch basin 9. 18-inch CMP Flows west from catch basin to 1 1,612 - 1,928 None Noted None Noted catch basin 10. 18-inch CMP Flows west from catch basin to 1 1,928 - 2,134 None Noted None Noted catch basin 11. 18-inch CMP Flows west across 1 2,134 - 2,174 None Noted None Noted 160th Avenue S.E. 12. 18-inch CMP Flows west from catch basin to 1 2,174 - 2,304 None Noted None Noted catch basin i»�s.003.ao� Basin: Cedar River Subbasin Name: Subbasin Number. Distance Observations of rield lnspector, Drainage Component Drainage Component from Site Existing Yotential Resourcc Reviewer,or Symbol Type, Name,and Size Description Slope Discharge Problems Problems Resident Constnctions,under capaciry,ponding, Type: sheet flow,swale,strcam, overtopping,tla�ding,hahitat or organism channel,pipe,pond;size, Drainage basin,vegetation,cover, destruction,scouring,bank sloughing, Tributary area,likelihooJ of problem, See Map diameter,surface area depth,type of sensitive area,volume °Io Ft. sedimentation,incision,other erosion overflow pathways,potential impacts 13. 18-inch CMP Flows west from catch basin to 1 2,304 - 2,458 None Noted None Noted catch basin 14. 18-inch CMP Flows west catch basin to catch 1 2,458 - 2,632 None Noted None No�ed basin i i��.ou�.��,� TASK 3 FIELD INSPECTION There were no problems observed during the resource review. Based on a review of the drainage complaints of the downstream drainage course, there were no existing constrictions or lack of capacity in the existing drainage system. 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 dces not constitute a severe flooding or erosion problem. Conveyance system nnisance problems are defined as flooding or erosion that results in the overflo�� of the constructed conveyance system for runoff events less than or equal to a 10-year eveni. 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/outbnildings I and minor erosion. �� Based on a review of the drainage complaints, there were no complaints associated with the downstream drainage course for this project site. However, there were complaints located on II both sides of the downstream drainage course, to which this project site may contr�bute some ronoff to under existing conditions; however, it was not likely. With the improvements of this I project site, there is the potential that problems on both sides of the do��rnstream drainage course I may be helped somewhat by mitigating probiems associated with those drainage complaints. ', 3.2 Severe Erosion Problems(Type 2) I� Severe erosion problems are defined as downstream channels, ravines, or slopes with evidence of I' or potential for erosion/incision, sufficient to pose a sedimentation hazard to downstream , conveyance systems ar propose a landslide hazard by undercutting adjacent slopes. Severe erosion problems do not include roadway or minor ditch erosion. ' The sensitive areas foIios indicated there ��ere no erosion/sensitive areas in the downstream � drainage course of the project site nor did the site visit find erosion problems evident anywhere along the downstream drainage course. 3.3 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 warrant additional attention because they pose a significant threat either to health and safety or to public or private property. Neither the review of the drainage complaints nor the site visit noted any severe flooding problems in the downstream drainage course. Portions of the downstream drainage course investigated by the site visit and a review of the soils map indicates that the downstream drainage course occurs through till type soils. The field reconnaissance for this off-site analysis drainage report was conducted on the morning of Octoher 27, 2005. The skies were partially overcast and the high temperature on this day was approximateIy 55 degrees. 1 i 778.003.doc TASK 4 DRAINAGE SYSTEM DESCRIPTION ; AND PROBLEM DESCRIPTIONS i TASK 4 DRAINAGE SYSTEA�i DESCRIPTION AND PROBLEI��i DESCRIPTIONS Runoff leaves the site by discharging off the southern property ]ine of the site where it courses through thickly forested areas with alternating trails for access to different portions of the site, and tends to sheetflow through forested areas into a seasonal stream that courses south and southwest into a blackberry bush area, ultimately discharging to a large channel, which may be a detention pond, adjacent to S.E. 144th Street, then flows are collected in an 18-inch CMP and catch basin pipe conveyance system, where it is coursed along the southern side of S.E. 144th Street for severai thousand feet in a westerly direction until over 0.5-mile from the project site where the off-site analysis was terminated. The drainage complaints are located on the following pages of this report; however, none of them were located on the do��ns[ream drainage course foilowed for this project site. They were placed into this report for reference only and, therefore, there are no anticipated problems associated with the development of this project site. EXHIBIT K Drainage Complaints tiOV. 3. 2:�G5 8: 3JAM KING C0. WLRD N0. 5845 P. 1 ��E �op� Kin Coun Watez and Land Resources R Division 201 S J�ckso�x St,Suite 600 Seattle,'9VA 981043855 �/ Date: � Ntamber of pages including cover shee�� '�o: From: Candi McKay,En�z Tech II ��, �-y ��_�y�� WLR Stormwater Services Section � Phone: 206-29b-1900 Phone: Fax Number: 206-296-0192 IlV,�ORTANT LEVEL 1 ANALYSIS NOTE: We do not send copies of certain complaint types that are not relevant such as BCVJ�, FT, FIR, FIH and WQA, and we do not send CL and�.S types. See key below. Type S 1, SZ and S3 wi11 not be f�ed due to size constraints. � f� � � �� The followi�g xs a list of complaint types received b�the�Vater and Land Resonrces Division Drainage - Sezvices Section, Cou�p�aint numbers beginning prior to 1990-��have been arct�ived and are no longe�in ovr possession. They can sti11 be retrieved,if necessary,but will take addidonat�time and . may not be ben�ficiai to your reseazch due to their age,aevelapment'Wluch has occurred,etc. If you are interested in revlewi�ag the actual complaints,rhey can be pulled (time permitting)for yowr xeviGew. - Copies caa be obtained far $ .15 per page, and$2.00 per page for plans. �evs: s 1`,yne o�f Xnve��stlon T�pe of Problem -C ncaon Rcqucu , nCn Develo�pmenUConstruction BCW Basiness for Gcan Watcr DDM Dninage-Muoeilanaoos CCF Rcsponsc W IIIquiry DE5 Dtoinuge—FrosioNSadimcotatiun • sQ. Claim Df.� Dtalnaga—I,andsliddEarch Mo�rcmcnt EH � Enfoiocss�c�+t on SoLi 17I'A Dralnage Tec�nlcat Assistsacc fiR Bnfo�csnwt RcYicw INQ D[ainage—(ieaenl Inqniry FC7C,�'Qi,FCS Facility Complsiurs MMA Maintea�mx-Aesthetics Fx SWM Feo 7nquiry MIvIP Mainlcnance-FIood'ing N1R 3WM Pee Raview MM� Ma�tcoaacc-Genaal i�IH SWM Fee ae Ho3d. MNII�Q Ma�ccnancc-Maw�g +I.S Lawsn3t � MNNI� Maiut�anac—NxdsMa�rn,nn�r RR FaC�ryF�gineedngReview MNW Mamtenanoe-Noxious Wocda I�IDA Ncigbbofiood Dr�ange Assistancs SWF 3WM Fee Quesrion4 . WQC Wata Qtality Complaiat WQ$ Werer Qun[ity—Best Manag�ent P[actixs WQE Wstar Quatity Bufo�c WQD Wetu Quallty—Dumping WQR Wster QaalitY Bs►�noam8 Revicw� WQI Waber Quelity�IDicit Conneaion WQA warer QuaL'ry Aa�c RF.M 5WM Fee-Remeasurtmept wQo wao�Que6ry-Ocbu c3xT swMF�c SI,S2,.SI�t3 FaginRam�g Sp=�rs NWD SNM FedNew Dlsoount •SubJect to Pub1le Dlselosure�qaisementa 1.Reeeipe aF wcit�nquest for docan�enu 2.Revicw and approval by Proseculing Attnme�s officc PJOV. 3. 2�07' 8: 31 AM�K I NG C0. WL RD N0. 5845—`P. 2 � - n��v� COvi� u�r�4RTM�NT O� PUB�,;� WOR�� SURr�� MANAGEMENT DIVISION $ 1 GOMPLA[N�' INVESTIGATfON REPORx ' � � z � , • oate aec�e: vA�uRE o�conn�.arr�r: � �J q/ LOGATION: SEC lWP RGE � KROLL PG. I ;OMPLAlNANT: COUNClL OIST. . R�OpE N0. ��f HOME: Address �/ —'� Clty State Z'ip WORK f�AfLS OF COMPLAlNT: �� S�fl�� o`Z/S�%l I COMPlAtNT RECEIVED BY: ' -ETAI�,S OF IPtVF..ST1GpT10N= Sketch.or►reverse sid�Yes� No O Photos:Yes� No O � Qwnt�h aN srr� Z �Z7_ `11. n�T�WE� ax� ,�-G,�e.-r,w r�dE o� s� �43�.nr PL �4r�'�� 7s�,c� �.�.�c�s�� . �iL" G�,o STvp�c� oc.T -rp c�e.rl' p� �r� �4-S �/�00 /Z "" G� �Goc�'b ,q6.o�,v.�T C,l' .vS S�✓�iv /ti P��T � � _ �0�'P.P�yk , 6 '� 6.��"S�' O13 S�.�v`E� � TH� /Z`�C� �E.�t�-TiivUES �i� �,o,vs/ SEcr�o.Us �U.vK�.cw.v ��.6-t��s� T� T�' �osT � svsP�GT �7" TE�Z.��.t„o'r�s �osT c� ,D�(lEG✓A y �7" /��O� Pe✓a rp O s,liGc✓-� ,a P�s s i� �r-x.�. s�,�,� c�,u�c u �o y a�' �,v� e�r�bk,� To s�,� ,�c�� o�' /�/f'� �CJp C-o 7r�v .L�d_f�.v oTjSE,ev�b �� r��S �C.o77�lU %"o T�i�F.,�..drr� p�P�' R1.�V� _ )MpIAtNT INVESTIGAY�D 6Y: �C.��cr� oN.t�Sm�. pqTE: Z'-�" / � �WTION TAKEN: . //� 6i L%G�-� 1!�2/ "�.�' �-►�a L�,,,.— ' �mplainant advl5ed of action possibcle ortaken by: Phone ❑ Letter p Personal Contact p :omplaint Action Handled By ��'�✓ Ciosed: � " 4 v ( � OK'd: w'�. aa�e �„�asi� NOV. 3. 2005 8:31AM KING C0. WLRD N0. 5845 P. 3 To � �� j F TZ� �M�t.� '�to-� �A� o �L�(s`(1— � . . M SUBJECT 5��rP► �{�, — P.:d�6� 'p� �tie�s�'. DATE � � � l MESSA[3E ,A� �. ��,e,t�C- 6F �(� (�,,,�5 � M�i t, fi� 5� A. �3rr� �; � �t►a`� 4.�s (�cxRT� - Ttt�- �D►�v'C' i5 Z'�t� c' �v iC�s Ct,d�a L t v�. (, t�r�1. "f� �Z� oG C,�u��-dJ 1 s ` 6� �.�..�� i.� 4des�-a-1t,� o�v „ �s� ci��5T6 +�� m � 'C��, i� c� 77�. �� M. C3� E TL� W 'tT � �'�Z rt�- 1�(.6> S"Ct�w.. � F�c�. �G GS� T' �C . , SIGNED 'CL�Zzt,•.� WEPLY SIGNED DATE SENd PARYS 1 AND 9 INTAt7- """"�' �S �� PART 3 Wltt BE RETUANm WiTF1 REPLY. POLY PAK (50 SETS) 4P472 .. , ------ -- - - ---- �- - - --. . � ' D �?,. -- S� t 44� �' .�-� r' ��'"'� � .,--�—NC�'. 3. 2GG�_ 8 ; 31AM.—KING C0. WLRC N0. 5845-.-.,P. 4 �ketC ' i � h � N � � � � � /Z„�p rrL� -� sca�e,.� ' T�j P.PSV/ot/�Ly a�,� ��l ' ' � 1��4� I��1 Q . 1 � i �, �� 2„� �=-�_` - ._(� � c,S. s-E �4.3.�►' �I 1 . � �v - , � o��s�' P�A� .To��►7T . � � � `� a � I � ' ��° ? � � . � � PE Y�R�vr3�a�(-Y U.�v�''.Jv�s � P� t! � PAST 189/0 p,e�vE��7 t I .� � - � -•_ -- _ , n \ � d . �F ? -�- ti� � �� i ❑ i , c<,,� � � ^ �_ ��^. ..�:` �1 �� Q �• t J \ � � '� — � , _ � � - �1 � �L _ ,11 � ii :,C I \� � � �� .. ��' _ t' � .ut — , �� , Z' � �� ANK---K I NG C0. WL RD V0. 5845� P• 5 NOV. 3. 200�a 8: 3,1 _ ��'?� s�i;��;,2z n.uno� �u�;�� o: .:�o�::( (Z , , � . `��'� ��►�y Surf'ace Water Management Division T�epartment ofPublfc works Yesler suilding 40�Yesler Way-Room ho0 Seattle,WA 98104-2637 (2os)286-6s'19 April $, 1993 Mr. and Ms. John McKay 16404 Southeast 143rd Place � Renton, �WA 98055 RE: Notice of King County Code Vialation - SWM-DIR 91--OI88 . Location: A portion of the northwest quarter (1/4) of Section 13, � Township 23 North, Range 5 East, W.M. lying north of and adj�.cent to southeast 143rd Place between 164th Avenue Southeast and 165th Place Southeast. Lot 32, in the plat of S�rena Park, in King County, Washington_ � Dear Mr. and Ms. McKay: ; . During an inspection of the property referenced �above on October 25, 1992, representatives of the Surface Water Management Divisian of King County's Department of Public W�rks fourtd the enclosing of �he roadside drainage ditch with subs��ndard materials in the County right-of-way without the �equired per- mits and approved plans_ This is a violation of King County Code 7itle 9.04.130; A drainage facility or construction site which: Adversely affects safety and operation of County right-of-way, utiiities, or other County � uwned and maintained property; �and Results in dirt, mud, water, and/or ice on the 'roadway. This i5 also a violation of King County Code Titie 14.24.Oi0; - Road construction work which does not comply with King County Road Standards; and Title 14.28.020; Work within King County right--of-way without a permit and approved plans. You are theref�re requested to contact Delite Koier, Drainage � -- investigation and Regulation Unit Engineer, at 296�1986 to discuss the correc- � tive work required to reso7ve these code violations. No drainage facilities, natural or manmade, may be altered or obstrvcted without prior permission. If you do not contact this Division within 20 days from the date of this letter, we may initiate appropriate enforcement action. 7his letter is not a Notice and Order as �escribed in King Gounty Code Title 23; however, the exis- tence of the vialation noted above may subject you to civil penaltie_s. and other methods of enforcement authorized by King County Code i'i�t7e 23. � � �:::::.. NOV. 3. 2005 8: 31AM KING C0. WLRD ,N0. 5845�P. 6 �,.....,....._ - ... . . - ----._...,.r..._ ,. _.....__....- �"�� . Mr. and Ms. John McKay . April 8, 1993 � � Page Two Your timely resolution of this violation wili be appreciated. If you have any questions concerning this matter, please call Delite Koler, Drainage Investigation and Regulation Unit Engineer, at 296-1986. 5fncerely, � �� Curt W. Crawford, P.E. � Supervising Engineer, Drainage - Investigation and Regulation Unit CC:DK:bg • . D11:LTI3 - � cc: Chuck Kleeberg; Director, bepartment of Deaelopment and Environmental Services - ' �17Tt�: Gary Kohler, Manager, Land Use Services Division Couis J. Haff, County Road Engineer � ATTN: Tony Ledbetter, Supervisor, Maintenance Section, Divisian 4 � Jim Kr�mer, Manager, Surface Water Management Division . ATTN; Ken Guy, Assistant Manager - , Dic[c Thiel , Manager, Engzneering and Enviranmental 5ervices Section � Larry Cettle, Senior Engineer, Drainage Investigation and Regulation Unit Delite Koler, �ng�neer J - NOY. 3. 2005 8:31AM KING C0. WLRD - N0. 5845 P. 7 oM1 a6ed £66i `8 Ltadb �fe�� uyo� 'sW Pue ',�W �Cng cocmty Surface Watet Management Division ricpartmtnt of I'ublic V4brks � 700 flfth Avew�e Suite 2?,00 sea[tle,WA 9620ti I (2Q1'+)298�Si8 (206)x96-Ox8�2 FAI{ February 11, 199� I� Mr, and Mrs. John McKay 16404 Southeast 143rd Place II Renton, WA 98�55 RE: Notice of King County Code Violation - SlJM - DTR 9I=0188 ' Second Notice �, Location: A portion of the northwest quarter (1/4) of Section 13, Town-- I ship 23 NQrth, Range 5 ,East, W.M., lying north of and adjacent to Southeast 143rd Place between 164th Avenue Southeast and 165th Place Southeast. Lot 32 in the plat of Sere�a park, in , King Countv, Wash�naton. ! Dear Mr, and Mrs. McKay: -puring an inspection of the property referenced above on February 1, 1994, representatives o-F t.he King County Surface Water Management Division found that the substandard pipe that was installed in the right-of-way in front of your lot and tied into the drainage system has not been removed. This suhstandard installation is on the south and west sides o� your lot. The fili that was placed in the roadsid� ditch also has nat been removed �nd the ditch restored � to �he or`igina7 design specffications. This is a violation of King County Cade Ttitle 9.04.130: A drainage facility or constructi�on site which: Adversely affect.s safety and aperation of Coun�y right-of--way, utilities, or other County owned/maintained property: Adverse7y affects other drainage facilities; and Results in dirt, mad, and/or ice nn the roadway. This -is alsa a violation o� King Caunty Code Title 14.24.010: Road construction work which does not� comply with King County road standards. � You are therefare requested to c�ntact Delite Ko1er, prainage Investigation and �egulation Unit Engineer, at 296-1986 to discuss the corrective work re�quired to resolve tf�ese code v�olations. No drainage facSlities, natural or roanmade, may he altered Ar obstructed witf�out prior permission. If you do not contact this Division wfthin 20 days from the date of this letter, we may initiate appropriate enfarcement action. This letter is not, a Natice .and Order as described in King County Code Title 23; however, the existence of the violation noted above may subject you to civil penalties and other methods of enforcement� authorized by King County Code Title 23. , � . .«...�> �JCV. 3. 2U;:� 8: 31AM KING C0. WLRD N0. 5845 P• 8 . Mr. and Mrs. John McKay February 11, 1994 Page Two Thank you for your attentfon to this matter. Your timely resolution of this violation wi11 be a�preciated. If you have any questions, please ca17 Deiite Koler. • Sincerel , � . Curt . Crawford, P.E Supervising Engineer, ra�nage Investigation and Regu7ation Unit � CC:DK:ss C/WP6:LT24 cc: Gary Kohler, Manager, l.and Use Services Division � Lou Haff, County Raad Engineer, Roads and Engineeryng Division AT�: Rod Matsuno, Operations Manager, Maintenance Section Tony Ledbetter, Maintenance Sapervisor, Division 4 � Jim Kramer, Manager, Surface Water Management Qivision ATTN: Ken Guy, Assistan't Manager ' Dick Thiel, Manager, Engineering and �nvironment Services Section Larry Get�le, Senior Engineer, Drainage Investigation and ' P j_ Unit , � �� ,: .-, Engineer :. . . , ;�� '�s., NOV. 3. 2005 8 : 31AM KING C0. WLRD N0. 5845 P. 9 ,-�--�- KING COUNTY SURFACE V�lA7ER MANAGEMENT �IVISlON D(�� DR.AINAG� 7N'VES'I'IGATI�N� REPORT Page 1: INVESTfGATiON�REQUEST 7ype � Received by: �� Date:�� c3 9� OK'd by: .��`��F!-�Fle No. 9�~ l 7� RBCeived f�OR7: � (Please print plainly for scanning). (oay) ��e) NAME: .S�J.sL�� .L1)7'l� PHOfV� �a�=��a� AD[�RESS: �7��0�Zh��L,� L��,�, City State zip � ��j tocatlon of problem, if different: ' � Reparfed P�ob/em: �C` ' . -�� /�� C�� dZI�L �' C� � ��L� . - ' (�/�� • . - . �J � ��/n-!i i . � , - . ��% Plat name: �Q/1.�, � Lot No: Bfock No: �� . Other agencies involved: No Field Investigation Needed QnRfals) �J 'yt #�r � >� M.,.:6��«�id»v •�• y •�' ��b. -- �� c�"_3F;;.�'��'� aw na �� uw�a��'��i wx��,�� .� �� s: i: �� Parcel No. ? � � b 3�� Ktoll �/07 f,t� Th.Bros: Ne �7 �� Z�4 5 7 Fi . O�d 2� �/ �✓ cv i Basin�� Councif D�st Charge No: �� U 0 J� � R�SPONSF: Citizen notified onl�j�by �phone_ letter �in person � � G�`9-''�Q �� oh Sr�_- �t�rii� ��f�-r�,-�o� `,Y f G--�� `u,c� �ra.i� ��-tG.��' � ' �'� . DlSPOS/TlON.- Turned to on by OR: No fuKher action recommencied becausE � Lead agency has beEn not�ed: _Problem has been coRected. �No prob)em has been identifed. Prior investigation addresses problem: �See Fi1e� - �Privare problem -ND�IP wiJl not con�ide�becaUse: � �'Water origfiates onsite and�or on neighboring parcel � Locatlon is outside SWM Service Area, � Other(SpecIfy}; - DaTE CLOSEfl: � I4°�� by: -~��" . �VTP�eOB NOV. 3. 2005 8: 32AM KING C0. WLRD N0. 5845 P. 10 . . �g� • � FILE NO 96�1724 TH�MAS PARE 65783 I�p9F�ee�t Of Nat�81 RC�OtTfOB.S NAME: (3E[�.+ R1VA3 . . $U�i1C8 w�Ci M�3gCIIleDt ADDRPSS: 14206 26�I'H A�SE � pRppE Z2g.g32q DATE IQ17.96 DRAINAGE INVEST�GATION REpORT �N,�� 4 �S � � . K�L,D IIWE.STIGATIOld . , N DETAII,S OF INVESTIGATION: I meet with Gene Rivas at his home to discuss his concerns abo�t a dr�inage problem in hi� backyard. Mr.Riva9 properiy abuts pp to a parcel of property owped by Kiag Connty Parks that is undeveloped. I1�t.Rivas property is sxtnrated from the ranoff from tbe Parks property. This water�t�ten gets an�der the ltivas hopse aAd into the driveway and into a catchbasin ua the front of the Riva� property. I eaplained to Mr.Ri�vag that he shonld contact a contracto��o see aboat i�astalling a French draid system. I said I wonld send� copy of the contraetots list�nd a French drain detail. . � SKETCH: . ; SURFACE�I.OWS' � V - � � : , SATURATED ARF.A V C� � . ' �-�'. YARD DRAIN ''-" - -� r �,c.. : ,�s�`��,i. , . AS 14206 "y � ��> s;r;'� � �.�; �I . _ •'14 w n y �!' }- ,�.', � }' . . . �� ; i�"�� . : .�'�' ; �:� �� ..�. �',.. ,� u''' ' �i 164TH AVE SE ,. . �•: NOV. 3. 20Q5 8: 32AM KING C0. WLRD . - � , N0. 5845 .P. 1 i ;, � , � = . � ' -�� -. � _-� __ � - � �c � ''"""'�` � � � t .��;:}�-�4UNTY SURFACE WATER MAN�GEMEt�'E'DIVI��' - . . = �" �RA�AC� �'TIGAT'IOI� REPORT . ,-� • E'age 1: -1NVESTIGAT{ON"REQUEST Type._� � Re�etved by. �� Date: //��/�� OK'd by: F�e•Na 7 / �DcU . � �_ ..f - .RecelVed fi'vm: , � (Pieage pric►t ptatNy for scanninfl). ; (QaY) . (E�s) NAME - �L��YI� � ' �.1�Q ~ . - � PHONE ��OI�� -- -/ . ADDRESS: ��2� � ,c� /�C[I C�'_��(l�� State .Tap� L4cat3on of problem. Ef d�feren� • • • • • :,;,; �� . . . , Reported Prrvblern: �,��,� � G�L��r, �ll�y :�;_p� ^ ! � r �/ � J�"a.�e��-r� ' � � ' •� `�.- i_ /�,,� .'��'c"�'/ / ✓ I � • �J`f��C��""—�/�F�t<�C.�"� �f'. Q� L�tyz(�I � �J�� 9��.G�� C,�v� �� 2��f , � .�� ' �� - � � �� , �.� ; . . � ./�.�.��;�� . w . � � . . . _ . � • �U�'`JT:f't- . . - . ' . . . ' ' ' . , t Yd .��%�.f�,.�,,0 � ' : - Piat•r+air+e: - �tG� L F,Q CI�S l _ , f_ot No: � f f BIoCk No: Other agencles lrnoived: . � � No Field Irnrestfgatfon Needed � � ��r ��r 3. 6 ��Y9 ,t �{ �� .�� r i �� 3 - � Parcel Na 7-� �37�� G/�b- - - Kroll �� Th.gro� Nev+��.��.i 1/4_ S T R . . � �^ • D�d �/�-'�� .� � —" '- c�J " Bas1n�� CouncA Dfst ��. ChargB No• • ,. � ?ESPONS� Cit¢en notified o —ao-9�Z by• �/ phone leite� In person . -_ �'s(�-�1 ero�.,�.c��( 1'yl„ �,�,,,,,f- (�c.r�o �,jati- . , �r-«� ' - . � �� ` • � � • . - . - �`b�-� �.,�� (�,,�,�;�-- ' . . . /� � �/SpOSJTlON; Tur�ed to V� `On �� "��-by. OR: No fuciher adlon recommended beca� Lead agency has been r►otifed: � � � - � � � _Problem has been<corrected. ,�No probtem has been ider�ti�ied. Prior irivesttgation addrss5es proWe ' ' - ^'See Frte# • Prltirate problem-NDAP�s�11/no�canslder because: • � - - � Water originates onstte and/or on neighboring pa�cel - ' _ � ' �Location�s otrtside SVYM Servlce'Area. • Oti�er(Specify): �� . � DATE C�OSED:,��/� �y' /� ` . �1�.17�� ' � NOV. 3. 200; 8: 32AM KING C0. WLRD N0. 5845 P. 12 � . � _ r�_ _ _._ �_ . �, Cobnplaint 9'7-206;Dan Grcygg, 16046 SE 1�2'd�l.,Renton Znvestigated b�i'Seaa Groom on Ol/14/9? Don Gxegg has lived at the above xeferenced loc�fion since tt�e early 60s(his house was second be�ilt in the deve2opmcut}. Surfaoe storm water f.�ows began flooding his garage 2pproximately five yesxs ago. At his own expense ai that timc b�e brought a back hoe in to cut a drainage dttch along the back side of his property. 'rhis open trench prwides reJief duxing most precigiLatio�f events siuface water moves azound his property. Storm w�ter does breech the top occasioually. The ditch fills sediments up and he clears the ditch of debris that#loats dowa and reduces flow. He walks the ci�ainage ditch during stnrm events(he wasn't around for the last storm event)to obseave its functionality as a preca�on as well. He want�the drauaage ta continus down 160`�Ave S�E inst�.ad or a conveyance system around his and neighbor's property. Appajently,as clevelopmeut north of his property has increased addi�onai re�noff is conceen�ated iziW the ci�a�age along 160`�Ave SE and subsequenfly runs to his ��rtY• Stauding water,nuioff from 160�'Avt SE . d'zscharges inm t�is area. Low percolaiioa. Gngg said the land can't bc deveioped becaUs�ihey dan't bave the�exColation for infiltration af septic sysGems_ . ••-� I 164�Ave ' � � s.�. � �- � y � `�''•x slope •�y � � � ��S �g S-�'i 4�� 6� 16 Y�� 1 �� . : SE 142nd P11Ce f(0'8�.3 � � c�wt�le SC �iC J��AiK�ie, )a � � �r e c� i �� ` `'p0 �t'� � � � - .�r 1�, � . �a �.� _ ��' ow . NOV. �. 2QJ5 8: 32AM _ KING CO'.. '�NLRD sa�unosau�ep,13o�trN0. 58451�LwJ3i� (,� _ .�. ._,__..�,_, . ._.._. `� xEaaxBvaaooD DaAi1�a$ Asszs�cs pRocxAx �r�ar� Co�lpLAII�i'�.' Ep21I,UATIOIQ t�cld0 DATE: 3-19-97 TO: FII,L FROM: Alan Meyera RE= NDAP EVAi.IIATIDNT FOR COMPLAINT N�. 97-0206 GRAGG � 16046 SL 7.42� PLACE RENTON 235,0168 Ca�t�LAINT c�tONOLOGY: ORIGINAL 1-ZO-97 FIELD INV 1-14-97 BY SEAN GROOM FIBLD EVAI,. 3-7-97 BY AI.AN 2�YERs. OLD FILES: NONE BAC1C(�AOUND: P2ease see the attactsed drainage complaint invegtigation xepozt dated 1-14-97 by sean aroom. FIHDIN(;S: 5ince the problem meets all of the ND,AP project criteria liated below, it qua�.ifies for al�d has been investigated under the NDAP program_ - • The, problem eite is within the SwM aervice area and does not involve a King Connty (KC) code violation. • Tha problem site shows evidence of or xeported Iocalized �looding, erosion and/or sedimeatation with£n the off road drainage syatem on private reafdential and/or co�aercial properrp due in part to �ater upgtreactt development. • The probism ie caueed by surface water from more than one adjoining property. , ' 60ILS: �ccording to the Kc soils map, the site ie locat�d in the following BoiZ association: � ALDBRWOOD ASSOCYATION: Moderately well drai.ned undulating to h��ly soflg that have dense, very slowly permeable glacial � till at a depth of 20 to �!0 inches; on uplandg and terraces. I met wf�h�Mr. Gragg on March 7th and toured his property. 1e,s � development continues ia the approximate 60 acre drainage baain north af his propes-ty, more drainage water has baen routed gouth into the pond looated juet NW of Yiis pxoperty which then draina eaet and souti� around the edge of his property. , 1 c�ss.?:��s , , c�wros y . , , . . �, P� *L..1 � ." -.<t ��rrr�rrc � • , — NOV. 3. 2005 8:32AM K I NG C0. WLRD N0. 5845 P. 14 He zequested that the drainaqe flowing south alonq the eaat side of 160th Avenue SE be rexonted strai.ght south along the east side of 160th past &E 142nd Place rather than �he current route whi.ch flowg east and eou�h around hia property. Mr. Gragg s�ated that several 3.ong terns residents have told h,im the drainage used to flow straight eouth along the weat and eaat 9idee of i60th all the way down to sE 1e�4�h. I �tat�d that may be true but the exiating drainage pattern ia old and cannot be revised becauae it is coneidered tha establiehed drainage pattern Eor hig area. I reviewed hfe and his two neighbor�s drai.nage related impacts and ecored the problem at i4 wit.h hie garage and septic system i.mpacts and yard damage to two propertiee. Atthough the laet few years have been especia].Ly wet and bad, I rated the event frequency at 10 or once every 2-5 yEaxs which is my estivaate of the frequency of how oftea his sep�ic system will be aeverely impaCtied over the Zong term. Mr. Gragq 9tated that his pump�d effluent septic system has workati fine for the gir9t 15 years. However, he has burned up four pumps within the laet three yearB due to the increased groundwater flows into hi� septic tank/drainfi.eld . area. From his wet/dry season obaervations, he is couvinced that moet of tt2e grou,ndwater comes from the drainage ditah located just above his drainfiald. � We reviewed ways of protecting his geptic drainfield from the movement of groundwater from the uphill �ond and draxnage ditch. we discnaeed ways to seal the earthen ditch itself uging a plas�ic liner or a largB half round or full pipe eectiona along about 50 feat of ditch above hi:� � drainfield_ I pointed out that coneic3erable groundwat:er may atil], flow from north to south below the ditch section so that eeali.ng tihe ditch may not svine the problem. Depencling on the depth to hardpan, an �rupervioua vertical layer of pla9tic or bentonite slurry located uphill of hi.s drainfieid betwaen his drainEield and the ditch would probably be the eagiest and moat effective eolution to this problem_ This irapervioua layer would run from the ground svrface down to the hardpan layer where i� wouZ�l be keyed down xnto the hardpan layar. BBcauee 9uch a layer would restrict tAe flow of ground water, hi.gher groundwa�er levels might result in �his part of Gragg's yard with more groundwateX surfacing during the 'wet 9eseon eepec�ally near each end of euch an impervious wall reauZting in more wet season surface water eeepage/flows and icy conditions on portiona of Mr. Gragg`a driveway_ Far any work this cloee to the @rai.nfield, any ya�cd drain or iiapervio�a faci�ity of this kind woukd have ta be reviewed and approved by the 1(ing Couaty Hesith Departman� (Wayne Olsen a�t 296-9737). 2 NOV. 3. 2045 8: 32AM KING C0. WLRD N0. 5845 P. 15 OPTIONS AND DI5CQSSION Hr. Gragq is concerned about contiuuing upstream development which typicaliy regulte in more eurface water flQws through hid drainage ditch and occaefonally into his yard_ I explained that for larger . developmenta where mare than 5,�00 aquare feet of impervioua surfaces _ are conatructed, the deveZoper'a enginear is on2y sequired to review the drainage syatem'e capacity�up to one quarter of a mils downstream from the propaaed plat'g outlet poS.nt. For single homeeites, tihere is norYpally no dowuetream analysis required since there is usually less than 5,000 aquare feet of new impervioua surfaces constructed. I suggested that Mr. Gragg laok for Developmeut Signe along 160th north of his hotne. When he eeea new sigaa, he can attend public heariags and write lettera expressinq hie concerns and ontlini�g hie drainage i.mpacts. ?DSPACT SCOR$ = 140 PROPOSSD SOLDTIOI�: No eoluti.ou to this drainage problem was identified. Mr. Gragg reques�ed that wg cleaa out hi� drafnage ditch. We affered to clean out pazt of his di.tch if our contractor can get the neceseary equipment froaQ Gragg's driveway into the ditch_ NO PRIOR�7.`Y SCORE WAS CALCULBTED SIHCE NO SOLDTZON WAS IDENrIFZEp 3 riot.�-\ncC �- ..._-.. .- '�• �� ..-.,...,--�..-�--..r . w � _ ._ h'OV. 3. 20Q5 8:32AM K1NG C0. WLRD N0. 5845 P. 16 I , � � K�TG COYJNTX�VA�ER AND�AND RESaXTRCEa�DI�SXUN . , - • � .; . DRAIAIAGE �'EST�GATZ01� RGPORT . ' �rv�sTro�norr R�Qv�sr , T.�pe�� PRdB RFC1Erv�D;�y�: Date: �K'd bv: Fn.E No. Z D�S ��" I' . • ��eCeived from: , - � � —. � �aY) L�._.� �Ye) �� NAz+�: � d PHor� _ ADDxEsS: . . Cify State Zip LOC.AIZON OF PRD�LEM,IF DIFFERENI'' � � �, � � �� ' ��7" 1'� �%�� Access Perrn�issaon Granted � Call Firsf (Would Li1ce To Se Present) � � , � . � - � ^ t! � . � �%��1�`'P'2' �C?� . . �/1h�� (/ ' � � � � � F��" ��Y . � � _ � ��` �' �? /� � � PIat nanae: � ►\O�� Lot No: Block No: Qther agencies involved: �� C�� No field investi ation r ' ed , ..�,,,,��„7, „ �,�.�.Y � �., � . ,:,.�' '�;:T:ua' - .:i' -1� 1 �. ,�_ b Q0��3 , . a . S -T � R Parcel N ' '7 Kxo�14��. ThB�os:. New 7 RUP Basin'�Cou�cil Dis�ici�_ City - Charge No. .R,B.s'poNSB: Citi�en notified on by, phone letter in person DXST�51170N: Tu�ned to on / / � by OR No further�ctioa recommend�ed b�cause: I-e�d a.gency h�s been noti�ied: Prob�em�a�beeA cor,rected. No problemhas been identified. Prior investigation addresses probtem: � � S]E�FII.E# � `� . Prxvate problem-NDi,Ap will not consider because: � Water or�ginates ansite andlor on neighboring parcei. � , ,^TOther(��Y)� . . . DA� (.'LOSTD: • / / By: . � . _ . 1--�, . . � � NOV, 3. 2005! 8: 32AM KING C0. WLRD . N0. 5845 P. 17 � K�rr�Co�Wa�Arm LaNn R�sovRc-Es DrvisTax , � - . , � 1 . DRAINAGE INVESTIGATIO�T 1�POR'Y' . - ., . INV�STI�ATION REQ�S'F , . �p8 �, PROB A� � .G4 �v� a �c.�� ':�: vc� �'I�1A�� Date: g q °� oK�a� �a.�No. 005 ��3�1 -Re . 'om: � � . (AsY) �� CE�e) �� N�: N�:�a L� ��Z �-�� PxoN� �-�� .3 7s�— AnD�s�: ,�� -�� ubtN��Rl�Ib � Cxty �tate Zip� IACA"F�ON CJF PR0.8I.�M,r�n��"r: �Q2�"i o�U S �'� ,16 Z �dE�� S�, ��-�� o F SE !��S7: Acce�'s Perntission Granted � Cnll�tst (W;ould�.ike To Be Prasen�t� ❑ _ � . � - � � Z � � � . . - � � . . � . : . � . Plat name: Lot No: � Black No: Other a encies iz�vo�v�ed: No�Zeld investi ation ' ed �'`�"� .�`� ,-v-.'�' �„ "'" ^";�;�•� �""�''"'� _�:':'r + •1:. V;�.: "�;'��' q,,.��.:�'..�•. -c =�',.r . ''�--;i;:- ,,,�� 1� �3 S 7 . . %a S T R Parcel No. �y5 7�0 4f'�.S Kmll�� T7�Szos: I�ew fo�7 j3. �DP Basin�� Council Dzs4rict�� City Charge N'o. . . RESPONSE: Citize[�notified on� � by: phozi►e letter in person� D1sPosz'�oN: '�'uxnod to on / I by OR No fiuther acrioz�xecommended because: Lead agency has bee�a notified: � - Problem has bee�corrected. �To problem has been identi�ied. Prior inves4�gation adt�resses problem: ' ' • � S��+'1[1,E#. P�vate problem-I�AP wiil z�ot consider becau$e: . _ Water originates o�site and/or on ueigliboring parcel. . . . . � ' Other(Specify): ' . DAT'�Ci.OSEA' I / By: . � 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Etcisting Site Hydrology The entire 9.91 acres of new development is considered till forest for pre-developed condition. However, there is an existing single-family residence located in the northwest corner of the project site, which will be demolished with this development_ T`here is a small amount of impervious surface associated with this single-family residence that contributes runoff to the downstream drainage course under existing conditions. However, this site is modeled entirely as till forest for the pre-developed condition. The flow control facility will be located at the southwest corner of the project site and ��ill discharge much as it does under existing conditions after being dispersed at the southwest corner of the project site. B. Developed Site Hydrolog� Under developed conditions, to determine the total amount of impervious surface contributing runoff to ihe pond, all of the streets and sidewalks were considered impervious surfaces and an area de[ernuned far all of them. Since this project site is zoned R-4, which requires that the maximum amount of impervious surface per lot be 55 percent, the total acreage of lots was multiplied by 55 percent to deternvne an impervious area for all of the lots. In addition, the wet/detention pond was considered to be impervious surface for the portion of the surface area of the wet/detention pond that is dead storage. This yielded a total impervious area of 6.37 acres with the remainder of the area as till grass (3.54 acres), totaling 9.91 acres of development. No Flow Control BMPs are included in these areas of development so the actual detention volume computed would be less in the final design when the Flow Control B1�4Ps are applied to the project site for each lot. C. Performance Standards The Area-Specific Flow Controi Standard required for this project site is Level 2 Flow Control, a.k.a. the Conservation Flow Control Standard. The applicable conveyance system capacity standard was mentioned in the Conditions and Requirements Summary, which is to size the on-site conveyance system by the Rational method utilizing an initial time of concentration of 6.3 minutes and a Manning's "n" value of 0.014 with the 25-year precipitation. T'he Area-Specific Water Quality Treatments Menu followed for this project was the Basic �'Vater Quality Menu,and the item selected from this rnenu is to use the wet pond located bclow the live s[orage in the �veUdetention pond. D. Flow Control System Please see the iliustrative sketch of the flow control facility located the following pages of the report, as well as the calculations provided for sizing the flow control system for this project. E. Water Quality�System Please refer to the same illustrative sketch referenced above, which is provided on the following pages of this report for the wet pond located below the live storage in the wet/detention pond provided with this development. In addition, the calculations for sizing the wet pond are included herewith. 11778_OO�.da [JYJ1tcp) l � , o � � � � � � � ' � � ,' � ' � � � ' . , � � � � :�� .y-. °"� I�I__�._ - --- --A �� € i � �� ' �� ; "s g�� g� y� '�( �`�" 0°��g � "�� M i �� i i �i� o�, � ,.al . F I � I I ^'�' �� _ ; �UNi)I.•��Il1r:'f�l � i � i .Q� �� I1 �o � C � i / � _ � � I � � / S I. I > � U � � _ „ � N , . �� - �_ �., . r� � -� �, i.� . . i �, � r � ; e � +--^^'--� �� k� , ��.. ,��—.� s7 a - I e � � m � � __.. ' x n �� I �� '. , � o ..,_.—_.... . ; . ,-,,,,,,�,, � 3, ,�, � a9t 8 _ �, ._I al an..'r v�.w �.' +. Su� ��..,W, t A�'��i6rd:�� f +f<�r 7� ��, r ^ � _ _ ., � . .�„ ,�. ,. � ..� r � - ' sl. 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'. . ...\� ..'.'. �� 45.2 � � .�.� .'. .'. .: � 4 B� ... .IN1ER5[47qN.�..Of..Rd1D B.. \ PJI SG �14+04 a . � . � . .. . _ ._ s�.,,.a;oo N F*n u�v-4ss.xo . . . . .. . . . . . ... . '"_'"461_Q_ . .. .. . . . � � �� , j Ho. Da4 By CkO. /.ypr. R�vl�lon I� dab N�me.r �GHq�� os�lqnee wP_ 5caic K.BA� '' 18215 72ND AVENUE SOUTH �,�o`w�SNMF� � Tlib� 11778 mP ` t�`Z KeNr, wn sao3z o,�.� __� „,.,,,�,,, o! �. KBS DEVELOPMENfT CORP. PRELIMINARY ROAD AND PROFILES (425)251-6222 � 5�.,, � 'T"�"' (a25)25i-e�sz Fnx °^•°4•^ �- ''-'°' � �' ` 12320 N.E. STH STREET, STE.100 AND DRAINAQE PLAN � U '"- �� a r ^°"""'-�'� °•^"'� � "f�°"Af� � BELLEVUE, WA 98005 V'� e� CNIL ENGINEERING, UND PUNNINC, F �Sii � FOR '' FP SURVEIINQ ENVIRONAIENTAL SERVICES Dal. t2lo7(�5 N/A �S�NA� �,G\ CAVALLA �-r.,eHc.�ae. - 2_ or_ 5_ _x�v+__i a o� ,_ . -�".�:�,e�,� .. �� '9 r�.;�»e�.g l t �.� �� i1...,:��OF .i��v .�oi� .:�n »:,��r�.�� e,e,. zir�?A-,.ri��g ur.� ;�H a�.do� n,:i;»3-r. � DETEN'I'ION POND SIZING CRITERIA No Flow Conuol B?�1Ys �vere applied f��r this initial sizing: ho��ever, they �vill be titilized with the final design. Zoning = R4 The maximum allowed impervious coverage per lot = �5 percent Roadway and Sidewalk = 1.63 ac. impervious 828 acres of lots x 0.�5 = �4.�5 acres impervious Pond = 0.19 ac. impervious Total impervious = 6.37 ac. til[ grass = 3.54 ac. ]1778.00S.doc�JPJ/tepl SIZE THE BASIC WET POND V� _ [0.9 A; +025 A�g] 0.039 V� _ [(Q9)(6.37)+(0.25)(3.54)] (0.039)(43,560} V� = 11,243 cu. ft. Vb = 3 V� = 33,729 cu. ft. � I 1778.00�.doc�3PJltep) � �� 7� � �v�� f � ��. KCRTS Command CREATE a new Time Series �p rG �^�� GY`�' '�� ------------------------ Production of Runoff Time Series // Z_ �� Project Location : Sea-Tac Computing Series : 11778pre.tsf Regional Scale Factor : 1.06 Data Type : Reduced Creating Hourly Time Series File Loading Time Series File:C: \KC_SWDM\KC_DATA\STTF60R.rnf . Till Forest 9.91 acres ---------- Total Area : 9.91 acres Peak Discharge: 0.799 CFS at 9:00 on Jan 9 in Year 8 Storing Time Series File:11778pre.tsf . Time Series Computed KCRTS Command Enter the Analysis TdOLS Module Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:12778pre.tsf . Flow Frequency Analysis ----------------------------------------------- Time Seri2s File:11778pre.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:11778pre_pks . il Analysis Tools Command ------------------- � RETURN to Previous Menu ---------------------- KCRTS Command CREATE a new Time Series -------------------- Production of Runoff Time Series Project Location : Sea-Tac Computing Series : 11778dev.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating Hourly Time Series File Loading Time Series File:C: \KC_SWDM\KC_DATA\STTG60R.rnf _ Till Grass 3 .54 acres Loading Time Series File:C.\KC_SWDM\KC_DATA\STEI60R.rnf . Impervious 6.37 acres -------------- Total Area : 9.91 acres Pea:c Discharge: 3 .?5 CFS at 6:00 on Jan 9 in Year 8 Flow Frequency Analysis Time Series File:11778pre.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 .625 2 2/09/O1 18:00 0.799 1 100. 00 0.990 0.170 7 1/06/02 3 :00 0. 625 2 25. 00 0.960 0_463 4 2/28/03 3 :00 0.480 3 1Q.00 0.900 0.017 8 3/24/04 20:00 0.463 4 5.00 0.800 0.275 6 1/05/05 8:00 0.404 5 3 .00 0.667 0.480 3 1/18/06 21:00 0.2�5 6 2 .00 0.50� 0.404 5 11i24/06 4:00 0.170 7 1 .30 0.231 Q.799 1 1/09/08 9:00 0.017 8 1 .10 0.091 CoMputed Peaks 0.741 50. 00 0.98Q Flow Frequency A_nalysis Time Series File:11778dev.tsf Project Location:Sea-Tac --Annual Peak Flow Rates-- ----Flow Frequ2ncy i�nalysis----- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS} (CFS} Period 1.86 6 2/09/Ol 2:00 3.76 1 100.00 0.990 1. 52 8 1/05/02 16:00 2.40 2 25.00 0.960 2.24 3 2/27�'03 7:00 2 .24 3 10.40 0.900 1. 65 7 8/26/04 2:00 1.99 4 5.00 0.800 1.99 4 1d/28/04 16:0� 1 .98 5 3.00 0.667 1.98 5 1/18/06 16:00 1. 86 6 2.00 0.500 2 .40 2 10/26/06 0:00 1. 65 7 1_30 0.231 3 .76 1 1/09/08 6:00 1.52 8 1.10 0.091 Computed Peaks 3 .31 50 .00 0. 980 Flow Frequency Analysis Time Series File:11778rdout.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 0.596 2 2/09/01 20:00 1.24 5.14 1 100.00 0.990 0.130 7 1/07/02 4 :00 0.596 5 .04 2 25.00 0.960 0.346 3 3/06/03 22 :0� 0_346 4 .51 3 10.00 0.900 0.107 8 8/26/04 7 :00 0.326 4.31 4 5 .00 0. 800 0.134 6 1/08/05 4:00 Q.228 3 .56 5 3 .00 0.667 0.228 5 1/19/06 2:00 0.134 3.I8 6 2.00 0.500 0.326 4 11/24/06 9:00 6.130 2.97 7 1.30 0.231 1.24 1 1/09/08 11:00 0.107 2.03 8 1_10 0.091 Computed Peaks 1.02 5.12 50.00 0.980 Retention!Detention Facility Type of Facilityc Detention Pond Side Slope: 2.00 H:1V Pond Bottom Length: 212.00 ft Pond Bottom Width: 106.00 ft Pond Bottom Area: 22472. sq. ft Top Area at 1 ft. FB: 30680. sq. ft 0.704 acres Effective Storage Depth: 5.00 ft Stage 0 Elevation: 432.00 ft Storage Volume: 128927. cu. ft 2.960 ac-ft Riser Head: 5.00 ft Riser Diameter: 18.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.66 0.168 2 3.30 2.50 0.221 6_0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft} (ac-ft) (cfs) icfs) (sq. ft) 0.00 432.00 0. 0.000 0.000 0_00 22472. 0.02 432 .02 450. 0_010 0. 010 0.00 22497. 0.03 432 .03 675. 0.015 0_014 0. 00 22510. 0. 05 432.05 1125. 0. 026 d.017 0.00 22536. 0. 07 432 .07 1576. 0_036 0.020 0. 00 22561. 0.09 432 .09 2028. 0.047 0.022 0. 00 22587. 0. 10 432 .10 2254. 0.052 0.024 0. 00 22599. 0.12 432 .12 2706. 0.062 0. 026 0.00 22625. 0.14 432 .14 3159. 0.073 0. 028 0.00 2265Q. 0.24 432.24 5430. 0.125 0.037 0.00 22778. 0.34 432.34 7714. 0.177 0.044 0. 00 22906. 0.44 432.44 10011. 0.230 0.050 0. 00 23035. 0 .54 432 .54 12321. 0.283 0.055 0. 00 23164. 0.64 432 .64 14644. 0_336 0.060 O.QO 23293. 0.74 432.74 16980. 0.390 0. 065 0.00 23422. 0.84 432 .84 19328. 0.444 0. 069 0. 00 23552. 0.94 432 .94 21690. 0_498 0.073 0. 00 23682. 1 .04 433 .04 24065. 0.552 0.077 0_00 23812. 1 .14 433 .14 26453. 0.607 0. 080 0.00 23943. 1 .24 433 .24 28853. 0.662 0.084 0.00 24074. 1 .34 433 .34 31267. 0.718 0. 087 0.00 24205. 1 .44 433 .44 33694. 0.774 0. 090 0_00 24337. 1 .54 433 .54 36135. 0. 830 O. Q93 0. 00 24469. 1 .64 433 .64 38588_ 0. 886 0.096 �. 00 24601. 1 .74 433.74 41055. 0.942 0.099 0.00 24734. 1.84 433 .84 43535. 0.999 0.102 O.OQ 24867_ 1 .94 433 .94 46028. 1.057 0. 105 0.00 25000. 2 .04 434 .04 48535. 1.114 0.107 O.OQ 25133. 2.14 434 .14 51055. 1.172 0.110 0.00 25267 . 2.24 434 .24 53588. 1.230 0. 113 0.00 25402 . 2.34 434 .34 56135. 1.289 0.115 0.00 25536 . 2_44 434 .44 58696. 1.347 0.117 0.00 25671. 2.54 434 .54 61269. 1.407 0.120 Q.00 25806. 2.64 434 .64 63857. 1.466 0.122 0.00 25942. 2.74 434 .74 66458. 1.526 0.124 0.00 26077. 2.84 434.84 69072. 1.586 0. 127 0.00 26214 . 2 .94 434.94 72701. 1 .646 0. 129 0.00 26350. 3 .04 435.04 74342. 1.707 0. 131 0.00 26487 . 3 .14 435_14 76998. 1 .768 0. 133 0_00 26624 . 3 .24 435.24 79667. 1 .829 0.135 O.OQ 26761. 3.30 435.30 81275. 1.866 0.137 0.00 26844. 3 .33 435.33 82081 . 1.884 0.139 0.00 26885. 3.35 435.35 82619. 1.897 0.144 0.00 26913. 3.38 435.38 83427 . 1.915 0.153 0.00 26954. 3.40 435. 40 83967 . 1.928 0.164 0.00 26982. 3 .43 435.43 84777 . 1.946 �.178 0.00 27023 . 3.46 435_46 85588. 1.965 0.195 0.00 27065. 3_48 435.48 86130. 1_977 0.213 0.00 27092. 3 .51 435.51 86943. 1.996 0.2Z8 0.00 27134. 3 .61 435.61 89663. 2.058 0.237 0.00 27272 . 3.71 435.71 92397. 2.121 0.253 0.00 27411 . 3.81 435.81 95146. 2.184 0.268 0.00 27551 . 3 .91 435.91 97908. 2 .248 0.281 0.00 27690. 4.01 436. 01 100684. 2.311 a.293 0.00 27830 . 4.11 436. 11 103474. 2.375 a.305 0.00 27970. 4.21 436_21 106278. 2.440 0.316 0. 00 28111 . 4.31 436. 31 109096. 2.504 0_326 0.00 28252. ' 4.41 436.41 111928. 2.570 0.336 0. 00 28393 . �i 4.51 436. 51 114774. 2. 635 0.346 0_00 28534 . 4.61 436_61 117635. 2.701 0.355 0.00 28676. 4.71 436_71 120509. 2.767 0.364 0_00 28818. 4.81 436.81 123398. 2.833 0.373 0.00 28960. 4.91 436. 91 126302. 2 .899 0.382 0.00 29103 . 5.00 437. 00 128927. 2.960 0. 389 6.00 29232 . 5.10 437 .10 131857. 3.027 0.859 0.00 29375. 5_20 437 .20 134802. 3.095 I.710 0.00 29519 . 5.30 437 .30 137761. 3.163 2.810 0_OQ 29663 . 5.40 437.40 140734. 3.231 4.120 0.00 29807 . 5.50 437 .50 143722. 3_299 5. 590 0_QO 29952 . 5.60 437.60 146725. 3.368 7. 030 O.OQ 30097. 5.70 437.70 149742. 3.438 7. 560 0.00 30242. 5.80 437 .80 152773. 3 .507 8. 060 0.00 30388. 5.90 437 .90 155819. 3 .577 8.53a 0.00 30534 . 6.00 438.00 158880. 3.647 8.97� 0.00 30680. 6. 10 438.10 161955. 3 .718 9.39Q 0.00 30827 . 6.20 438.20 165045. 3.789 9.800 0.00 30973. 6.30 438.30 168150. 3 .860 10.180 0.00 31121. 6.40 438.4d 171269. 3.932 10.560 0.00 31268. 6. 50 438.56 174404. 4 .004 10.920 0.00 31416. 6.60 438.60 177553. 4.076 11 .260 0.00 31564 . 6_70 438.76 180717. 4.149 11 .600 0.00 31713. 6.80 438. 80 183895. 4.222 11 .930 0.00 31861. 6.90 438. 90 187089. 4.295 12.250 0.00 32011. 7 . 00 439.00 190297 . 4.369 12.560 0. 00 32160. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 3 .76 ******* 1,24 5.14 437.14 133167. 3.057 2 1.86 0.63 0.59 5.04 437.04 130208. 2.989 3 2.24 ******* 0.35 4.52 436.52 114956. 2.639 4 2.40 ******* 0.33 4.31 436 .31 109151. 2.506 5 1_98 ******* 0.23 3.56 435 .56 88360. 2.028 6 1.29 ******* 0.13 3.18 435.18 78158. 1.794 . 1.52 ******* 0.13 2.97 434 .97 72545. 1.665 8 1.65 ******x 0.11 2.03 434 .03 48235. 1.107 ---------------------------------- Route Time Series through Facility Inflow Time Series File:11778dev.tsf Outflow Time Series File:11778rdout Inflow/Outflow Analysis Peak Inflow Discharge: 3.76 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 1.24 CFS at 11:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.14 Ft Peak Reservoir Elev: 437.14 Ft Peak Reservoir Storage: 133167. Cu-Ft . 3 .057 Ac-Ft �low Frequency Analysis Time Series File:11778rdout.tsr 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. 596 2 2/09/O1 20:00 1.24 5.14 1 100.00 0.990 0. 130 7 1/07!02 4:00 0.596 5.04 2 25.00 0.960 0.346 3 3/06/03 22:00 0.346 4 .51 3 lO.OQ 0_9Q0 0.107 8 8/26/04 7:00 0.326 4 .31 4 5.00 0.800 0.134 6 1/08/05 4:00 0.228 3 .56 5 3 .00 0.667 0.228 5 1/19/06 2:00 0.134 3.18 6 2.00 �.500 0.326 4 11/24/06 9:00 0.130 2.97 7 1.30 0.231 1 .24 1 1/09/08 11:00 0.107 2.03 8 1. 10 0.091 Computed Peaks 1 .02 5.12 50.00 0.98Q Flow Duration from Time Series File:11778rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS $ � $ a. 0�8 30132 49.139 49.139 5�.861 0.509E+00 0 . 025 6536 10.659 59.798 4�.202 0.402E+00 0. 042 6230 10_160 69.958 30.Q42 0.300E+p0 0_059 5661 9.232 79.189 20.811 0.208E+�0 0.076 4632 7.554 86.743 13 .257 0.133E+00 0. 092 3438 5.607 92.350 7 .650 0.765E-01 0. 109 1476 3.222 95.572 4 .428 0.443E-01 0. 126 1510 2.462 98.035 1 .965 0.197E-01 0. 143 773 1_261 99.296 0.705 0.705E-02 0. 154 47 0_077 99.372 0.628 0.628E-02 0. 176 28 0.046 99.418 0.582 0.582E-02 0. 193 28 0.046 99.463 0. 537 0.537E-02 0.210 17 0. 028 99.491 0 . 509 0_ 509E-02 0_226 57 0.093 99.584 0.416 0.416E-02 0.243 59 0.096 99.680 0.320 0.320E-02 0.260 34 0.055 99.736 0.264 0.264E-02 0.277 24 0.039 99.775 0.225 0_225E-02 0.293 22 0.036 99.811 0.189 0_189E-02 0.310 19 0.031 99.842 0.158 0.158E-02 0.327 30 0.049 99.89Z 0.109 0.109E-02 0_344 17 0.028 99.918 0.082 0. 815E-03 0.360 15 0.024 99.943 0.057 0.571E-03 0.377 19 0.031 99.974 0.026 0.261E-03 0.394 11 0.018 99.992 0_008 0.815E-04 0.411 1 a.002 99_993 0.007 0.652E-04 0.427 1 0.002 99.995 0.005 0_489E-04 0.444 0 0.000 99.995 0.005 0.489E-04 0.461 0 0.000 99.995 0_005 0_489E-04 0.478 6 �.000 99.995 0.005 0.489E-04 0.494 1 0.002 99.997 0.003 0.326E-04 0.511 0 0.000 99.99i 0.003 0.326E-04 0 .528 0 0.000 99.997 0.�03 0.326E-04 0.545 0 0.000 99.997 0.003 0.326E-04 0 .561 0 0.000 99.997 0.003 0.326E-04 0.578 1 0.602 99.998 0.002 0.163E-04 0 .595 0 0.000 99.998 0.002 0.163E-04 Duration Comparison Anaylsis Base File: 11778pre.tsf New File: 11778rdout. tsf Cutoff Units: Discharge in CFS ----Fraction of Time---- -------Check of Tolerance----- Cutoff Base New �Change Probability Base New �Change 0.138 � 0.94E-02 0.75E-02 -20.0 � 0.94E-02 0.138 0.134 -3.0 0 .176 � 0.62E-02 0.58E-02 -6.5 � 0.62E-02 0.176 0.161 -8.3 0.213 � 0.49E-02 0.50E-02 2 .7 � 0.49E-02 0.213 0.214 0.4 0 .251 � 0.37E-02 0.3QE-02 -19.9 � 0.37E-02 0.251 0.233 -7. 0 0.288 � 0.28E-02 0.20E-02 -28.2 � 0.28E-02 0.288 0.255 -11.4 0 .325 � 0.22E-02 0.12E-02 -46.7 � 0_22E-02 0.325 0.279 -14.1 0 .363 � 0.15E-02 0.55E-03 -62.2 � 0.15E-02 0.363 0.314 -13.5 0.400 � O.10E-02 0.65E-04 -93 .5 � 0.10E-02 0.400 0.332 -17.1 0.438 � 0.62E-03 0.49E-04 -92 .1 ( Q.62E-03 0.438 0.355 -19.0 0.475 � 0.34E-03 0.49E-04 -85.7 � 0.34E-03 0.475 0.373 -21 .6 0.513 � 0.21E-03 0.33E-04 -84.6 C 0.21E-03 0.513 0.379 -26.1 0.550 � 0.16E-03 0.33E-04 -80.0 � 0_16E-03 0.550 0.382 -30.6 0.588 � 0.98E-04 0.16E-a4 -83 .3 � 0.98E-04 a.588 0.387 -34 .1 Maximum positive excursion = 0.005 cfs ( 2 .3$) occurring at Q.208 cfs on the Base Data:11778pre.tsf and at 0.223 cfs on the New Data:11778rdout.tsf Maximum negative excursion = 0.200 cfs (-34 .1�) occurring at 0.587 cfs on the Base Data:11778pre.tsf and at 0.386 cfs on the New Data:11778rdout.tsf Flow Duration from Time Series File:11778pre_tsf Cutoff Count Frequency CDF Exceedence_Probability CFS $ $ � 0.138 60737 99.049 99.049 0.951 0_951E-02 0.155 116 0.189 99.238 0.762 0.762E-02 0.172 74 0.121 99.359 0.641 0_641E-02 0.189 39 0.064 99.423 0.577 0_577E-02 0.206 38 0.062 99_485 0.515 0.515E-02 0.223 39 0.064 99.548 0.452 0.452E-02 0.241 34 0.055 99.604 0_396 0.396E-02 0.258 31 0.051 99.654 0.346 0.346E-02 0.275 20 0.033 99.687 0.313 0.313E-02 0.292 21 0.034 99.721 Q.279 0.279E-02 0.309 18 0.029 99.750 0.250 0.250E-02 0.327 19 0.031 99.781 0.219 0.219E-02 0.344 25 0.041 99.822 0.178 0.178E-02 0.361 17 0.028 99.850 0.150 0.150E-02 0.378 13 0.021 99.871 0.129 0.129E-02 0.395 14 0.023 99.894 0.106 0.106E-02 0.413 14 0.023 99.917 0.083 0.832E-03 0.430 9 0.015 99.932 0.068 0.685E-03 0.447 10 0.016 99.948 0.052 0.522E-03 0.464 8 0.013 99.961 0.039 0.391E-03 0.481 6 0.010 99.971 0.029 0.294E-03 0 .499 2 0.003 99.974 0.026 0.261E-03 0 .516 3 0.005 99.979 0_021 0.212E-03 0 .533 2 0.003 99.982 0. 018 0.179E-03 0 .550 1 0.002 99.984 0.�16 0.163E-03 0.567 1 0.002 99.985 0_015 0.147E-03 � 0.585 2 0.003 99.989 0. 011 0.114E-03 0.602 3 0.005 99_993 0. 007 0.652E-04 0.619 3 0.005 99_998 0. 002 0.163E-04 0. 636 1 O.Oa2 100.000 O.OQO O.O00E+00 �.653 6 0.000 100.00� 0.000 0_O00E+00 0 .671 0 0.000 100_000 0.000 O.00OE+Op 0.688 0 0.000 100_000 0_000 O.O00E+00 0.705 0 0.000 100.000 0.000 O. O00E+00 0.722 0 0.000 100.000 0_000 O.O00E+00 � 0 .739 0 0.000 100_000 0.000 O.O00E+00 � Flow Duration from Time Series File:11778rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS g � � 0.008 30132 49.139 49.139 50.861 0.509E+00 0.025 6536 10.659 59.798 40.202 0.402E+00 0.042 6230 10.160 69.958 30.042 0.300E+00 0.059 5661 9.232 79_189 20.811 0.208E+00 0.076 4632 7 .554 86.743 13 .257 0.133E+00 0. 092 3438 5.607 92.350 7 .650 0.765E-OI 0. 109 1976 3.222 95.572 4.428 0.443E-01 0.126 1510 2.462 98.035 1.965 0.197E-01 0.143 773 1.261 99.296 0.705 0.705E-02 0.159 47 0.077 99.372 0.628 0.628E-02 0.176 28 0.046 99.418 0.582 0.582E-02 0 .193 28 0.046 99.463 0.537 0.537E-02 0.210 17 0.028 99.491 0.509 0_509E-02 0.226 57 0.093 99.584 0.416 0.416E-02 0.243 59 0.096 99.680 0.320 0.320E-02 0.260 34 0.055 99.736 0.264 0.264E-02 0.277 24 0.039 99.775 0.225 6.225E-02 0.293 22 0.036 99.811 0.189 0.189E-02 Q.310 19 0.031 99.842 0.158 0.158E-02 0.327 30 0.049 99.891 0.109 0.109E-02 a.344 17 0.028 99.918 0.082 0.815E-03 0.360 15 0.024 99.943 0.057 0.571E-03 0.377 19 0.031 99.974 0.026 0.261E-03 0.394 11 0.018 99.992 0_008 0.815E-04 0.411 1 0.002 99.993 0.007 0.652E-04 0.427 1 0.002 99.995 0.005 0.489E-04 0.444 0 0.000 99.995 0.005 0.489E-04 0.461 0 0.000 99.995 O.Q05 0.489E-04 0.478 0 0.000 99.995 0.005 0.489E-04 0.494 1 0.002 99.997 0.003 0.326E-04 0.511 0 0.000 99.997 0.003 0.326E-G4 0.528 0 0.000 99.997 0.003 0.326E-04 0.545 0 0.000 99.997 0.003 0.326E-04 0.561 0 0.000 99.997 0.003 0.326E-04 0.578 1 0.002 99.998 0.002 0.163E-04 0 .595 0 0. 000 99 .998 0. 002 0. 163E-04 � Duration Comparison Anaylsis Base File: 11778pre.tsf New File: 11778rdout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New �Change Probability Base New �Change a.138 � 0.94E-02 0.75E-02 -20_0 � 0.94E-02 0.138 0.134 -3_0 0.176 � 0.62E-02 0.58E-02 -6.5 � 0.62E-02 0.176 0_161 -8.3 0.213 � 0.49E-02 0.50E-02 2 .7 � 0.49E-02 0.213 0.214 0_4 0.251 � 0.37E-02 0.30E-02 -19.9 � 0.37E-02 0.251 0.233 -7.0 0_288 ( 0.28E-02 0.20E-02 -28.2 � 0.28E-02 0.288 0.255 -11_4 �.325 � 0.22E-02 0_12E-02 -46.7 � 0.22E-02 0.325 0.279 -14.1 0.363 ( O.ZSE-02 0.55E-03 -62 .2 � 0.15E-02 0.363 0.314 -13 .5 0.400 � 0.10E-02 6.65E-04 -93.5 � O.10E-02 0.400 0.332 -17.1 0.438 � 0.62E-03 0.49E-04 -92.1 � 0.62E-03 0.438 0.355 -19.0 � 0.475 � 0.34E-03 0.49E-04 -85.7 � 0.34E-03 0.475 0.373 -21.6 0.513 � 0.21E-03 0.33E-04 -84.6 � 0_21E-03 0.513 0.379 -26.1 0.550 � 0.16E-03 0.33E-04 -80.� � 0.16E-03 0.550 0.382 -30.6 0.588 � �.98E-04 0.16E-04 -83.3 � 0.98E-04 0.588 0.387 -34 .1 ' biaximum positive excursion = 0.005 cfs ( 2.3�) occurring at 0_208 cfs on the Base Data:11778pre. tsf and at 0.213 cfs on the New Data:11778rdout.tsf Maximum negative excursion = 0.200 cfs (-34. 1%) occurring at 0.587 cfs on the Base Data:11778p=�. tsf and at 0. ?86 cfs on the I.e•.ti� �ata:li?78rdout .tsf