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HomeMy WebLinkAbout03642 - Technical Information Report J 0(17 . SN D. R. STRONG � n ( D ENGINEERS \ r�X CONSULTING ENGINE S I It) •leas• Engineers se.■ 1 less ' Surveyors i a►i ViLandscape Architects • Full Service Engineering Since 1981 1 3eepd TECHNICAL INFORMATION REPORT (TI R) for ALTMYER 11022 and 11023 SE 184th Place Renton, Washington ER • JO Alratt Y ,71 45232 0 /' r � AL� �t �/ DRS Project No. 12011 Renton File No. Owner/Applicant Harbour Homes LLC 1441 North 34th Street, Suite 200 Seattle, Washington 98103 14 Report Prepared by 611.(O v Q \D S, aEc MPS 2 22' 17- D. R. STRONG Consulting Engineers, Inc. D`v`c�\ON 10604 N.E. 38th Place, Suite 101 130\15130\15)\—GV1� �l�1G Kirkland WA 98033 (425) 827-3063 Report Issue Date March 29, 2012 Report Revision Date May 23, 2012 2012 a R.STRONG Consulting Engineers Inc. TECHNICAL INFORMATION REPORT ALTMYER TABLE OF CONTENTS SECTION I 1 Project Overview 1 Predeveloped Site Conditions 1 Developed Site Conditions 1 Natural Drainage System Functions 1 SECTION Il 9 Conditions and Requirements Summary 9 Hearing Examiner's Preliminary Plat Conditions of Approval: 10 SECTION III 14 Off-Site Analysis 14 SECTION IV 15 Flow Control and Water Quality Facility Analysis and Design 15 Existing Site Hydrology (Part A) 15 Pre-developed Hourly Time Step Modeling Input: 16 Pre-developed Hourly Time Step Modeling Output: 16 Developed Site Hydrology (Part B) 18 Developed Site Area Hydrology 18 Developed Hourly Time Step Modeling Input: 19 Developed Hourly Time Step Modeling Output. 19 Performance Standards (Part C) 21 Flow Control System (Part D) 21 Flow Control BMP Selection 21 Flow Control Facility Design Output 23 Flow Frequency Analysis 28 Duration Analysis 28 Water Quality Treatment System (Part E) 29 SECTION V 31 Conveyance System Analysis and Design 31 Developed 15-Minute Time Step Modeling Input 33 Developed 15-Minute Time Step Modeling output 33 Backwater Analysis 34 Backwater Table 34 Backwater Analysis Map 37 BackWater Computer Program for Pipes 38 ©2012 D.R.STRONG Consulting Engineers Inc. Page i of ii Technical Information Report Altmyer March 29,2012 SECTION VI 42 Special Reports and Studies 42 SECTION VII 43 Other Permits, Variances and Adjustments 43 SECTION VIII 44 ESC Plan Analysis and Design (Part A) 44 SWPPS Plan Design (Part B) 47 SECTION IX 48 Bond Quantities, Facility Summaries, and Declaration of Covenant 48 Stormwater Facility Summary Sheet 49 SECTION X 51 Operations and Maintenance Manual 51 APPENDICES 52 List of Figures Figure 1 TIR Worksheet 2 Figure 2 Vicinity Map 5 Figure 3 Drainage Basins, Subbasins, and Site Characteristics 6 Figure 4 Soils 7 Figure 5 Predevelopment Area Map 17 Figure 6 Post Development Area Map 20 Figure 7 Detention & Water Quality Facility Details 30 Appendices Appendix A Bond Quantity Worksheet 53 Appendix B CSWPPP 54 Appendix C Offsite Analysis by J3ME with Existing Pond Backwater Analysis 55 ©2012 D.R.STRONG Consulting Engineers Inc. Page ii of ii Technical Information Report Altmyer March 29,2012 SECTION I PROJECT OVERVIEW The subject site ("Site") is located at 11022, and 11023 SE 184th Place in Renton, Washington. The applicant has gained approval to subdivide two existing parcels (Parcel Numbers 3223059302 and 3223059294) into 21 lots for single-family detached residences ("Project"). The City of Renton ("City") annexed the Site in 2008. The property while located within the City is entitled to processing under the King County zoning and platting regulations. The Project is vested to the 2005 King County Surface Water Design Manual ("KCSWDM") and the 2007 King County Road and Construction Design Standards ("KCRCDS"). PREDEVELOPED SITE CONDITIONS Total Site area is approximately 3.12 acres with a total Project area of approximately 3.18 acres. The Parcels are currently developed with two single-family residences. The Site is mostly residential lawn and landscaping. The Site generally slopes from southwest to northeast at an average grade of 1%. The Site is surrounded by single family residences and an existing detention pond located on the north side of SE 184th Place. The predeveloped Site is contained within one Threshold Discharge Area (TDA) and has one Natural Discharge Area (NDA). Runoff sheet flows to the existing drainage system within SE 184th Place and enters into the detention pond or combines with the discharge from the detention pond. The outfall system was analyzed by J3ME Engineers at the preliminary plat phase of this Project; that analysis can be found in Section III of this report. DEVELOPED SITE CONDITIONS The Project will create 21 lots with lot sizes ranging from approximately 3,063 to 6,238 s.f. The Project area is approximately 3.18 acres (includes minimal frontage improvements on 112th Avenue SE). Post-developed impervious areas including rights-of-way, private access tracts, roofs, driveways and site frontage total approximately 98,276 s.f. The remainder of the Site will be modeled as till grass and totals approximately 40,199 s.f. Runoff will be collected and conveyed to the detention facility located in Tract "B" and discharged through the existing conveyance system near the northwest corner of the Site. The facility will provide Level 3 Flow Control and Basic Water Quality. NATURAL DRAINAGE SYSTEM FUNCTIONS A review of the SCS soils map for the area (see Figure 4, Soils) indicates Alderwood gravelly sandy loam with 0 to 6 percent slopes (AgB). Per the Manual, this soil type is classified as "Till" material. The SCS Soil series descriptions follow Figure 4. In evaluating the upstream area, we reviewed the existing offsite analysis and King County IMAP aerial topography and imagery and conducted field reconnaissance and have concluded that upstream tributary area for the Site is negligible. 2012 D. R.STRONG Consulting Engineers Inc. Page 1 of 55 Technical Information Report Altmyer March 29,2012 FIGURE 1 TIR WORKSHEET King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER DESCRIPTION Project Owner: Project Name: Harbour Homes LLC Altmyer Address/Phone: Location: 1441 North 34th Street, Suite 200 Township: 23 North Seattle, WA 98103 Range: 05 East (206) 315-8130 Section: 32 Project Engineer: Maher A. Joudi, P.E. D. R. STRONG Consulting Engineers Inc. Address/Phone: 10604 NE 38th Place, Suite 101 Kirkland WA 98033 (425) 827-3063 Part 3 TYPE OF PERMIT Part 4 OTHER REVIEWS AND PERMITS APPLICATION N Subdivision I I DFW HPA Shoreline Short Subdivision Management Clearing and Grading COE 404 Rockery n Commercial DOE Dam Safety Structural Vault Other: FEMA Floodplain Other: COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community: Soos Creek Area Drainage Basin Black River CD 2012 D. R.STRONG Consulting Engineers Inc. Page 2 of 55 Technical Information Report Altmyer March 29,2012 Part 6 SITE CHARACTERISTICS River: Floodplain n Wetlands Stream: Seeps/Springs 1 I Critical Stream Reach ❑ High Groundwater Table Depressions/Swales Groundwater Recharge Lake: H Other: Steep Slopes Part 7 SOILS Soil Type: Slopes: Erosion Potential: Erosive Velocities: Alderwood 0-6% Slight Slow (AgB) Fl Additional Sheets Attached: SCS Map and Soil Description, Figure 4 Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ® Level 1 Downstream Analysis None ® Geotechnical Engineering Study n Environmentally Sensitive Areas 1 I Level 2 Off-Site Stormwater Analysis 7 Level I Traffic Impact Analysis f Structural Report Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION ❑ Sedimentation Facilities ❑ Stabilize Exposed Surface ® Stabilized Construction ❑ Remove and Restore Temporary ESC Entrance Facilities ® Perimeter Runoff Control ❑ Clean and Remove All Silt and Debris ® Clearing and Grading ® Ensure Operation of Permanent Facilities Restrictions Flag Limits of SAO and open space preservation ® Cover Practices areas ® Construction Sequence Other n Other ©2012 D. R.STRONG Consulting Engineers Inc. Page 3 of 55 Technical Information Report Altmyer March 29,2012 Part 10 SURFACE WATER SYSTEM n Grass Lined Tank I I Infiltration Method of Analysis: Channel ® Vault I J Depression KCRTS ® Pipe System Energy Dissipater I I Flow Dispersal Compensation/Mitigatio n Open Channel Wetland Waiver n of Eliminated Site I I Dry Pond Stream I I Regional Storage J Wet Pond Detention N/A Brief Description of System Operation: Runoff from impervious surfaces will be collected and conveyed to the detention facility. From there it will be discharged to the existing piped conveyance system located at the Site's northwest corner. Facility Related Site Limitations: Reference Facility Limitation Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS ® Cast in Place Vault ® Drainage Easement Retaining Wall Access Easement Rockery > 4' High Native Growth Protection Easement n Structural on Steep Slope NI Tracts n Other: I I Other: Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision have visited the site. Actual site conditions as observe,, were incorporated into this worksheet and the attachments. To the best of my k owledge the information provided here is accurate. 14 . /I/74 1 n Signe /Date 2012 D. R. STRONG Consulting Engineers Inc. Page 4 of 55 Technical Information Report Altmyer March 29,2012 FIGURE 2 VICINITY MAP-7, 11171.11C T I* • 1\k, 1 A1 'r 1444-1 k!, i ._ri. - _ .., , ,-, . SC WM Ft :.___ iiiiP '1! - 54 ' I 22:FEL ' SE117133117' . II 4 .... '-''*1....V ....._ _. i ti �~�= ^ .). Tatkt / / L ` ( ' 114111 G1 ': t � ' mm�wm[ ._: -4| ' �m�� iii \ � ' et - ^ ` usteIST cz | oc*�u/� / � / | -Tl '__ = _ ' � w,*mumn m ` \ � ��_ L Kent � n ��� A os*m°mv ,u/��� w = ` w�w"~pc~^� _� �` 01 1925S The information included on this map has been compiled by King County staff from a variety of sources and is subject to change without notice. King County makes no representations or warranties,express or implied,as to accuracy,completeness,timeliness, or rights to the use of such information. King County shall not be liable for any gennny|, apooia|, indimcx, inoidenta|, or consequential damages including, but not limited to,lost revenues or lost profits resulting from the use or misuse of the information contained on this map.Any sale of this map or information on this map is prohibited except by written permission of King County. ©2012 D.R.STRONG Consulting Engineers Inc. Page 5 of 55 FIGURE 3 DRAINAGE BASINS, SUBBASINS, AND SITE CHARACTERISTICS ©2012 D.R.STRONG Consulting Engineers Inc. Page 6 of 55 Technical Information Report Altmyer March 29,2012 I , \ � / , � � ' . D p � '�I I FO�D LE-.D h 7.�'J( � I .. FOUti7 t;,l':3�t CA GICH&S=8! \ I � IN SiEEL Cl�E I ' ' %4-43:OI � y p,,�y4 Tf E 1 0.3Y N'J2TN.^if�cC� . ( C SEC LKE&I�-:y � 1�N 477�� G'Tc . D.R.STRONG � ( S.i'lir5 fFEE"0 i� � IGV=42d2? J!$(iE' 7) — { � n�$ 4 f.�E it7.i2 � � / . � �i2'CWF�:C-ay557 6 F�'C E a�59i � � � - i � ___"" .'_ ' .. _�, . ,, ' . � `, �! .*_ ` i �' �36a.Ykt�F�2429� � _'__1h^__ I � _,-"" � _. � r.._' SO �Sil SO __-""_ _ . . , . . ; ; i �. .'� - " wyy _ � . I � �� __--"'_ . 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FIGURE 4 SOILS Sn;Mzp--}ting Coui:j Area,VJash;rg!m Ilk a .at 1 iv SITE 4 - a # +,sr amµ` y_ �' c. fi 4111L 4.• "' A fiat' ,..„..., iT 2611' _:'EO '...0;6] SEG'.0: :EG:20 561+5_: 55CC' 55:3:0 '07300, .. `✓.Me -to kW:',ae.11.0:0/Fmx_or•sr.tS-a 11,si1. R Moen 3 j` m a7 A7 00 Irl J G '0 Ip] Feer?p] app lhD-1 Nabrai Resources Web Sod Survey milk Conservation SeMce National Cooperative Sod Survey Pages o53 AgB—Alderwood gravelly sandy loam, 0 to 6 percent slopes Map Unit Setting Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 180 to 220 days Map Unit Composition Alderwood and similar soils: 75 percent Minor components: 25 percent Description of Alderwood Setting Landform: Moraines, till plains Parent material: Basal till with some volcanic ash Properties and qualities ©2012 D. R.STRONG Consulting Engineers Inc. Page 7 of 55 Technical Information Report Altmyer March 29,2012 Slope: 0 to 6 percent Depth to restrictive feature: 24 to 40 inches to dense material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table:About 18 to 37 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Very low (about 2.5 inches) Interpretive groups Land capability (nonirrigated): 4s Typical profile 0 to 12 inches: Gravelly sandy loam 12 to 27 inches: Very gravelly sandy loam 27 to 60 inches: Very gravelly sandy loam Minor Components Buckley Percent of map unit: 10 percent Landform: Depressions Norma Percent of map unit: 4 percent Landform: Depressions Bellingham Percent of map unit: 4 percent Landform: Depressions Tukwila Percent of map unit: 4 percent Landform: Depressions Shalcar Percent of map unit: 3 percent Landform: Depressions ©2012 D. R.STRONG Consulting Engineers Inc. Page 8 of 55 Technical Information Report Altmyer March 29,2012 SECTION II CONDITIONS AND REQUIREMENTS SUMMARY The Project must comply with the following Core and Special Requirements: • C.R. #1 — Discharge at the Natural Location: Runoff from the Site will discharge at the natural location which is an existing piped storm conveyance system located at the northwest corner of the Site. • C.R. #2 — Offsite Analysis: A Level Three Downstream Analysis was conducted by J3ME Engineers as part of the preliminary plat phase of this Project. A copy of the analysis is included in Section III. • C.R. #3 — Flow Control: The Project is required to provide Level 3 Flow Control to mitigate for historic flooding problems. The proposed flow control facility is a combined detention/wet vault located in Tract "C". The Level 3 Flow Control standard requires the Project to match developed discharge durations to predeveloped durations for the range of predeveloped discharge rates from 50% of the two-year peak flow up to the full 50-year peak flow, and also match developed peak discharge rates to predeveloped peak discharge rates for the 2, 10, and 100- year return periods, assuming historic conditions as the predeveloped condition. (KCSWDM, Sec. 1.2) Furthermore, the Project must meet the Flow Control BMP requirements as specified in Section 1.2.3.3 of the Manual. The Project will utilize the reduced impervious surface credit to meet this requirement. • C.R. #4 — Conveyance System: New pipe systems and ditches/channels are required to be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions for any offsite tributary areas. Pipe system structures and ditches/channels may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a "severe flooding problem" or "severe erosion problem" as defined in C.R. #2. Any overflow occurring onsite for runoff events up to and including the 100- year event must discharge at the natural location for the project site. In residential subdivisions, such overflow must be contained within an onsite drainage easement, tract, covenant or public right-of-way. The proposed conveyance system was analyzed using the KCBW program, and is capable of conveying the 100-year peak storm without overtopping any structures or channels (see Section V). • C.R. #5 — Erosion and Sediment Control: The Project provides the nine minimum ESC measures. A CSWPPP is included in Appendix B. • C.R. #6 — Maintenance and Operations: Maintenance of the proposed storm drainage facilities will be the responsibility of the City. An Operation and Maintenance Manual is included in Section X. • C.R. #7 — Financial Guarantees: Prior to commencing construction, the Applicant must post a drainage facilities restoration and site stabilization financial guarantee. ©2012 D. R.STRONG Consulting Engineers Inc. Page 9 of 55 Technical Information Report Altmyer March 29,2012 For any constructed or modified drainage facilities to be maintained and operated by the City, the Applicant must: 1) Post a drainage defect and maintenance financial guarantee for a period of two years, and 2) Maintain the drainage facilities during the two-year period following posting of the drainage defect and maintenance financial guarantee. • C.R. #8 - The Project is located in the Basic Water Quality Treatment area. A combined detention/wet vault is proposed to meet this requirement. • S.R. #1 — Other Adopted Area-Specific Requirements: Not applicable for this Project. • S.R. #2 — Floodplain/Floodway Delineation: Not applicable for this Project. • S.R. #3 — Flood Protection Facilities: Not applicable for this Project. • S.R. #4 — Source Control: Not applicable for this Project. HEARING EXAMINER'S PRELIMINARY PLAT CONDITIONS OF APPROVAL: The City Council should approve the 21-lot plat subject to the following conditions: 1. Compliance with all platting provisions of Title 19 of the King County Code. 2. All persons having an ownership interest in the subject property shall sign on the face of the final plat a dedication which includes the language set forth in King County Council Motion No. 5952. 3. The plat shall comply with the King County base density (and minimum density) requirements of the R-8 zone classification. All lots shall meet the minimum dimensional requirements of the R-8 zone classification and shall be generally as shown on the face of the approved preliminary plat, except that minor revisions to the plat, which do not result in substantial changes may be approved at the discretion of the City of Renton Community & Economic Development Department. 4. Any/all plat boundary discrepancy shall be resolved to the satisfaction of the City of Renton Community & Economic Development Department prior to the submittal of the final plat documents. As used in this condition, "discrepancy" is a boundary hiatus, an overlapping boundary or a physical appurtenance, which indicates an encroachment, lines of possession or a conflict of title. 5. All construction and upgrading of public and private roads shall be done in accordance with the King County Road Design & Construction Standards (2007KCRD&CS) established and adopted by King County Ordinance No. 15753. 6. The applicant must obtain the approval of the City of Renton Fire Marshall for the adequacy of the fire hydrant, water main, and fire flow standards of Chapter 17.08 of the King County Code. 7. Final plat approval shall require full compliance with drainage provisions set forth in King County Code 9.04. Compliance may result in reducing the number and/or location of lots as shown on the preliminary approved plat. The following conditions represent portions of the Code. Requirements shall apply to all plats. The following conditions specifically address drainage issues for this plat: 2012 D. R.STRONG Consulting Engineers Inc. Page 10 of 55 Technical Information Report Altmyer March 29, 2012 a. The drainage facilities shall meet the requirements of the 2005 King County Surface Water Design Manual (KCSWDM). The drainage design shall meet at a minimum the Level 3 Flow Control and Basic Water Quality in the KCSWDM, unless otherwise approved by the reviewing agency. b. The existing County detention pond on Lot 1 [Short Plat 4740409 (Parcel 3223059313)] shall be retrofitted with an overflow riser in the control manhole as shown on the Preliminary Road and Storm Drainage Plan received April 30, 2008. This design can be modified, as approved by the engineering plan reviewing jurisdiction. c. To implement the required Best Management Practices (BMPs) for treatment of storm water, the final engineering plans and Technical Information Report (TIR) shall clearly demonstrate compliance with all applicable design standards. The requirements for best management practices are outlined in Chapter 5 of the 2005 KCSWDM. The design engineer shall address the applicable requirements on the final engineering plans and provide all necessary documents for implementation. The final recorded plat shall include all required covenants, easements, notes, and other details to implement the required BMPs for site development. d. Current standard plan notes and ESC notes, as established by the King County Department of Development and Environmental Services (DDES) Engineering Review, shall be shown on the engineering plans. e. The following note shall be shown on the final recorded plat: "All building downspouts, footing drains, and drains from all impervious surfaces such as patios and driveways shall be connected to the permanent storm drain outlet as shown on the approved construction drawings # on file with DDES and/or the King County Department of Transportation. This plan shall be submitted with the application of any building permit. All connections of the drains must be constructed and approved prior to the final building inspection approval. For those lots that are designated for individual lot infiltration systems, the systems shall be constructed at the time of the building permit and shall comply with plans on file." 8. The following road improvements are required for this subdivision to be constructed according to the 2007 King County Road Standards: a. The internal access road SE 184th Place shall be improved at a minimum to the urban sub-access street standard with a permanent cul-de-sac at the west end. b. Sufficient right-of-way (ROW) shall be dedicated for the SE 184th Place improvement with the final plat. Note that this includes ROW acquisition from King County/City of Renton for the needed ROW adjoining Lot 1 of SP 474040, known as an existing County detention pond. A 25-foot R/W radius is proposed at 112th Avenue SE. c. Any proposed joint use driveways or private access tracts shall be improved per Section 3.01 and 2.09 of the KCRDCS. These tracts shall be owned and maintained by the lot owners served. 2012 D. R. STRONG Consulting Engineers Inc. Page 11 of 55 Technical Information Report Altmyer March 29,2012 d. Modifications to the above road conditions may be considered according to the variance provisions in Section 1.12 of the KCRS. 9. All utilities within proposed rights-of-way must be included within a franchise approved by the City of Renton prior to final plat recording. 9. The applicant or subsequent owner shall comply with King County Code 14.75, Mitigation Payment System (MPS), by paying the required MPS fee and administration fee as determined by the applicable fee ordinance. The applicant has the option to either: (1) pay the MPS fee at final plat recording, or (2) pay the MPS fee at the time of building permit issuance. If the first option is chosen, the fee paid shall be the fee in effect at the time of plat application and a note shall be placed on the face of the plat that reads, "All fees required by King County Code 14.75, Mitigation Payment System (MPS), have been paid." If the second option is chosen, the fee paid shall be the amount in effect as of the date of building permit application. 10.0ff-site access to the subdivision shall be over a full-width, dedicated and improved road, which has been accepted by King County for maintenance. If the proposed access road has not been accepted by King County at the time of recording, then said road shall be fully bonded by the applicant of this subdivision. 11.The planter islands (if any) within the cul-de-sacs shall be maintained by the abutting lot owners or homeowners association. This shall be stated on the face of the final plat. 12.A suitable recreation space shall be provided within the combined drainage/ recreation tract. The recreation space may be placed above the vault. The recreation area must be accessible and consistent with the requirements of KCC 21A.14.180 and KCC 21A.14.190 (i.e., sport court[s], children's play equipment, picnic table[s], benches, etc.) and landscaping of KCC 21A.16. a. A detailed recreation space plan (i.e., landscape specs consistent with 21A.14 and KCC 21A.16) shall be submitted for review and approval by the City of Renton Community & Economic Development Department and City of Renton Parks Department concurrent with the submittal of the engineering plans. This plan shall include location, area calculations, dimensions, finished grades, access to underground vault (access grate) and general improvements, i.e., landscaping, fencing, and trail. b. The vault maintenance shall not interfere with the recreation area improvements. c. If the engineering requirements for the construction of the drainage facility prevent provision of a suitable recreation tract, a separate recreation tract shall be provided. A revision to the plat may be required. d. All landscaping shall be maintained in good condition and be irrigated. The landscape plan shall include the method of irrigation. e. A performance bond for recreation space improvements shall be posted prior to recording of the plat. 13.A homeowners' association or other workable organization shall be established, to the satisfaction of the City of Renton Community & Economic Development 2012 D. R.STRONG Consulting Engineers Inc. Page 12 of 55 Technical Information Report Altmyer March 29,2012 Department, which provides for the ownership and continued maintenance of the recreation tract. 14.Street trees shall be provided as follows: a. Trees shall be planted at a rate of one tree for every 40 feet of frontage along SE 184th Place. Spacing may be modified to accommodate sight distance requirements for driveways and intersections. b. Trees shall be located within the street right-of-way and planted in accordance with Drawing No. 5-009 of the 2007 King County Road Standards, unless the City of Renton Department of Public Works determines that trees should not be located in the street right-of-way. c. If the City of Renton determines that the required street trees should not be located within the right-of-way, they shall be located no more than 20 feet from the street right of-way line. d. The trees shall be owned and maintained by the abutting lot owners or the homeowners association or other workable organization unless the City of Renton has adopted a maintenance program. This shall be noted on the face of the final recorded plat. e. The species of trees shall be approved by the City of Renton Community & Economic Development Department if located within the right-of-way, and shall not include poplar, cottonwood, soft maples, gum, any fruit-bearing trees, or any other tree or shrub whose roots are likely to obstruct sanitary or storm sewers, or that is not compatible with overhead utility lines. f. The applicant shall submit a street tree plan and bond quantity sheet for review and approval by the City of Renton Community & Economic Development prior to engineering plan approval. g. The street trees must be installed and inspected, or a performance bond posted prior to recording of the plat. If a performance bond is posted, the street trees must be installed and inspected within one year of recording of the plat. At the time of inspection, if the trees are found to be installed per the approved plan, a maintenance bond must be submitted or the performance bond replaced with a maintenance bond, and held for one year. After one year, the maintenance bond may be released after the Community & Economic Development Department has completed a second inspection and determined that the trees have been kept healthy and thriving. h. A landscape inspection fee shall also be submitted prior to plat recording. 15.The proposed plat shall comply with the requirements of KCC 16.82 including the significant tree retention as required by 16.82.156. A significant tree retention/replacement plan shall be submitted with the engineering plans. ©2012 D. R.STRONG Consulting Engineers Inc. Page 13 of 55 Technical Information Report Altmyer March 29,2012 SECTION III OFF-SITE ANALYSIS An offsite analysis was conducted by J3ME Engineers as part of the preliminary plat phase of this Project. A copy of the analysis has been included for your review in Appendix C. O 2012 D. R.STRONG Consulting Engineers Inc. Page 14 of 55 Technical Information Report Altmyer March 29,2012 SECTION IV FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY (PART A) KCRTS was used to model the peak runoff from the Site. Per Table 3.2.2.b of the Manual the soil type is modeled as "Till" for the Alderwood gravelly sandy loam SCS classification as shown in Figure 4. Soils. The entire Site is modeled as "Forest." Results of the KCRTS analysis are included in this section. Area Breakdown Predeveloped Till Forest 138475.00 3.179 (Historic Conditions) Impervious 0.00 0.000 ©2012 D. R.STRONG Consulting Engineers Inc. Page 15 of 55 Technical Information Report Altmyer March 29,2012 PRE-DEVELOPED HOURLY TIME STEP MODELING INPUT: 4)" Land Use Summary ` o I i Area ------ Till ---___-__Till Forest! 3.18 acres _1 Till Pasture 0.00 acres Till Grass 0.00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres -Total---- 3.18 acres Scale Factor : 1.00 Hourly Reduced Time Series: PREDEV »l Compute Time Series Modify User Input File for computed Time Series [.TSF[ PRE-DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.201 2 2/09/01 18:00 0.256 1 100.00 0. 990 0.054 7 1/06/02 3: 00 0.201 2 25.00 0. 960 0.149 4 2/28/03 3:00 0. 154 3 10.00 0. 900 0.005 8 3/24/04 20:00 0. 149 4 5. 00 0.800 0.088 6 1/05/05 8:00 0. 130 5 3. 00 0. 667 0.154 3 1/18/06 21:00 0.088 6 2.00 0.500 0. 130 5 11/24/06 4:00 0.054 7 1.30 0.231 0.256 1 1/09/08 9:00 0.005 8 1. 10 0.091 Computed Peaks 0.238 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 16 of 55 Technical Information Report Altmyer March 29,2012 FIGURE 5 PREDEVELOPMENT AREA MAP 2012 D. R.STRONG Consulting Engineers Inc. Page 17 of 55 Technical Information Report Altmyer March 29,2012 � � � � 5.,�R r.��.���; ---�–-- � � � � � ��::� . i _ �m, - .�— — �s ., r�89'32'70'E^a67.57' ,,�E �DS RR�TRONG - --=-- saz�z� � � � - �,�.s �-1 ` '' ----------------------------------� , o.� �. . ':"^\ __ �s a.v+xEns aeeuEmzs I �`3'?�I�T I�'.SS' a�.'"_'1'"_a�_—_-SP SO SD •: �� i�TI iL SL SU ,SD SD ' _ 1M0/lES�1R.d01 q�QA�Q WAitl11V __ . �. � r7' c, � • � '. ,� __-""' ' Ol3��OR7PIZS��III � � i�' � - �� P,pC1[RY / ------_-________________ - . _ "'___' ' r / __-__-__-___ � . - I .:�NNkG -, -- 73.1' -'_ ey'__ - , "___" I � N.uL � \ `I ' u ' �LdaOorVmn � �� � � ' '__' -' �Y t � i. .V S8"7. P�g� �� ��+ �r _ -+i? � 7 .� �-r'� �� � "� I � [ �arnw r� 4' ' �� - � ' LOT 1 Q rn�usc � _--------- -;� � G. 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L� `�� ^ �' � `. . � . . . . 1.��� o Y IiK 7705110Si2 �� ��qbS �.�"1 ���" __ N ' � ` . il _ _'"_"'"_'__" �yx ���`--_'_'_'_"_"'___"_'_'_"__"____.�' I , 's�. ` ii r.�tl� '� ^ f � s k7� ''r i -- ` s- y '.'� i � ^ x : � �� ,__ � � z , 3 �` ; '�.,TD_A• ;,, . �,,. ;;� �� � = ' `-��-------------:--------------i, \��;'' T/LL FORES T 138 4�'.� S.F.-r,'�{ �r � �`�`�^ � � ' �- "� �'�'� � � ' ,, --�, ��, � ;:';I: ;y� ' ."��/ ' x kc+dg�,�—' _ .� i —� - x z �_"�r+h rr�e y � I I ''� �� u 3. 179 AC. ��' , �o — 9�„u- ,�.,,� - — � .�i� ��'9'38'tt"�V �763.':2' �3' � �°,� ``f ss ss ss SS � »--__ �/ i' ���' / ��. unoo r� _ `` - - __ � nerse',i'� c.sos' ` ` S'---- - ' �\ _ / // —// J/ _________��__ ___ �____ � ���1-P.i1�1 �T� )���'���/ ����/ _� � __ _.TBfl 10� K :TAiM` W : � i_� ��.s��Y-r� ��`�� a � u `\ . . • � i � � : ` � ` . ' " ' - � . . • •� � "_' "' ' '""' __ """'G '_ "_'"_�"""'_'_'_ """_ ' . ^ ' _ ,�'^ z� ,n.r ,�.—.a�����o� _:-_� "Y�^ ���----. �.�,- —� �-- - ,��yt ?ar,�� , 1 ^J ��� \ ' � -----Hr---- �,. � ,�r '' 4..'� ..�tl-fi , V4Ds'k^: � ' f ' ^ � ��'- I f,''� O ' I I %� �^i Y� i�� (�, :" i i/ens�r.�; =� (; n � ' —S.Y `� . 'E�(ISfiPK � � �� � �`�� / I �BUICRu, ^ E\ `�)`� i 'I ,\/ , �f'� '!I B� IXINC �` V {i5.�IEEL?OS� � KEYST.7iE WAtI _ — �C ':L Q � I ��;-;��`-' 1 l E ' � ;` �' `aV`1��/�� ✓` �� � ����' �:� i' ;1 1`\^- ~ O � `,y��' ' v�y � m � '�_ �� � � ' � 2 ��. a�-� � LOT 1 I � a-� W W � „ . , . . . . . . , �. _ . . .____ , _ � , _ ,� �' ' � PARCEL B,' H«,sE •� ' � ----- --- - E�� ��,� ;�; � '�� � � Q ,.� � � """- = L4NGSCAPE /�?I q2�319Q�7 ��µWWK fffLE 1 �Lr;iiEtiFq,NG � ' '� , • . ' ' ��=: � _ I rh'2':;.�_L'. ' � . � � . ., �" ..= , ` , . / ,- - '•- , -'� .%,'� ; I ' _ 1 I. � 1 � . i . I. - � , , , , � �- i �, ------- � LOT 2 � 0 � I 11AfiE9F�5 � �`,� - '- � SP E91:152 ' � �,�y '� AFN 85C308033] JfiOX �II' � � I _\ �rC� � � ` '� � ' --_. -"• I P�� � Q W � u�,e� LOT 2 O� Q ''YF�D I /� 1>S�' ` � I SP 580011 �� � V I _) __ '_""' �r � Kli 9':<AiI90E? I .t�� � � rrs:�reu � _ I �i r��� so � � Y --.s:-------� -- � i�'�' l; `� � � ��, �����`1-r� � '-�•:_ -'- �`� �� - � . � • _ � --`• "------- , -- . � , ... - I ' �I u..�:f�cia-'_ � - �-___________ . S59'44'12'1'r ?�?7.43 � • , ; .� � � jl i I I I I I I � aj I � � � � � � I I � `� "',,"EL�,�" N GFZAPHIC SCALE 0L�3L0 60 120 IW i GRAFTED B15 YLP 1 INCH =60 FT. o£S��N£D 6Y. YLP PROJECT£NG/Nf£R:MAJ DA7E 05.13.12 PRO,.'FC7 NO.:71011 R:A2u12\0���12C'1�3��Cra�:�irgs\Base�P,EPCR- FGURES���-1=�IG5.d:vg 5�23;2C12 12:�2:54 =,; PD- FrGURE: 5 COFYRIG=;-�2G12, DR. ST1�'.G C5•,'_.LL It,G ='JG'.=E?5 iVC. DEVELOPED SITE HYDROLOGY (PART B) DEVELOPED SITE AREA HYDROLOGY KCRTS was used to model the developed peak runoff from the Site. The soil types are unchanged from the pre-developed conditions. The portions of the Site within the proposed clearing limits tributary to the proposed detention vault were modeled as "Till Grass" and Impervious as appropriate. Results of the KCRTS analysis are included in this section. Area Breakdown Developed Lot Area 96471.00 2.215 65% Impervious 62706.15 1.440 35% Pervious 33764.85 0.775 ROW and Access Tracts Area 33752.00 0.775 100% Impervious 33752.00 0.775 Tract B Area 8252.00 0.189 Impervious,Access Road 1817.50 0.042 Pervious, Remainder 6434.50 0.148 Totals Impervious 98275.65 2.256 Pervious 40199.35 0.923 (Till Grass) 2012 D. R.STRONG Consulting Engineers Inc. Page 18 of 55 Technical Information Report Altmyer March 29,2012 DEVELOPED HOURLY TIME STEP MODELING INPUT: 40 Land Use Summary c= Area -------- J Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.92 acres Outwash Forest 0.00 acres Outwash Pasture' 0.00 acres Outwash Grass! 0.00 acres Wetland 0.00 acres Impervious 2.26 acres Total 3.18 acres Scale Factor : 1.00 Hourly Reduced Time Series: DEV >>I Compute Time Series I Modify User Input I File for computed Time Series [.TSFj DEVELOPED HOURLY TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ----Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0. 629 6 2/09/01 2:00 1.26 1 100.00 0.990 0.524 8 1/05/02 16:00 0.843 2 25.00 0. 960 0.755 3 2/27/03 7:00 0.755 3 10.00 0. 900 0.580 7 8/26/04 2:00 0. 695 4 5.00 0.800 0.695 4 10/28/04 16:00 0. 669 5 3.00 0.667 0.669 5 1/18/06 16:00 0. 629 6 2.00 0.500 0.843 2 10/26/06 0:00 0.580 7 1.30 0.231 1.26 1 1/09/08 6:00 0.524 8 1. 10 0.091 Computed Peaks 1. 12 50.00 0. 980 ©2012 D. R.STRONG Consulting Engineers Inc. Page 19 of 55 Technical Information Report Altmyer March 29,2012 FIGURE 6 POST DEVELOPMENT AREA MAP ©2012 D. R.STRONG Consulting Engineers Inc. Page 20 of 55 Technical Information Report Altmyer March 29,2012 � I , � i � � � . FWNC 1/7'RE�}.R CpP I (ilRr'D LEAO 4' A 75 15639 O.iC'I NGR7H I P!i:cEL C. \ (//--' �l�'N6RTN CF�,..� \ J OF SEC.J:`lE& I / LIWz�FEB 2 %) \�— ———— �DS`RTS�O�EERS I 5.4'YIESi(FE3]Ai) " ' � � 1__ , I I --- — . . .. �� --,s___�_ _ - ------ -i s� � . �.�, ,, ,�„��,�.�o,��� �_ -sn st \ _ ---- . o�so���, --- ' I __ --"�---'"� �-------- I I I � ;�� ��/�,' �,� �� ,o• -- i , ., � ; � �. I I ____ 'af-� .i� 1 + � ;I ' ~ . ------------------------ � `''�., � �' �I . l �-�"�Q � � �� ;�I II � � ��: � �.�� , �� , ` . � / ��/j �� � I+ �I ��_� ' I � ,� � I ' i i :� - �% � „ ► , , . . . �. .: __ : : , �.,,, �� , _ � �- : - �- __ ------- - �:,� - - --_--_�- � � , �,� `•�, 'i.,, � .\ ----- � ; -- ---- . ';i''`,-_____________________________________ I' , „ . . � � ------- . , • , • - , . r ------- ---------- i I � ' - - - - - - r---� _ `�- -----_ �� � i. i �`, �� � �" 1 i�/ :s s� s, ss=---- _M _ _ — �� a,;`:j�._ --=: „ _ _ _ . , I •, _, __ _ — �� T.tJ . .,_-) —.,nr . . - —_ y ` ____' _ y�� I ._'_______ � -. ..�i —T .\ _ � _ _,Z,�� '� .� �� --`�c�— S �, '��`ff.�� �� : 1� _ _ _ f ________ _ I 0. ' C\�\ I q�� � �' ` �� S=3�ii � ' � .\ `'` _ � .. � �� � �' + � I .��----«----- \,� //—— — — ---�, �� � ��� —' � � r I ���^ ` �, � � � ` � u � '�-- W �� , \ — — / !i , Z7_���`J� i � � ,J� `� � � ; ��. � �� "�°- ��� Q Z � — f II q �1P7� ,� �C 0 ,�� �'� i I � ii i ' +_-. � I� h _ _ � � �.. � , ; : - WzQ � ; ;.,,� - � i�; � � ;� \' � � � `�s � I �� � j ' � ° z _�I� � __ �--� = i � � ��;''' Q W Q ��. _ ,� ,, --__ , �: o Z I � __-------__ ,�'. 1} Y ' � � �,Y —r z�, . , , , � ��,. �� . L Yt -�---------'-- -'-- _l ///����--- ~ , +, ' r�Y. ' L , . . , . x 1 i i , _.. — . �. ., ...._.__ -- __ ,. — ., . , - -�-----_----''----- ` � � � � { TDA �38t 4 75 S.F. �� , I ; � IMP�,R 1/10US 98 2�75.65 S.F. � I TIL�GRASS �0, 199.35 S.F. I ( I I I � I I I I I I I I � � '_.�N ,�s��C� N GRAPHIC SCALE 0 30 60 120 DR?.FT£D BY.� ttP 1 INCH — 60 FT. o�s.�cNED BY. ttP F.ROJECT ENGlNE£R:MAJ 00.7£: 05.2d 12 FROJc'CT,VQ:1?011 R:�2012��0�12D'1�3�Crawings�3cse\R=FO4T �I„1RE5\'_-IRFIGo.dv:g 5/_3,/2�12 "2'.�:_`2 ?�d PDT FiG;RE: 6 COPYP,I�N-0 20i2. D.R. c7RONG CDv�UL�1N� �NG'JE�RS INC. PERFORMANCE STANDARDS (PART C) The Project is required to meet the Level 3 Flow Control and Basic Water Quality Treatment requirements. The Level 3 performance requires the developed condition discharge rates to match the predeveloped rates ranging from 50% of the two-year peak up to the 50-year peak. Also match developed peak discharge rates to predeveloped peak discharge rates for the 2-, 10- and 100-year return periods. The Basic Water Quality Treatment goal is to remove 80% of TSS for flows or volumes up to and including the WQ design flow or volume. Conveyance criteria for the Project require that all new pipes be designed to convey and contain (at minimum) the 25-year peak flow. The conveyance system as designed will convey the 100-year peak storm with overtopping of the two most upstream structures; the overtopping is slight and will be contained within the right of way. FLOW CONTROL SYSTEM (PART D) The Site will utilize a detention vault meeting the Level 3 Flow Control Criteria. The King County Runoff Time Series (KCRTS) software was used to size the detention facility. The detention vault design information is included in this section. FLOW CONTROL BMP SELECTION Subdivision projects are required to mitigate for impervious surface equal to a minimum of 10% of each lot area by use of Flow Control Best Management Practices (BMP's). Projects are required to first analyze the feasibility of dispersal and infiltration before choosing another method. The Site's location and surrounding urban environment, together with the size of the proposed lots are not conducive to stormwater dispersal. Per the geotechnical evaluation by Associated Earth Sciences, Inc. dated April 18, 2008, the Site soils contain "lenses and interbeds of higher permeability, granular , outwash type soils within them". The lack of consistency of these outwash soils indicates that the Site is not highly suitable for infiltration. Therefore, the Reduced Impervious Surface Credit BMP as described in Appendix C, Section C.2.9 of the KCSWDM will be utilized for the Project. The maximum impervious surface allowed per zoning code for the total lot area (2.214 acres) is 1.661 acres using the maximum allowable build-out rate of 75%. Lots 1-21 inclusive shall be restricted to a maximum impervious coverage equal to 65% of each lot area (1.439 acres). A restricted footprint covenant shall be recorded on the face of the final plat map. This satisfies the flow control BMP requirements in Section 1 .2.3.3 and 5.2 of the KCSWDM. 2012 D. R.STRONG Consulting Engineers Inc. Page 21 of 55 Technical Information Report Altmyer March 29,2012 MAXIMUM ALLOWABLE RESTRICTED LOT NO. LOT AREA IMPERVIOUS AREA PER CODE IMPERVIOUS FOOTPRINT 1 4609 3457 2996 2 4705 3529 3058 3* 5693 4270 3431 4* 6207 4655 3379 5 4307 3230 2800 6 4130 3098 2685 7 5218 3914 3392 8 4998 3749 3249 9 4250 3188 2763 10 4235 3176 2753 11 4282 3212 2783 12 5265 3949 3422 13 3696 2772 2402 14 3890 2918 2529 15 5020 3765 3263 16* 6238 4679 3376 17 5252 3939 3414 18 4882 3662 3173 19 3293 2470 2140 20 3063 2297 1991 21 3175 2381 2064 *PER SECTION 5.2.1.1 OF THE KCSWDM 2005, RESTRICTED FOOTPRINT IS ESTABLISHED BY RESTRICTING THE FOOTPRINT TO 4,000 SF LESS AN AREA EQUAL TO 10% OF THE LOT AREA. ©2012 D.R.STRONG Consulting Engineers Inc. Page 22 of 55 Technical Information Report Altmyer March 29,2012 FLOW CONTROL FACILITY DESIGN OUTPUT Type of Facility: Detention Vault Facility Length: 73. 83 ft Facility Width: 73.83 ft Facility Area: 5451. sq. ft Effective Storage Depth: 8.50 ft Stage 0 Elevation: 419.40 ft Storage Volume: 46333. cu. ft Riser Head: 8.50 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.83 0.055 2 4 .85 1.46 0. 110 4 . 0 3 8.00 2.18 0.091 6.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0. 00 419.40 0. 0.000 0.000 0. 00 0.01 419.41 55. 0.001 0.002 0.00 0. 02 419.42 109. 0.003 0.002 0. 00 0.03 419.43 164. 0.004 0.004 0.00 0. 04 419.44 218. 0.005 0.004 0. 00 0.05 419.45 273. 0.006 0.004 0.00 0. 06 419.46 327. 0.008 0.005 0.00 0.07 419.47 382. 0.009 0.005 0. 00 0.24 419. 64 1308. 0.030 0.009 0.00. 0. 40 419.80 2180. 0.050 0.012 0. 00 0. 57 419.97 3107. 0.071 0.014 0.00 0.74 420. 14 4034. 0.093 0.016 0. 00 0. 90 420.30 4906. 0.113 0.018 0.00 1. 07 420.47 5833. 0. 134 0.020 0.00 1.24 420.64 6759. 0.155 0.021 0.00 1. 40 420.80 7631. 0. 175 0.022 0.00 1.57 420.97 8558. 0.196 0.024 0.00 1.74 421. 14 9485. 0.218 0.025 0. 00 1. 90 421.30 10357. 0.238 0.026 0.00 2. 07 421.47 11283. 0.259 0.027 0.00 2.24 421. 64 12210. 0.280 0.028 0.00 2. 40 421.80 13082. 0.300 0.029 0.00 2. 57 421. 97 14009. 0.322 0.030 0. 00 2.74 422.14 14936. 0.343 0.031 0.00 2. 90 422.30 15808. 0.363 0.032 0.00 3.07 422.47 16734 . 0.384 0.033 0.00 3.24 422. 64 17661. 0. 405 0.034 0.00 3. 40 422.80 18533. 0.425 0.035 0.00 3.57 422.97 19460. 0.447 0.036 0.00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 23 of 55 Technical Information Report Altmyer March 29,2012 3.74 423. 14 20387. 0. 468 0.036 0.00 3. 90 423.30 21259. 0. 488 0.037 0. 00 4.07 423.47 22185. 0.509 0.038 0.00 4.24 423.64 23112. 0.531 0.039 0.00 4.40 423.80 23984. 0. 551 0.040 0. 00 4.57 423. 97 24911. 0.572 0. 040 0.00 4.74 424.14 25837. 0. 593 0.041 0. 00 4.85 424 .25 26437. 0. 607 0.042 0. 00 4.87 424.27 26546. 0. 609 0.042 0. 00 4. 88 424.28 26601. 0. 611 0.043 0. 00 4. 90 424 .30 26710. 0. 613 0.046 0.00 4. 91 424 .31 26764. 0. 614 0.049 0. 00 4. 93 424 .33 26873. 0. 617 0.053 0.00 4.94 424.34 26928. 0. 618 0.058 0.00 4. 96 424 .36 27037. 0. 621 0.061 0. 00 4. 97 424 .37 27091. 0. 622 0.062 0.00 4. 99 424.39 27200. 0. 624 0.063 0. 00 5.15 424.55 28072. 0. 644 0.075 0.00 5.32 424 .72 28999. 0. 666 0.083 0. 00 5.49 424.89 29926. 0. 687 0.090 0.00 5. 65 425.05 30798. 0.707 0.096 0. 00 5.82 425.22 31724. 0.728 0.102 0. 00 5. 99 425.39 32651. 0.750 0.108 0.00 6. 15 425.55 33523. 0.770 0.113 0. 00 6.32 425.72 34450. 0.791 0.117 0.00 6. 49 425.89 35377. 0. 812 0.122 0. 00 6. 65 426.05 36249. 0.832 0.126 0.00 6. 82 426.22 37175. 0.853 0.130 0.00 6. 99 426.39 38102. 0.875 0.134 0.00 7.15 426.55 38974 . 0.895 0.138 0. 00 7.32 426.72 39901. 0. 916 0.142 0.00 7. 49 426.89 40828. 0. 937 0.145 0. 00 7. 65 427.05 41700. 0.957 0.149 0.00 7.82 427.22 42626. 0. 979 0.152 0.00 7. 99 427.39 43553. 1.000 0.155 0.00 8. 00 427.40 43608. 1.001 0.156 0. 00 8.02 427.42 43717. 1.004 0.157 0. 00 8. 05 427.45 43880. 1.007 0.161 0.00 8.07 427.47 43989. 1.010 0.168 0. 00 8.09 427.49 44098. 1.012 0.177 0.00 8.11 427.51 44207 . 1.015 0.188 0. 00 8. 14 427.54 44371. 1.019 0.201 0.00 8. 16 427.56 44480. 1.021 0.210 0.00 8 . 18 427.58 44589. 1.024 0.214 0. 00 8.35 427.75 45515. 1.045 0.238 0.00 8.50 427.90 46333. 1.064 0.256 0. 00 8. 60 428.00 46878 . 1.076 0.575 0. 00 8.70 428.10 47423. 1.089 1.150 0.00 8.80 428.20 47968. 1.101 1.890 0. 00 8. 90 428.30 48513. 1. 114 2.690 0.00 9.00 428.40 49058. 1. 126 2. 980 0. 00 9. 10 428 .50 49604. 1.139 3.240 0. 00 9.20 428. 60 50149. 1. 151 3.480 0.00 9.30 428.70 50694. 1. 164 3.710 0. 00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 24 of 55 Technical Information Report Altmyer March 29,2012 9. 40 428.80 51239. 1. 176 3.920 0.00 9.50 428. 90 51784. 1. 189 4. 120 0. 00 9. 60 429.00 52329. 1.201 4.310 0.00 9.70 429.10 52874. 1.214 4.500 0.00 9.80 429.20 53419. 1.226 4. 670 0.00 9. 90 429.30 53964. 1.239 4.840 0.00 10.00 429.40 54509. 1.251 5.000 0.00 10. 10 429.50 55054. 1.264 5.160 0.00 10.20 429. 60 55600. 1.276 5.320 0. 00 10.30 429.70 56145. 1.289 5.460 0.00 10.40 429.80 56690. 1.301 5. 610 0.00 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 1.26 0.26 0.25 8.49 427. 89 46270. 1.062 2 0. 63 ******* 0. 19 8. 11 427.51 44219. 1.015 3 0.75 ******* 0. 13 6. 93 426.33 37796. 0.868 4 0.84 ******* 0. 13 6.88 426.28 37489. 0.861 5 0. 67 ******* 0. 09 5.56 424. 96 30315. 0.696 6 0.69 ******* 0.06 4. 94 424.34 26921. 0. 618 7 0.52 ******* 0.04 4.86 424.26 26516. 0.609 8 0.58 ******* 0.03 3.26 422. 66 17758. 0.408 Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 1.26 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.255 CFS at 12:00 on Jan 9 in Year 8 Peak Reservoir Stage: 8.49 Ft Peak Reservoir Elev: 427.89 Ft Peak Reservoir Storage: 46270. Cu-Ft . 1.062 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0.189 2 2/09/01 20:00 0.255 8.49 1 100.00 0.990 0.042 7 1/07/02 4:00 0.189 8.11 2 25.00 0.960 0.133 3 3/06/03 22:00 0. 133 6. 93 3 10. 00 0.900 0.034 8 8/26/04 8:00 0. 131 6.88 4 5.00 0.800 0.057 6 1/08/05 3:00 0.093 5.56 5 3. 00 0.667 0.093 5 1/19/06 0:00 0.057 4. 94 6 2.00 0.500 0.131 4 11/24/06 8:00 0.042 4.86 7 1.30 0.231 0.255 1 1/09/08 12:00 0.034 3.26 8 1. 10 0.091 Computed Peaks 0.233 8.31 50. 00 0.980 Flow Duration from Time Series File:rdout.tsf ©2012 D.R.STRONG Consulting Engineers Inc. Page 25 of 55 Technical Information Report Altmyer March 29,2012 Cutoff Count Frequency CDF Exceedence Probability _ CFS ° 0 % 0 0.003 27857 45.429 45.429 54.571 0.546E+00 0.008 7546 12.306 57.735 42.265 0. 423E+00 0.013 6536 10. 659 68.394 31. 606 0.316E+00 0.019 5775 9.418 77.811 22.189 0.222E+00 0.024 4950 8.072 85.884 14. 116 0. 141E+00 0.029 3980 6.491 92.374 7. 626 0. 763E-01 0.034 1859 3.032 95.406 4.594 0. 459E-01 0.040 1743 2 .842 98.249 1.751 0. 175E-01 0.045 642 1.047 99.296 0.705 0. 705E-02 0.050 21 0.034 99.330 0. 670 0. 670E-02 0.056 18 0.029 99.359 0. 641 0. 641E-02 0.061 16 0.026 99.385 0.615 0. 615E-02 0.066 35 0.057 99.442 0.558 0. 558E-02 0.072 31 0.051 99. 493 0.507 0.507E-02 0.077 38 0.062 99.555 0.445 0. 445E-02 0.082 41 0.067 99. 622 0.378 0.378E-02 0.087 38 0.062 99. 684 0.316 0.316E-02 0.093 28 0.046 99.729 0.271 0.271E-02 0.098 26 0.042 99.772 0.228 0.228E-02 0.103 16 0.026 99.798 0.202 0.202E-02 0. 109 10 0.016 99.814 0.186 0. 186E-02 0.114 17 0.028 99.842 0. 158 0. 158E-02 0. 119 14 0.023 99.865 0.135 0. 135E-02 0.124 15 0.024 99.889 0. 111 0. 111E-02 0. 130 17 0.028 99. 917 0.083 0.832E-03 0. 135 16 0.026 99.943 0.057 0.571E-03 0. 140 8 0.013 99. 956 0.044 0. 440E-03 0. 146 11 0.018 99.974 0.026 0.261E-03 0.151 6 0.010 99. 984 0.016 0.163E-03 0. 156 5 0.008 99.992 0.008 0.815E-04 0. 162 2 0.003 99. 995 0.005 0. 489E-04 0. 167 1 0.002 99. 997 0.003 0.326E-04 0. 172 0 0.000 99. 997 0.003 0.326E-04 0.177 0 0.000 99. 997 0.003 0.326E-04 0. 183 1 0.002 99.998 0.002 0. 163E-04 0.188 0 0.000 99. 998 0.002 0. 163E-04 Duration Comparison Anaylsis Base File: predev.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS Fraction of Time Check of Tolerance Cutoff Base New %Change Probability Base New %Change 0.044 I 0. 95E-02 0.72E-02 -24.4 I 0. 95E-02 0.044 0.041 -6. 1 0.056 I 0. 63E-02 0. 64E-02 1.3 I 0. 63E-02 0.056 0. 059 5. 1 0.068 I 0.50E-02 0.54E-02 9.2 I 0.50E-02 0.068 0.072 6. 9 0.080 0.37E-02 0.41E-02 10.5 0.37E-02 0. 080 0. 083 3. 9 0.092 I 0.29E-02 0.28E-02 -0. 6 0.29E-02 0. 092 0.091 -0.4 0.104 I 0.22E-02 0.20E-02 -11.0 I 0.22E-02 0. 104 0.099 -4 .3 0.116 I 0. 15E-02 0. 15E-02 1.1 I 0. 15E-02 0. 116 0. 116 0. 1 0.128 I 0. 10E-02 0. 91E-03 -9.7 I 0.10E-02 0.128 0.126 -1. 6 0. 140 I 0. 62E-03 0. 44E-03 -28.9 I 0. 62E-03 0. 140 0. 133 -5. 1 ©2012 D. R.STRONG Consulting Engineers Inc. Page 26 of 55 Technical Information Report Altmyer March 29,2012 0. 152 0.34E-03 0.15E-03 -57. 1 1 0.34E-03 0.152 0. 143 -5. 9 0.164 I 0.21E-03 0.49E-04 -76. 9 1 0.21E-03 0. 164 0.149 -9.2 0. 176 I 0. 16E-03 0.33E-04 -80.0 1 0.16E-03 0. 176 0. 151 -14.1 0.188 0. 11E-03 0.16E-04 -85.7 1 0.11E-03 0. 188 0.154 -18.4 0.200 I 0. 16E-04 0.00E+00 -100.0 1 0.16E-04 0.200 0. 189 -5. 6 Maximum positive excursion = 0.005 cfs ( 8.2%) occurring at 0.064 cfs on the Base Data:predev.tsf and at 0.069 cfs on the New Data:rdout.tsf Maximum negative excursion = 0. 035 cfs (-18. 4%) occurring at 0.188 cfs on the Base Data:predev.tsf and at 0. 154 cfs on the New Data:rdout.tsf ©2012 D.R.STRONG Consulting Engineers Inc. Page 27 of 55 Technical Information Report Altmyer March 29,2012 FLOW FREQUENCY ANALYSIS Paused-Flaw Frequency-KCRiS Return Period 2 5 10 20 50 100 -o rdout.pksin Sea-Tac -• PREDEV.pks 4'-r0 DEV.pks • 0 100_ 0 0 0 0 0 R • 000 • . m E4 1 10 =— • `m m — • O .m _ O 00 0 t _ • • 104- _ - • • 10-3 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Cumulative Probability DURATION ANALYSIS 15 Paused-Duration-Analysis-K• _ ...• • 0 37 O rdout dur o TARGET.dur • � o Ooo N LL Of L p� . O m 00 0 5 I 1 I I I I III A I I I I 1 1 1 1 1 3 I I I 1 1 1 1 11 1 I I t 1 1 111 I I f / 1 1 111 10 10 10 10 10-r 100 Probability Exceedence ©2012 D. R.STRONG Consulting Engineers Inc. Page 28 of 55 Technical Information Report Altmyer March 29,2012 WATER QUALITY TREATMENT SYSTEM (PART E) The Project is located in the Basic Water Quality (WQ) Treatment area. The Project will utilize a combined wetvault meeting Basic Water Quality treatment criteria. The design information is as follows: A 21.75-foot by 128-foot by 5.5-foot wetpool will be provided below the live storage in the western bay of the detention vault. This will provide a 6:1 length to width ratio which exceeds Manual requirements. A depth of 5.5 feet will provide 15,312 cu-ft of water quality treatment volume, exceeding the minimum volumetric requirement for basic water quality treatment. Furthermore, per Section 6.4.2.2, when the length to width ratio is greater than 5:1, no baffle is required and the wetvault may be one celled. BASIC WETVAULT ANALYSIS As required per Section 6.2 2005 KCSWDM Step 1: Identify required water quality facility volume factor("f') f= 3 (basic wetpond volume factor) Step 2: Determine rainfall (R)for the mean annual storm per Fig. 6.4.1.A R= 0.47 in. Step 3: Calculate runoff from the mean annual storm (Vr)for the developed site. Vr= (0.9A,+0.25At9+0.10Atf+0.01A0)x R/12 where . . . Vr= volume of runoff from mean annual storm (c.f.) A;= area of impervious surface(s.f.) Atg= area of till soil covered with grass(s.f.) Atf= area of till soil covered with till forest(s.f.) A0= area of outwash soil covered with grass or forest(s.f.) R= rainfall from mean annual storm (in.) A;= 98,276 s.f. Atg= 40,199 s.f. Atf= 0 s.f. A0 0 s.f. R= 0.47 in. V,= 3,858 c.f. Step 4: Calculate water quality volume(Vb). Vb= f x Vr where . . Vb= water quality volume(cf) f= volume factor from Step 1 Vr= runoff volume from Step 3 Vb= 11,574 c.f. (minimum wetpool volume required) ©2012 D.R.STRONG Consulting Engineers Inc. Page 29 of 55 Technical Information Report Altmyer March 29,2012 FIGURE 7 DETENTION & WATER QUALITY FACILITY DETAILS 2012 D. R.STRONG Consulting Engineers Inc. 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NIIH OR/f/Cf AS SPECI�AED BY: Date: ELBOW RESTRfCTOR D£TA/L gY: Date: �y,P 6�a*`�N�GO� N75 �'0 / qN COYYENTS DAIED WY S,2012 � 05.2J.12 YAJ D.R.STRONG � �ns noren �""'"' � CITY CF ALTMYER a03-29-12 c�z wa�onye eera.e ra,o� 9R'�y , � ������ yE� �� -� R E N TO`� DETENTION VAULT DETAILS r 1-800-424-5555 �° � � �""""�� � �°.r, �' � � rawrexav�eim�saaa�ntnaa+mv �� �_� M7LIY Uh7EeaUndergaadLocationCmler ���i� OtzS�5ro9F�Sez7a�27 '� �I��i�inajE��lc'�rg/P�blic N'orY,s Depl. � (ID).liND,OF�WN °/o9AL r�xe�pmn h0. R=VI=IGN EY DA.TE AFPR � ""`�`'' � � ��C10�-10 A-NNNNAA SECTION V CONVEYANCE SYSTEM ANALYSIS AND DESIGN Per C.R. #4 of the KCSWDM, the conveyance system must be analyzed and designed for existing tributary and developed onsite runoff from the proposed project. Pipe systems shall be designed to convey the 100-year design storm. The Rational Method was used to calculate the Q-Ratio for each pipe node. A conveyance system consisting primarily of pipes and catch basins has been designed for the Project. Onsite runoff will be collected by the multiple catch basins. Pipes are typically twelve- and eighteen-inch diameter LCPE material. The pipes will have a minimum slope of 1.00%. The vault primary overflow riser is designed to convey the 100-year peak storm (design storm), based on the KCRTS 15-minute time series for developed, undetained conditions on site. This is calculated at 3.07 cfs. The results of the 15-minute KCRTS time series, overflow riser analysis, and KCBW Calculations are included in this Section. Pond Outfall As part of the preliminary plat of this Project, extensive analysis of the outfall system from the adjacent detention pond (Pond A) was conducted (See Appendix C). It was determined that the 100-year maximum discharge from Pond A would be 9.68 cfs. The analysis of the basin area for Pond A included the Project Site; however, the Project will be constructing a separate detention system for the development at a Level 3 flow control standard using historic site conditions. Therefore, development of the Project will actually reduce this 100-year flow. However, in order to remain conservative, the full 9.68 cfs will be utilized for purposes of this discussion. The proposed reconstruction of the outfall conveyance system out of Pond A will consist of 24-inch LCPE pipes at a minimum slope of 0.60%. Per the backwater analysis by J3ME Engineers, overtopping of the existing 24-inch pipe conveyance system (with minimum slope of 0.53%) occurs at the upstream most pipe run, just downstream of Pond A, at a discharge of 15.63 cfs; well above the anticipated developed flow of 9.68 cfs. The proposal will increase the slope in the 24-inch pipe run, therefore increasing the pipe capacity and will decrease the flow with the installation of the Level 3 facility. Therefore, it is our determination that the proposed outfall system from Pond A (per the backwater analysis by J3ME) combined with the outfall from the proposed detention vault will convey the 100-year storm without overtopping. Furthermore, an overflow riser will be added to the existing control structure in Pond A per Hearing Examiner's Condition 7b. Currently, the existing 24-inch outlet pipe is set at elevation 417.40 and is fitted with a shear gate that is open 3.5 inches. The existing shear gate will be removed and an overflow riser with a shear gate will be installed on the outlet pipe. It will be fitted with a shear gate that will be open 3.5 inches to maintain the existing outflow from Pond A while providing emergency overflow through the top of the riser. See Engineering Plans for details. CD 2012 D. R.STRONG Consulting Engineers Inc. Page 31 of 55 Technical Information Report Altmyer March 29,2012 Vault Outfall Per the backwater analysis, it appears that the headwater elevation in the existing CB near the northwest corner of the Site is anticipated to be 419.06 at 9.68 cfs. The vault outlet elevation is set at 419.40, therefore, no surcharge into the detention vault is anticipated during the 100-year event. ©2012 D.R.STRONG Consulting Engineers Inc. Page 32 of 55 Technical Information Report Altmyer March 29,2012 DEVELOPED 15-MINUTE TIME STEP MODELING INPUT: 45) Land Use Summary F o I J Area ?� Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.92 acres L: 240.00 S: 0.01 Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 2.26 acres L: 360.00 S: 0.01 !-Total---- 3.18 acres Scale Factor : 1.00 15-Min Reduced Edit Flow Paths I Time Series: 15-Minute >>1 Compute Time Series i Modify User Input I File for computed Time Series [.TSF] DEVELOPED 15-MINUTE TIME STEP MODELING OUTPUT: Flow Frequency Analysis Time Series File:15-minute.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 1.07 6 8/27/01 18: 00 3.08 1 100.00 0. 990 0.855 8 1/05/02 15:00 2. 15 2 25.00 0. 960 2. 15 2 12/08/02 17:15 1. 62 3 10.00 0. 900 1. 02 7 8/26/04 1:00 1.20 4 5.00 0.800 1.20 4 11/17/04 5:00 1.15 5 3.00 0. 667 1.15 5 10/27/05 11:00 1.07 6 2.00 0.500 1. 62 3 10/25/06 22 :45 1.02 7 1.30 0.231 3.08 1 1/09/08 6:30 0.855 8 1. 10 0.091 Computed Peaks 2.77 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 33 of 55 Technical Information Report Altmyer March 29,2012 BACKWATER ANALYSIS BACKWATER TABLE Storm Water Runoff Variables: A= Total of Subasin and Tributary Areas C= Runoff Coefficient(the anticipated proportion of rainfall volume that runs off the area)see 2005 KCSWM Table 3.2.1A Cc= Composite Runoff Coefficient Cc= S(Cn*A„)/ATotal Tc= Time of Concentration(Typically 6.3 minutes which is the minimum value used in calculations) R= design return frequency iR= Unit peak rainfall intensity factor IR= (aR)(Tc)^(-bR) aR,bR= coefficients from'98 KCSWM Table 3.2.1.6 used to adjust the equation for the design storm IR= Peak rainfall intensity factor for a storm of return frequency'R' IR= PR*IR PR= total precipitation(inches)for the 24-hour storm event for the given frequency. See Isopluvial Maps in 2005 KCSWM Figures 3.2.1.A-D QR= peak flow(cfs)for a storm of return frequency'R' QR= Cc*iR*A The Q-Ratio describes the ratio of the tributary flow to the main upstream flow. R= -year storm aR= 2.61 bR= 0.63 PR= inches Conveyance System Variables: d= pipe diameter n= Manning's Number 1= length of pipe ©2012 D.R.STRONG Consulting Engineers Inc. Page 34 of 55 Technical Information Report Altmyer March 29,2012 Pipe Structures Sub A A C CC Tc iR IR QR SQR Q- d Mat'I n I Slope invert invert over- Q V Bend CB subasin Ratio in out flow Full Full Dia From To elev. Flow Flow sf Ac Ac Min. cfs cfs in ft % ft ft ft cfs fps CB#6 TO INLET 1 6 6 5 6 3386 0.08 0.90 6.3 0.82 3.19 0.22 0.22 0.00 12 N-12 0.012 23 1.01 425.13 424.9 428.13 3.88 4.94 0 2 5 5 4 5 3122 0.07 0.90 6.3 0.82 3.19 0.21 0.43 0.92 12 N-12 0.012 142 1.00 424.90 423.48 428.12 3.87 4.93 100.56 2 RUN 104-4 4298 0.10 0.90 4 4 3 4 4298 0.10 0.90 4 4 3 4 8596 0.20 0.90 6.3 0.82 3.19 0.57 1.00 1.32 18 N-12 0.012 241 1.00 423.48 421.07 429.91 11.40 6.45 0 4 RUN 103-3 17007 0.39 0.70 RUN 203-3 18819 0.43 0.70 3 3 2 3 9818 0.23 0.68 3 3 2 3 45644 1.05 0.70 6.3 0.82 3.19 2.33 3.32 2.34 18 N-12 0.012 48 1.00 421.07 420.59 431.98 11.39 6.44 0 4 RUN 102-2 19768 0.45 0.69 2 2 1 2 17813 0.41 0.74 2 2 1 2 37581 0.86 0.71 6.3 0.82 3.19 1.97 5.29 0.59 18 N-12 0.012 22 0.98 420.59 420.37 431.71 11.32 6.41 90.25 4 RUN 101-1 26260 0.60 0.68 1 1 VLET 1 5427 0.12 0.90 1 1 VLET 1 31687 0.73 0.72 6.3 0.82 3.19 1.68 6.97 0.32 18 N-12 0.012 13 25.82 420.37 416.9 431.71 57.98 32.81 0 4 CB#101 TO CB#1 101 101 1 101 26260 0.60 0.68 6.3 0.82 3.19 1.32 1.32 0.00 12 N-12 0.012 87 9.92 429.00 420.37 432.89 12.19 15.52 0 2 CB#102 TO CB#2 102 102 2 102 19768 0.45 0.69 6.3 0.82 3.19 1.00 1.00 0.00 12 N-12 0.012 94 9.62 429.64 420.59 432.64 12.01 15.29 0 2 ©2012 D.R.STRONG Consulting Engineers Inc. Page 35 of 55 Technical Information Report Altmyer March 29,2012 Pipe Structures Sub A A C CC Tc iR IR QR SQR Q- d Mat'I n I Slope invert invert over- Q V Bend CB subasin Ratio in out flow Full Full Dia From To elev. Flow Flow sf Ac Ac Min. cfs cfs in ft % ft ft ft cfs fps CB#103 TO CB#3 103 103 3 103 17007 0.39 0.70 6.3 0.82 3.19 0.87 0.87 0.00 12 N-12 0.012 129 4.45 426.80 421.07 431.04 8.16 10.40 0 2 CB#104 TO CB#4 104 104 4 104 4298 0.10 0.90 6.3 0.82 3.19 0.28 0.28 0.00 12 N-12 0.012 22 15.35 426.91 423.48 429.91 15.16 19.31 0 2 CB#203 TO CB#3 203 203 3 203 18819 0.43 0.70 6.3 0.82 3.19 0.97 0.97 0.00 12 N-12 0.012 125 5.43 427.86 421.07 430.86 9.02 11.48 0 2 ©2012 D.R.STRONG Consulting Engineers Inc. Page 36 of 55 Technical Information Report Altmyer March 29,2012 BACKWATER ANALYSIS MAP ©2012 D.R.STRONG Consulting Engineers Inc. Page 37 of 55 Technical Information Report Altmyer March 29,2012 5.� � - ��;F � _ -,_�*' h �F 2 _ . - i. YS,#^ I, ',':�� � . . . . '}^`:�(" � ._.. 'i D � � � � i � � � � � i I � � D.R.STRONG � \ / � I � , � �,�� ��� I / . I . ,mw�xa�e.no,�w�ax� i � o�zsev�F�arn I I' I \ � I � I � �� I � I ' I ' tl I� - -T I � � LOT 101 i I i I 24,862 S. . i � LOT 103 � i 15,007 S.F. I � ----- o� i � I � ROAD 10J ��� p o y . � 1.3 9 8 S F `.Z -{ o o I I �N . I Y� I + i I ' � ROAD 1 i � � � 5,427 SF . 4,298 SF 3,386 SF ~ � i ROAD 3 ROAD 4 RDAD 5 � � � � ROAD 2 , . , � y � � � 5,207 SF . ' f� ---- � , 1 r---- z � i � � W � o I T � '� � � ,,- I � Q Q I � � / ,.�� LOT 3 � I � Q � I LOT i02 i o� o� 9,530 S.F. I � I � � � � 18,031 S.F. i � Q� I I � Q Q J � Q r.� LOT 2 � I O� 12,606 S. . N � I � V i � �" I � Q 2 � i I m C=j i i � � i ti � L �- -� LOT 203 I I � 16,372 S.F. . I � � � I ' � � � � � � � I � N GRAPHIC SCALE 0 30 60 120 i D,4AF7E0 BN. 12P . 1 INCH = 60 FT. oEs,c,vfo ar.� rzP PP,OJfCT£NGWE£R:YAJ � DAT£: 05.2312 �.. PROJECT h'O.:12017 '., � �i2�0 2G'1'3'Drcv.ln '3c=_e P.E�C@- =iGUR=S\B'.ti.dw � �C12 72�1E�3� F�A PGT FIGL�RE: � I -�= \ �' \ \ ' 9�'•, � 9 5/2_/" . . CGFYRIG-i?'�^<C12, �-R. ST;�'-:G C6NSJ-T'•:� _?JGINEE�cS '._ I BACKWATER COMPUTER PROGRAM FOR PIPES BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#6 TO INLET 1.bwp Surcharge condition at intermediate junctions Tailwater Elevation:427.51 feet Discharge Range:0.675 to 6.97 Step of 0.675 [cfs] Overflow Elevation:428.13 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 13 LF - 18"CP @ 25.82% OUTLET: 416.90 INLET: 420.37 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 431.71 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.32 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.68 7.15 427.52 * 0.012 0.31 0.12 10.61 10.61 7.15 7.15 0.22 1.35 7.15 427.52 * 0.012 0.44 0.16 10.61 10.61 7.14 7.15 0.40 2.03 7.17 427.54 * 0.012 0.54 0.20 10.61 10.61 7.14 7.17 0.54 2.70 7.19 427.56 * 0.012 0.63 0.23 10.61 10.61 7.15 7.19 0.67 3.38 7.21 427.58 * 0.012 0.71 0.25 10.61 10.61 7.15 7.21 0.79 4.05 7.24 427.61 * 0.012 0.78 0.27 10.61 10.61 7.16 7.24 0.90 4.73 7.28 427.65 * 0.012 0.84 0.29 10.61 10.61 7.16 7.28 1.00 5.40 7.33 427.70 * 0.012 0.90 0.31 10.61 10.61 7.17 7.33 1.10 6.08 7.37 427.74 * 0.012 0.96 0.33 10.61 10.61 7.18 7.37 1.20 6.75 7.43 427.80 * 0.012 1.01 0.35 10.61 10.61 7.19 7.43 1.30 7.43 7.49 427.86 * 0.012 1.06 0.37 10.61 10.61 7.20 7.49 1.40 PIPE NO. 2: 22 LF - 18"CP @ 0.98% OUTLET: 420.37 INLET: 420.59 INTYP: 5 JUNC NO. 2: OVERFLOW-EL: 431.71 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.59 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.51 6.94 427.53 * 0.012 0.27 0.22 7.15 7.15 6.94 6.94 0.35 1.03 6.94 427.53 * 0.012 0.38 0.31 7.15 7.15 6.93 6.94 0.51 1.54 6.97 427.56 * 0.012 0.47 0.38 7.17 7.17 6.95 6.97 0.64 2.05 7.01 427.60 * 0.012 0.55 0.44 7.19 7.19 6.97 7.01 0.75 2.56 7.06 427.65 * 0.012 0.61 0.49 7.21 7.21 7.00 7.06 0.86 3.08 7.12 427.71 * 0.012 0.67 0.54 7.24 7.24 7.04 7.12 0.96 3.59 7.20 427.79 * 0.012 0.73 0.59 7.28 7.28 7.08 7.20 1.06 4.10 7.28 427.87 * 0.012 0.78 0.63 7.33 7.33 7.13 7.28 1.15 4.61 7.38 427.97 * 0.012 0.83 0.67 7.37 7.37 7.19 7.38 1.25 5.13 7.49 428.08 * 0.012 0.88 0.71 7.43 7.43 7.25 7.49 1.34 5.64 7.61 428.20 * 0.012 0.92 0.75 7.49 7.49 7.32 7.61 1.44 PIPE NO. 3: 48 LF - 18"CP @ 1.00% OUTLET: 420.59 INLET: 421.07 INTYP: 5 JUNC NO. 3: OVERFLOW-EL: 431.98 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 2.34 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.32 6.47 427.54 * 0.012 0.21 0.18 6.94 6.94 6.47 6.47 0.27 0.64 6.47 427.54 * 0.012 0.30 0.25 6.94 6.94 6.46 6.47 0.40 0.97 6.50 427.57 * 0.012 0.37 0.30 6.97 6.97 6.49 6.50 0.49 1.29 6.55 427.62 * 0.012 0.43 0.35 7.01 7.01 6.54 6.55 0.57 1.61 6.61 427.68 * 0.012 0.48 0.39 7.06 7.06 6.59 6.61 0.65 1.93 6.69 427.76 * 0.012 0.53 0.42 7.12 7.12 6.66 6.69 0.72 2.25 6.77 427.84 * 0.012 0.57 0.46 7.20 7.20 6.74 6.77 0.79 2.58 6.88 427.95 * 0.012 0.61 0.49 7.28 7.28 6.83 6.88 0.85 ©2012 D.R.STRONG Consulting Engineers Inc. Page 38 of 55 Technical Information Report Altmyer March 29,2012 2.90 6.99 428.06 * 0.012 0.65 0.52 7.38 7.38 6.93 6.99 0.91 3.22 7.12 428.19 * 0.012 0.69 0.55 7.49 7.49 7.05 7.12 0.97 3.54 7.27 428.34 * 0.012 0.72 0.58 7.61 7.61 7.17 7.27 1.03 PIPE NO. 4: 241 LF - 18"CP @ 1.00% OUTLET: 421.07 INLET: 423.48 INTYP: 5 JUNC NO. 4: OVERFLOW-EL: 429.91 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.32 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.10 4.07 427.55 * 0.012 0.12 0.10 6.47 6.47 4.07 4.07 0.15 0.19 4.06 427.54 * 0.012 0.17 0.14 6.47 6.47 4.06 4.06 0.21 0.29 4.09 427.57 * 0.012 0.20 0.17 6.50 6.50 4.09 4.09 0.26 0.39 4.14 427.62 * 0.012 0.23 0.19 6.55 6.55 4.14 4.14 0.30 0.48 4.21 427.69 * 0.012 0.26 0.22 6.61 6.61 4.21 4.21 0.34 0.58 4.28 427.76 * 0.012 0.29 0.24 6.69 6.69 4.28 4.28 0.37 0.68 4.38 427.86 * 0.012 0.31 0.25 6.77 6.77 4.37 4.38 0.41 0.77 4.48 427.96 * 0.012 0.33 0.27 6.88 6.88 4.48 4.48 0.44 0.87 4.60 428.08 * 0.012 0.35 0.29 6.99 6.99 4.60 4.60 0.46 0.97 4.74 428.22 * 0.012 0.37 0.30 7.12 7.12 4.73 4.74 0.49 1.06 4.88 428.36 * 0.012 0.39 0.31 7.27 7.27 4.88 4.88 0.52 PIPE NO. 5: 141 LF - 12"CP @ 1.00% OUTLET: 423.48 INLET: 424.90 INTYP: 5 JUNC NO. 5: OVERFLOW-EL: 428.12 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.92 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.04 2.66 427.56 * 0.012 0.09 0.08 4.07 4.07 2.66 2.66 0.11 0.08 2.64 427.54 * 0.012 0.12 0.11 4.06 4.06 2.64 2.64 0.15 0.12 2.68 427.58 * 0.012 0.15 0.13 4.09 4.09 2.68 2.68 0.19 0.17 2.73 427.63 * 0.012 0.17 0.15 4.14 4.14 2.73 2.73 0.22 0.21 2.79 427.69 * 0.012 0.19 0.16 4.21 4.21 2.79 2.79 0.25 0.25 2.87 427.77 * 0.012 0.21 0.18 4.28 4.28 2.87 2.87 0.27 0.29 2.97 427.87 * 0.012 0.23 0.19 4.38 4.38 2.96 2.97 0.30 0.33 3.08 427.98 * 0.012 0.24 0.20 4.48 4.48 3.07 3.08 0.32 0.37 3.20 428.10 * 0.012 0.26 0.22 4.60 4.60 3.19 3.20 0.34 **************** OVERFLOW ENCOUNTERED AT 0.42 CFS DISCHARGE ***************** ******** OVERFLOW CONDITIONS CALCULATED ASSUMING SURCHARGE CONDITIONS ********* 0.42 3.34 428.24 * 0.012 0.27 0.23 4.74 4.74 3.33 3.34 0.36 0.46 3.49 428.39 * 0.012 0.29 0.24 4.88 4.88 3.48 3.49 0.38 PIPE NO. 6: 22 LF - 12"CP @ 1.01% OUTLET: 424.90 INLET: 425.13 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.02 2.44 427.57 * 0.012 0.06 0.06 2.66 2.66 2.44 2.44 0.07 0.04 2.41 427.54 * 0.012 0.09 0.08 2.64 2.64 2.41 2.41 0.11 0.06 2.45 427.58 * 0.012 0.11 0.10 2.68 2.68 2.45 2.45 0.13 0.09 2.50 427.63 * 0.012 0.12 0.11 2.73 2.73 2.50 2.50 0.16 0.11 2.56 427.69 * 0.012 0.14 0.12 2.79 2.79 2.56 2.56 0.18 0.13 2.64 427.77 * 0.012 0.15 0.13 2.87 2.87 2.64 2.64 0.19 0.15 2.74 427.87 * 0.012 0.16 0.14 2.97 2.97 2.74 2.74 0.21 0.17 2.85 427.98 * 0.012 0.18 0.15 3.08 3.08 2.85 2.85 0.23 0.19 2.97 428.10 * 0.012 0.19 0.16 3.20 3.20 2.97 2.97 0.24 **************** OVERFLOW ENCOUNTERED AT 0.22 CFS DISCHARGE ***************** 0.22 3.11 428.24 * 0.012 0.20 0.17 3.34 3.34 3.11 3.11 0.25 0.24 3.27 428.40 * 0.012 0.21 0.17 3.49 3.49 3.26 3.27 0.27 ©2012 D.R.STRONG Consulting Engineers Inc. Page 39 of 55 Technical Information Report Altmyer March 29,2012 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#101 TO CB#1.bwp Surcharge condition at intermediate junctions Tailwater Elevation:427.82 feet Discharge Range:1.32 to 1.32 Step of 1.32 [cfs] Overflow Elevation:432.89 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 87 LF - 12"CP @ 9.92% OUTLET: 420.37 INLET: 429.00 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.32 0.65 429.65 * 0.012 0.49 0.23 7.45 7.45 0.49 ***** 0.65 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#102 TO CB#2.bwp Surcharge condition at intermediate junctions Tailwater Elevation:428.12 feet Discharge Range:l. to 1. Step of 1. [cfs] Overflow Elevation:432.64 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 94 LF - 12"CP @ 9.62% OUTLET: 420.59 INLET: 429.64 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.00 0.55 430.19 * 0.012 0.43 0.20 7.53 7.53 0.43 ***** 0.55 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#103 TO CB#3.bwp Surcharge condition at intermediate junctions Tailwater Elevation:428.24 feet Discharge Range:0.87 to 0.87 Step of 0.87 [cfs] Overflow Elevation:431.04 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 128 LF - 12"CP @ 4.45% OUTLET: 421.07 INLET: 426.80 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.87 1.54 428.34 * 0.012 0.40 0.23 7.17 7.17 1.51 1.54 0.53 ©2012 D.R.STRONG Consulting Engineers Inc. Page 40 of 55 Technical Information Report Altmyer March 29,2012 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#104 TO CB#4.bwp Surcharge condition at intermediate junctions Tailwater Elevation:428.27 feet Discharge Range:0.28 to 0.28 Step of 0.28 [cfs] Overflow Elevation:429.91 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 22 LF - 12"CP @ 15.35% OUTLET: 423.48 INLET: 426.91 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.28 1.37 428.28 * 0.012 0.22 0.10 4.79 4.79 1.37 1.37 0.22 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:CB#203 TO CB#3.bwp Surcharge condition at intermediate junctions Tailwater Elevation:428.24 feet Discharge Range:0.97 to 0.97 Step of 0.97 [cfs] Overflow Elevation:430.86 feet Weir:NONE Upstream Velocity:0. feet/sec PIPE NO. 1: 125 LF - 12"CP @ 5.43% OUTLET: 421.07 INLET: 427.86 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.97 0.65 428.51 * 0.012 0.42 0.23 7.17 7.17 0.51 0.65 0.56 ©2012 D.R.STRONG Consulting Engineers Inc. Page 41 of 55 Technical Information Report Altmyer March 29,2012 SECTION VI SPECIAL REPORTS AND STUDIES The following report and studies are or have been provided for this Project: 1. Altmyer/Sinclair Property Wetland Reconnaissance Study — Watershed, December 22, 2006 2. Traffic Analysis for Altmyer 21 Lot P-Plat — Gary Struthers Associates, Inc., September 2007 3. Altmyer 100 year storm backwater modeling — J3ME, June 10'2008 4. Geotechnical Evaluation Letter—Associated Earth Sciences, Inc., April 18, 2008. 2012 D. R.STRONG Consulting Engineers Inc. Page 42 of 55 Technical Information Report Altmyer March 29, 2012 SCIENCE & DESIGN WATERSHED December 22, 2006 MJF Holdings c/o Centurion Development Services 22617—8th Drive SE Bothell, WA 98021 Attn: Mike Romano Re: Altmyer/Sinclair Property Wetland Reconnaissance Study—TWC Ref# 061209 Dear Mike: On December 19, 2006 I conducted a wetland reconnaissance study at the properties located at 112th Avenue SE and SE 184th Place north of Panther Lake in unicorporated King County. This letter summarizes the finding of this study. Data sheets and a site sketch are attached. The sketch depicts the project area boundary and shows the approximate location of data points. Methods The subject property was screened for wetlands using methodology from the Washington State Wetland Identification and Delineation Manual (Manual) (Washington State Department of Ecology [Ecology], 1997). Areas meeting the criteria set forth in the Manual were determined to be wetlands. My determination is based on observations in the field and by reviewing an online GIS mapping resource provided by King County (iMap). Soil, vegetation, and hydrologic data were sampled at several locations on the property to make the determination. I recorded data at three of these locations. Findings I was given permission to access the Altmyer and Sinclair properties in the project area(parcels 3223059302 and 3223059294). A third property in the project area (parcel 3223059300) was visually scanned from the adjacent property and public right-of-way. No wetlands were found in the project area. Soil from 0-12 inches on parcel 3223059302 (see Reconnaissance Sketch, data point 1) is characterized by a very dark brown sandy clay loam with no redoximorphic features (RMF). The soil from 12-14 inches is a dark yellowish brown(l OYR 3/4) sandy clay loam with no RMF. The soil was saturated to the surface on the day of my site visit and free water was present in the soil pit at 6 inches below the surface. The vegetation is dominated by lawn grass (Poa sp.). Dandelion (Taraxacum officinale) and other grasses, such as fescue (Festuca sp.), are also present. Although vegetation comprises a mix of facultative species and soils were saturated, recent rainfall was heavy, and soil parameters are not met. Therefore this area is not wetland. 750 Sixth Street South Kirkland,WA 98033 p 425.822.5242 J 425.827.8136 watershedco.com Romano,M. December 22,2006 Page 2 of 2 The soil at 10 inches on parcel 3223059294 (see Reconnaissance Sketch, data point 2) is characterized by a pale brown (10YR 6/3) sandy clay with dark yellowish brown (10YR 4/6) RMF. The soil was saturated to the surface on the day of my site visit and free water was present in the soil pit at 6 inches below the surface. Lawn grasses (Poa and Festuca sp.) and dandelion are the dominant species. Clover(Trifolium sp.) is also present. Again the soil does not meet the wetland parameters;this area is not wetland. The other property in the project area (parcel 3223059300) had similar landscaping and did not exhibit any obvious wetland features. A storm water detention pond (parcel 3223059313) east of the project area contains cattails, but it is deemed an allowed alteration and is exempt from wetland regulations(KCC 21 A.24.045). Please call if you have any questions or if we can provide additional information. Sincerely, "I/d/X1J Nell Lund Ecologist Enclosures ,.7'-' ; .3: •. C18 1/ o 5089 ,x.30-• ,l i • LT(i) 4JPthS 089/Acs.. itlH••i,% tl =Mail) M•i1/.0k.T • .. -� i Gr�xticm 41‘ - , : ,, SpYldi�f.1''i;4 ilk t4 OW _:y._I i.x...—_, Detention Pond r ' Nb • 4 . .. zyrJ.:a;s}x,F.1 t r . liiii_. iii;_, . 0 2230592• i N DP-2 iv!, 1 i'% • 3059-.. 1_ . AT (c}moxi„yca�r9gv h rib's t91A7110o29oMill'W7155-6,12 W71-ti 12 Off 0015, ill Note: Sketch areas depicted are Wetland Reconnaissance Sketch Legend: p Unincorporated King County east of Renton, Washington approximate and not to scale. project area Prepared for Mike Romano, MJF Holdings boundary Altmyer/Sinclair Properties December 19, 2006 © data point E[ { [ WATERSHED 750 Sixth Street South I Kirkland i WA 98033 p 425.822.5242 f 425.827.8136 WETLAND DETERMINATION DATA FORM T H E 750 Sixth Street South WATERSHED Kirkland, Washington 98033 CO1v1 IIA N Y (425) 822-5242 Fax (425) 827-8136 WETLAND? YES /CL/C0 Date: December 19, 2006 Data point: DP-1 Wetland #: Project Name: Altmyer/Sinclair Property Data point location: Parcel 3223059302, in a low Biologist(s): NL point in the back yard Do normal environmental conditions exist? NO mowed grass Has vegetation, soils 8/or hydrology been si.- tly disturbed within the past 5 yrs? YES NO Stratum: T=tree, S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Lawn grass (Poa sp.) H FAC Lawn grass (Fectuca sp.) H FAC Taraxacum officinale H FACU Percent of dominant species that are FAC, FACW or OBL 100% Vegetation criteria met? ® NO Notes: Recently mo•• -d lawn with few weeds SOILS MottlesDepth Horizon Matrix Color aStincl,Promine nti Texture Hydric Indicators: 0-12" B 10YR 2/2 NO Sandy clay loam Gleyed/Low Chroma 12-14" B 10YR 3/4 NO Sandy clay loam Sulfidic odor Histosol Other(list in notes) Soil Criteria Met? YES NO Notes: HYDROLOGY Surface saturation? NO Primary Indicators:(1 required) Secondary Indicators:(>2 required) Depth to saturation01) _ Observation of inundation Oxidized root channels Depth of inundation N/A x Observation of soil saturation Water-stained leaves Depth to free ,- - in pit 6" _ Water marks Local soil survey data Flow? YE". NO Drift lines or drainage patterns FAC-neutral test Channel? : eet? _ Sediment deposits Hydrologic Criteria Met? co NO Recent rainfall: Very high High Normal Low Very low Notes: WILDLIFE OBSERVATIONS AND GENERAL NOTES WETLAND DETERMINATION DATA FORM -F1-1 E WATERSHED Iso sixth street south Kirkland, Washington 98033 COM PAN1" (425) 822-5242 Fax (425) 827-8136 WETLAND? YES NO Date: December 19, 2006 Data point: DP-2 Wetland#: Project Name: Altmyer/Sinclair Property Data point location: Parcel 3223059294, in low Biologist(s): NL point in the back yard Do normal environmental conditions exist? 43o NO mowed grass Has vegetation, soils 8/or hydrology been sig .ntly disturbed within the past 5 yrs? YES 0 Stratum:T=tree, S=shrub, H=herb, V=vine VEGETATION Dominant Species Stratum WIS Other Species Stratum WIS Poa sp. H FAC Trifolium sp. H FAC- Fectuca sp. H FAC Taraxacum officinale H FACU Percent of dominant species that are FAC, FACW or OBL 67% Vegetation criteria met? 40 NO Notes: Lawn grass ixed with many weedy plants SOILS Depth Horizon Matrix Color Mottles P ,�ebncUFrominent, Texture Hydric Indicators: 10" B 10YR 6/3 Yes Sandy clay loam Gleyed/Low Chroma 1 Sulfidic odor Histosol 10YR 4/6 Other(list in notes) Soil Criteria Met? YES(NO) Notes: 450 HYDROLOGY Surface saturation? NO Primary Indicators:(1 required) Secondary Indicators:(>2 required) Depth to saturation 1 _ Observation of inundation Oxidized root channels Depth of inundation N/A x Observation of soil saturation Water-stained leaves Depth to free at r inpit 6" _ Water marks Local soil survey data FI w? YES t NO) Drift lines or drainage patterns FAC-neutral test Channel? Sheet? — Sediment deposits Hydrologic Criteria Met? CO NO Recent rainfall: Very high High Normal Low Very low Notes: WILDLIFE OBSERVATIONS AND GENERAL NOTES TRAFFIC ANALYSIS FOR ALTMYER 21 LOT P - PLAT September 2007 4U `- \\7 • ,,' Prepared by GARRY STRUTHERS ASSOCIATES, INC. 3150 Richards Road, Suite 100 Bellevue, WA 98005 (425) 519-0300 TABLE OF CONTENTS Executive Summary Introduction .1 Trip Generation .1 Trip Distribution/Traffic Assignment .1 School Walkway Conditions 2 Conclusions 10 Recommendations 10 LIST OF FIGURES Figure 1 -Project Vicinity Map Figure 2—Project Site Plan Figure 3—A.M.Peak Hour Trip Distribution Figure 4-P.M.Peak Hour Trip Distribution Figure 5 -A.M.Peak Hour Trip Assignment Figure 6-P.M.Peak Hour Trip Assignment Figure 7—School Bus Stop Locations LIST OF TABLES Table 1 Project Trip Generation Table 2 A.M.Peak Hour Trip Assignment Table 3 P.M.Peak Hour Trip Assignment APPENDIX Trip Generation Calculation EXECUTIVE SUMMARY The purpose of this analysis is to evaluate the trip generation and distribution for Altmyer 21 Lot P-Plat project. The results of the analysis were evaluated and conclusions and recommendations made. CONCLUSIONS The Altmyer 21 Lot P-Plat project will not create any significant adverse conditions on the surrounding transportation network. The new site will generate approximately 200 daily, 16 AM peak hour and 21 PM peak hour new vehicle trips. The walking conditions between the proposed project site and the nearest school bus stops for Lindberg High School and Nelsen Middle School are good. RECOMMENDATIONS Based of the analysis presented in this report,no off site roadway improvements will be needed to mitigate the traffic impacts of this project. • Introduction The following report was prepared to address the traffic analysis for the Altmyer 21 Lot P-PIat project.The project is located west of intersection of 112`h Avenue SE and SE 184`h Place(private road) in the Panther Creek area of King county east of the Benson Hwy. The project's vicinity map is presented in Figure 1.The project site plan is presented in Figure 2. This report summarizes the evaluation of trip generation for Altmyer 21 Lot P-Plat project and assignment of the resultant trips to the transportation network. The results of analysis were evaluated and appropriate course of action was proposed.The report also contains a school walkway inventory and documents walking conditions between the proposed project site and Lindberg High School and Nelsen Middle School bus stops. Trip Generation Trip generation for Altmyer 21 Lot P-Plat was calculated using the Institute of Transportation Engineers(ITE)Trip Generation,7th Edition. A summary of the anticipated trip generation is presented in Table 1. Table 1.Project Trip Generation Weekday Daily Trips A.M.Peak Hour Trips P.M.Peak Hour Trips Total Enter. Exit Total Enter. Exit. Total Enter Exit. 200 100 100 16 4 12 21 13 8 As shown in table 1,the proposed project site will generate 200 daily trips, 16 AM Peak Hour and 21 PM Peak Hour trips. Trip Distribution/Traffic Assignment Trip distribution percentages for Altmyer 21 Lot P-Plot project were based on the existing trip distribution at the key intersections along SE 186th Street.The trips generated by the new development were assigned to the roadway network using the existing directional distribution. The AM Peak Hour Trip Distribution expressed as percentages and as number of trips is presented in Figure 3.The PM Peak Hour Trip Distribution expressed as percentages and as number of trips is presented in Figure 4.The AM and PM Peak Hour Trip Assignment at key intersections is presented in figures 5 and 6 and in Table 2 and Table 3. 1 Table 2 AM Peak Hour Trip Assignment Intersection EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR SE184th P1/112'h Ave SE 4 0 8 0 0 0 3 0 0 0 0 112th Ave SE/SE186th Ave 3 0 0 0 0 1 . 0 0 0 4 0 4 Table 3 PM Peak Hour Trip Assignment Intersection EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR SE184th P1/112th Ave SE 2 0 6 0 0 0 9 . 0 0 . 0: 0 4 ... . 112th Ave SE/SE186th Ave 5 0 0 0 0 .4 0 0 0 2 0 4 School.Walkway Conditions The school walkway inventory was performed on September 25 and 26,2007,The proposed project site is located at 112`h Ave SE and SE 184th Place.In the close proximity of project site there are four bus stops for Lindberg High School and Nelsen Middle School.The bus stops for Nelsen Middle School are located along 116th Ave.SE at the intersections with SE 186th St.and SE 178th Pl.The bus stops for Lindberg high School are located at 176th St.near the intersection with 110th Ave.SE.and at SE 186th St near the intersection with 109th Ave SE.The Project site nearest bus stop locations for Lindberg High School and Nelsen Middle School are presented in Figure 7 There is a 5'wide sidewalk on the west side of 112th Avenue that extends 157'towards 186th St. The section of 112t Ave that do not have sidewalk have a 5'— 10' shoulder that provides adequate separation from the roadway. There are several speed bumps along 186th St.with posted suggested speed limits of 15 mph. This slows down vehicles traveling along 186th,making it easier for them to react to pedestrians. There are two 5'-10'shoulders along most of 186th St. As 186th reaches 116th Ave,there is only one 9'shoulder. These shoulder lanesprovide adequate separation from the roadway for pedestrians. There are sidewalks on both sides of SE 176th St. They run along the entire length of the street. The walking conditions around the proposed project site are very good. There are large shoulders or sidewalks along the roadways and multiple speed bumps.There are no major hazards to pedestrians around the proposed project site. 2 47°26'23"N, 122°11'34"W NAD27 122°13'00"W '�` li4rtie,„...,- -.4 122°12'00 W 122°11'00"W NAD27 122°10'00"W `^ Vy.( r 1� I®``Ik\. n n -W i� ,✓~' :1'1��\`'�;T'illan lam•' I- ,7.�. -1.- ;,.. tArrl el•. � 9.1111.0-1111k1 .- �::: . � g 141 off . �11illi � n111.11111111 %it • - ill, 1 III 1.—magiel "1 "it ii to . a. „ '1.,,. 1.0,1 VI 'I 11011_ it _ IF_ ARMAZ1111 riP. .ili z ii, q r 1., .t4Vii , (V .e.,,,,,,„....,. ' ' •�.. O , II. i• I lir �� . r,,_ ,iiits kiii ....4 .. 1/4,14e \ `111t0 . . ._,./ .,,,, . koraveir. 0...„,..., 4c.,,s- , i).,_, 1"1 * � Wt': 4N - -, ... 1 11 1 2 II6:\ �, ., � , i �. _ 1i _.__. I� .. -;- — , 1` pkteltl,..gNiilf alr: ? ) VI 1riN \ .y';_I' iiik .:!'',By /,\I'AFrj \ f.‘ ' ' A it It"' liosir'N.ik--deC...,‘ii ...../atil rk 1 ,. . 1 A 1 -- " 'sit 5 I -ilt i• a IV ! `'( , 1iii i w o .14 �' �' /TIIILLcI ' --.-- '..-- fr7--T---49iiikkrgire'' .r: • , i, 0.i--' , ►�411iIii \, l ti ; 1 f I., w ._:„.,7_16.,...,,c,,,,, '4,F� �' - \sis,. .7..c.... �.��� Vii.' �:1117": . ii, if.:6-4 .sett„,,,.. _. � . '.r•. N r.1,4 . �, ; iii!'r'� ' -� °' ^ ;,;� : ,,''fir, -�,..�..�. 1. .i . . ,.„, • X61s,',',.S..S., ..•\ �� `,` �. • , ” _... ,.• ., ss., (le . rabititirii:4,..,:4 H 11(.1E4:7&;.\\QI:\. '...Alli trjr.4 ./— .. Itil .... -., 122°13'00"W 122°12'00"W 122°11'00"W NAD27 122°10'00°W TN riN ° ____IOO NEI 9_,___„__„,,,_24,..„____ ___„...41):0!AGMS Printed from TOPOI®7001 National Geographic Holdings(www.topo,com) GARRY STRUTHERS ASSOCIATES,INC = "B•° wA°si° � 'e P1.2513, VICINITY MAP Altmyer 21 Lot _� F4x Ia]Sl9505 enc Plat Proposal MIP/Mww°N.soumc cart. FIGURE 1 1 a.s�rnia.--'t' �h;� j ;� Iii iiif it a 7 11 III r III I1I 111 `1111,I m , . i , 1 . 1 .i -i .l , a . t . . 1 ` I 4 1 `i , I . L ___ •hop , 1 1111111 I pi II i i it '111 tt I. -t 0.1 .. . .......... ......_,1 , .... L11511L195 NOT TO SCALE GARRY STRUTHERS ASSOCIATES.INC. Altmyer L Lot �.0' 5,68° SITE PLAN ,O� m Plat Proposal FIGURE 2 112th Ave.SE 30% 11 14 5 16 25% PROJECT SITE MN 4 SE 184th P1. 75% 70% 81 13 11 40% 30% 6 5 SE 186th St. 4 4 1 SE 186th St. 2 , Q LEGEND XX Number of Trips-Both Directions 112th Ave.SE ► Number of Trips-One Direction XX% Percent Trip Distribution NOT TO SCALE GARRY STRUTHERS ASSOCIATES.INC. "8."'"..(7;4:7:t4"6w� ° A.M. PEAK HOUR TRIP DISTRIBUTION Altmyer 21 Lot A phone. p.a:N23,5,D-030D Plat Proposal Eblip#Daa@Da4aaee-arc mrn Mtp/Mow 999990c-1m corn FIGURE 3 112th Ave.SE 30% 4I 12 6 21 63% PROJECT SITE Com- 13 SE 184th PI. 37% 70% 61 9 15 40% 30% 9 6 SE 186th Sc4 SE 186th Sc 2 o- LEGEND XX Number of Trips-Both Directions Number of Trips-One Direction 112th Ave.SE XX% Percent Trip Distribution NOT TO SCALE CARRY STRUTHERS ASSOCIATES,INC. Altmyer 21 Lot Be:�.'wA98005-41.5P.M. PEAK HOUR TRIP DISTRIBUTION 40., Phene:(425)519-0300 Faaa(425)5140309 Plat Proposal E-meiR g..euoe+ne tom hllp/Awe..,9Mssac-inc own FIGURE 4 112th Ave.SE .r.f.."-- ---'N 4—� ............„) 8—1 3 PROJECT SITE OM SE 184th Pt. 4 4 JL 3_.) ...----2 SE 186th St • SE 186th St LEGEND 112th Ave.SE t—XX PM PEAK HOUR TURNING MOVEMENT VOLUMES NOT TO SCALE / GARRY STRUTHER5 A65OC1ATE6,INC. Altmyer 21 Lot 3 Phone,(4 Ree19-030 200 A.M. PEAK HOUR TRIP ASSIGNMENT eawo. wA)5I-O Oo �.. 7Mna 02)519--0900 Fax(025)519-0309 E�9..�..x.a�.xK.� Plat Proposal FIGURE 5 112th Ave.SE 4 J 6-1 9 PROJECT SITE III. SE 184th Pl. (<.---2 4, 4 J L X SE 186th St SE 186th St LEGEND 112th Ave.SE XX PM PEAK HOUR TURNING MOVEMENT VOLUMES NOT TO SCALE GARRY$TRUTHERS ASSOCIATES.INC. I ti I Iyer G. Lot 3150 lowe W 900 5u0.500 P.M. PEAK HOUR TRIP ASSIGNMENT �„».42 .0 ... ono-..:2$)55140300 F.(425)519-030D Plat Proposal Fw,WI:pswgyuswcYc.Oom MO/Mww.pMewc•nc wm FIGURE 6 6,1----_.:••!. EZI g. . •cg . SE 168M St sk- lesah Si SE 168th SI .._.•7 'f' 0 7' • . •'•-- ---• I r 1 -- • : 1-4 M -i-71 III 4*' 1 ..0 • ' 0! _. -..4'.0.1 • 1.'4‘‘• I-. ". j: —I 14 •."..5.. .Z., ;s11 5' 5E lt1V-.at -•c?. -`44- - N .- g I I %•-• , -,• tr.; , -- I -4 ' • .t.i 4, 57.,! • , ..7,5,...•. I-) • :•1,11i! •''''' -•••!!')•--;-.; ). ,o-1 c's, 1 • ,..,E itch•st . .0 e. ..0 • .,1., „7, R , . rn .., , .),. .. , . 0,,* • ,M • crtl •to• NI' .ml 1 • s..-•{A ...•• . . 14'•. I 1 - ! • Imo In I , , + . .-(...§.1A... cv• - 0. I I I 1, t WY!Si . - --- - "' . i.5.E 17:.!nd Sit.' ' 'T',..1..s 1 ' -,_ ,, . 1 ! i ','.\''. I. '• ' ' - —SE ffind si•41•-— SE i7;rtd 8.T .._ .. ! ; SE!72nd Ln. ...., _ ---- • —_-- .5: _ 4(41 3-111 S? i '.14 , - (5 -." .i_,,_•• ) . 9 0. ,t...) ,Nr':- 17 , I ..'•*..-.( ••'.Pr--.§E-1-aia-st • " .,011.P.` ) 1 ..-,, .:0", .<1.7.• , . 1 !._. et t; ,), ,/,:..: _j • i' ---1 I ; • • - .'••-. ,,t, . , :-.11 .. '• - , -- .W 7,.si„- V, . —:.;- 7 ( , ---- — - ..5, >t •gn i i •-, . -- • j f i i 1-1§.; ) -- . •). g 4 .r,.------ -._. r....7...., :-.-.. • -. • ': ' - -4 ./.. --R-1,75,th I i i I I, •'' ; .•"'1;1114° - I .., -- —.-- EPOro!its*YRO ------- — I' _,.. I._ ..r.• . ,--• . . , _11 il ii •-,. 1 (- •-• 74 i , a. . 1_,. 10 I.8: 4.1t1..... (..ILS) H i ' i ... 131% ..-1: '• I : 1/1 • ! I .. .',11) -C,• i ...,. • :1i :1• It ;-,': 1.• ,..,..•:-: --:. I it • ,,,?. ! • 8 ; • ! r. . . c III• 5, 1 •I i ?Id I ,---., I 31-7-' 0*: (-•• 1.B-'. I I • -. , : ; i• • i• ... 11....•',.J•53..:.' 1 IE'I - : ; ...--': ,-- • : At 79th SI _ . .. i L_ . _i. -1s g_Tegiti4t.-1 .i(•17 e? ' 41i'i1. • S1 StkT1 r sEiacppt _ •-----.- SE 1110111 Pi .. .-.. --. C. ,,1/4...' i t ie' 1 ---,;.* Lc% • I i ' ' - I .r..--', 1-1 "zre-----i t -6E1-8-1-0..,- .--] ;- .u,-• -4 i ---,------:%-.. .Iai' 78'.-1 'is - 'g1 ..,1 L. Iv ,4- ---4. i- : tt flu,.pt sE.1.57.04 st -""-2--P-r—'' );•---,. r---- --- ! ;g i i 1 1 "i: -to I r— 1 in A t<I ..I ,co `.---.U184,.. ' --- . ! irlw , ,rn ,• :- . 1 I • •___ t•tt t 1 r , : i'9%_.,_,' " s--.• a• tco .'....I :.--, .. •• i , i ..._-frni.,-. __ _! _.'i I 4.I ( __Ag.184th St -- '' ,-••.---1.• Lr., F', --- - 5. . .. . —--1 •:-.C..... I .1 ET ,.....§;iiten--r • ( - , --: i .tYI----" I>. . -• ,MI ...,._ L I'l. • .§. E53bi -— lil en fli-p-g•loein 41-) . 1 :,•‘. e.i'aelp-OPI i . I L." ; ' I ) '•-drib.*Or' .------ I ' ---, .4_13,411443y9r4. : , • La-FE,Park'-'N i . , , I c 1 1 1 I 1 . 1 r igtViri Ln . • 147111PS , '' 1'—ix1 in• •. _ _... '8E I Baul Si SE.iseth st tE-iffiftli-s1‘ ..-. .1-•) • -- : 1-...t. .-} •;..tv -c: sai3/ la' ' 1 1 j • • t ••••,.‘.. ,' •— -•••? . •- I • .,) III NELSEN MIDDLE SCHOOL 116th Ave. SE/SE 178th Pl. 116th Ave. SE/SE 186th Pl. ALINBERG HIGH SCHOOL SE 176th St./110th Ave. SE SE 186th St./109th Ave.SE NOT TO SCALE GARRY STRUTHERS ASSOCIATES.INC. 3150 F0551005 Rood.3011.•200 SCHOOL BUS STOP Altrnyer 21 Lot tiollavue.WA oesoos-.4.3 P0on•1025)519.0303 7,401P Fax:(825)S19-0309 E•11I.II 0.401r........C.C.T. at Proposal hIlp.fiveorw fpaasoc,inc corn LOCATIONS Plat FIGURE 7 CONCLUSION$ The Altmyer 21 Lot P-Plat project will.not create any significant adverse conditions on the surrounding transportation network.The new site will generate approximately 200 daily, 16 AM peak hour and 21 PM peak hour new vehicle trips. The walking conditions between the proposed project site and the nearest school bus stops for Lindberg High School and Nelsen Middle School are good. RECOMMENDATIONS Based of the analysis presented in this report,no off site roadway improvements will be needed to mitigate the traffic impacts of this project. 10 APPENDIX Trip Generation Calculation for Altmyer 21 Lot P-Plat Single Family Detached Housing ITE Code 210,Trip Generation,Page 269 • Weekday: 9.57 x 21 =200,Entering 50%(100),Exiting 50%(100) • A.M.Peak Hour:0.75 x 21 = 16,Entering 25%(4),Exiting 75%(12) • P.M.Peak Hour: 1.01 x 21 =21,Entering 63%(13),Exiting 37%(8) • • 1375 NW Mai!Street,Suite 3 Issaquah,WA 98027 425.313.1078(Bus) J3ME425.313.1077(Fax) June 10th, 2008 King County D.D.E.S. Attn: Bruce Whittacker, Engineering Review Section 900 Oakesdale Avenue Southwest Renton, WA 95057-5212 RE: Altmyer LO7P0016: Drainage Study— 100-year storm backwater modeling Dear Mr. Whittaker, Per your email request of June 3r1, 2008 this memo addresses your questions regarding the backwater analysis of the Ruddell conveyance system between Pond A and Pond B during a 100-year storm. The conveyance system was modeled using the Hydraflow Storm Sewers 2005 engineering software by InteliSolve. Hydraflow uses the energy-based Standard Step method when computing the hydraulic profile. The model was created for the existing system using the same parameters used in the backwater model in the Preliminary TIR(KC Backwater). The flows used are from the TIR and are introduced at CB's 15 (9.68 cfs), 10(4.87 cfs), 8 (3.08 cfs), and 5 (4.79 cfs). The Hydraflow modeling output is attached and shows that the 100-year flows do stay in the pipe system with the new proposed overflow pipe from Pond A. The modeling also shows that there is no 100-year floodplain for this system. If you have any questions please call me at 425-313-1078. • Sincerely, 1�2 /rrit J. Jima, P.E. J3 Mecum Engineering, Inc. 1375 NW Mall Street, Suite 3 Issaquah, WA 98027 (425) 313-1078 Attachments; 100-Year Storm Conveyance Profile—Pond A to Pond B Hydraflow output; Plan View, Storm Sewer Inventory Report, &Storm Sewer Tabulation X:\ProjeetsUbtJF-0031MJF-003 100-Year Backwater Ana[ysis.da; Hydraflow Plan View Outfall 4 CB 3 4t CB 4 CB 5 05` i F`` \ CB CB 6A CB 7 CB 6 .> 4---- • 8 CB 9 9 0810 O C8 11 • ---+� 11 I C812 N i C813 j *t, POND?A HEADWALL M —1 • +►44CB15 Cfl513A CB 14 Project File: mfj-0O3convey.stm No. Lines: 16 06-10-2008 Hydraflow Storm Sewers 2005 Storm Sewer Inventory Report Page 1 Line Alignment Flow Data 1 Physical Data Line ID No. Dnstr Line Defl Junc 'Known Drng Runoff inlet Invert Line Invert Line Line N J-loss Inlet) line length angle type Q area coeff time El Dn slope El Up size type value coeff Rim El No. (ft) (deg) (cfs) (ac) (C) (min) (ft) (%) (ft) (in) (n) (K) (ft) 1 End 56.0 60.2 MH 0.00 0.00 0.00 0.0 404.66 9.07 409.74 30 Cir 0.012 0.30 417.50 1 2 1 126.0 -14.8 1 MH 0.00 0.00 0.00 0.0 409.74 0.67 410.59 30 Cir 0.012 0.15 417.50 2 3 2 27.5 1.1 MH 4.79 0.00 0.00 0.0 410.59 -0.51 410.45 30 Cir 0.012 0.15 419.50 3 4 3 109.0 3.7 MH 0.00 0.00 0.00 0.0 410.45 0.78 411.30 30 Cir 0.012 0.15 422.50 4 5 4 81.0 -5.9 MH 0.00 0.00 0.00 0.0 411.30 0.51 411.71 30 Cir 0.012 0.38 422.00 5 6 5 80.0 -19.4 MH 0.00 0.00 0.00 0.0 411.70 0.52 412.12 30 Cir 0.012 015 422.75 6 7 6 44.0 -0.4 MH 3.08 0.00 0.00 0.0 412.12 0.39 412.29 30 Cir 0.012 0.48 423.00 7 8 7 72.0 1 -25.2 MH 0.00 0.00 0.00 0.0 412.29 -0.10 412.22 30 Cir 0.012 0.15 426.00 8 9 8 145,5 0.0 MH 4.87 0.00 • 0.00 0.0 412.22 0.73 413.28 30 Cir 0.012 1.00 427.00 9 10 9 144.0 90.0 MH 0.00 0.00 0.00 0.0 413.38 0.22 413.70 24 Cir 0.012 1.00 429.50 10 I 11 10 264.5 -90.0 MN 0.00 0.00 0.00 0.0 413.70 0.53 415.10 24 Cir 0.012 1.00 427.68 11 12 11 147.0 91.7 MH 0.00 0.00 0.00 0.0 (415.10 0.61 416.00 24 Cir 0.012 1.00 426.65 12 13 12 134.0 -91.7 MH 0.00 0.00 0.00 0.0 416.00 0.60 416.80 24 Cir 0.012 0.15 426.60 13 14 13 47.0 0.0 MH 0.00 0.00 0.00 0.0 416.80 1.04 417.29 24 Cir 0.012 0.81 423.56 14 15 14 20.0 -50.7 MH 0.00 0.00 0.00 0.0 i 417.29 0.55 417.40 24 Cir 0.012 0.15 419.60 15 16 15 30.0 0.0 Hdwl 9.68 0.00 0.00 0.0 417.40 0.67 417.60 24 Cir 0.012 1.00 419.60 16 1 Project File: mfj-003convey.stm j Number of lines:16 I Date: 06-10-2008 Hydrallow Storm Sewers 2005 war.w.w.w--..nvn•.wv+v�m'-ww.nn..n___...-...��.w...Mnwwnn'.`.rsw�wMV✓.nrwrvw+rw....+r- Storm Sewer Tabulation Page 1 • Station Len Dmg Area Rnoff 1 Area x C Tc I Rain Total Cap Vel Pipe Invert Elev HGL Elev Gmd/Rim Elev Line ID coeff I- 11 (I) flow full Line To lncr Total Incr Total Inlet Syst -- .---' Line Y Size Slope Up Dn Up Dn Up Dn 1 E (ft)__.(ac) (ac).. (C) (min) (min) (in/hr) (cfs) (cfs) (ftls) (in) (%) (ft) (ft) (ft) (ft) (ft) (ft) 1 End 56.0 0.00 0.00 0.00 0.00 0.00 0.0 6.8 0.0 22.42 133.8 4.57 30 9.07 409.74 404.66 414.14 414.00 417.50 416.50 1 2 1 126.0 0.00 0.00 0.00 0.00 0.00 0.0 6.4 0.0 22.42 36.49 4.57 30 0.67 410.59 409.74 414.56 414.24 417.50 417.50 2 3 2 27.5 0.00 0.00 0.00 0.00 0.00 0.0 6.3 0.0 22.42 0.00 4.57 30 -0.51 410.45 410.59 414.68 414.61 419.50 417.50 3 4 3 109.0i 0.00 0.00 0.00 0.00 0.00 0.0 5.7 0.0 17.63 i 39.23 3.59 30 0.78 411.30 410.45 415.02 414.85 422.50 '419.50 4 5 4 81.0 0.00 0.00 0.00 0.00 0.00 0.0 5.4 0.0 17.63 31.61 3.59 30 0.51 411.71 411.30 415.18 415.05 422.00 422.50 5 6 5 80.0 0.00 0.00 0.00 0.00 0.00 0.0 5.0 0.0 17.63 32.19 3.59 30 0.52 412.12 411.70 415.38 415.26 422.75 422.00 6 7 6 44.0 0.00 0.00 0.00 0.00 0.00 0.0 4.8 0.0 17.63 27.62 3.59 30 0.39 412.29 412.12 415.48 415.41 423.00 422.75 7 8 7 72.0 0.00 0.00 0.00 0.00 0.00 0.0 4.4 0.0 14.55 0.00 2.96 30 -0.10 412.22 412.29 415.72 415.64 426.00 423.00 8 9 � 8 145.5 0.00 0.00 0.00 0.00 0.00 0.0 3.6 0.0 14.55 37.92 2.96 30 0.73 413.28 412.22 415.90 415.74 427.00 426.00 1 9 10 i 9 144.0 0.00 0.00 0.00 0.00 0.00 0.0 2.8 0.0 9.68 11.55 3.08 24 0.22 413.70 413.38 416.26 416.03 429.50 427.00 10 11 10 264.5 0.00 0.00 0.00 0.00 0.00 0.0 1.4 0.0 9,68 17.83 3.26 24 0.53 415.10 413.70 416.78 416.41 427.68 429.50 11 12 11 147.0 0.00 0.00 0.00 0.00 0.00 0.0 0.9 0.0 9.68 19.17 4.24 24 0.61 416.00 415.10 417.27 417.00 426.65 427.68 12 13 12 134.0 0.00 0.00 0.00 0.00 0.00 0.0 0.4 0.0 9.68 18.93 4.42 24 0.60 416.80 416.00 417.90 417.71 426.60 426.65 13 14 13 47.0 0.00 0.00 0.00 0.00 0.00 0.0 0.2 0.0 9.68 25.02 4.76 24 1.04 417.29 416.80 418.39 418.22 423.56 426.60 14 15 14 20.0 0.00 0.00 0.00 0.00 0.00 0.0 0.1 0.0 9.68 18.17 4.27 24 0.55 417.40 417.29 418.55 418.71 419.60 423.56 c 15 16 15 30.0 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 9.68 20.01 4.39 24 0.67 417.60 417.40 418.79 418.86 419.60 419.60 ! 16 1 1 I I .. 1 Project File: n4-003convey.stm -- -- _. Number of lines:16 Run Date: 06-10-2008 NOTES:. -- _.._...--_..- _____�. __ Hydraflew Storm Sewers 2005 ... . ..-..,-..,,,,..-.--------,....w.....-..-", ..-.......,,,....v.......,-,-,m,•x,:•>:440.x.xii•x:::zk.v-.mm4 ...m ,.......... )1 I . 1 94464444444.1 • i II I 11 11 11 11 1 1g ill ! i! i LU --I 3 7.101.10.0 WWI. 4. 43000 : .. '5 . - . . . 0 1 * 1.- I . . • . • ! • I Es i. 00 ... . . . . : . . . • ‘,. ; • . • ; • ! Z 425 ! ! 4 • • 4- •1• •N. ! _ '1' :, . . • k IQ q 1 1 . . - • o u '".I 2 $ • i • . . ______ Nits=ammemeast2210aciarrnic=iiiil um. •81;:e........% , . . • i 42000 . I 4 • , ,. , i • . .r.lei.cra•'rt. .._, ,rtR11., Cl rl.1•31rsir ie.--.- - - .1. T g it W.114 1 • "MOW . _A- V E- LLI 415 00 1 1 a...1th ..- ...o .,—..............e.r176.....-.. .pl, , . ••11.1014 • 10•3e11.6•••/. N... ,. .,.. "aasnati wiNiseall iljejSa 1111111.1 aim : ,,._Z Z 2 ! .: \I. • .1•41. ; Om • 4....4•51.!:” ; • I nel:•4.41e7s.am - 1.0 I 1.7.11:6! ...... 0,77 - -1-- 1111,,,,, ---1 • •-7......! . -.7.11:11E.-- ---- irtigr .1.--•• ••-•••.! y:.:.. c6 .. i 114....1.11..1.. - "s ICOM ....Min' - ;• 1.111.01•1.1c 14 Q. I ..I.• •I• : 1 I 1 I . • 0.101 MC it ICt I i 1 1 0 47.6 1•1.n, Ir I i 14tr't 44;so:" t tr.ii - _ c... ; ; h....r 411.211.; • • 1 • SA•41.111•Ge 13 g i : 54.1424,•In, . :‘ .1. tr. -'• . 'Elir-714, .• _ .• i 305.00 - .4- ..- .1., .1. !. • ; . :• "I' '• 4; •-1.-• I .i . ;•;, 5 . . • . . . : ; . ; • I • • . . , I . . • 1 I • .• I • : r 300.00 : ! • • : I i . : • : • • : i 0.00 040 140 140 2.00 240 340 345 440 440 540 540 040 540 7.00 740 0.00 540 040 MO 10.00 10.110 11.00 1140 1240 1240 1340 1340 1440 14.40 15.00 1540 . ; 1 STAMP NOT MC iMUSS SIGNED ANO OVED i 111 I 1 J3ME . i i 137540041150444 5.s,3 Issequoh,WA 96077 i 141(425)313 1071 544(475)313 1077 i• Jal NUMBER 5. MJF-003 5. I 1 Associated Earth Sciences, Inc. Cele rrafinjc Over 25`Years of Service April 18, 2008 Project No. KE080196A MJF Development c/o Centurion Development Services P.O. Box 2668 Redmond, Washington 98073 Subject: Limited Evaluation and Classification of the Surficial Soils Altmyer P-Plat King County, Washington As requested, Associated Earth Sciences, Inc. (AESI) is pleased to provide this letter presenting the results of our limited evaluation and classification of the surficial soils within the drainage basin surrounding the proposed subdivision at the above-referenced site. This letter is based on observation of three hand-excavated explorations within the proposed development area, grain-size analysis of a representative soil sample collected from the explorations, review of United States Department of Agriculture (USDA) Natural Resources Conservation Services (NRCS) data for the area, review of United States Geological Survey (USGS) data for the area, and review of AESI geotechnical data from a nearby project. This letter has been prepared for the exclusive use of MJF Development and their agents for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our letter was prepared. No other warranty, express or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. No other geotechnical, geologic, or engineering services have been requested by MJF Development for this project, and none have been supplied. The site is located at the west end of SE 184th Place, roughly 1 block west of the intersection of SE 184th Place and 112th Avenue SE in King County, Washington. The area is currently occupied by residential property and a storm water detention pond. A new subdivision is currently planned for the area. Kirkland a Everett Tacoma 425-827-7701 425-259-0522 253-722-2992 www.aesgeo.com The field portion of this study was performed using hand tools to access the below-surface soils in the vicinity of the proposed development, as well as a general reconnaissance of the area. A Washington State licensed geologist from our firm conducted the subsurface exploration. Three hand explorations were advanced just beyond the west end of SE 184t Place. The logs for these three explorations are attached to this letter. A composite soil sample was retrieved and returned to our laboratory for sieve analysis. The number, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions beyond the field exploration is necessary. Differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations beyond the field explorations may not be fully evident. The hand explorations encountered sediments that were interpreted to be weathered lodgement till. AESI explorations conducted on a nearby project (slightly to the east of the subject site) generally encountered a relatively thin layer of lodgement till containing scattered sand lenses and overlying outwash sands. The sieve analysis data was compared to the USDA Soil Textural Triangle and the soil sampled from the explorations most closely resembles a gravelly sandy loam as defined by the USDA. The USDA NRCS website indicates over half of the area is mapped as "Alderwood gravelly sandy loam, 0 to 6 percent slopes" (AgB) or "Alderwood gravelly sandy loam, 6 to 15 percent slopes" (AgC) and the remainder as "Arents, Alderwood material, 0 to 6 percent slopes" (AmB) or "Arents, Alderwood material, 6 to 15 percent slopes" (AmC). The NRCS indicates that "Alderwood" soils are derived from moraines or till plains and that "Arents, Alderwood" soils are also derived from till plains. "Alderwood" and "Arents, Alderwood" soils are classified as "Moderately Well Drained" by the NRCS. The Pacific Northwest Center for Geologic Mapping Services' publication titled, Geologic Map of King County, Washington, dated 2006, by Booth and Wisher, indicates that the area is underlain by Vashon-age lodgement till. Based on the above data, it appears that the near-surface geology in and near the proposed Altmyer P-Plat consists of lodgement till and lodgement till derived soils. These till soils appear to have lenses and interbeds of higher permeability, granular, outwash type soils within them. Based on the interbedding of the granular outwash type soils within the area till soils, storm water runoff is expected to be less than the volume normally associated with lodgement till. 2 Instead, runoff volumes would likely occur in a range between that of the granular (Everett series) soils and the finer grained (Alderwood series) soils. We appreciate the opportunity to be of service to you on this project. Should you have any questions regarding this letter or other geotechnical aspects of the project, please call us at your earliest convenience. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ��...0- ocE riLyt rT a '4,90i, ''VS‘,,,,,c----;--til' tie c; `� �` c,. fri,,, -.°1111. 1. b.' lk...-4-`�` � 2+`F4 r �.a Enpineennp G/cbpst `,i_ , ff:+f. s ♦f h �l 'c��S 608 0 .y Z6�,,:.,:::02;:A8 �"1�J��������, John D. Coleman I EXPi ,Etl5 1V I John D. Coleman, P.E.G. Bruce L. Blyton, P.E. Project Geologist Principal Engineer Attachments: Exploration Logs J DC/ts KE080196A2 Projects\20080196\KE\W P 3 SECTION VII OTHER PERMITS, VARIANCES AND ADJUSTMENTS No other permits, variances or adjustments have been required as part of this development, as of the date of this report. 2012 D.R.STRONG Consulting Engineers Inc. Page 43 of 55 Technical Information Report Altmyer March 29,2012 SECTION VIII ESC PLAN ANALYSIS AND DESIGN (PART A) The Erosion and Sedimentation Control Design meets the nine minimum requirements: 1. Clearing Limits — Areas to remain undisturbed shall be delineated with a high- visibility plastic fence prior to any site clearing or grading. 2. Cover Measures — Disturbed Site areas shall be covered with mulch and seeded, as appropriate, for temporary or permanent measures. 3. Perimeter protection — Perimeter protection shall consist of a silt fence down slope of any disturbed areas or stockpiles. 4. Traffic Area Stabilization — A stabilized construction entrance will be located at the point of ingress/egress. 5. Sediment Retention — Two sediment traps (Trap #1 and Trap #2) will be utilized for sediment retention. The sediment traps are designed per Section D.3.5.2 of the Manual, which requires 2080 s.f. of surface area per cfs of inflow calculated using KCRTS 15-minute time steps to analyze the developed Site condition. The catchment areas are 0.900 ac and 2.280 ac., and the 2-year flow rates are calculated at 0.305 cfs and 0.771 cfs respectively, for Trap #1 and Trap #2. The required surface areas are 635 s.f. and 1,603 s.f., and the areas provided are 1,622 s.f. and 2,136 s.f., respectively. The KCRTS analysis is included in this section. See Sheet C3 of the Plans for sediment trap details. 6. Surface Water Control — Surface water control will be provided by interceptor swales. 7. Dewatering Control — Not Applicable to this Site. 8. Dust Control — Dust control shall be provided by spraying exposed soils with water until wet. This is required when exposed soils are dry to the point that wind transport is possible which would impact roadways, drainage ways, surface waters, or neighboring residences. 9. Flow Control — Runoff collected in the sediment traps will discharge to the permanent detention vault outfall system. 2012 D. R.STRONG Consulting Engineers Inc. Page 44 of 55 Technical Information Report Altmyer March 29, 2012 KCRTS ANALYSIS FOR SEDIMENT TRAPS Land Use Summary T2o= Q ,,,£;,;.., Area .J Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.26 acres Outwash Forest 0.00 acres; Outwash Pasture 0.00 acres' Outwash Grass 0.00 acres Wetland' 0.00 acres Impervious 0.64 acres -Total--1 0.90 acres Scale Factor : 1.00 15-Min Reduced Edit Flow Paths Time Series: f15-Minute Trapl >>I Compute Time Series I Modify User Input File for computed Time Series [.TSF) Flow Frequency Analysis Time Series File: 15-minute trapl.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 0.305 6 8/27/01 18:00 0.885 1 100.00 0.990 0.212 8 9/17/02 17:45 0. 633 2 25.00 0.960 0. 633 2 12/08/02 17: 15 0. 421 3 10.00 0. 900 0.245 7 8/23/04 14:30 0.357 4 5.00 0.800 0.342 5 11/17/04 5:00 0.342 5 3.00 0.667 0.357 4 10/27/05 10: 45 0.305 6 2.00 0.500 0.421 3 10/25/06 22:45 0.245 7 1.30 0.231 0.885 1 1/09/08 6:30 0.212 8 1. 10 0.091 Computed Peaks 0.801 50.00 0.980 ©2012 D. R. STRONG Consulting Engineers Inc. Page 45 of 55 Technical Information Report Altmyer March 29,2012 Q. Land Use Summary o J X J Area ?J Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.66 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 1.62 acres -Total 2.28 acres Scale Factor : 1.00 15-Min Reduced Edit Flow Paths I Time Series: 15-Minute Trap2 >>I Compute Time Series I Modify User Input I File for computed Time Series [.TSF] Flow Frequency Analysis Time Series File:15-minute trap2.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 0.771 6 8/27/01 18:00 2.25 1 100.00 0. 990 0.538 8 9/17/02 17: 45 1.61 2 25.00 0. 960 1. 61 2 12/08/02 17: 15 1.07 3 10.00 0. 900 0. 620 7 8/23/04 14:30 0. 905 4 5.00 0.800 0.867 5 11/17/04 5:00 0.867 5 3.00 0.667 0. 905 4 10/27/05 10: 45 0.771 6 2.00 0.500 1. 07 3 10/25/06 22: 45 0. 620 7 1.30 0.231 2.25 1 1/09/08 6: 30 0. 538 8 1. 10 0.091 Computed Peaks 2.03 50.00 0.980 2012 D. R.STRONG Consulting Engineers Inc. Page 46 of 55 Technical Information Report Altmyer March 29, 2012 SWPPS PLAN DESIGN (PART B) Construction activities that could contribute pollutants to surface and storm water include the following, with applicable BMP's listed for each item: 1. Storage and use of chemicals: Utilize source control, and soil erosion and sedimentation control practices, such as using only recommended amounts of chemical materials applied in the proper manner; neutralizing concrete wash water, and disposing of excess concrete material only in areas prepared for concrete placement, or return to batch plant; disposing of wash-up waters from water-based paints in sanitary sewer; disposing of wastes from oil-based paints, solvents, thinners, and mineral spirits only through a licensed waste management firm, or treatment, storage, and disposal (TSD) facility. 2. Material delivery and storage: Locate temporary storage areas away from vehicular traffic, near the construction entrance, and away from storm drains. Material Safety Data Sheets (MSDS) should be supplied for all materials stored, and chemicals kept in their original labeled containers. Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other potentially hazardous materials. 3. Building demolition: Protect stormwater drainage system from sediment-laden runoff and loose particles. To the extent possible, use dikes, berms, or other methods to protect overland discharge paths from runoff. Street gutter, sidewalks, driveways, and other paved surfaces in the immediate area of demolition must be swept daily to collect and properly dispose of loose debris and garbage. Spray the minimum amount of water to help control windblown fine particles such as concrete, dust, and paint chips. Avoid excessive spraying so that runoff from the site does not occur, yet dust control is achieved. Oils must never be used for dust control. 4. Sawcutting: Slurry and cuttings shall be vacuumed during the activity to prevent migration offsite and must not remain on permanent concrete or asphalt paving overnight. Collected slurry and cuttings shall be disposed of in a manner that does not violate ground water or surface water quality standards. The complete CSWPPP can be found in Appendix B of this report. The site plans can be found in the engineering plan set. 2012 D. R.STRONG Consulting Engineers Inc. Page 47 of 55 Technical Information Report Altmyer March 29,2012 SECTION IX BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 1. Bond Quantity Worksheet — See Appendix A. 2. The Stormwater Facility Summary Sheet is included in this section. See Figure 7 for facility sketch. 2012 D. R.STRONG Consulting Engineers Inc. Page 48 of 55 Technical Information Report Altmyer March 29,2012 STORMWATER FACILITY SUMMARY SHEET Development Altmyer Date March 29, 2012 Location 11022 & 11023 SE 184th Place, Renton, Washington ENGINEER DEVELOPER Name Maher A. Joudi, P.E. Name Firm D. R. STRONG Consulting Firm Harbour Homes LLC Engineers, Inc. Address 10604 NE 38th Place, #101 Address 1441 North 34th Street, Suite 200 Kirkland, WA 98033 Seattle, WA 98103 Phone (425) 827-3063 Phone (206) 315-8130 Developed Site: 3.18 acres Number of lots 21 Number of detention facilities on site: Number of infiltration facilities on site: ponds ponds 1 vaults vaults tanks tanks Flow control provided in regional facility (give location) No flow control required Exemption number Downstream Drainage Basins Immediate Major Basin Basin Black River Green River Number & type of water quality facilities on site: biofiltration swale (regular/wet/ or continuous inflow?) sand filter (basic or large?) sand filter, linear (basic or large?) ADS BayFilter combined detention/WQ pond sand filter vault (basic or large?) combined detention/wetvault stormwater wetland compost filter wetpond (basic or large?) filter strip 1 wetvault flow dispersion pre-settling pond farm management plan flow-splitter catchbasin landscape management plan oil/water separator (baffle or coalescing plate?) ©2012 D.R.STRONG Consulting Engineers Inc. Page 49 of 55 Technical Information Report Altmyer March 29,2012 catch basin inserts: Manufacturer pre-settling structure: Manufacturer DESIGN INFORMATION INDIVIDUAL BASIN Water Quality design flow Water Quality treated volume Drainage basin(s) Onsite area (inlcudes frontage) 3.18 Offsite area 0 Type of Storage Facility Vault Live Storage Volume (required) 46,333 Predev Runoff Rate 2-year 0.088 10-year 0.154 100-year 0.256 Developed Runoff Rate 2-year 0.629 10-year 0.755 100-year 1.26 Type of Restrictor Frop-Tee Size of orifice/restriction No. 1 0.83 No. 2 1.46 No. 3 2.18 ©2012 D.R.STRONG Consulting Engineers Inc. Page 50 of 55 Technical Information Report Altmyer March 29,2012 SECTION X OPERATIONS AND MAINTENANCE MANUAL See attached excerpts from the 2005 King County Surface Water Design Manual. 2012 D. R.STRONG Consulting Engineers Inc. Page 51 of 55 Technical Information Report Altmyer March 29,2012 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 3-DETENTION TANKS AND VAULTS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Tank or Vault Trash and debris Any trash and debris accumulated in vault or tank No trash or debris in vault. Storage Area (includes floatables and non-floatables). Sediment Accumulated sediment depth exceeds 10%of the All sediment removed from storage accumulation diameter of the storage area for 1/2 length of area. storage vault or any point depth exceeds 15%of diameter. Example:72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than%length of tank. Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of Any part of tank/pipe is bent out of shape more Tank repaired or replaced to design. shape than 10%of its design shape. Gaps between A gap wider than1/2-inch at the joint of any tank No water or soil entering tank sections,damaged sections or any evidence of soil particles entering through joints or walls. joints or cracks or the tank at a joint or through a wall. tears in wall Vault Structure Damage to wall, Cracks wider than%-inch,any evidence of soil Vault is sealed and structurally frame,bottom,and/or entering the structure through cracks or qualified sound. top slab inspection personnel determines that the vault is not structurally sound. Inlet/Outlet Pipes Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than'1A-inch at the joint of the No cracks more than'/.-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-5 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 3-DETENTION TANKS AND VAULTS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Manhole access covered. Any open manhole requires immediate maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. not working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and remove cover/lid after applying 80 lbs of lift. reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs,misalignment,rust,or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access Damaged or difficult Large access doors or plates cannot be Replace or repair access door so it doors/plate to open opened/removed using normal equipment. can opened as designed. Gaps,doesn't cover Large access doors not flat and/or access Doors close flat and covers access completely opening not completely covered. opening completely. Lifting Rings missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to lift or rusted or plate. remove door or plate. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-6 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Trash and debris Trash or debris of more than'/cubic foot which No Trash or debris blocking or is located immediately in front of the structure potentially blocking entrance to opening or is blocking capacity of the structure by structure. more than 10%. Trash or debris in the structure that exceeds 1/3 No trash or debris in the structure. the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60%of the depth from the Sump of structure contains no bottom of the structure to the invert of the lowest sediment. pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Damage to frame Corner of frame extends more than%inch past Frame is even with curb. and/or top slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than/4 inch. Frame not sitting flush on top slab,i.e., Frame is sitting flush on top slab. separation of more than%inch of the frame from the top slab. Cracks in walls or Cracks wider than 1/2 inch and longer than 3 feet, Structure is sealed and structurally bottom any evidence of soil particles entering structure sound. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe. of soil particles entering structure through cracks. Settlement/ Structure has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than'A-inch at the joint of the No cracks more than'%-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the structure at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing Ladder is unsafe due to missing rungs, Ladder meets design standards and or unsafe misalignment,rust,cracks,or sharp edges. allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure T section securely attached to wall wall and outlet pipe structure should support at and outlet pipe. least 1,000 lbs of up or down pressure. Structure is not in upright position(allow up to Structure in correct position. 10%from plumb). Connections to outlet pipe are not watertight or Connections to outlet pipe are water show signs of deteriorated grout. tight;structure repaired or replaced and works as designed. Any holes—other than designed holes—in the Structure has no holes other than structure. designed holes. Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. 2009 Surface Water Design Manual–Appendix A 1/9/2009 A-7 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO.4-CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance Is Performed Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily and maintenance person. is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to Plate is in place and works as missing,out of place,or bent orifice plate. designed. Obstructions Any trash,debris,sediment,or vegetation Plate is free of all obstructions and blocking the plate. works as designed. Overflow Pipe Obstructions Any trash or debris blocking(or having the Pipe is free of all obstructions and potential of blocking)the overflow pipe. works as designed. Deformed or damaged Lip of overflow pipe is bent or deformed. Overflow pipe does not allow lip overflow at an elevation lower than design Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than'A-inch at the joint of the No cracks more than'A-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. Metal Grates Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s)of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs.of lift. reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Sediment Sediment exceeds 60%of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of more than 1/2 cubic foot which No Trash or debris blocking or is located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capacity of the catch basin catch basin. by more than 10%. Trash or debris in the catch basin that exceeds No trash or debris in the catch basin. 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Damage to frame Corner of frame extends more than 3/4 inch past Frame is even with curb. and/or top slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than'A inch. Frame not sitting flush on top slab,i.e., Frame is sitting flush on top slab. separation of more than 3/4 inch of the frame from the top slab. Cracks in walls or Cracks wider than 1/2 inch and longer than 3 feet, Catch basin is sealed and bottom any evidence of soil particles entering catch structurally sound. basin through cracks,or maintenance person judges that catch basin is unsound. Cracks wider than'A inch and longer than 1 foot No cracks more than 1/4 inch wide at at the joint of any inlet/outlet pipe or any evidence the joint of inlet/outlet pipe. of soil particles entering catch basin through cracks. Settlement/ Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than'''A-inch at the joint of the No cracks more than''/.-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the catch basin at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than'A-inch at the joint of the No cracks more than'/,-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 5-CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design (Catch Basins) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s)of the grate. Grate is in place and meets design Any open structure requires urgent standards. maintenance. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools.Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs.of lift. reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual—Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 6-CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20%of the diameter of the pipe. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged;rust or corrosion Pipe repaired or replaced. coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%or is determined to have weakened structural integrity of the pipe. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all sediment accumulation design depth. and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion observed on a ditch slope. Slopes are not eroding. slopes Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. place or missing(If area 5 square feet or more,any exposed native Applicable) soil. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 12-ACCESS ROADS Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway drivable by maintenance square feet(i.e.,trash and debris would fill up vehicles. one standards size garbage can). Debris which could damage vehicle tires or Roadway drivable by maintenance prohibit use of road. vehicles. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Blocked roadway Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restricting the access to a 10-to At least 12-foot of width on access 12 foot width for a distance of more than 12 feet road. or any point restricting access to less than a 10 foot width. Road Surface Erosion,settlement, Any surface defect which hinders or prevents Road drivable by maintenance potholes,soft spots, maintenance access. vehicles. ruts Vegetation on road Trees or other vegetation prevent access to Maintenance vehicles can access surface facility by maintenance vehicles. facility. Shoulders and Erosion Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches in hinder maintenance access. height or cleared in such a way as to allow maintenance access. Modular Grid Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of Pavement pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damaged or missing Access surface compacted because of broken on Access road surface restored so missing modular block. road infiltrates. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-17 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL,CONVEYANCE,AND WQ FACILITIES NO. 17-WETVAULT Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Treatment Area Trash and debris Any trash and debris accumulated in vault No trash or debris in vault. (includes floatables and non-floatables). Sediment Sediment accumulation in vault bottom exceeds No sediment in vault. accumulation the depth of the sediment zone plus 6 inches. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil,gasoline,concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vault Structure Damage to wall, Cracks wider than%-inch,any evidence of soil Vault is sealed and structurally frame,bottom,and/or entering the structure through cracks,vault does sound. top slab not retain water or qualified inspection personnel determines that the vault is not structurally sound. Baffles damaged Baffles corroding,cracking,warping and/or Repair or replace baffles or walls to showing signs of failure or baffle cannot be specifications. removed. Ventilation Ventilation area blocked or plugged. No reduction of ventilation area exists. Inlet/Outlet Pipe Sediment Sediment filling 20%or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes(includes floatables and non-floatables). Damaged Cracks wider than%-inch at the joint of the No cracks more than''h-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won't seal Valve does not seal completely. Valve completely seals closed. Access Manhole Access cover/lid Access cover/lid cannot be easily opened by one Access cover/lid can be opened by damaged or difficult to person. Corrosion/deformation of cover/lid. one person. open Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. not working maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and remove cover/lid after applying 80 lbs of lift. reinstalled by one maintenance person. Access doors/plate Large access doors not flat and/or access Doors close flat and covers access has gaps,doesn't opening not completely covered. opening completely. cover completely Lifting Rings missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to lift or rusted or plate. remove door or plate. Ladder rungs unsafe Missing rungs,misalignment,rust,or cracks. Ladder meets design standards. Allows maintenance person safe access. 2009 Surface Water Design Manual—Appendix A 1/9/2009 A-23 APPENDICES ©2012 D.R.STRONG Consulting Engineers Inc. Page 52 of 55 Technical Information Report Altmyer March 29,2012 APPENDIX A BOND QUANTITY WORKSHEET ©2012 D.R.STRONG Consulting Engineers Inc. Page 53 of 55 Technical Information Report Altmyer March 29,2012 Site Improvement Bond Quantity Worksheet Web date 12/02/2008 Ul King County Department of Development & Environmental Services 900 Oakesdale Avenue Southwest Renton, Washington 98057-5212 For alternate formats, call 206-296-6600. 206-296-6600 TTY 206-296-7217 Project Name: Altmyer Date: 10-May-12 Location: Renton Project No.: Activity No.: Note: All prices include labor, equipment, materials, overhead and Clearing greater than or equal to 5,000 board feet of timber? profit. Prices are from RS Means data adjusted for the Seattle area or from local sources if not included in the RS Means database. yes no If yes, Forest Practice Permit Number: (RCW 76.09) Page 1 of 9 Unit prices updated: 02/12/02 Version: 11/26/2008 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Unit #of Reference# Price Unit Quantity Applications Cost EROSION/SEDIMENT CONTROL Number Backfill & compaction-embankment ESC-1 $ 5.62 CY Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 $ 67.51 Each 40 1 2700 Crushed surfacing 1 1/4" minus ESC-3 WSDOT 9-03.9(3) $ 85.45 CY Ditching ESC-4 $ 8.08 CY 225 1 1818 Excavation-bulk ESC-5 $ 1.50 CY Fence, silt ESC-6 SWDM 5.4.3.1 $ 1.38 LF 800 1 1104 Fence, Temporary (NGPE) ESC-7 S 1.38 LF 725 1 1001 Hydroseeding ESC-8 SWDM 5.4.2.4 $ 0.59 SY 11635 1 6865 Jute Mesh ESC-9 SWDM 5.4.2.2 $ 1.45 SY Mulch, by hand, straw, 3" deep ESC-10 SWDM 5.4.2.1 $ 2.01 SY Mulch, by machine, straw, 2"deep ESC-11 SWDM 5.4.2.1 $ 0.53 SY Piping, temporary, CPP, 6" ESC-12 $ 10.70 LF Piping, temporary, CPP, 8" ESC-13 $ 16.10 LF Piping, temporary, CPP, 12" ESC-14 $ 20.70 LF 500 1 10350 Plastic covering, 6mm thick, sandbagged ESC-15 SWDM 5.4.2.3 $ 2.30 SY Rip Rap, machine placed; slopes ESC-16 WSDOT 9-13.1(2) $ 39.08 CY Rock Construction Entrance, 50'x15'x1' ESC-17 SWDM 5.4.4.1 $ 1,464.34 Each 1 1 1464 Rock Construction Entrance, 100'x15'x1' ESC-18 SWDM 5.4.4.1 $ 2,928.68 Each Sediment pond riser assembly ESC-19 SWDM 5.4.5.2 $ 1,949.38 Each Sediment trap, 5' high berm ESC-20 SWDM 5.4.5.1 $ 17.91 LF 325 1 5821 Sed.trap, 5' high, riprapped spillway berm section ESC-21 SWDM 5.4.5.1 $ 68.54 LF Seeding, by hand ESC-22 SWDM 5.4.2.4 $ 0.51 SY Sodding, 1" deep, level ground ESC-23 SWDM 5.4.2.5 $ 6.03 SY Sodding, 1"deep, sloped ground ESC-24 SWDM 5.4.2.5 $ 7.45 SY TESC Supervisor ESC-25 $ 74.75 HR 120 1 8970 Water truck, dust control ESC-26 SWDM 5.4.7 $ 97.75 HR 80 1 7820 WRITE-IN-ITEMS **** (see page 9) Each ESC SUBTOTAL: $ 47,912.64 30% CONTINGENCY& MOBILIZATION: $ 14,373.79 ESC TOTAL: $ 62,286.43 COLUMN: A Page 2 of 9 Unit prices updated: 02/12/02 Version: 11/26/2008 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Existing Future Public Private Quantity Completed Right-of-Way Right of Way Improvements (Bond Reduction)* &Drainage Facilities Quant. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost GENERAL ITEMS No. Backfill&Compaction-embankment GI-1 $ 5.62 CY 727 4,085.74 2182 12,262.84 Backfill&Compaction-trench GI-2 $ . 8.53 CY 7 59.71 1410 12,027.30 210 1,791.30 Clear/Remove Brush,by hand GI-3 $ 0.36 SY Clearing/Grubbing/Tree Removal GI-4 $ 8,876.16 Acre 0.8 7,100.93 2.4 21,302.78 Excavation-bulk GI-5 $ 1.50 CY 965 1,447.50 2896 4,344.00 Excavation-Trench GI-6 $ 4.06 CY 7 28.42 1410 5,724.60 210 852.60 Fencing,cedar,6'high GI-7 $ 18.55 LF Fencing,chain link,vinyl coated, 6'high GI-8 $ 13.44 LF 155 2,083.20 Fencing,chain link,gate,vinyl coated, 2 GI-9 $ 1,271.81 Each 1 1,271.81 Fencing,split rail,3'high GI-10 $ 12.12 LF Fill&compact-common barrow GI-11 $ 22.57 CY Fill&compact-gravel base GI-12 $ 25.48 CY Fill&compact-screened topsoil GI-13 $ 37.85 CY Gabion, 12"deep,stone filled mesh GI-14 $ 54.31 SY Gabion, 18"deep,stone filled mesh GI-15 $ 74.85 SY Gabion,36"deep,stone filled mesh GI-16 $ 132.48 SY Grading,fine,by hand GI-17 $ 2.02 SY Grading,fine,with grader GI-18 $ 0.95 SY Monuments,3'long GI-19 $ 135.13 Each 1 135.13 Sensitive Areas Sign GI-20 $ 2.88 Each Sodding, 1"deep,sloped ground GI-21 $ 7.46 SY Surveying,line&grade GI-22 $ 788.26 Day 10 7,882.60 Surveying,lot location/lines GI-23 $ 1,556.64 Acre 2.2 3,424.61 Traffic control crew(2 flaggers) GI-24 $ 85.18 HR Trail,4"chipped wood GI-25 $ 7.59 SY Trail,4"crushed cinder GI-26 $ 8.33 SY Trail,4"top course GI-27 $ 8.19 SY Wall,retaining,concrete GI-28 $ 44.16 SF Wall,rockery GI-29 $ 9.49 SF Page 3 of 9 SUBTOTAL 88.13 41,758.81 43,978.13 • Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Existing Future Public Private Bond Reduction* Right-of-way Right of Way Improvements &Drainage Facilities Quant. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost ROAD IMPROVEMENT No. AC Grinding,4'wide machine<1000sy RI-1 $ 28.00 SY AC Grinding,4'wide machine 1000-2000 RI-2 $ 15.00 SY AC Grinding,4'wide machine>2000sy RI-3 $ 7.00 SY AC Removal/Disposal/Repair RI-4 $ 67.50 SY 2475 167,062.50 Barricade,type I RI-5 $ 30.03 LF Barricade,type III(Permanent) RI-6 $ 45.05 LF Curb&Gutter,rolled RI-7 $ 17.00 LF Curb&Gutter,vertical RI-8 $ 12.50 LF 50 625.00 1130 14,125.00 Curb and Gutter,demolition and disposal RI-9 $ 18.00 LF 10 180.00 Curb,extruded asphalt RI-10 $ 5.50 LF Curb,extruded concrete RI-11 $ 7.00 LF Sawcut,asphalt,3"depth RI-12 $ 1.85 LF 80 148.00 Sawcut,concrete,per 1"depth RI-13 $ 1.69 LF Sealant,asphalt RI-14 $ 1.25 LF 80 100.00 Shoulder,AC, (see AC road unit price) RI-15 $ - SY Shoulder,gravel,4"thick RI-16 $ 15.00 SY Sidewalk,4"thick RI-17 $ 35.00 SY 30 1,050.00 650 22,750.00 Sidewalk,4"thick,demolition and dispos RI-18 $ 29.50 SY 10 295.00, Sidewalk,5"thick RI-19 $ 38.50 SY Sidewalk,5"thick,demolition and dispos RI-20 $ 37.50 SY Sign,handicap RI-21 $ 85.28 Each Striping,per stall RI-22 $ 5.82 Each Striping,thermoplastic,(for crosswalk) RI-23 $ 2.38 SF Striping,4"reflectorized line RI-24 $ 0.25 LF Page 4 of 9 SUBTOTAL 2,398.00 203,937.50 Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date:5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Existing Future Public Private Bond Reduction* Right-of-way Right of Way Improvements &Drainage Facilities Quant. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost ROAD SURFACING (4"Rock=2.5 base&1.5"top course) For'93 KCRS(6.5"Rock=5"base&1.5"top course) For KCRS'93,(additional 2.5"base)add RS-1 $ 3.60 SY AC Overlay, 1.5"AC RS-2 $ 11.25 SY AC Overlay,2"AC RS-3 $ 15.00 SY AC Road,2",4"rock,First 2500 SY RS-4 $ 21.00 SY 65 1,365.00 1660 34,860.00 805 16,905.00 AC Road,2",4"rock,Qty.over 2500SY RS-5 $ 19.00 SY AC Road,3",4"rock,First 2500 SY RS-6 $ 23.30 SY AC Road,3",4"rock,Qty.over 2500 SY RS-7 $ 21.00 SY AC Road,5",First 2500 SY RS-8 $ 27.60 SY AC Road,5",Qty.Over 2500 SY RS-9 $ 25.00 SY AC Road,6",First 2500 SY RS-1C $ 33.10 SY AC Road,6",Qty.Over 2500 SY RS-11 $ 30.00 SY Asphalt Treated Base,4"thick RS-12 $ 20.00 SY 65 1,300.00 1660 33,200.00 Gravel Road,4"rock,First 2500 SY RS-12 $ 15.00 SY Gravel Road,4"rock,Qty.over 2500 SY RS-14 $ 8.50 SY PCC Road,5",no base,over 2500 SY RS-15 $ 27.00 SY PCC Road, 6",no base,over 2500 SY RS-16 $ 25.50 SY Thickened Edge RS-17 $ 8.60 LF 370 3,182.00 Page 5 of 9 SUBTOTAL 2,665.00 68,060.00 20,087.00 Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Existing Future Public Private Bond Reduction* Right-of-way Right of Way Improvements 8 Drainage Facilities Quant. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost DRAINAGE (CPP=Corrugated Plastic Pipe, N12 or Equivalent) For Culvert prices, Average of 4'cover was assumed.Assume perforated PVC is same price as solid pipe. Access Road, R/D D-1 $ 21.00 SY 230 4,830.00 Bollards-fixed D-2 $ 240.74 Each Bollards-removable D-3 $ 452.34 Each (CBs include frame and lid) CB Type I D-4 $ 1,257.64 Each 1 1,257.64 3 3,772.92 4 5,030.56 CB Type IL D-5 $ 1,433.59 Each CB Type II,48"diameter D-6 $ 2,033.57 Each 8 16,268.56 for additional depth over 4' D-7 $ 436.52 FT 56.77 24,781.24 CB Type II,54"diameter D-8 $ 2,192.54 Each for additional depth over 4' D-9 $ 486.53 FT CB Type II,60"diameter D-10 $ 2,351.52 Each for additional depth over 4' D-11 S 536.54 FT CB Type II,72"diameter D-12 $ 3,212.64 Each for additional depth over 4' D-13 $ 692.21 FT Through-curb Inlet Framework(Add) D-14 $ 366.09 Each 4 1,464.36 Cleanout, PVC,4" D-15 $ 130.55 Each Cleanout, PVC,6" D-16 $ 174.90 Each Cleanout, PVC,8" D-17 $ 224.19 Each Culvert, PVC.4" D-18 $ 8.64 LF Culvert, PVC,6" D-19 $ 12.60 LF Culvert,PVC, 8" D-20 $ 13.33 LF Culvert, PVC, 12" D-21 $ 21.77 LF Culvert,CMP,8" D-22 $ 17.25 LF Culvert,CMP, 12" D-23 $ 26.45 LF Culvert,CMP, 15" D-24 S 32.73 LF Culvert,CMP, 18" D-25 $ 37.74 LF Culvert,CMP,24" D-26 $ 53.33 LF Culvert,CMP,30" D-27 S 71.45 LF Culvert,CMP,36" D-28 S 112.11 LF Culvert,CMP,48" D-29 $ 140.83 LF Culvert,CMP,60" D-30 $ 235.45 LF Culvert,CMP,72" D-31 $ 302.58 LF Page 6 of 9 SUBTOTAL 1,257.64 51,117.08 5,030.56 Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Web date: 12/02/2008 Site Improvement Bond Quantity Worksheet Existing Future Public Private Bond Reduction* Right-of-way Right of Way Improvements DRAINAGE CONTINUED &Drainage Facilities Quant. No. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost Culvert,Concrete,8" D-32 $ 21.02 LF Culvert,Concrete, 12" D-33 $ 30.05 LF Culvert,Concrete, 15" D-34 $ 37.34 LF Culvert,Concrete, 18" D-35 S 44.51 LF Culvert,Concrete,24" D-36 5 61.07 LF Culvert,Concrete,30" D-37 $ 104.18 LF Culvert,Concrete,36" D-38 $ 137.63 LF Culvert,Concrete,42" D-39 $ 158.42 LF Culvert,Concrete,48" D-40 5 175.94 LF Culvert,CPP,6" D-41 S 10.70 LF Culvert,CPP,8" D-42 5 16.10 LF Culvert,CPP, 12" D-43 $ 20.70 LF 25 517.5 375 7762.5 915 18940.5 Culvert,CPP, 15" D-44 $ 23.00 LF Culvert, CPP, 18" D-45 $ 27.60 LF 330 9108 Culvert,CPP,24" D-46 $ 36.80 LF 610 22448 Culvert,CPP,30" D-47 S 48.30 LF Culvert,CPP,36" D-48 $ 55.20 LF Ditching D-49 $ 8.08 CY Flow Dispersal Trench (1,436 base+) D-50 S 25.99 LF French Drain (3'depth) D-51 $ 22.60 LF Geotextile, laid in trench, polypropylene D-52 $ 2.40 SY Infiltration pond testing D-53 $ 74.75 HR Mid-tank Access Riser,48"dia, 6'deep D-54 $ 1,605.40 Each Pond Overflow Spillway D-55 $ 14.01 SY Restrictor/Oil Separator, 12" D-56 $ 1,045.19 Each 1 1045.19 Restrictor/Oil Separator, 15" D-57 $ 1,095.56 Each Restrictor/Oil Separator, 18" D-58, $ 1,146.16 Each Riprap,placed D-59 $ 39.08 CY Tank End Reducer(36"diameter) D-60 $ 1,000.50 Each Trash Rack, 12" D-61 $ 211.97 Each Trash Rack, 15" D-62 $ 237.27 Each Trash Rack, 18" D-63 $ 268.89 Each Trash Rack,21" D-64 $ 306.84 Each Page 7 of 9 SUBTOTAL 517.5 40363.69 18940.5 Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Existing Future Public Private Bond Reduction* Right-of-way Right of Way Improvements &Drainage Facilities Quant. Unit Price Unit Quant. Price Quant. Cost Quant. Cost Complete Cost PARKING LOT SURFACING No. 2"AC,2"top course rock&4"borrow PL-1 S 21.00 SY • 2"AC, 1.5" top course&2.5"base cour PL-2 $ 28.00 SY 4"select borrow PL-3 $ 4.55 SY 1.5"top course rock&2.5"base course PL-4 $ 11.41 SY UTILITY POLES & STREET LIGHTING Utility pole relocation costs must be accompanied by Franchise Utility's Cost Statement Utility Pole(s)Relocation UP-1 Lump Sum Street Light Poles w/Luminaires UP-2 $ 3,000.00 Each WRITE-IN-ITEMS (Such as detention/water quality vaults.) No. Detention/Water Quality Vault WI-1 lJ/NIdNl ItJt Each 1 200,000.00 WI-2 Each WI-3 Each WI-4 LF WI-5 FT WI-6 WI-7 WI-8 WI-9 wi-io SUBTOTAL 200,000.00 SUBTOTAL(SUM ALL PAGES): 6,926.27 605,237.08 88,036.19 30%CONTINGENCY&MOBILIZATION: 2,077.88 181,571.12 26,410.86 GRANDTOTAL: 9,004.15 786,808.20 114,447.05 COLUMN: B C D E Page 8 of 9 Unit prices updated: 02/12/02 *KCC 27A authorizes only one bond reduction. Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 Site Improvement Bond Quantity Worksheet Web date: 12/02/2008 Original bond computations prepared by: Name: Maher A. Joudi Date: 10-May-12 PE Registration Number: 45232 Tel.#: (425) 827-3063 Firm Name: DR STRONG Consulting Engineers, Inc. Address: 10604 NE 38th Place, Suite 101 Kirkland, WA 98033 Project No: ROAD IMPROVEMENTS&DRAINAGE FACILITIES FINANCIAL GUARANTEE REQUIREMENTS PERFORMANCE BOND* PUBLIC ROAD&DRAINAGE AMOUNT BOND*AMOUNT MAINTENANCE/DEFECT BOND* REQUIRED AT RECORDING OR Stabilization/Erosion Sediment Control (ESC) (A) $ 62,286.4 TEMPORARY OCCUPANCY*** Existing Right-of-Way Improvements (B) $ 9,004.2 Future Public Right of Way& Drainage Facilities (C) $ 786,808.2 Private Improvements (D) $ 114,447.0 Calculated Quantity Completed (E) $ - Total Right-of Way and/or Site Restoration Bond*/** (A+B) $ 71,290.6 (First$7,500 of bond*shall be cash.) Performance Bond*Amount (A+B+C+D) = TOTAL (T) $ 972,545.8 T x 0.30 $ 291,763.8 OR Minimum bond*amount is$2000. Reduced Performance Bond*Total*** (T-E) $ 972,545.8 Use larger of Tx30%or(T-E) (B+C)x Maintenance/Defect Bond*Total 0.25= $ 198,953.1 NAME OF PERSON PREPARING BOND*REDUCTION: Date: *NOTE: The word"bond"as used in this document means a financial guarantee acceptable to King County. **NOTE: KCC 27A authorizes right of way and site restoration bonds to be combined when both are required. The restoration requirement shall include the total cost for all TESC as a minimum, not a maximum. In addition,corrective work, both on-and off-site needs to be included. Quantities shall reflect worse case scenarios not just minimum requirements. For example, if a salmonid stream may be damaged,some estimated costs for restoration needs to be reflected in this amount. The 30%contingency and mobilization costs are computed in this quantity. ***NOTE: Per KCC 27A,total bond amounts remaining after reduction shall not be less than 30%of the original amount(T)or as revised by major design changes. REQUIRED BOND*AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY DDES Page 9 of 9 Unit prices updated: 02/12/02 Check out the DDES Web site at www.kingcountv.gov/permits Version: 11/26/08 Bond Quantity Worksheet12011.xlsx Report Date: 5/23/2012 APPENDIX B CSWPPP 2012 D. R.STRONG Consulting Engineers Inc. Page 54 of 55 Technical Information Report Altmyer March 29, 2012 STORMWATER POLLUTION PREVENTION PLAN For ALTMYER Prepared For Northwest Regional Office 3190 160th Avenue SE Bellevue, WA 98008-5452 425-649-7000 Owner Developer Operator/Contractor Harbour Homes LLC Harbour Homes LLC Maher A. Joudi, P.E. 1441 N 34th Street, Suite 200 1441 N 34th Street, Suite 200 10604 NE 38th Place, Suite 101 Seattle, Washington 98103 Seattle, Washington 98103 Kirkland, Washington 98033 Project Site Location 11022 and 11023 SE 184th Place Renton, Washington Certified Erosion and Sediment Control Lead TBD XXX.XXX.XXXX SWPPP Prepared By D.R. Strong Consulting Engineers, Inc. 10604 NE 38th Place, Suite 101 Kirkland, Washington 98033 Maher A. Joudi, P.E., Senior Project Engineer SWPPP Preparation Date March 20, 2012 Approximate Project Construction Dates TBD ©2012 D. R.STRONG Consulting Engineers Inc. STORMWATER POLLUTION PREVENTION PLAN TABLE OF CONTENTS 1.0 INTRODUCTION 1 2.0 SITE DESCRIPTION 3 2.1 Existing Conditions 3 2.2 Proposed Construction Activities 3 3.0 CONSTRUCTION STORMWATER BMPS 5 3.1 The 12 BMP Elements 5 3.1.1 Element#1 — Mark Clearing Limits 5 3.1.2 Element #2 — Establish Construction Access 5 3.1.3 Element #3 — Control Flow Rates 6 3.1.4 Element#4 — Install Sediment Controls 6 3.1.5 Element#5 — Stabilize Soils 7 3.1.6 Element#6 — Protect Slopes 8 3.1.7 Element #7 — Protect Drain Inlets 9 3.1.8 Element#8 — Stabilize Channels and Outlets 9 3.1.9 Element#9 — Control Pollutants 10 3.1.10 Element#10 — Control Dewatering 11 3.1.11 Element#11 — Maintain BMPs 11 3.1.12 Element#12 — Manage the Project 11 3.2 Site Specific BMPs 13 3.3 Additional Advanced BMPs 13 4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION 14 5.0 POLLUTION PREVENTION TEAM 15 5.1 Roles and Responsibilities 15 5.2 Team Members 15 6.0 SITE INSPECTIONS AND MONITORING 16 6.1 Site Inspection 16 6.1.1 Site Inspection Frequency 16 6.1.2 Site Inspection Documentation 16 6.2 Stormwater Quality Monitoring 17 6.2.1 Turbidity Sampling 17 6.2.2 pH Sampling 17 6.2.3 Temperature Monitoring 18 7.0 REPORTING AND RECORDKEEPING 19 7.1 Recordkeeping 19 7.1.1 Site Log Book 19 7.1.2 Records Retention 19 ©2012 D.R.STRONG Consulting Engineers Inc. Page i of ii Stormwater Pollution Prevention Plan Altmyer March 20,2012 7.1.3 Access to Plans and Records 19 7.1.4 Updating the SWPPP 19 7.2 Reporting 20 7.2.1 Discharge Monitoring Reports 20 7.2.2 Notification of Noncompliance 20 7.2.3 Permit Application and Changes 20 Appendices Appendix A — Site Plans 21 Appendix B — Construction BMPs 22 Appendix C —Alternative BMPs 23 Appendix D — General Permit 24 Appendix E — Site Inspection Forms (And Site Log) 25 Appendix F — Engineering Calculations 33 Appendix A Site Plans • Vicinity map (with all discharge points) • Site plan with TESC measures Appendix B Construction BMPs • Possibly reference in BMPs, but likely it will be a consolidated list so that the applicant can photocopy from the list from the SWMM. Appendix C Alternative Construction BMP list • List of BMPs not selected, but can be referenced if needed in each of the 12 elements Appendix D General Permit Appendix E Site Log and Inspection Forms Appendix F Engineering Calculations • Flows, ponds, etc... ©2012 D. R.STRONG Consulting Engineers Inc. Page ii of ii Stormwater Pollution Prevention Plan Altmyer March 20, 2012 Stormwater Pollution Prevention Plan 1 .0 INTRODUCTION This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the Altmyer residential project located in Renton, Washington. The site is located at 11022 and 11023 SE 184th Place Renton, Washington. The proposed development consists of the construction of 21 single family dwelling units, roadway improvements, stormwater detention facility, and landscaping on 3.12 acres. Construction activities will include, grading, roadway construction, utility installation and home construction. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: 1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on July 2, 2005. This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2005) and in the Stormwater Management Manual for Eastern Washington (SWMMEW 2004). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: • Section 1 — INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. • Section 2 — SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post— construction conditions. • Section 3 — CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP (SWMMEW 2004). ©2012 D. R.STRONG Consulting Engineers Inc. Page 1 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan • Section 4 — CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. • Section 5 — POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non-emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector • Section 6 — INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all stormwater discharge locations from the site. • Section 7 — RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A— Site plans Appendix B — Construction BMPs Appendix C —Alternative Construction BMP list Appendix D — General Permit Appendix E — Site Log and Inspection Forms Appendix F — Engineering Calculations 2012 D. R.STRONG Consulting Engineers Inc. Page 2 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 2.0 SITE DESCRIPTION 2.1 Existing Conditions Total site (Site) area is approximately 136,064 s.f. (3.1236 ac.). The Site's developable area is approximately 138,475 s.f. (3.1790 ac.), which includes 2,411 s.f. (0.0553 ac) for the offsite right-of-way improvements. The Site is currently developed with two single family residences, associated driveways and landscaping. A large portion of the Site is residential lawn and landscaping. For purposes of flow control analysis and design, the Site will be considered till forest in its predeveloped state. 2.2 Proposed Construction Activities The applicant is seeking approval to subdivide 3.18 acres into 21 single-family residential lots (Project), with lot sizes ranging from approximately 3,063 to 6,238 s.f. The proposed impervious surface area will include new right of ways with 24 feet of curb to curb, curb, gutter, and a 5-foot sidewalk (38-foot right of way). The proposed right-of- way improvements total approximately 25,943 s.f. The 21 single-family residences and their driveways combined will create approximately 62,706 s.f. of impervious area using the maximum allowable build-out rate specified in the King County Zoning Code and deducting 10% to accommodate flow control bmp requirements. The Site is contained within one Threshold Discharge Area (TDA) and has one Natural Discharge Area (NDA). Runoff sheet flows to the existing drainage system within SE 184th Place and enters into the detention pond or combines with the discharge from the detention pond. The outfall system was analyzed by J3ME Engineers at the preliminary plat phase of this Project. Per the 2005 King County Surface Water Design Manual (KCSWDM), each project is required to mitigate an area equal to 10% of the lot area. This Project will utilize the impervious surface reduction option by reducing the allowable impervious surface per lot to 65% of the total lot area. A note will be placed on the face of the final plat. The following summarizes details regarding site areas: • Total site area: 3.18 acres • Percent impervious area before construction: 22.6 • Percent impervious area after construction: 71.0 % • Disturbed area during construction: 3.18 acres • Disturbed area that is characterized as impervious (i.e., access roads, staging, parking): 0.72 acres TDA 2012 D. R.STRONG Consulting Engineers Inc. Page 3 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan • 2-year stormwater runoff peak flow prior to construction (existing): 0.088 cfs • 10-year stormwater runoff peak flow prior to construction (existing): 0.154 cfs • 2-year stormwater runoff peak flow during construction: 0.157 cfs • 10-year stormwater runoff peak flow during construction: 0.292 cfs • 2-year stormwater runoff peak flow after construction: 0.057 cfs • 10-year stormwater runoff peak flow after construction: 0.133 cfs All stormwater flow calculations are provided in Appendix F. 2012 D. R. STRONG Consulting Engineers Inc. Page 4 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 3.0 CONSTRUCTION STORMWATER BMPS 3.1 The 12 BMP Elements 3.1.1 Element#1 — Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: • High Visibility Plastic or Metal Fence (BMP C103) The plastic fence will be placed around the perimeter of the developable area of the Site. BMP will be implemented at the start of construction. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element #2 — Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: • Stabilized Construction Entrance (BMP C105) • Construction Road/Parking Area Stabilization (BMP C107) A Stabilized Construction Entrance will be placed at the entrance of the Site on SE 184th Place. This BMP will be implemented at the start of construction. Construction Road and Parking Area Stabilization will take place along the road into the site. This will occur as the project goes along. Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues 2012 D. R. STRONG Consulting Engineers Inc. Page 5 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element#3 — Control Flow Rates In order to protect the properties and waterways downstream of the project site, stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: • Detention Vault A detention/water quality vault will be installed in Tract B. The vault will be constructed and used as a sedimentation device during construction. Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, the project must comply with Minimum Requirement 7 (Ecology 2005). In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element#4 — Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence (BMP C233) • Storm Drain Inlet Protection (BMP C220) • Interceptor Swale (BMP C200) • Sediment Trap • Detention Vault Silt fence will be installed around the perimeter of the Site in areas where runoff could sheet-flow offsite. This BMP will be installed at the start of construction. Storm Drain Inlet Protection will be installed on all newly constructed catch basins throughout the site as well as the tie in catch basins. The tie in catch basin protection CD 2012 D. R.STRONG Consulting Engineers Inc. Page 6 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan will be installed at the start of construction, and protection for the newly constructed catch basins will occur as they are installed. The interceptor swale and sediment trap will be installed during the time of grading. The detention vault will be installed and used for sedimentation during construction. Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. The following BMPs will be implemented as end-of-pipe sediment controls as required to meet permitted turbidity limits in the site discharge(s). Prior to the implementation of these technologies, sediment sources and erosion control and soil stabilization BMP efforts will be maximized to reduce the need for end-of-pipe sedimentation controls. • Construction Stormwater Filtration (BMP C251) • Construction Stormwater Chemical Treatment (BMP C 250) (implemented only with prior written approval from Ecology). 3.1.5 Element#5 — Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: • Temporary and Permanent Seeding (BMP C120) 2012 D. R.STRONG Consulting Engineers Inc. Page 7 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan • Plastic Covering (BMP C123) • Dust Control (BMP C140) Permanent Seeding will occur as grading is completed. All stabilized sections will be seeded and vegetated. Plastic Covering will occur throughout the site as deemed necessary by the contractor and CESCL. Dust Control will occur throughout the site as deemed necessary by the contractor and CESCL. Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no soils shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element#6 — Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes erosion. The following specific BMPs will be used to protect slopes for this project: • Temporary and Permanent Seeding (BMP C120) • Pipe Slope Drains (BMP C204) • Check Dams (BMP C207) Permanent Seeding will occur throughout the site as slopes are stabilized. Pipe Slope Drains will be installed to convey runoff across 2:1 slopes. These will be installed throughout the grading process as slopes are constructed and stabilized. Checks Dams will be installed every 50' as shown on the plan. Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General O 2012 D. R. STRONG Consulting Engineers Inc. Page 8 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element #7 — Protect Drain Inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment-laden runoff on and near the project site. The following inlet protection measures will be applied on this project: Drop Inlet Protection • Catch Basin Filters There two existing catch basins which will require protection. The outlet catch basin in Tract B will require a catch basin filter be installed while the outfall system is being constructed for the detention vault. If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element #8 — Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: • No BMPs to be implemented The project will not discharge to any outlets or channels; therefore no BMP's are required. Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site conveyance channels shall be designed, constructed, and stabilized to prevent 2012 D. R.STRONG Consulting Engineers Inc. Page 9 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan erosion from the expected peak 10 minute velocity of flow from a Type 1A, 10-year, 24- hour recurrence interval storm for the developed condition. Alternatively, the 10-year, 1- hour peak flow rate indicated by an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems. 3.1.9 Element #9 — Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well-organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. Vehicles, construction equipment, and/or petroleum product storage/dispensing: • All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks or spills. • On-site fueling tanks and petroleum product storage containers shall include secondary containment. • Spill prevention measures, such as drip pans, will be used when conducting maintenance and repair of vehicles or equipment. • In order to perform emergency repairs on site, temporary plastic will be placed beneath and, if raining, over the vehicle. • Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Demolition: • Dust released from demolished sidewalks, buildings, or structures will be controlled using Dust Control measures (BMP C140). • Storm drain inlets vulnerable to stormwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet Protection (BMP C220 as described above for Element 7). • Process water and slurry resulting from sawcutting and surfacing operations will be prevented from entering the waters of the State by implementing Sawcutting and Surfacing Pollution Prevention measures (BMP C152). Concrete and grout: • Process water and slurry resulting from concrete work will be prevented from entering the waters of the State by implementing Concrete Handling measures (BMP C151). Sanitary wastewater: CD 2012 D. R.STRONG Consulting Engineers Inc. Page 10 of 41 Stormwater Pollution Prevention Plan Altmyer March 20, 2012 Stormwater Pollution Prevention Plan • Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Solid Waste: • Solid waste will be stored in secure, clearly marked containers. Other: • Other BMPs will be administered as necessary to address any additional pollutant sources on site. The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act (CWA). 3.1.10 Element#10 — Control Dewatering There will be no dewatering as part of this construction project. 3.1.11 Element #11 — Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications (attached). Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element#12 — Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: • Design the project to fit the existing topography, soils, and drainage patterns. • Emphasize erosion control rather than sediment control. • Minimize the extent and duration of the area exposed. • Keep runoff velocities low. • Retain sediment on site. • Thoroughly monitor site and maintain all ESC measures. • Schedule major earthwork during the dry season. In addition, project management will incorporate the key components listed below: (West Response) As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: 2012 D. R.STRONG Consulting Engineers Inc. Page 11 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan Phasing of Construction • The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. • Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations • From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt-laden runoff will be prevented from leaving the site through a combination of the following: o Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and o Limitations on activities and the extent of disturbed areas; and o Proposed erosion and sediment control measures. • Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. • The following activities are exempt from the seasonal clearing and grading limitations: o Routine maintenance and necessary repair of erosion and sediment control BMPs; o Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and o Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions • Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. Inspection and Monitoring • All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: ©2012 D. R. STRONG Consulting Engineers Inc. Page 12 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan o Assess the site conditions and construction activities that could impact the quality of stormwater, and o Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. • A Certified Erosion and Sediment Control Lead shall be on-site or on-call at all times. • Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP • This SWPPP shall be retained on-site or within reasonable access to the site. • The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. • The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. If the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 3.3 Additional Advanced BMPs 2012 D. R.STRONG Consulting Engineers Inc. Page 13 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 4.0 CONSTRUCTION PHASING AND BMP IMPLEMENTATION The BMP implementation schedule will be driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. The BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October 1 to April 30. Schedule to be determined • Estimate of Construction start date: • Estimate of Construction finish date: • Mobilize equipment on site: • Mobilize and store all ESC and soil stabilization products: • Install ESC measures: • Begin clearing and grubbing: • Demolish existing buildings: • Begin Site Grading: • End Site Grading • Begin Utility Construction • End Utility Construction • Begin implementing soil stabilization and sediment control BMPs throughout the site: • Begin Paving and Sidewalk Installation: • End Paving and Sidewalk Installation: • Final landscaping and planting begins: • Permanent erosion control measures (hydroseeding): 2012 D. R. STRONG Consulting Engineers Inc. Page 14 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 5M POLLUTION PREVENTION TEAM 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: • Certified Erosion and Sediment Control Lead (CESCL) — primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. • Resident Engineer — For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative • Emergency Ecology Contact — individual to be contacted at Ecology in case of emergency • Emergency Owner Contact — individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. • Non-Emergency Ecology Contact — individual that is the site owner or representative of the site owner than can be contacted if required. • Monitoring Personnel — personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Phone Number Certified Erosion and Sediment Control Lead(CESCL) Resident Engineer Maher A.Joudi, P.E. 425.827.3063 Emergency Ecology Contact NW Regional Office 425.649.7000 Emergency Owner Contact Jamie Waltier 206.315.8130 Non-Emergency Ecology Contact Monitoring Personnel ©2012 D. R.STRONG Consulting Engineers Inc. Page 15 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 6.0 SITE INSPECTIONS AND MONITORING Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements; • Site inspections; and, • Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL) per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month. 6.t2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but will be maintained on-site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. ©2012 D. R.STRONG Consulting Engineers Inc. Page 16 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 6.2 Stormwater Quality Monitoring The Site will discharge into an existing storm drainage systems. Before project discharge leaves the Site, it enters a detention/water quality vault which includes a stormfilter manhole along its outfall. This will be sufficient in accommodating water quality requirements. Testing at the outlet will still occur as necessary. 6.2.1 Turbidity Sampling Sampling and monitoring will be conducted during the entire construction phase of the project. Samples will be collected daily at the downstream catch basin for the vault. If there is no flow in this catch basin, the attempt to sample will be recorded in the site log book and reported to Ecology in the monthly Discharge Monitoring Report (DMR) as "No Discharge". Samples will be analyzed for turbidity using the EPA 180.1 analytical method. The key benchmark turbidity value is 25 nephelometric turbidity units (NTU) for the downstream receiving water body. If the 25 NTU benchmark is exceeded in any sample collected from the tested catch basins, the following steps will be conducted: 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document modified BMPs in the SWPPP as necessary. 3. Sample discharge daily until the discharge is 25 NTU or lower. If the turbidity exceeds 250 NTU at any time, the following steps will be conducted: 1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of this SWPPP for contact information). 2. Continue sampling daily until the discharge is 25 NTU or lower Initiate additional treatment BMPs such as off-site treatment, infiltration, filtration and chemical treatment within 24 hours, and implement those additional treatment BMPs as soon as possible, but within a minimum of 7 days. 3. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Sampling Sampling and monitoring for pH will occur during the phase of construction when concrete pouring will be conducted until fully cured (3 weeks from last pour) and discharges are documented to be below pH 8.5. Samples will be collected weekly at the sedimentation traps prior to discharge to surface water. Once the vault is constructed, samples will be collected weekly from the outfall. Samples will be analyzed for pH using a calibrated pH meter and recorded in the site log book. The key benchmark pH value for stormwater is a maximum of 8.5. If a pH greater than 8.5 is measured in the sedimentation traps that have the potential to discharge to surface water, the following steps will be conducted: ©2012 D.R.STRONG Consulting Engineers Inc. Page 17 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 1. Prevent (detain) all discharges from leaving the site and entering surface waters or storm drains if the pH is greater than 8.5 2. Implement CO2 sparging or dry ice treatment in accordance with Ecology BMP C252. Describe inspection results and remedial actions that are taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.3 Temperature Monitoring No temperature monitoring is required for this construction site. 2012 D. R.STRONG Consulting Engineers Inc. Page 18 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 7.0 REPORTING AND RECORDKEEPING 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: • A record of the implementation of the SWPPP and other permit requirements; • Site inspections; and, • Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. 7.1.2 Records Retention Records of all monitoring information (site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s) that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. O 2012 D. R. STRONG Consulting Engineers Inc. Page 19 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan 7.2 Reporting 7.2.1 Discharge Monitoring Reports Water quality sampling results will be submitted to Ecology monthly on Discharge Monitoring Report (DMR) forms in accordance with permit condition S5.B. If there was no discharge during a given monitoring period, the form will be submitted with the words "no discharge" entered in place of the monitoring results. If a benchmark was exceeded, a brief summary of inspection results and remedial actions taken will be included. If sampling could not be performed during a monitoring period, a DMR will be submitted with an explanation of why sampling could not be performed. 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: 1. Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Any time turbidity sampling indicates turbidity is 250 nephelometric turbidity units (NTU) or greater or water transparency is 6 centimeters or less, the Ecology regional office will be notified by phone within 24 hours of analysis as required by permit condition S5.A (see Section 5.0 of this SWPPP for contact information). In accordance with permit condition S4.F.6.b, the Ecology regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water (see Section 5.0 of this SWPPP for contact information). 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit. ©2012 D. R.STRONG Consulting Engineers Inc. Page 20 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan APPENDIX A - SITE PLANS CD 2012 D. R. STRONG Consulting Engineers Inc. Page 21 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Ili SE 1/4 SE OF SECTION 32, TOWNSHIP 23N, RANGE 5E, W.M. 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(+-�o) z 4l+IED/A7EkY. n�iv io-a5x rao' �p s �.rc�c si+�ui e[wsuum�s fccrss+rrr ro ncs�cr nursx ro n�cavsrxr�cnow c�vne.urcc , d� RECOMMENDED FOR APPOVAL � z If INF fACNlIIES PO N07 R£C�(ILARLY RETAW STCq/RLNdF,n+c c��am�.�m�uv �z_i� �. g S NMENfY£R P�0.5576LE, iNE fNTRANCE 9!A!L BE CQ45TR'JC7ED PY A MµLWlPALiED SUB�PPAAE. IHS fREWENCY Q�1HE DKES/$WAlFS SHALL BE MCREASEA M 1V ?'.rSOi SO' ¢Arj�,r,g�ry�p+p�{�p,�ys BY: D318: CAN$LH57ANRAfLY INfREASE 71fE EffEC711fNE55 Q�ME PAD AND REDUCE TNE NEED fOR 4AMiENANfF BY: Date: � STABILIZED CONSTRUCAON ENTRANCE INTERCEPTOR SWALE ROCK CNECK DAM BY: Date: j N75 N75 NTS a BY: Date: p !. e �.6�aq y������f . 1 diY COWENTS DATED WY 3,2012 N.P 05.21.14 WlJ °�""' � CITY CF "°'-29-'z " °� ��� D.R.STRONG ys �AS NOTED "-�`'�, � ALTMYER �s c�s w�oars aa�.e rw o� � � � � ara�ass a�vozs a�nverovs �� �„ R E N T 0�� TESC NOTES AND DETAILS 1-800-424-5555 �,�. � �"' NJ +oew�a�+vcn��aa,wo,w�a�u �"' '� UlLtieeUnaergaaWLoca4onCenter c�°¢�a.���{� OQe�sWF�u�.�c! "'� � �n� F.c�nirc/c�'Ic�nq/Pub�ic l4�rks DeG�� � /u �K��. (D,I.fTND,OR,WN �O�AL ��� �p REVISION BY �ATE APPR � � C4a10 A-NNNNAA APPENDIX B - CONSTRUCTION BMPS High Visibility Plastic or Metal Fence (BMP C103) Stabilized Construction Entrance (BMP C105) Construction Road/Parking Area Stabilization (BMP C107) Temporary and Permanent Seeding (BMP C120) Plastic Covering (BMP C123) Dust Control (BMP C140) Interceptor Swale (BMP C200) Pipe Slope Drains (BMP C204) Check Dams (BMP C207) Storm Drain Inlet Protection (BMP C220) Silt Fence (BMP C233) Detention Vault 2012 D. R. STRONG Consulting Engineers Inc. Page 22 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Stormwater Pollution Prevention Plan APPENDIX C - ALTERNATIVE BMPS The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. 2012 D. R.STRONG Consulting Engineers Inc. Page 23 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 APPENDIX D - GENERAL PERMIT ©2012 D.R.STRONG Consulting Engineers Inc. Page 24 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 APPENDIX E - SITE INSPECTION FORMS (AND SITE LOG) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this SWPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. c. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief". ©2012 D.R. STRONG Consulting Engineers Inc. Page 25 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.F of the permit. ©2012 D. R.STRONG Consulting Engineers Inc. Page 26 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 SITE INSPECTION FORM General Information Project Name: Inspector Name: Title: CESCL# : Date: Time: Inspection Type: ❑ After a rain event ❑ Weekly ❑ Turbidity/transparency benchmark exceedance ❑ Other Weather Precipitation Since last inspection In last 24 hours Description of General Site Conditions: Inspection of BMPs Element 1: Mark Clearing Limits BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 2: Establish Construction Access BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 3: Control Flow Rates BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. Page 27 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 4: Install Sediment Controls BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 5: Stabilize Soils BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. Page 28 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 6: Protect Slopes BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 7: Protect Drain Inlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. Page 29 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Element 8: Stabilize Channels and Outlets BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 9: Control Pollutants BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Element 10: Control Dewatering BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP ©2012 D.R.STRONG Consulting Engineers Inc. Page 30 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 BMP: Location Inspected Functioning Problem/Corrective Action Y N Y N NIP Stormwater Discharges From the Site Observed? Y N Problem/Corrective Action Location Turbidity Discoloration Sheen Location Turbidity Discoloration Sheen Water Quality Monitoring Was any water quality monitoring conducted? ❑ Yes o No If water quality monitoring was conducted, record results here: If water quality monitoring indicated turbidity 250 NTU or greater; or transparency 6 cm or less, was Ecology notified by phone within 24 hrs? ❑ Yes ❑ No If Ecology was notified, indicate the date, time, contact name and phone number below: Date: Time: Contact Name: Phone#: General Comments and Notes Include BMP repairs, maintenance, or installations made as a result of the inspection. Were Photos Taken? ❑ Yes o No If photos taken, describe photos below: ©2012 D. R.STRONG Consulting Engineers Inc. Page 31 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 ©2012 D.R.STRONG Consulting Engineers Inc. Page 32 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 APPENDIX F - ENGINEERING CALCULATIONS FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN EXISTING SITE HYDROLOGY For the purpose of these calculations the predeveloped site conditions were modeled as "Till Forest". Modeling input # Land Use Summary o I i —Area ?� Till Forest 3.18 acres Till Pasture 0.00 acres Till Grass 0.00 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres Wetland 0.00 acres Impervious 0.00 acres [Total 3.18 acres Scale Factor: 1.00 Hourly Reduced Time Series: PREDEV >> Compute Time Series Modify User Input I File for computed Time Series I.TSF] Table 1 Pre-Developed KCRTS Modeling Input Modeling results Flow Frequency Analysis Time Series File:predev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.201 2 2/09/01 18:00 0.256 1 100.00 0.990 0.054 7 1/06/02 3:00 0.201 2 25.00 0.960 0. 149 4 2/28/03 3:00 0.154 3 10.00 0.900 0.005 8 3/24/04 20:00 0.149 4 5. 00 0.800 0.088 6 1/05/05 8:00 0. 130 5 3.00 0.667 0.154 3 1/18/06 21:00 0.088 6 2.00 0.500 0.130 5 11/24/06 4:00 0.054 7 1.30 0.231 0.256 1 1/09/08 9:00 0.005 8 1. 10 0.091 Computed Peaks 0.238 50.00 0.980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 33 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 DEVELOPED SITE HYDROLOGY Soil type The soil types are unchanged from pre developed conditions. Land covers The portions of the Site within the proposed clearing limits tributary to the proposed detention vault were modeled as "Till Grass" and impervious as appropriate. Modeling input Land Use Summary? = aMke X -Area ?J Till Forest 0.00 acres Till Pasture 0.00 acres Till Grass 0.92 acres Outwash Forest 0.00 acres Outwash Pasture 0.00 acres Outwash Grass 0.00 acres • Wetland 0.00 acres Impervious 2.26 acres Total 3.18 acres Scale Factor: 1.00 Hourly Reduced Time Series: DEV »I Compute Time Series I Modify User Input I File for computed Time Series[.TSF] Table 2 Developed KCRTS Modeling Input Modeling Results Flow Frequency Analysis Time Series File:dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0. 629 6 2/09/01 2:00 1.26 1 100.00 0.990 0.524 8 1/05/02 16:00 0. 843 2 25.00 0. 960 0.755 3 2/27/03 7: 00 0.755 3 10.00 0. 900 0.580 7 8/26/04 2:00 0. 695 4 5.00 0.800 0. 695 4 10/28/04 16:00 0. 669 5 3.00 0.667 0. 669 5 1/18/06 16:00 0. 629 6 2.00 0.500 0.843 2 10/26/06 0:00 0.580 7 1.30 0.231 1.26 1 1/09/08 6:00 0.524 8 1. 10 0.091 Computed Peaks 1.12 50.00 0. 980 ©2012 D.R.STRONG Consulting Engineers Inc. Page 34 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 FLOW CONTROL SYSTEM The Project will utilize a detention vault meeting the Level Three Flow Control criteria. The King County KCRTS software was used to size the detention facilities. Flow Control Facility Design Output Type of Facility: Detention Vault Facility Length: 73.83 ft Facility Width: 73.83 ft Facility Area: 5451. sq. ft Effective Storage Depth: 8.50 ft Stage 0 Elevation: 419. 40 ft Storage Volume: 46333. cu. ft Riser Head: 8.50 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.83 0.055 2 4 .85 1. 46 0. 110 4.0 3 8.00 2. 18 0.091 6.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 419.40 0. 0. 000 0.000 0.00 0.01 419.41 55. 0.001 0.002 0.00 0. 02 419.42 109. 0.003 0.002 0. 00 0. 03 419.43 164. 0.004 0.004 0.00 0.04 419.44 218. 0.005 0.004 0. 00 0. 05 419. 45 . 273. 0.006 0.004 0.00 0.06 419.46 327. 0.008 0.005 0.00 0. 07 419.47 382. 0.009 0.005 0. 00 0.24 419.64 1308. 0.030 0.009 0.00 0.40 419.80 2180. 0.050 0.012 0. 00 0.57 419. 97 3107. 0.071 0.014 0.00 0.74 420.14 4034 . 0.093 0.016 0.00 0. 90 420.30 4906. 0. 113 0.018 0. 00 1. 07 420.47 5833. 0.134 0.020 0.00 1.24 420. 64 6759. 0.155 0.021 0. 00 1.40 420.80 7631. 0. 175 0.022 0.00 1.57 420. 97 8558. 0.196 0.024 0.00 1.74 421. 14 9485. 0.218 0.025 0. 00 1. 90 421.30 10357. 0.238 0.026 0.00 2.07 421.47 11283. 0.259 0.027 0.00 2.24 421. 64 12210. 0.280 0.028 0.00 2.40 421.80 13082. 0.300 0.029 0.00 2.57 421. 97 14009. 0.322 0.030 0.00 2.74 422. 14 14936. 0.343 0.031 0.00 2. 90 422 .30 15808. 0.363 0.032 0.00 3.07 422 .47 16734. 0.384 0.033 0.00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 35 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 3.24 422. 64 17661. 0.405 0.034 0. 00 3.40 422.80 18533. 0.425 0.035 0.00 3.57 422.97 19460. 0. 447 0.036 0.00 3.74 423. 14 20387. 0.468 0.036 0.00 3. 90 423.30 21259. 0.488 0.037 0.00 4.07 423.47 22185. 0.509 0.038 0. 00 4.24 423. 64 23112. 0.531 0.039 0.00 4 . 40 423.80 23984. 0.551 0.040 0.00 4.57 423.97 24911. 0.572 0.040 0. 00 4.74 424.14 25837. 0.593 0.041 0.00 4. 85 424.25 26437. 0. 607 0.042 0. 00 4 .87 424.27 26546. 0. 609 0.042 0. 00 4.88 424 .28 26601. 0. 611 0.043 0.00 4. 90 424.30 26710. 0. 613 0.046 0. 00 4 . 91 424.31 26764. 0. 614 0.049 0. 00 4. 93 424.33 26873. 0. 617 0.053 0.00 4. 94 424.34 26928. 0. 618 0.058 0. 00 4. 96 424.36 27037. 0. 621 0.061 0. 00 4. 97 424.37 27091. 0. 622 0.062 0.00 4. 99 424.39 27200. 0. 624 0.063 0.00 5. 15 424.55 28072. 0. 644 0.075 0.00 5.32 424.72 28999. 0. 666 0.083 0.00 5.49 424 .89 29926. 0. 687 0.090 0.00 5. 65 425.05 30798. 0.707 0.096 0.00 5.82 425.22 31724. 0.728 0.102 0. 00 5. 99 425.39 32651. 0.750 0.108 0.00 6. 15 425.55 33523. 0.770 0.113 0. 00 6.32 425.72 34450. 0.791 0.117 0.00 6.49 425.89 35377. 0.812 0. 122 0.00 6. 65 426.05 36249. 0.832 0.126 0. 00 6.82 426.22 37175. 0.853 0. 130 0.00 6. 99 426.39 38102. 0.875 0.134 0. 00 7. 15 426.55 38974. 0.895 0.138 0.00 7.32 426.72 39901. 0. 916 0. 142 0. 00 7. 49 426.89 40828. 0. 937 0.145 0.00 7. 65 427.05 41700. 0.957 0. 149 0. 00 7.82 427.22 42626. 0. 979 0.152 0.00 7. 99 427.39 43553. 1.000 0.155 0.00 8.00 427.40 43608. 1.001 0.156 0.00 8.02 427.42 43717. 1.004 0. 157 0.00 8.05 427. 45 43880. 1.007 0.161 0.00 8.07 427. 47 43989. 1.010 0.168 0. 00 8.09 427.49 44098. 1.012 0.177 0.00 8.11 427.51 44207. 1.015 0.188 0.00 8. 14 427.54 44371. 1.019 0.201 0.00 8.16 427 .56 44480. 1.021 0.210 0.00 8. 18 427.58 44589. 1.024 0.214 0.00 8.35 427.75 45515. 1.045 0.238 0. 00 8.50 427. 90 46333. 1.064 0.256 0.00 8. 60 428.00 46878. 1.076 0.575 0.00 8.70 428. 10 47423. 1.089 1.150 0.00 8.80 428 .20 47968. 1. 101 1.890 0.00 8. 90 428.30 48513. 1. 114 2 . 690 0.00 9.00 428.40 49058. 1. 126 2 .980 0.00 ©2012 D.R.STRONG Consulting Engineers Inc. Page 36 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 9. 10 428.50 49604. 1. 139 3.240 0.00 9.20 428. 60 50149. 1. 151 3.480 0. 00 9.30 428.70 50694. 1. 164 3.710 0. 00 9.40 428.80 51239. 1.176 3.920 0.00 9.50 428.90 51784. 1. 189 4. 120 0. 00 9. 60 429.00 52329. 1.201 4.310 0.00 9.70 429. 10 52874. 1.214 4.500 0. 00 9.80 429.20 53419. 1.226 4. 670 0.00 9. 90 429.30 53964. 1.239 4.840 0. 00 10.00 429.40 54509. 1.251 5.000 0. 00 10.10 429.50 55054. 1.264 5.160 0. 00 10.20 429. 60 55600. 1.276 5.320 0. 00 10.30 429.70 56145. 1.289 5.460 0. 00 10.40 429.80 56690. 1.301 5. 610 0.00 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 1.26 0.26 0.25 8.49 427.89 46270. 1.062 2 0. 63 ******* 0. 19 8.11 427.51 44219. 1.015 3 0.75 ******* 0. 13 6. 93 426.33 37796. 0.868 4 0.84 ******* 0. 13 6.88 426.28 37489. 0.861 5 0. 67 ******* 0.09 5.56 424. 96 30315. 0. 696 6 0. 69 ******* 0. 06 4. 94 424.34 26921. 0. 618 7 0.52 ******* 0. 04 4. 86 424.26 26516. 0. 609 8 0.58 ******* 0.03 3.26 422. 66 17758. 0.408 Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 1.26 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.255 CFS at 12 :00 on Jan 9 in Year 8 Peak Reservoir Stage: 8 .49 Ft Peak Reservoir Elev: 427.89 Ft Peak Reservoir Storage: 46270. Cu-Ft . 1.062 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- Flow Frequency Analysis Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 0. 189 2 2/09/01 20:00 0.255 8. 49 1 100.00 0. 990 0.042 7 1/07/02 4:00 0. 189 8. 11 2 25.00 0.960 0. 133 3 3/06/03 22:00 0. 133 6. 93 3 10.00 0. 900 0.034 8 8/26/04 8:00 0. 131 6. 88 4 5.00 0.800 0.057 6 1/08/05 3:00 0.093 5. 56 5 3.00 0. 667 0.093 5 1/19/06 0:00 0.057 4. 94 6 2.00 0.500 0.131 4 11/24/06 8:00 0.042 4. 86 7 1.30 0.231 0.255 1 1/09/08 12:00 0.034 3.26 8 1. 10 0.091 ©2012 D.R.STRONG Consulting Engineers Inc. Page 37 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Computed Peaks 0.233 8.31 50.00 0.980 Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS o a o 0.003 27857 45.429 45.429 54 .571 0.546E+00 0.008 7546 12 .306 57.735 42.265 0. 423E+00 0.013 6536 10.659 68.394 31. 606 0.316E+00 0.019 5775 9.418 77.811 22.189 0.222E+00 0.024 4950 8.072 85.884 14.116 0. 141E+00 0.029 3980 6.491 92.374 7.626 0.763E-01 0.034 1859 3.032 95.406 4.594 0.459E-01 0.040 1743 2.842 98.249 1.751 0. 175E-01 0.045 642 1.047 99.296 0.705 0.705E-02 0.050 21 0.034 99.330 0. 670 0. 670E-02 0.056 18 0.029 99.359 0. 641 0. 641E-02 0.061 16 0.026 99.385 0. 615 0. 615E-02 0.066 35 0.057 99.442 0.558 0.558E-02 0.072 31 0.051 99.493 0.507 0.507E-02 0.077 38 0.062 99.555 0.445 0.445E-02 0.082 41 0.067 99.622 0.378 0.378E-02 0.087 38 0.062 99. 684 0.316 0.316E-02 0.093 28 0.046 99.729 0.271 0.271E-02 0.098 26 0.042 99.772 0.228 0.228E-02 0.103 16 0.026 99.798 0.202 . 0.202E-02 0.109 10 0.016 99.814 0. 186 0. 186E-02 0.114 17 0.028 99.842 0.158 0.158E-02 0.119 14 0.023 99.865 0.135 0. 135E-02 0. 124 15 0.024 99.889 0. 111 0. 111E-02 0.130 17 0.028 99. 917 0.083 0.832E-03 0.135 16 0.026 99. 943 0.057 0.571E-03 0. 140 8 0.013 99.956 0.044 0.440E-03 0.146 11 0.018 99. 974 0.026 0.261E-03 0.151 6 0.010 99.984 0.016 0. 163E-03 0. 156 5 0.008 99. 992 0.008 0. 815E-04 0.162 2 0.003 99. 995 0.005 0. 489E-04 0. 167 1 0.002 99.997 0.003 0.326E-04 0. 172 0 0.000 99. 997 0.003 0.326E-04 0.177 0 0.000 99.997 0.003 0.326E-04 0.183 1 0.002 99.998 0.002 0.163E-04 0.188 0 0.000 99. 998 0.002 0. 163E-04 Duration Comparison Anaylsis Base File: predev.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS Fraction of Time Check of Tolerance Cutoff Base New %Change Probability Base New %Change 0.044 0. 95E-02 0.72E-02 -24.4 I 0. 95E-02 0.044 0.041 -6.1 0.056 0. 63E-02 0. 64E-02 1.3 I 0. 63E-02 0.056 0.059 5.1 0.068 0.50E-02 0.54E-02 9.2 I 0.50E-02 0.068 0.072 6. 9 0.080 0.37E-02 0. 41E-02 10.5 I 0.37E-02 0.080 0.083 3.9 0.092 0.29E-02 0.28E-02 -0.6 I 0.29E-02 0.092 0.091 -0.4 0.104 0.22E-02 0.20E-02 -11.0 I 0.22E-02 0.104 0.099 -4.3 ©2012 D. R.STRONG Consulting Engineers Inc. Page 38 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 0. 116 0. 15E-02 0.15E-02 1.1 I 0.15E-02 0. 116 0.116 0. 1 0. 128 0.10E-02 0.91E-03 -9.7 I 0.10E-02 0. 128 0. 126 -1. 6 0. 140 0. 62E-03 0.44E-03 -28.9 I 0.62E-03 0. 140 0.133 -5. 1 0. 152 0.34E-03 0.15E-03 -57. 1 I 0.34E-03 0. 152 0.143 -5. 9 0. 164 0.21E-03 0.49E-04 -76. 9 I 0.21E-03 0. 164 0. 149 -9.2 0. 176 0.16E-03 0.33E-04 -80.0 I 0.16E-03 0. 176 0.151 -14. 1 0. 188 0.11E-03 0.16E-04 -85.7 I 0.11E-03 0. 188 0.154 -18 .4 0.200 0.16E-04 0.00E+00 -100.0 I 0.16E-04 0.200 0. 189 -5.6 Maximum positive excursion = 0.005 cfs ( 8.2%) occurring at 0.064 cfs on the Base Data:predev.tsf and at 0.069 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.035 cfs (-18.4%) occurring at 0.188 cfs on the Base Data:predev.tsf and at 0. 154 cfs on the New Data:rdout.tsf ©2012 D. R.STRONG Consulting Engineers Inc. Page 39 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Peaks Plot Paused-Flow Frequency-KCRTS .7,1=11 Return Period 2 5 10� 20r 50 100 _ r r o rdout.pks in Sea-Tac -• PREDEV.pks "-0 DEV.pl s 0 10°- , 0 O O O O 0 in R • - o000 • a E rn 10'1_ •• `m - N — • .t _ 0 00 O 10y u— • 10-3 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 Cumulative Probability Duration Curve .151;Paused-Duralion Analysis-KCRTS -- O rdoutdur o •-_ TARGET.dur • co 000 U o , d a `m L6r V ❑ O 111 00 *IL •n I I 1 1 1 1 1 1 1 1 I I I I I ll I I I 1 1 1 1 1 I 1 1 1 1 1 1 1 1 I I I 1 1 1 1 1 1 10 5 10-4 10-3 10 10-1 10° Probability Exceedence ©2012 D.R.STRONG Consulting Engineers Inc. Page 40 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 Water Quality Treatment The Project is located in the Basic Water Quality (WQ) Treatment area. The Project will utilize a combined wetvault meeting Basic Water Quality treatment criteria. The design information is as follows: A 21.75-foot by 128-foot by 5.5-foot wetpool will be provided below the live storage in the western bay of the detention vault. This will provide a 6:1 length to width ratio which exceeds Manual requirements. A depth of 5.5 feet will provide 15,312 cu-ft. of water quality treatment volume, exceeding the minimum volumetric requirement for basic water quality treatment which is 11,574 cu-ft. Furthermore, per Section 6.4.2.2, when the length to width ratio is greater than 5:1, no baffle is required and the wetvault may be one celled. 2012 D. R.STRONG Consulting Engineers Inc. Page 41 of 41 Stormwater Pollution Prevention Plan Altmyer March 20,2012 APPENDIX C OFFSITE ANALYSIS BY J3ME WITH EXISTING POND BACKWATER ANALYSIS O 2012 D. R.STRONG Consulting Engineers Inc. Page 55 of 55 Technical Information Report Altmyer March 29, 2012 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 SECTION 3: OFF-SITE ANALYSIS Adopted Basin Plan: The project site is located within the Black River Drainage Basin, which is in the Green River-Duwamish Watershed. Upstream Tributary Area: Based on the analysis of topographical maps as well as the Ruddells Drainage Investigation performed in December of 1992, and our site visits, we have concluded that there is a negligible amount of tributary runoff to the project site. However, there is an existing detention pond within close proximity of the project site (Pond 'A') that receives and detains runoff from roughly 80 acres. This water is conveyed through the project site towards a second detention pond which receives an additional 58 acres of tributary runoff. As part of this analysis, the current condition of the existing detention ponds were analyzed to ensure that they can adequately convey flows. See Figure 3: Tributary Area Map and Figure 4: Pond A Tributary Areas Breakdown. Downstream Analysis: A field investigation was performed on May 3, 2007. The weather was partly cloudy and the temperature was approximately 57 degrees. A visual site inspection was performed of the drainage system surrounding the project site utilizing detailed aerial and drainage maps. See Figure 5: Downstream Map and Table 1: Downstream Analysis Table. Upon inspection of the site as well as through the analysis of topographical maps, the site was found to be generally flat and slopes slightly from southwest to northeast at an average of 1%. Present on the site are 2 single family residences and related outbuilding structures. Runoff from the residences is collected by a series of yard drains and catch basins and is routed to a catch basin located on the northwestern side of SE 184th Place. There is an existing grass lined detention pond located northeast of the site that collects runoff from the tributary areas to the site (Point A). The pond could not directly be inspected due to the presence of a wire fence, but two 24" inlet pipes and a "birdcage" control structure could be observed. According to the Ruddells Drainage Improvements Plans, flows are conveyed into the storm drainage manhole on the northwestern side of SE 184th Place through a 24" pipe (Point B). The manhole receives flow from the detention pond through a 24" pipe as well as flows from the residences through an 8" pipe and conveys the water in.a northerly direction through a 24" pipe. Approximately 250 feet from the project site, the pipe changes to 35" x 24" arch pipe (Point C). Flow continues for approximately 250 feet until the pipe size changes to 30" (Point D) and continues to convey flow to a detention pond located SE 182nd Street and 108 Avenue SE, approximately 800 feet northwest of the project site (Point E). Upon inspection of the second pond, it was seen that the outfall from the conveyance system is located on the southeastern portion of the pond (Point F). There is an additional 6" pipe that was observed as an inlet to the pond, however, no flow was seen during the inspection (Point G) and there appeared to be cracks in the pipe. The pond is grass-lined and appears to be in good condition as no erosion or sloughing was observed. Two drainage structures roughly 5 feet apart located in the northwest corner of the pond are equipped with birdcages. The northernmost drainage structure is J3ME 6 • r iS • . ).. • .: 1 . ..• _ t i. • . ' .. 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JOB NUMBER MJF-003 3 „ . :r... ..........TT,„1........r,,..,,.. i 7......,.... , f (,..,,... .,..._....,..__. 7:::,4,,.,.._............_,.......,t:j.....t......„......___._____.._,,,................... el CD I I .f. '....4-. .V.:ii:'..s. '1 ::f , •-•••' '- . •'• ..,.. I. FIGURE 'f J.,-- ---,-- L t 4., ••• ' . " '' u , 11,1, 1 243 ;. c)---- ?: , k.., ..:;:f :Ir.::f•04,-0,,t, :Jr ae..7,re-%'7,7 7, ' • —------------ '" — ... I / f Nib- SE 176TH ST Xco > _ I PONTK Q h• 0)0 • I w 1 - J 1 r 1 = o 1 1 I w W u) CO POINT J ¢ Q >kew n H F Q m a) _ 0 o F- o r i I _ 1 - SE 179TH PL IPOINT I E— _ X 1 SE 180TH ST LL U, LL Q SEE DOWNSTREAM MAP 1 i •` a I SE 180TH ST DOWNSTREAM MAP 12 SE 1/4 SEC. 32, TWP, 23N., RGE. 5E. AL TMYER DWN. BY: DATE: JOB NO. 1375 NW Mall Street, Suite 3 Issaquah WA 98027 AAB 08/20/07 MJF-003 Tel (425) 313-1078 CHKD. BY: SCALE: J3ME Fax (425) 313-1077 J. JOLMA NTS FIGURES-13 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 equipped with a valve which appears to serve as flow control, while the southernmost structure appears to have once served as an overflow structure for the pond. Flow from the pond is conveyed through a 24" pipe located on the northern end of the pond (Point H) and is directed toward the southernmost drainage structure. Water from this structure is conveyed in a northerly direction and connects to the conveyance system along SE 182nd Street. Following the system downstream, flow is conveyed north along 108 Avenue SE for approximately 700 feet before diverging flows west along SE 180th Street. Flow is conveyed through a 30" pipe and enters a grass-lined drainage channel roughly 10 feet wide and 4 deep running along the north side of SE 1801 Street (Point I). Water continues to flow along the drainage channel for approximately 750 feet before rerouting north along the east side of 105th Place SE. Roughly 450 feet from the corner of SE 180th Street and 105th Place SE, flow enters a 36" pipe (Point J) and continues north for 730 feet before crossing under SE Carr Road and outfalling to the forested area on the north side of SE Carr road (Point K). At this point, the analysis is approximately 1/2 mile from the project site. Downstream Concerns & Effects of Proposed Project: As evident by the drainage complaints recorded with King County, the project area has experience past flooding. A drainage investigation of the area was performed by R.W. Beck and Associates in December of 1992. According to the drainage investigation, the subject site and the area surrounding was encompassed within a naturally closed depression. As urbanization began in the area, attempts were made to try to provide a drainage outlet from this closed depression, including the construction of a 12 inch diameter concrete outlet pipe located in the general vicinity of where the current outlet from Pond 'A' is located. However, there were no engineering standards in place at the time and several houses were constructed without consideration for the floodplain or other drainage related issues. Detention Pond 'B' was constructed in 1976 with the development of the Maple Glen Division and Pond 'A' was constructed in 1978 with the Ruddells 1st Division. As areas tributary to Pond 'A' developed, the frequency of flooding increased and according to some residents, the severity of the flooding culminated with the construction of the Springfield Apartment Complex which drained to a pipe immediately downstream of the outlet pipe to Pond 'A'. As discussed in the drainage investigation, a level of protection for the 100-year storm even was not attainable through any possible detention/conveyance system due to topographical constraints. The maximum storm event that could effectively be detained and conveyed is the 25-year storm event. Four Alternatives were proposed as a result of the drainage investigation: 1. Add detention volume at Pond 'A' to the maximum extent in order to try to eliminate the flooding problem without increasing downstream flows. To achieve this, two additional detention ponds would be constructed in the undeveloped areas within the vicinity of Pond 'A'. This alternative was not taken into consideration as the frequent flooding problem could not effectively be solved by this configuration. 2. Construct an addition detention pond to help supplement the detention volume at J3ME 12 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 97-0084: In January of 1997, the resident at 18504 112th Avenue SE expressed concern over the detention pond overflowing and the new construction washing out onto 112th Avenue. 97-0085: In January of 1997, the resident at 11202 SE 186th Street expressed concern over the detention pond overflowing and flooding SE 186th Street. She requested to find out about the proposed development. 97-0173: In January of 1997, the resident at 18304 108th Place SE expressed concern over flooding. She was enquiring about the proposed drainage system schedule so that she could coordinate doing her work after the scheduled drainage repair. 97-0334: In January of 1997, the resident at 18425 112th Avenue SE expressed concern over the detention pond overflowing and threatening the homes surrounding the pond. 97-0668: In March of 1997, the resident at 18425 112th Avenue SE expressed concern over the detention pond being plugged and backing up. The trash racks were cleared of debris, but during the investigation it was found that the drainage system couldn't handle the water from a normal storm and that the pond would have to be checked every 4-6 hours during a normal rain storm. 98-0546: The resident at 10810 SE 182nd Street expressed concern over the water that was flooding her yard and driveway, almost flooding her garage and leaving a large amount of debris. She is directly across the street from the rebuilt detention pond, but the actual source of her problem wasn't related to the pond. The problem was related to a road overlay that had been done which essentially reduced the capacity of the gutter and adversely affected the ability of the catch basin near her house to collect the water. Also, because her house is lower than the road, there is a possibility of her yard flooding during severe storms. 98-0691: The resident at 18424 112th Avenue SE expressed concern over her neighbor regarding his property and flooding her yard as a result. The flooding resulted from her neighbor connecting his downspouts to a small pipe which drains into the yard and sheet flows onto her property since her property sits on a low point. It was recommended that she try to pipe the water to the street. SCS Soils Map: Based on the King County Soil Survey the on-site soils are mapped as Alderwood gravelly sandy loam (AgB) series. Alderwood series have slow permeability; runoff potential is slow to medium, and a moderate to severe erosion hazard. See Figure 6: Soils Map. In addition to the available mapping, a Limited Evaluation and Classification of the Surficail Soils was prepared by AESI. There evaluation states that the tills soils appear to have lenses of higher permeable soils within them. Therefore, the basin study will assume that soils within basin are half till and half outwash. A copy of AESI's memo is included in Appendix C for reference. J3ME 14 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 Drainage Basin Analysis: As previously discussed, the Ruddells Drainage system has experienced historic flooding problems. These drainage problems appear to have been alleviated with the construction of the Ruddells Drainage Improvement project constructed in 1998. However, in accordance with King County Core Requirement #2: Offsite Analysis, a more detailed analysis was performed to investigate how the improved system was functioning. A model of the existing drainage system was created as part of this analysis. Basin area values from the Ruddells Drainage Investigation as well as County records of the existing development within the basin were used to create a KCRTS runoff model. The Ruddells Drainage Improvement As-builts were used to create a backwater analysis of the improved drainage system as well as to model Pond A. Pond 'A' Based on County records, aerial photos, tax assessor mapping and field investigation, our basin delineation found that 80.47 acres is tributary to Pond 'A', see Figure 4: Pond A Tributary Areas Breakdown. The assumed ground cover is based on measurement of road and sidewalk areas and by using an average impervious area of the lots within each basin, calculated using aerial photos. Basins 10 and 11 (7.02 ac) are tributary to an infiltration pond constructed as part of the Emerald Glen Development and therefore have been subtracted from the basin gross acreage. See Table 2: Pond A Tributary Areas. Per the recommendations of the project geotechnical engineer, half of area within the basin was modeled as till and half was modeled as outwash. Any impervious area that was not identifiable as forest with aerial photography was considered pasture per Section 3.2.2 of the 2005 KCSWDM. Additionally, half of the impervious area was assumed to be pasture to account for non-effective impervious surfaces within the basin. The resulting areas used in the runoff model are shown below. Net Basin Area — 73.5 Acres Existing (Acres) Till Forest 4.4 ac Outwash Forest 4.4 ac Till Pasture 25.9 ac Outwash Pasture 25.9 ac Impervious 12.9 ac • J3ME 16 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 Pond 'A' Tributary Flow Rates Flow Frequency Analysis Time Series File:ex-5.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 4. 99 4 2/09/01 2:00 9. 68 1 100.00 0.990 3.51 7 1/05/02 16:00 5.56 2 25.00 0. 960 5.56 2 2/27/03 7:00 5.09 3 10.00 0.900 3.33 8 8/26/04 2:00 4. 99 4 5.00 0.800 4 .01 6 10/28/04 16:00 4.84 5 3.00 0.667 5.09 3 1/18/06 16:00 4.01 6 ' 2.00 0.500 4 .84 5 11/24/06 3:00 3.51 7 1.30 0.231 9. 68 1 1/09/08 6:00 3.33 8 1. 10 0.091 Computed Peaks 8.31 50.00 0. 980 Per the County's asbuilt plans (see Appendix D), Pond A has an active storage depth of 5.6 feet and a storage volume of approximately 57,223 cubic feet with the maximum water surface at 423.0. The control structure consists of a single orifice 24 inches in diameter at elevation 417.4 with a shear gate opened to a height of 3.5-inches (per field measurements). Based on the surface area of the opening, the equivalent orifice size translates to roughly 10.3 inches (see orifice calculations in Appendix B). The pond was modeled in KCRTS by routing the basin runoff time series through a single outlet reservoir. It was found that the full head discharge from the control structure is 6.81 cfs, which can adequately convey the 25-year generated basin flow rate of 4.28 cfs. The pond modeling analysis shows that the pond can effectively detain flows beyond 25-year storm, and only slightly overtop (0.13-ft) during the 100-year event. See Appendix B for Pond A Analysis. The results of the modeling analysis are verifiable based on the lack of drainage complaints and through interviews with local residents who confirmed that the pond no longer is a flooding issue. Pond `B' Based on the Ruddells Drainage Investigation prepared by RW Beck, the tributary area for Pond B is approximately 158 acres, which includes the Pond A area. Per Table 1 of RW Beck's report, a 100-year runoff event creates 21.8 cfs, please see Appendix C for RW Becks report. A field investigation found the outlet riser in Pond B to consist of a 24-inch diameter pipe equipped with a shear gate which is completely open. A 24-inch diameter outlet that is acting as an orifice has the capacity to flow 49.18 cfs when the pond is filled to it's maximum stage of 414.0', please see orifice calculations in Appendix B. Therefore Pond B has the capacity to outflow more than twice the predicted inflow, thus overflow is extremely unlikely. )3ME 18 Preliminary Technical Information Report for Altmyer Plat April 28, 2008 2. Although modeling results suggest that flooding is not longer an issue in the vicinity of Pond A, Level — 3 Flood Control is recommended as an additional factor of safety. J3ME 20 Table 4: CB Tributary Areas Summary Conveyance from Pond A to Pond B CB # Additional Tributary Area Cumulative Area Perilous Impervious Pervious Impervious (Ac) (Ac) Total (Ac) (Ac) (Ac) Total (Ac) 15 60.6 12.9 73.5 60.6 12.9 73.5 14 0.0 0.0 0.0 60.6 12.9 73.5 13A 0.0 0.0 0.0 60.6 12.9 73.5 13 0.0 0.0 0.0 60.6 12.9 73.5 12 0.0 0.0 0.0 60.6 12.9 73.5 11 0.0 0.0 0.0 60,6 12.9 73.5 10 7.1 2.8 9.9 67.7 15.7 83.4 9 0.0 0.0 0.0 67.7 _ 15.7 83.4 8 4.6 1.8 6.4 72.3 17.5 89.8 7 0.0 0.0 0.0 72.3 17.5 89.8 6A 0.0 0.0 0.0 72.3 17.5 89.8 6 0.0 0.0 0.0 72.3 17.5 89.8 5 4.3 3.3 7.6 76.6 20.8 97.4 4 0.0 0.0 0.0 76.6 20.8 97.4 3 0.0 0.0 0.0 76.6 20.8 • 97.4 Total 76.6 20.8 97.4 Tributary to Pond B (Not tributary to Subject Conveyance) Basin Area # Pervious (Ac) Impervious (Ac) Area (Ac) 1 1.9 0.9 2.80 2 1.6 0.8 2.40 3 1.4 0.7 2.10 4 1.9 1.0 2.90 5 1.4 1.2 2.60 6 1.7 0.8 2.50 7 1.6 0.3 1.90 8 0.7 0.0 0.70 9 0.8 0.0 0.80 10 12.5 3.1 15.60 Total 25.5 8.8 34.30 Total Area Tributary to Conveyance System: 97.4 Acres Basin Area Not Tributary to Conveyance System: 34.30 Acres Total Basin Area: 131.7 Acres denotes areas determined by J3ME, remainder are per Ruddell's Drainage Investigation All areas use 15-minute time step except flow leaving Pond A APPENDIX B L palati A- - 41-00-(ysts Flow Frequency Analysis Time Series File:pondaout5.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 4 .13 5 2/09/01 5:00 6.89 5.73 1 100.00 0. 990 2.91 7 1/05/02 17:00 4.28 2.23 2 25.00 0. 960 4 .15 4 2/27/03 9:00 4.21 2. 16 3 10.00 0. 900 2.63 8 8/26/04 3:00 4. 15 2.09 4 5.00 0.800 3.35 6 10/28/04 18:00 4 .13 2.06 5 3.00 0. 667 4 .28 2 1/18/06 17:00 3.35 1.40 6 2.00 0.500 4 .21 3 11/24/06 5:00 2.91 1.02 7 1 .30 0.231 6.89 1 1/09/08 10:00 2. 63 0. 91 8 1.10 0.091 Computed Peaks 6.02 4 .38 50.00 0. 980 Fdw CL I7-€F44-1- 5. lc, c.-Fva 1) �ac.A2( gest, ►vt S(i 5(tii- oa-ter-tLJ aJ )Oo-lecL,r- 2.19 2 12/08/02 17:15 1.18 3 10.00 0. 900 0. 691 7 8/23/04 14:30 1.05 4 5.00 0.800 1.01 5 10/28/04 16:00 1.01 5 3.00 0. 667 1.05 4 10/27/05 10:45 0.893 6 2.00 0.500 1.18 3 10/25/06 22:45 0.691 7 1.30 0.231 3.08 1 1/09/08 6:30 0. 668 8 1. 10 0.091 Computed Peaks 2.78 50.00 0. 980 CB 5 Flow Frequency Analysis Time Series File:cb-5.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 1.57 6 8/27/01 18:00 4.79 1 100.00 0. 990 1' 13 8 1/05/02 15:00 3.50 2 25:00 0.960. 3.50 2 12/08/02 17:15 2.15 3 10.00 0.900 1.27 7 8/23/04 14:30 1.85 4 5.00 0.800 1.75 5 10/28/04 16:00 1.75 5 3.00 0. 667 1.85 4 10/27/05 10:45 1.57 6 2.00 0.500 2.15 3 10/25/06 22:45 1.27 7 1.30 0.231 4.79 1 1/09/08 6:30 1. 13 8 1. 10 0.091 Computed Peaks 4.36 50.00 0. 980 All analysis uses 15-minute time steps, except flow leaving Pond A Runoff analysis uses till pasture as pervious surface 25-year cumulative flows 5.56 3.40 2.19 3.50 Total = 14. 65 24.86 4.65 414.39 * 0.012 1.70 0.73 9.34 9.34 4.44 4.65 2.16 25.36 . 4.66 414.40 * 0.012 1.72 0.74 9.34 9.34 4.44 4. 66 2.19 25.86 4.68 414.42 * 0.012 1.74 0.75 9.34 9.34 4.45 4. 68 2.21 26.36 4.70 414.44 * 0.012 1.76 0.76 9.34 9.34 4.46 4.70 2.23 26.86 4.71 414.45 * 0.012 1.77 0.76 9.34 9.34 4.46 4.71 2.25 27.36 4.73 414.47 * 0.012 1-.79 0.77 9.34 9.34. 4.47 4.73 2.30 27.86 4.75 414.49 * 0.012 1.81 0.78 9.34 9.34 4.48 4.75 2.32 28.36 4.77 414.51 * 0.012 1.82 0.79 9.34 9.34 4.49 4.77 2.35 28.86 4.78 414.52 * 0.012 1.84 0.79 9.34 9.34 4.50 4.78 2.37 29.36 4.80 414.54 * 0.012 1.85 0.80 9.34 9.34 4.50 4.80 2.40 29.86 4.82 414.56 * 0.012 1.87 0.81 9.34 9.34 4.51 4.82 2.42 30.36 4.84 414.58 * 0.012 1.88 0.81 9.34 9.34 4.52 4.84 2.45 30.86 4.86 414.60 * 0.012 1.90 0.82 9.34 9.34 4.53 4.86 2.47 31.36 4.88 414.62 * 0.012 1.91 0.83 9.34 9.34 4.54 4.88 2.55 31.86 4.90 414. 64 * 0.012 1.93 0.84 9.34 9.34 4.55 4. 90 2.58 32.36 4.92 414.66 * .0.012 1.94 0.84 9.34 9.34 4.56 4. 92 2.61 32.86 4.94 414.68 * 0.012 1.96 0.85 9.34 9.34 4.57 4.94 2.64 33.36 4.96 414.70 * 0.012 1.97 0.86 9.34 9.34 4.58 4.96 2.67 33.86 4.98 414.72 * 0.012 1.98 0.86 9.34 9.34 4.59 4.98 2.70 PIPE NO. 2: 126 LF - 30"CP @ 0.67% OUTLET: 409.74 INLET: 410.59 INTYP: 2 JUNC NO. 2: OVERFLOW-EL: 417.50 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 6.36 3.48 414.07 * 0.012 0.84 0.71 4.29 4 .29 3.47 3.48 1.12 6.86 3.49 414.08 * 0.012 0.87 0.74 4.29 . 4.29 3.47 3.49 1.16 7.36 3.50 414.09 * 0.012 0.91 0.77 4.29 4.29 3.48 3.50 1.21 7.86 3.51 414. 10 * 0.012 0.94 0.79 4.30 4.30 3.49 3.51 1.25 8.36 3.52 414.11 * 0.012 0.97 0.82 4.30 4 .30 3.50 3.52 1.29 8.86 3.54 414.13 * 0.012 1.00 0.84 4.31 4 .31 3.51 3.54 1.33 9.36 3.55 414.14 * 0.012 1.03 0.87 4.32 4 .32 3.52 3.55 1.37 9.86 3.57 414. 16 * 0.012 1.05 0.89 4.32 4.32 3.53 3.57 1.41 10.36 3.58 414.17 * 0.012 1.08 0.92 4.33 4 .33 3.55 3.58 1. 44 10.86 3.60 414.19 * 0.012 1.11 0.94 4.33 4 .33 3.56 3.60 1.48 11.36 3. 62 414.21 * 0.012 1.13 0.96 4.34 4 .34 3.57 3.62 1.51 11.86 3. 64 414.23 * 0.012 1.16 0.99 4.35 4.35 3.59 3.64 1.55 12.36 3.65 414.24 * 0.012 1.19 1.01 4 .36 4.36 3.60 3.65 1.58 12.86 3.68 414.27 * 0.012 1.21 1.03 4.36 4.36 3.62 3.68 1. 61 13.36 3.70 414.29 * 0.012 1.23 1.05 4.37 4 .37 3.64 3.70 1. 65 13.86 3.72 414.31 * 0.012 1.26 1.07 4.38 4 .38 3.65 3.72 1. 68 14.36 3.74 414.33 * 0.012 1.28 1.09 4.39 4 .39 3.67 3.74 1.71 14.86 3.76 414.35 * 0.012 1.30 1.12 4.40 4.40 3.69 3.76 1.74 15.36 3.79 414.38 * 0.012 1.33 1.14 4.41 4.41 3.71 3.79 1.77 15.86 3.81 414.40 * 0.012 1.35 1.16 4.42 4 .42 3.73 3.81 1.80 16.36 3.84 414.43 * 0.012 1.37 1.18 4.43 . 4 .43 3.75 3.84 1.83 16.86 3.87 414.46 * 0.012 1.39 1.20 4.44 4.44 3.77 3.87 1.86 17.36 3.89 414.48 * 0.012 1.42 1.22 4.45 4.45 3.79 3.89 1.88 17.86 3.92 414.51 * 0.012 1.44 1.24 4.46 4.46 3.81 3.92 1.91 18.36 3. 95 414.54 * 0.012 1.46 1.26 4.47 4.47 3.84 3.95 1. 94 18.86 3.98 414.57 * 0.012 1.48 1.28 4.48 4.48 3.86 3. 98 1. 97 19.36 4.01 414.60 * 0.012 1.50 1.30 4.50 4 .50 3.88 4.01 1.99 19.86 4.04 414.63 * 0.012 1.52 1.32 4.51 4.51 3.91 4.04 2 . 02 20.36 4.07 414.66 * 0.012 1.54 1.34 4.52 4 .52 3.94 4.07 2 .04 20.86 4. 11 414.70 * 0.012 1.56 1.36 4.53 4 .53 3.96 4.11 2.07 21.36 4.14 414.73 * 0.012 1.58 1.38 4.55 4 .55 3.99 4.14 2.09 18.86 4.34 414.79 * 0.012 1.48 0.00 3.98 3.98 4.17 4.34 2.03 19.36 4.38 414.83 * 0.012 1.50 0.00 4.01 4.01 4.20 4.38 2.06 19.86 4.42 414.87 * 0.012 1.52 0.00 4.04 4.04 4.24 4.42 2.09 20.36 4 .47 414. 92 * 0.012 1.54 0.00 4.07 4.07 4.27 4.47 2.11 20.86 4.51 414. 96 * 0.012 1.56 0.00 4.11 4.11 4.31 4.51 2.14 21.36 4 .56 415.01 * 0.012 1.58 0.00 4.14 4.14 4.34 4.56 2.17 21.86 4.61 415.06 * 0.012 1.60 0.00 4.18 4.18 4.38 4.61 2.20 22.36 4.66 415. 11 * 0.012 1.61 0.00 4.21 4.21 4.42 4. 66 2.23 22.86 4.71 415.16 * 0.012 1.63 0.00 4.25 4.25 4.46 4.7-1 2.25 23.36 4.76 415.21 * 0.012 1.65 0.00 4 .28 4.28 4.50 4.76 2.28 23.86 4.81 415.26 * 0.012 1.67 0.00 4.32 4.32 4.54 4.81 2.31 24.36 4.86 415.31 * 0.012 1.69 0.00 4.36 4.36 4.58 4.86 2.33 24.86 4.92 415.37 * 0.012 1.70 0.00 4.40 4.40 4. 63 4.92 2.36 25.36 4.97 415.42 * 0.012 1.72 0.00 4.44 4.44 4.67 4.97 2.39 25.86 5.03 415.48 * 0.012 1.74 0.00 4.48 4 .48 4.71 5.03 2.41 26.36 5.09 415.54 * 0.012 1.76 0.00 4.52 4.52 4.76 5.09 2.44 26.86 5.15 415. 60 * 0.012 1.77 0.00 4.57 4.57 4.81 5.15 2.46 27.36 5.21 415. 66 * 0.012 1.79 0.00 4.61 4.61 4.85 5.21 2.51 27.86 5.27 415.72 * 0.012 1.81 0.00 4. 65 4.65 4.90 5.27 2.54 28.36 5.33 415.78 * 0.012 1.82 0.00 4.70 4 .70 4.95 5.33 2.57 28.86 5.39 415. 84 * 0.012 1.84 0.00 4.74 4.74 5.00 5.39 2.60 29.36 5.46 415. 91 * 0.012 1.85 0.0.0 4.79 4.79 5.05 5.46 2.62 29.86 5.52 415. 97 * 0.012 1.87 0.00 4.84 4.84 5.10 5.52 2.65 30.36 5.59 416.04 * 0.012 1.88 0.00 4.89 4.89 5.16 5.59 2.68 30.86 5.66 416. 11 * 0.012 1.90 0.00 4.94 4 .94 5.21 5.66 2.71 31.36 5.73 416.18 * 0.012 1.91 0.00 4.99 4.99 5.26 5.73 2.79 31.86 5.80 416.25 * 0.012 1.93 0.00 5.04 5.04 5.32 5.80 2.82 32.36 5.87 416.32 * 0.012 1.94 0.00 5.09 5.09 5.37 5.87 2.86 32.86 5.94 416.39 * 0.012 1.96 0.00 5.14 5.14 5.43 5.94 2.89 33.36 6.01 416.46 * 0.012 1.97 0.00 5.19 5.19 5.49 6.01 2.93 33.86 6.09 416.54 * 0.012 1.98 0.00 5.25 5.25 5.55 6.09 2.96 PIPE NO. 4: 109 LF - 30"CP @ 0.78% OUTLET: 410.45 INLET: 411.30 INTYP: 2 JUNC NO. 4: OVERFLOW-EL: 419.50 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00. Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.89 2.83 414.13 * 0.012 0.81 0.66 3. 65 3.65 2.82 2.83 1.07 6.35 2.84 414.14 * 0.012 0.84 0.69 3.65 3.65 2.83 2.84 1.12 6.81 2.86 414.16 * 0.012 0.87 0.71 3. 67 3.67 2.85 2.86 1.16 7.28 2. 88 414.18 * 0.012 0.90 0.73 3. 69 3.69 2.87 2.88 1.20 7.74• 2.91 414.21 * 0.012 0.93 0.76 3.70 3.70 2.89 2.91 1.24 8.20 2. 93 414.23 * 0.012 0.96 0.78 3.72 3.72 2.91 2.93 1.28 8.67 2.96 414.26 * 0.012 0.99 0.80 3.74 3.74 2.94 2.96 1.31 9.13 2. 99 414.29 * 0.012 1.01 0.83 3.77 3.77 2.96 2. 99 1.35 9.59 3.02 414.32 * 0.012 1.04 0.85 3.79 3.79 2.99 3.02 1.39 10.06 3.05 414.35 * 0.012 1.06 0.87 3.81 3.81 3.02 3.05 1.42 10.52 3.08 414.38 * 0.012 1.09 0.89 3.84 3.84 3.05 3.08 1.45 10.98 3. 12 414.42 * 0.012 1.11 0.91 3.86 3.86 3.08 3.12 1.49 11.44 3.15 414.45 * 0.012 1.14 0.93 3.89 3.89 3.11 3.15 1.52 11.91 3.19 414.49 * 0.012 1.16 0.95 3.92 3.92 3.14 3.19 1.55 12.37 3.23 414.53 * 0.012 1.19 0.97 3.94 3.94 3.18 3.23 1.58 12.83 3.27 414.57 * 0.012 1.21 0.99 3.97 3.97 3.22 3.27 1. 61 13.30 . 3.31 414.61 * 0.012 1.23 1.01 4.01 4.01 3.25 3.31 1.64 13.76 3.36 414.66 * 0.012 1.25 1.03 4.04 4.04 3.29 3.36 1.67 14.22 3.40 414.70 * 0.012 1.28 1.05 4.07 4.07 3.33 3.40 1.70 11.91 2.89 414.60 * 0.012 1.16 1.07 3.19 3.19 2.84 2.89 1.55 12.37 2.93 414. 64 * 0.012 1. 19 1.09 3.23 3.23 2.88 2.93 1.58 12.83 2.98 414.69 * 0.012 1.21 1.11 3.27 3.27 2.93 2.98 1.61 13.30 3.03 414.74 * 0.012 1.23 1.14 3.31 3.31 2.98 3.03 1.64 13.76 3.09 414.80 * 0.012 1.25 1.16 3.36 3.36 3.02 3.09 1.67 14.22 3.14 414.85 * 0.012 1.28 1.18 3.40 3.40 3.07 3.14 1.70 14.69 3.20 414.91 * 0.012 1.30 1.20 3.45 3.45 3.13 3.20 1.73 15.15 3.26 414.97 * 0.012 1.32 1.22 3.50 3.50 3.18 3.26 1.76 15.61 3.32 415.03 * 0."012 1.34 1.25 3.55 3.55 3.24 3.32 1.79 16.07 3.38 415.09 * 0.012 1.36 1.27 3. 60 3.60 3.29 3.38 1.81 16.54 3.44 415.15 * 0.012 1.38 1.29 3.65 3.65 3.35 3.44 1.84 17.00 3.51 415.22 * 0.012 1.40 1.31 3.70 3.70 3.41 3.51 1.87 17.46 3.57 415.28 * 0.012 1.42 1.33 3.76 3.76 3.47 3.57 1.89 17.93 3.64 415.35 * 0.012 1.44 1.35 3.81 3.81 3.54 3.64 1.92 18.39 3.71 415.42 * 0.012 1.46 1.37 3.87 3.87 3.60 3.71 1.94 18.85 3.79 415.50 * 0.012 1.48 1.40 3.93 3.93 3. 67 3.79 1.97 19.31 3.86 415.57 * 0.012 1.50 1.42 3.99 3.99 3.74 3.86 1.99 19.78 3.94 415.65 * 0.012 1.51 1.44 4.06 4.06 3.81 3.94 2.02 20.24 4.02 415.73 * 0.012 1.53 1.46 4.12 4.12 3.88 4.02 2.04 20.70 4.10 415.81 * 0.012 1.55 1.48 4.19 4.19 3.95 4.10 2.06 21.17 4.18 415.89 * 0.012 1.57 1.50 4.25 4.25 4.03 4.18 2.09 21.63 4.26 415.97 * 0.012 1.59 1.52 4.32 4.32 4.10 4.26 2.11 22.09 4.35 416.06 *. 0.012 1. 60 1.54 4.39 4.39 4.18 4.35 2.13 22.56 4.43 416.14 * 0.012 1.62 1.57 4.46 4.46 4.26 4.43 2.15 23.02 4.52 416.23 * 0.012 1.64 1.59 4.54 4.54 4.34 4.52 2.18 23.48 4.61 416.32 * 0.012 1. 66 1.61 4. 61 4 .61 4.43 4.61 2.20 23.94 4.71 416.42 * 0.012 1. 67 1.63 4.69 4. 69 4.51 4.71 2.22 24.41 4.80 416.51 * 0.012 1.69 1.65 4.77 4.77 4.60 4.80 2.24 24 .87 4.90 416. 61 * 0.012 1.70 1.68 4.84 4.84 4.69 4.90 2.26 25.33 4.99 416.70 * 0.012 1.72 1.70 4.93 4 .93 4.78 4.99 2.29 25.80 5.09 416.80 * 0.012 1.74 1.72 5.01 5.01 4.87 5.09 2.31 26.26 5.20 416. 91 * 0.012 1.75 1.74 5.09 5.09 4.96 5.20 2.33 26.72 5.30 417.01 * 0.012 1.77 1.77 5.18 5.18 5.06 5.30 2.35 27.19 5.40 417.11 * 0.012 1.78 1.79 5.26 5.26 5.16 5.40 2.39 27 .65 5.51 417.22 * 0.012 1.80 1.82 5.35 5.35 5.25 5.51 2.41 28.11 5.62 417.33 * 0.012 1.81 1.84 5.44 5.44 5.35 5.62 2.43 28.57 5.73 417.44 * 0.012 1.83 1.87 5.53 5.53 5.46 5.73 2.46 29.04 5.84 417.55 * 0.012 1.84 1.89 5. 62 5.62 5.56 5.84 2.48 29.50 5.96 417.67 * 0.012 1.86 1.92 5.72 5.72 5.66 5.96 2.50 29.96 6.07 417.78 * 0.012 1.87 1.95 5.81 5.81 5.77 6.07 2.52 30.43 6.19 417.90 * 0.012 1.89 1.97 5.91 5.91 5.88 6.19 2.55 30.89 6.31 418.02 * 0.012 1.90 2.00 6.01 6.01 5.99 6.31 2.57 31.35 6.43 418.14 * 0.012 1.91 2.04 6.11 6.11 6.10 6.43 2. 64 PIPE NO. 6: 80 LF - 30"CP @ 0.51% OUTLET: 411.71 INLET: 412.12 INTYP: 2 JUNC NO. 6: OVERFLOW-EL: 422.00 BEND: 0 DEG DIA/WIDTH: 4.5 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.89 2.07 414.19 * 0.012 0.81 0.73 2.45 2.45 2.05 2.07 1.08 6.35 2.09 414.21 * 0.012 0.84 0.76 2.46 2.46 2.07 2.09 1.12 6.81 2.12 414.24 * 0.012 0.87 0.79 2.49 2.49 2.09 2.12 1.16 7 .28 2.16 414.28 * 0.012 0.90 0.82 2.52 2.52 2.13 2.16 1.20 7.74 2.19 414.31 * 0.012 0.93 0.84 2.55 2.55 2.16 2.19 1.24 8.20 2.22 414.34 * 0.012 0.96 0.87 2.57 2 .57 2.19 2.22 1.28 8.67 2.26 414.38 * 0.012 0.99 0.90 2.61 2.61 2.22 2.26 1.32 • 6.35 2.00 414.29 * 0.012 0.84 0.82 2.09 2.09 1.93 2.00 1.16 6.81 2.03 414.32 * 0.012 0.87 0.85 2 .12 2.12 1.96 2.03 1.20 7.28 2.08 414.37 * 0.012 0.90 0.88 2.16 2.16 2.00 2.08 1.25 7.74 2.12 414.41 * 0.012 0.93 0.91 2.19 2.19 2.03 2.12 1.29 8.20 2.17 414.46 * 0.012 0.96 0. 94 2.22 2.22 2.07 2.17 1.34 8.67 2.21 414.50 * 0.012 0.99 0.97 2.26 2.26 2.10 2.21 1.38 9.13 2.25 414.54 * 0.012 1.01 0. 99 2.30 2.30 2.14 2.25 1.43 9.59 2.30 414.59 * 0.012 1.04 1.02 . 2.34 2.34 2.18 2.30 1.47 10.06 2.37 414. 66 * 0.012 1.06 1.05 2.39 2.39 2.24 2.37 1.51 10.52 2.42 414.71 * 0.012 1.09 1.07 2.43 2.43 2.28 2.42 1.55 10.98 2.49 414.78 * 0.012 1.11 1.10 2.48 2 .48 2.34 2.49 1.59 11.44 2.55 414. 84 * 0.012 1.14 1. 13 2.53 2.53 2.39 2.55 1. 63 11.91 2.62 414. 91 * 0.012 1.16 1.15 2.59 2 .59 2.45 2.62 1.67 12.37 2.69 414. 98 * 0.012 1.19 1.18 2.64 2.64 2.51 2.69 1.72 12.83 2.76 415.05 * 0.012 1.21 1.20 2.70 2 .70 2.56 2.76 1.76 13.30 2.83 415. 12 * 0.012 1.23 1.23 2.76 2.76 2.63 2.83 1.80 - 13.76 2.91 415.20 * 0.012 1.25 1.25 2.82 2.82 2.69 2.91 1.84 14.22 3.00 415.29 * 0.012 1.28 1.28 2.88 2.88 2.76 3.00 1.88 14.69 3.08 415.37 * 0.012 1.30 1.30 2.95 2.95 2.83 3.08 1.91 15.15 3.17 415.46 * 0.012 1.32 1.33 3.02 3.02 2.90 3.17 1.95 15.61 3.26 415.55 * 0.012 1.34 1.35 3.09 3.09 2.97 3.26 1.99 16.07 3.35 415. 64 * 0.012 1.36 1.37 3.16 3.16 3.05 3.35 2.03 16.54 3.45 415.74 * 0.012 1.38 1.40 3.23 3.23 3.13 3.45 2.07 17.00 3.55 415.84 * 0.012 1.40 1.42 3.31 3.31 3.21 3.55 2.11 17.46 3.65 415.94 * 0.012 1.42 1.45 3.39 3.39 3.29 3.65 2.15 . 17.93 3.75 416.04 * 0.012 1.44 1.47 3.47 3.47 3.37 3.75 2.19 18.39 3.86 416. 15 * 0.012 1.46 1.50 3.56 3.56 3.46 3.86 2.23 18.85 3.97 416.26 * 0.012 1.48 1.52 3.64 3.64 3.55 3.97 2.27 19.31 4.08 416.37 * 0.012 1.50 1.55 3.73 3.73 3. 64 4.08 2.31 19.78 4.20 416.49 * 0.012 1.51 1.57 3.82 3.82 3.73 4.20 2.35 20.24 4.31 416. 60 * 0.012 1.53 1.59 3.91 3.91 3.83 4.31 2.39 20.70 4.43 416.72 * 0.012 1.55 1. 62 4 .00 4.00 3.93 4.43 2.43 21.17 4.56 416.85 * 0.012 1.57 1.64 4.10 4.10 4.03 4.56 2.47 21.63 4.68 416. 97 * 0.012 1.59 1.67 4.20 4.20 4.13 4.68 2.51 22.09 4.81 417.10 . * 0.012 1.60 1.70 4 .30 4.30 4.24 4.81 2.55 22.56 4.94 417.23 * 0.012 1.62 1.72 4.40 4.40 4.34 4.94 2.59 23.02 5.08 417.37 * 0.012 1.64 1.75 4.50 4.50 4.45 5.08 2.63 23.48 5.21 417.51 * 0.012 1.66 1.78 4 . 61 4. 61 4.56 5.21 2.67 23.94 5.35 417. 64 * 0.012 1.67 1.80 4.72 4.72 4.68 5.35 2.71 24.41 5.50 417.79 * 0.012 1.69 1.83 4.83 4.83 4.79 5.50 2.75 24.87 5.64 417. 93 * 0.012 1.70 1.86 4.94 4.94 4. 91 5.64 2.79 25.33 5.79 418.08 * 0.012 1.72 1.89 5.06 5.06 5.03 5.79 2.83 25.80 5.94 418.23 * 0.012 1.74 1.92 5.18 5.18 5.15 5.94 2.87 26.26 6.09 418.38 * 0.012 1.75 1.95 5.30 5.30 5.28 6.09 2.91 26.72 6.25 418.54 * 0.012. 1.77 1.98 5.42 5.42 5.41 6.25 2.95 27.19 6.41 418.70 * 0.012 1.78 2.02 5.54 5.54 5.54 . 6.41 3.02 27.65 6.57 418.86 * 0.012 1.80 2.06 5.67 5.67 5.67 6.57 3.06 28.11 6.73 419.02 * 0.012 1.81 2.10 5.79 5.79 5.80 6.73 3.10 28.57 6.90 419.19 * 0.012 1.83 2.14 5.92 5. 92 5.94 6.90 3.15 29.04 7.07 419.36 * 0.012 1.84 2.19 6.06 6.06 6.07 7.07 3.19 29.50 7.24 419.53 * 0.012 1.86 2.27 6.19 6.19 6.22 7.24 3.24 29.96 7.42 419.71 * 0.012 1.87 2.50 6.33 6.33 6.36 7.42 3.28 30.43 7.59 419.88 _ * 0.012 1.89 2.50 6.47 6.47 6.50 7.59 3.33 30.89 7.78 420.07 * 0.012 1.90 2.50 6.61 6. 61 6.65 7.78 3.38 31.35 7.96 420.25 * 0.012 1.91 2.50 6.75 6.75 6.80 7.96 3.47 • 28.27 8.05 420.27 * 0.012 1.82 0.00 7.42 7.42 7.78 8.05 2.45 28.70 8.24 420.46 * 0.012 1.83 0.00 7.59 7.59 7.97 8.24 2.47 29.14 8:44 420.66 * 0.012 1.85 0.00 7.78 7.78 8. 16 8.44 2.49 29.58 8.64 420.86 * 0.012 1.86 0.00 7.96 7.96 8.35 8.64 2.51 PIPE NO. 9: 145 LF - 30"CP @ 0.80% OUTLET: 412.22 INLET: 413.38 INTYP: 2 JUNC NO. 9: OVERFLOW-EL: 426.00 BEND: 0 DEG DIA/WIDTH: 4.5 Q-RATIO: 0.11 Q(CFS) HW(FT) HW ELEV. * N-FAC , DC DN TW DO DE HWO HWI ******************************************************************************* 5.56 1.15 414.53 * 0.012 0.78 0. 64 2.08 2.08 0.92 1.15 1.03 5.99 .1.19 414.57 * 0.012 0.81 0.66 2.11 2.11 0.94 1.19 1.06 6.43 1.24 414.62 * 0.012 0.84 0. 69 2.15 2.15 0. 98 1.24 1.10 6.87 1.28 414.66 * 0.012 0.87 0.71 2.19 2.19 1.03 1.28 1.14 7.30 1.32 414.70 * 0.012 0. 90 0.73 2.24 2.24 1.07 1.32 1.17 7.74 1.36 414.74 * 0.012 0.93 0.75 2.29 2.29 1.12 1.36 1.21 8.18 1.40 414.78 _ * 0.012 0. 96 0.78 2.33 2.33 1.16 1.40 1.24 8.61 1.44 414.82 * 0.012 0. 98 0.80 2.38 2.38 1.22 1.44 1.27 9.05 1.48 414.86 * 0.012 1.01 0.82 2.43 2.43 1.27 1.48 1.30 9.49 1.54 414.92 * 0.012 1.03 0.84 2.51 2.51 1.36 1.54 1.33 9.92 1.58 414.96 * 0.012 1.06 0.86 2.56 2.56 1.42 1.58 1.36 10.36 1.64 415.02 * 0.012 1.08 0.88 2.63 2.63 1.50 1. 64 1.39 10.80 1.70 415.08 * 0.012 1.10 0.90 2.70 2.70 1.57 1.70 1.41 11.23 1.76 415.14 *0.012 1. 13 0.92 2.78 2.78 1. 66 1.76 1.44 11.67 1.83 415.21 * 0.012 1. 15 0.93 2.86 2. 86 1.75 1.83 1.46 12.11 1.90 415.28 * 0.012 1.17 0.95 2.93 2.93 1.84 1.90 1.49 12.54 1.98 415.36 * 0.012 1.19 0.97 3.01 3.01 1.94 1.98 1.51 12.98 2.06 415.44 * 0.012 1.22 0.99 3.10 3.10 2.04 2.06 1.54 13.42 2.14 415.52 * 0.012 1.24 1.01 3.19 3.19 2.14 2.14 1.56 13.85 2.25 415.63 * 0.012 1.26 1.02 3.29 3.29 2.25 2.24 1.58 14.29 2.36 415.74 * 0.012 1.28 1.04 3.38 3.38 2.36 2.33 1. 60 14.73 2.48 415.86 * 0.012 1.30 1.06 3.48 3.48 2.48 2.44 1. 62 15.16 2.60 415.98 * 0.012 1.32 1.08 3.58 3.58 2. 60 2.56 1. 64 15.60 2.71 416.09 * 0.012 1.34 1.09 3.69 3. 69 2.71 2.67 1. 66 16.04 2.83 416.21 * 0.012 1.36 1.11 3.80 3.80 2.83 2.78 1.68 16.47 2.95 416.33 * 0.012 1.38 1.13 3.91 3.91 2.95 2.90 1. 69 16.91 3.07 416.45 * 0.012 1.40 1.14 4.02 4.02 3.07 3.03 1.71 17.35 3.20 416.58 * 0.012 1.41 1.16 4.14 4.14 3.20 3.15 1.73 17.78 3.33 416.71 * 0.012 1.43 1.18 4.26 4 .26 3.33 3.28 1.75 18.22 3.47 416.85 * 0.012 1.45 1.19 4.38 4.38 3.47 3.41 1.76 18.66 3.61 416.99 * 0.012 1.47 1.21 4.51 4.51 3.61 3.55 1.78 19.10 3.75 417.13 * 0.012 1.49 1.23 4.64 4. 64 3.75 3. 69 1.79 19.53 3.89 417.27 * 0.012 1.50 1.24 4.77 4.77 3.89 3.83 1.81 19.97 4.04 417.42 * 0.012 1.52 1.26 4.91 4.91 4.04 3.97 1.82 20.41 4.19 • 417.57 * 0.012 1.54 1.28 5.05 5.05 4.19 4.12 1.83 20.84 4.35 417.73 * 0.012 1.56 1.29 5.19 5.19 4.35 4.27 1.85 21.28 4.51 417.89 * 0.012 1.57 1.31 5.33 5.33 4.51 4.43 1.86 21.72 4. 67 418.05 * 0.012 1.59 1.32 5.48 5.48 4.67 4.59 1.87 22.15 4.83 418.21 * 0.012 1.61 1.34 5.63 5.63 4.83 4.75 1.88 22.59 5.00 418.38 * 0.012 1.62 1.36 5.78 5.78 5.00 4.91 1.89 23.03 5.17 418.55 * 0.012 1.64 1.37 5.94 5.94 5. 17 5.08 1.90 23.46 5.34 418.72 * 0.012 1.65 1.39 6.10 6.10 5.34 5.25 1.91 23.90 5.52 418.90 * 0.012 1.67 1.40 6.26 6.26 5.52 5.42 1.93 24.34 5.70 419.08 * 0.012 1.69 1.42 6.43 6.43 5.70 5.60 1.93 24.77 5.89 419.27 * 0.012 1.70 1 .44 6.59 6.59 5.89 5.78 1.94 25.21 6.07 419.45 * 0.012 1.72 1.45 6.77 6.77 6.07 5.96 1.95 • • 20.74 7.12 420.82 * 0.012 1.64 2.00 5.17 5.17 5.88 7.12 3.25 21.14 7.38 421.08 * 0.012 1.65 2.00 5.34 5.34 6.10 7.38 3.32 21.53 7.64 421.34 * 0.012 1.67 2.00 5.52 5.52 6.31 7. 64 3.39 21.92 7.91 421.61 * 0.012 1.68 2.00 5.70 5.70 6.54 7.91 3.47 22.32 8.19 421.89 * 0.012 1. 69 2.00 5.89 5.89 6.76 8.19 3.54 22.71 8.47 422.17 * 0.012 1.70 2.00 6.07 6.07 6.99 8.47 3.62 23.10 8.76 422.46 * 0.012 1.71 2.00 6.26 6.26 7.22 8.76 3.70 23.50 9.05 422.75 * 0.012 1.73 2.00 6.46 6.46 7.46 9.05 3.78 23. 9 9.34 423.04 * 0.012 1.74 2.00 6'.66 6. 66 7.70 9.34 3.86 24.29 9.64 423.34 * 0.012 1.75 2.00 6.86 6.86 7.95 9. 64 3.94 24.68 9.95 423.65 * 0.012 1.76 2.00 7.06 7.06 8.20 9.95 4.02 25.07 10.26 423.96 * 0.012 1.77 2.00 7.27 7.27 8.45 10.26 4.11 25.47 10.57 424.27 * 0.012 1.78 2.00 7.48 7.48 8.71 10.57 4.19 25.86 10.89 424.59 * 0.012 1.79 2.00 7.69 7. 69 8. 97 10.89 4.28 26.25 11.22 424.92 * 0.012 1.80 2.00 7.91 7 .91 9.24 11.22 4.37 26.65 11.55 425.25 * 0.012 1.81 2.00 8.13 8.13 9.51 11.55 4.46 PIPE NO.11 : 264 LF - 24"CP @ 0.53% OUTLET: 413.70 INLET: 415.10 INTYP: 2 JUNC NO.11: OVERFLOW-EL: 429.50 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.01 1.11 - 416.21 * 0.012 0.79 0.73 1.25 1.25 0.79 ***** 1.11 5.40 1.16 416.26 * 0.012 0.82 0.76 1.30 1.30 0.82 ***** 1.16 5.79 1.21 416.31 * 0.012 0.86 0.79 1.36 1.36 0.86 ***** 1.21 6.19 1.26 416.36 * 0.012 0.89 0.82 1.41 1.41 0.89 ***** 1.26 6.58 1.31 416.41 * 0.012 0.91 0.85 1.47 1.47 0.91 ***** 1.31 6.97 1.36 416.46 * 0.012 0.94 0.87 1.53 1.53 0.94 ***** 1.36 7.37 1.40 416.50 * 0.012 0.97 0.90 1.58 1.58 0. 97 ***** 1.40 7.76 1.45 416.55 * 0.012 1.00 0.93 1.64 1.64 1.00 ***** 1.45 8.15 1.50 416.60 * 0.012 1.02 0.95 1.69 1.69 1.02 ***** 1.50 8.55 1.55 416.65 * 0.012 1.05 0.98 1.75 1.75 1.05 ***** 1.55 8.94 1.59 416.69 * 0.012 1.07 1.01 1.81 1.81 1.07 ***** 1.59 9.33 1.64 416.74 * 0.012 1.10 1.03 1.87 1.87 1.10 ***** 1.64 9.73 1.69 416.79 * 0.012 1.12 1.06 1.94 1.94 1.12 ***** 1.69 10.12 1.73 416.83 * 0.012 1.14 1.08 2.02 2.02 1.14 ***** 1.73 10.51 1.92 417.02 * 0.012 1.17 1.11 2.10 2 .10 1.22 1.92 1.78 10.91 1.95 417.05 * 0.012 1.19 1.14 2.19 2.19 1.30 1.95 1.83 11.30 2.01 417.11 * 0.012 1.21 1.16 2.31 2.31 1.44 2.01 1.87 11.69 2.11 417.21 * 0.012 1.23 1.19 2.46 2 .46 1.61 2.11 1.92 12.09 2.24 417.34 * 0.012 1.25 1.21 2.59 2 .59 1.78 2.24 1.97 12.48 2.49 417.59 * 0.012 1.28 1.24 2.75 2.75 2.04 2.49 2.01 12.87 2.72 417.82 * 0.012 1.30 1.26 2.91 2 .91 2.24 2.72 2.06 13.27 2.97 418.07 * 0.012 1.32 1.29 3.09 3.09 2.46 2.97 2.11 13.66 3.22 418.32 * 0.012 1.34 1.32 3.26 3.26 2.68 3.22 2.16 14.05 3.47 418.57 * 0.012 1.36 1.34 3.43. 3 .43 2.90 3.47 2.20 14.45 3.72 418.82 * 0.012 1.37 1.37 3.61 3.61 3.13 3.72 2.25 14.84 3.99 419.09 * 0.012 1.39 1.40 3.79 3.79 3.36 3.99 2.30 15.24 4.26 419.36 * 0.012 1.41 1.43 3.98 .3 .98 3. 60 4.26 2.35 15.63 4.54 419.64 * 0.012 1.43 1.46 4.17 4 .17 3.84 4.54 2.42 16.02 4.83 419.93 * 0.012 1.45 1.49 4.37 4 .37 4.10 4.83 2.47 16.42 5.13 420.23 * 0.012 1.47 1.52 4.57 4 .57 4.36 5.13 2.52 16.81 5.43 420.53 * 0.012 1.48 1.55 4.78 4 .78 4 . 62 5.43 2.57 17.20 5.74 420.84 * 0.012 1.50 1.58 4.99 4.99 4.89 5.74 2.63 17.60 6.06 421.16 * 0.012 1.52 1.62 5.20 5.20 5.17 6.06 2.68 17.99 6.38 421.48 * 0.012 1.53 1.66 5.43 5.43 5.45 6.38 2.78 • 15.24 4.60 420. 60 * 0.012 1.41 1.35 4.26 4.26 3.93 4. 60 2.35 15.63 4.94 420. 94 * 0.012 1.43 1.38 4.54 4.54 4.24 4.94 2.42 16.02 5.30 421.30 * 0.012 1.45 1.40 4.83 4.83 4.56 5.30 2.47 16.42 5.66 421. 66 * 0.012 1.47 1.43 5.13 5.13 4.89 5. 66 2.52 16.81 6.03 422.03 * 0.012 1.48 1.46 5.43 5.43 5.22 6.03 2.57 17.20 6.41 422.41 * 0.012 1.50 1.48 5.74 5.74 5.56 6.41 2.63 17.60 6.80 422. 80 * 0.012 1.52 1.51 6.06 6.06 5.91 6.80 2.68 17 .99 7.20 423.20 * 0.012 1.53 1.54 6.38 6.38 6.27 7.20 2.78 18 .38 7.61 423. 61 * 0.012 1.55 1.57 6.71 6°.71 6. 64 7. 61 2.84 18.78 8.02 424.02 * 0.012 1.56 1.61 7.05 7.05 7.01 8.02 2.91 19.17 8.45 424.45 * 0.012 1.58 1.64 7.39 7 .39 7.39 8.45 2.97 19.56 8.88 424.88 * 0.012 1.60 1.68 7.74 7.74 7.78 8.88 3.04 19.96 9.32 425.32 * 0.012 1.61 1.73 8.10 8.10 8.18 9.32 3.10 20.35 9.77 425.77 * 0.012 1. 62 1.79 8.47 8 .47 8.58 9.77 3.17 20.74 10.23 426.23 * 0.012 1.64 2.00 8.84 8.84 9.00 10.23 3.24 21.14 10.70 426.70 * 0.012' 1.65 2.00 9.23 9.23 9.42 10.70 3.31 21.53 11.18 427.18 * 0.012 1.67 2.00 9.61 9.61 9.85 11.18 3.39 21.92 11.66 427. 66 * 0.012 . 1.68 2.00 10.01 10.01 10.29 11.66 3.46 **************** OVERFLOW ENCOUNTERED AT 22.32 CFS DISCHARGE ***************** ******** OVERFLOW CONDITIONS CALCULATED ASSUMING SURCHARGE CONDITIONS ********* 22.32 12.16 428.16 * 0.012 1.69 2.00 10.41 10.41 10.73 12.16 3.54 22.71 12.66 428. 66 * 0.012 1.70 2.00 10.82 10.82 11.18 12. 66 3.61 23.10 13.17 429.17 * 0.012 1.71 2.00 11.24 11.24 11.64 13.17 3.69 23.50 13.70 429.70 * 0.012 1.73 2.00 11.66 11.66 12. 11 13.70 3.77 23.89 14.23 430.23 * 0.012 1.74 2.00 12.09 12.09 12.59 14.23 3.85 24.29 14.76 430.76 * 0.012 1.75 2.00 12.53 12.53 13.07 14.76 3.94 24.68 15.31 431.31 * 0.012 1.76 2.00 12. 97 12 .97 13.57 15.31 4.02 25.07 15.87 431.87 * 0.012 1.77 . 2.00 13.43 13.43 14.07 15.87 4.10 25.47 16.43 432.43 * 0.012 1.78 2.00 13.89 13.89 14.57 16.43 4.19 25.86 17.01 433.01 * 0.012 1.79 2 .00 14.35 14.35 15.09 17.01 4.28 26.25 17.59 433.59 * 0.012 1.80 2.00 14.83 14.83 15.61 17.59 4.37 26.65 18.18 434.18 * 0.012 1.81 2.00 15.31 15.31 16.15 18.18 4.46 PIPE NO.13: 134 LF - 24"CP @ 0.60% OUTLET: 416.00 INLET: 416.80 INTYP: 2 JUNC NO.13: OVERFLOW-EL: 426.65 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.01 1.06 417.86 * 0.012 0.79 0.71 1.11 1.11 0.79 ***** 1.06 5.40 1.10 417. 90 * 0.012 0.82 0.74 1.16 1.16 0.82 ***** 1.10 5.79 1.14 417. 94 * 0.012 0.86 0.76 1.21 1.21 0.86 ***** 1.14 6.19 1.18 417.98 * 0.012 0.89 0.79 1.26 1.26 0.89 ***** 1.18 6.58 1.22 418.02 * 0.012 0.91 0.82 1.31 1.31 0.91 ***** 1.22 6.97 1.26 418.06 * 0.012 0.94 0.84 1.36 1.36 0.94 ***** 1.26 7.37 1.29 418.09 * 0.012 0.97 0.87 1. 40 1.40 0.97 ***** 1.29 7.76 1.33 418.13 * 0.012 1.00 0.90 1.45 1.45 1.00 ***** 1.33 8.15 1.36 418. 16 * 0.012 1.02 0.92 1.50 1.50 1.02 ***** 1.36 8.55 1.40 418.20 * 0.012 1.05 0.95 1.55 1.55 .1.05 ***** 1.40 8.94 1.43 418.23 * 0.012 1.07 0.97 1.59 1.59 1.07 ***** 1.43 9.33 1.46 418.26 * 0.012 1.10 1.00 1. 64 1.64 1.10 ***** 1.46 9.73 1.49 418.29 * 0.012 1.12 1.02 1. 69 1.69 1.12 ***** 1.49 10.12 1.52 418.32 * 0.012 1.14 1.05 1.73 1.73 1.14 ***** 1.52 10.51 1.55 418.35 * 0.012 1.17 1.07 1.78 1.78 1.17 ***** 1.55 10.91 1.71 418.51 * 0.012 1.19 1.09 1.97 1.97 1.32 1.71 1.58 11.30 1.74 418.54 * 0.012 1.21 1.12 2.00 2 .00 1.39 1.74 1. 61 11.69 1.78 418.58 * 0.012 1.23 1.14 2.06 2.06 1.48 1.78 1.64 8.94 1.42 418.71 * 0.012 1.07 0.83 1.43 1.43 1.07 ***** 1.42 9.33 1.46 418.75 * 0.012 1.10 0.85 1.46 1.46 1.10 ***** 1.46 9.73 1.49 418.78 * 0.012 1.12 0 .87 1.49 1.49 1.12 ***** 1.49 10.12 1.52 418.81 * 0.012 1.14 0.89 1.52 1.52 1.14 ***** 1.52 10.51 1.55 418.84 * 0.012 1.17 0.91 1.55 1.55 1.17 ***** 1.55 10. 91 1.58 418.87 * 0.012 1.19 0.93 1.71 1.71 1.19 ***** 1.58 11.30 . 1.61 418.90 * 0.012 1.21 0.95 1.74 1.74 1.21 ***** 1.61 11.69 1.63 418.92 * 0.012 1.23 0.97. 1.78 1.78 1.23 ***** 1.63 12.09 1.66 418.95 * 0.012 1.25 0.98 1.85 1.85 1•.25 ***** 1.66 12.48 1.87 419.16 * 0.012 1.28 1.00 2.07 2.07 1. 62 1.87 1.69 12.87 2.20 419.49 * 0.012 1.30 1.02 2.42 2.42 2.06 2.20 1.72 13.27 2.53 419.82 * 0.012 1.32 1.04 2.74 2.74 2.39 2.53 1.74 13.66 2.89 420.18 * 0.012 1.34 1.06 3.08 3.08 2.74 2.89 1.77 14.05 3.24 420.53 * 0.012 1.36 1.08 3.42 3.42 3.08 3.24 1.79 14.45 .3.61 420.90 * 0.012 1.37 1.10 3.77 3.77 3.44 3. 61 1.82 14.84 4.00 421.29 * 0.012 1.39 1.11 4.13 4.13 3.82 4.00 1.84 15.24 4.39 421.68 * 0.012 1.41 1.13 4.51 4 .51 4.20 4.39 1.87 15.63 4.79 422.08 * 0.012 1.43 1.15 4.89 4.89 4.59 4.79 1.91 16.02 5.20 422.49 * 0.012 1.45 1.17 5.28 5.28 4.99 5.20 1.94 16.42 5.62 422.91 * 0.012 1.47 1.19 5.68 5.68 5.40 5.62 1.96 16.81 6.06 423.35 * 0.012 1.48 1.20 6.09 6.09 5.82 6.06 1.99 17.20 6.50 423.79 * 0.012 1.50 1.22 6.51 6.51 6.26 6.50 2.02 17. 60 6.95 424.24 * 0.012 1.52 1.24 6.95 6.95 6.70 6.95 2.05 17.99 7.41 424.70 * 0.012 1.53 1.26 7.39 7.39 7.15 7.41 2.11 18.38 7.89 425.18 * 0.012 1.55 1.28 7.84 7.84 7.61 7.89 2.15 18.78 8.37 425.66 * 0.012 1.56 1.30 8.30 8.30 8.08 8.37 2.18 19.17 8.87 426.16 * 0.012 1.58 1.32 8.77 8.77 8.56 8.87 2.21 **************** OVERFLOW ENCOUNTERED AT 19.56 CFS DISCHARGE ***************** ******** OVERFLOW CONDITIONS CALCULATED ASSUMING SURCHARGE CONDITIONS ********* 19.56 9.37 426.66 * 0.012 1.60 1.34 9.25 9.25 9.06 9.37 2.25 19.96 9.88 427.17 * 0.012 1.61 1.36 9.74 9.74 9.56 9.88 2.28 20.35 10.41 427.70 * 0.012 1.62 1.37 10.24 10.24 10.07 10.41 2.32 20.74 10.94 428.23 * 0.012. 1.64 1.39 10.74 10.74 10.59 10.94 2.36 21.14 11.49 428.78 * 0.012 1. 65 1.41 11.26 11.26 11.12 11.49 2.40 21.53 12.04 429.33 * 0.012 1.67 1.44 11.79 11.79 11.66 12.04 2.43 21.92 12. 61 429.90 * 0.012 1.68 1.46 12.33 12.33 12.22 12.61 2.47 22.32 13.19 430.48 * 0.012 1.69 1.48 12.88 12 .88 12.78 13.19 2.51 22.71 13.77 431.06 * 0.012 1.70 1.50 13.44 13.44 13.35 13.77 2.55 23.10 14.37 431.66 * 0.012 1.71 1.52 14.00 14.00 13.93 14.37 2. 60 23.50 14.97 432.26 * 0.012 1.73 1.54 14.58 14.58 14.52 14.97 2.64 23.89 15.59 432.88 * 0.012 1.74 1.57 15.17 15.17 15.12 15.59 2.68 24.29 16.22 433.51 * 0.012 1.75 1.59 15.76 15.76 15.73 16.22 2.72 24.68 16.86 434.15 * 0.012 1.76 1.62 16.37 16.37 16.36 16.86 2.77 25.07 17.50 434.79 * 0.012 _ 1.77 1.65 16.99 16.99 16.99 17.50 2.81 25.47 18.16 435.45 * 0.012 1.78 1.68 17.61 17.61 17. 63 18.16 2.86 25.86 18.83 436.12 * 0.012 1.79 1.71 1.8.25 18 .25 18.28 18.83 2. 91 26.25 19.51 436.80 * 0.012 1.80 1.75 18.89 18.89 18.94 19.51 2.95 26.65 20.19 437.49 * 0.012 1.81 1.80 19.55 19.55 19. 61 20.19 3.00 PIPE NO.15: 20 LF - 24"CP @ 0.55% OUTLET: 417.29 INLET: 417.40 INTYP: 2 JUNC NO.15: OVERFLOW-EL: 423.56 BEND: 45 DEG DIA/WIDTH: 6.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.01 1.19 418.59 * 0.012 0.79 0.72 1.05 1.05 0. 93 1.19 1.07 5.40 1.24 418.64 * 0.012 0.82 0.75 1.10 1.10 0.97 1.24 1.12 • PIPE NO.16: 30 LF - 24"CP @ 0. 67% OUTLET:" 417 .40 INLET: 417.60 INTYP: 2 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 5.01 1.21 418.81 * 0.012 0.79 0. 69 1.19 1.19 0.97 1.21 1.08 5.40 1.27 418.87 * 0.012 0.82 . 0.71 1.24 1.24 1.02 1.27 1.13 5.79 1.32 418.92 * 0.012 0.86 0.74 1.29 1.29 1.07 1.32 1.18 6.19 1.38 418.98 * 0.012 0.89 0.77 1.34 1.34 1.12 1.38 1.22 6.58 1.43 419.03 * 0.012 0.91 0.79 1.38 1.38 1.17 1.43 1.27 6.97 1.48 419.08 * 0.012 0.94 0.82 1.42 1.42 1.21 1.48 1.32 7.37 1.53 419.13 * 0.012 0.97 0.84 1.47 1.47 1.25 1.53 1.36 7.76 1.58 419.18 * 0.012 1.00 0.87 1.51 1.51 1.30 1.58 1.40 8.15 1.63 419.23 * 0.012 1.02 0.89 1.55 1.55 1.34 1.63 1.45 8.55 1.69 419.29 * 0.012 1.05 0.92 1.59 1.59 1.39 1. 69 1.49 8.94 1.74 419.34 * 0.012 1.07 0.94 1.63 1. 63 1.43 1.74 1.54 9.33 1.79 419.39 * 0.012 1.10 0.97 1.67 1. 67 1.47 1.79 1.58 9.73 1.84 419.44 * 0.012 1.12 0.99 1.70 1.70 1.51 1.84 1.62 10.12 1.88 419.48 * 0.012 1.14 1.01 1.74 1.74 1.55 1.88 1.66 10.51 1.93 419.53 * 0.012 1.17 1.03 1.78 1.78 1.59 1.93 1.71 10.91 1.98 419.58 * 0.012 1.19 1.06 1.81 1.81 1.63 1.98 1.75 11.30 2.03 419.63 * 0.012 1.21 1.08 1.85 1.85 1.67 2.03 1.79 11.69 2.08 419. 68 * 0.012 1.23 1.10 1.88 1.88 1.71 2.08 1.83 12.09 2.14 419.74 * 0.012 1.25 1.13 1.92 1.92 1.76 2.14 1.88 12.48 2.28 419.88 * 0.012 1.28 1.15 2.05 2.05 1.92 2.28 1.92 12.87 2.65 420.25 * 0.012 1.30 1.17 2.38 2.38 2.27 2.65 1.96 13.27 3.02 420. 62 * 0.012 1.32 1.19 2.73 2.73 2.61 3.02 2.00 13.66 3.42 421.02 * 0.012 1.34 1.22 3.10 3.10 3.00 3.42 2.04 14.05 3.83 421.43 * 0.012 1.36 1.24 3.48 3.48 3.38 3.83 2.09 14.45 4.25 421.85 * 0.012 1.37 1.26 3.87 3.87 3.77 4.25 2.13 14.84 4.68 422.28 * 0.012 1.39 1.29 4.27 4.27 4.18 4.68 2.17 15.24 5.13 422.73 * 0.012 1.41 1.31 4 .68 4. 68 4.60 5.13 2.22 **************** OVERFLOW ENCOUNTERED AT 15.63 CFS DISCHARGE ***************** 15.63 5.59 423. 19 * 0.012 1.43 1.33 5.10 5.10 5.03 5.59 2.28 16.02 6.06 423.66 * 0.012 1.45 1.36 5.54 5.54 5.46 6.06 2.32 16.42 6.54 424.14 * 0.012 1.47 1.38 5.98 5.98 5.92 6.54 2.37 16.81 7.03 424.63 * 0.012 1.48 1.41 6.44 6.44 6.38 7.03 2.42 17.20 7.53 425.13 * 0.012 1.50 1.43 6.90 6.90 6.85 7.53 2.46 17.60 8.05 425.65 * 0.012 1.52 1.46 7.38 7 .38 7.33 8.05 2.51 17.99 8.58 426.18 * 0.012 1.53 1.49 7.87 7.87 7.83 8.58 2.60 18.38 9.12 426.72 * 0.012 1.55 1.51 8.36 8 .36 8.33 9.12 2.66 18.78 9.67 427.27 * 0.012 1.56 1.54 8.87 8.87 8.85 9.67 2.71 19.17 10.23 427.83 * 0.012 1.58 1.57 9.39 9.39 9.38 10.23 2.77 19.56 10.80 428.40 * 0.012 1.60 1.61 9.92 9.92 . 9.91 10.80 2.83 19.96 11.39 428.99 * 0.012 1.61 1.64 10.46 10.46 10.46 11.39 2.89 20.35 11.99 429.59 * 0.012 1.62 1.68 11.02 11.02 11.02 11.99 2.95 20.74 12.60 430.20 * 0.012 1.64 1.72 11.58 11.58 11.59 12.60 3.01 21.14 13.22 430.82 * 0.012 1.65 1.77 12.15 12 .15 12.18 13.22 3.07 21.53 13.85 431.45 . * 0.012 1.67 2.00 12.74 12 .74 12.77 13.85 3.14 21.92 14.49 432.09 * 0.012 1. 68 2.00 13.33 13.33 13.37 14.49 3.20 22.32 15.15 432.75 * 0.012 1.69 2.00 13.94 13.94 13.99 15.15 3.27 22.71 15.82 433.42 * 0.012 1.70 2.00 14.56 14 .56 14.61 15.82 3.34 23.10 16.50 434.10 * 0.012 1.71 2.00 15.18 15.18 15.25 16.50 3.41 23.50 17.19 434.79 * 0.012 1.73 2.0015.82 15.82 15.90 17.19 3.48 23.89 17.89 435.49 * 0.012 1.74 2.00 16.47 16.47 16.56 17.89 3.55 24.29 18.60 436.20 * 0.012 1.75 2.00 17.13 17 .13 17.23 18.60 3.62 24.68 19.33 436.93 * 0.012 1.76 2.00 17.80 17.80 17.91 19.33 3.70 -RDA)D -1 - ru LL 14e4)12) t)(Sc.-1-14-re-IA Orifice Q - Flow H C - Orifice Coefficient A - Area of Orifice d - Diameter of Orifice d H - Head Input Output Q (cfs) 0.00 6.81 C 0.62 0.62 A (sf) 0.00 0.58 d (in) 10.30 10.30 10 4 /16 inches H (ft) 5.60 5.60 Job: Altmyer By: J3 Date: 4/25/2008 Page 1 Axl � 1,11^a ?1fl7 � cvc=. •-•03 „A.-4 L 2 vo,A i`zi z � e L 1 Q/l,lL� 1.."4 5n?1( 0)e. n= C;,,-,Nv\rr-3© • • fj-t �,Al ,;© - -M gr/ca