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Ex08_Preliminary_Technical_Information_Report_(TIR)
Shum Short Plat Preliminary Technical Information Report (Full Drainage Review) Site Location: 1157 Queen Ave NE Renton, WA 98056 Parcel#: 106570-0100 Prepared for: Hoi-Fung Shum 17723 110th Pl. SE Renton, WA 98055 Schwin Chaosilapakul, P.E. Nick Millman, E.I.T. PATRICK HARRON & ASSOCIATES, LLC 14900 Interurban Avenue South, Suite 279 Seattle, WA 98168 PHA Project #: 21807 Date: December 10, 2021 Revised: April 1st, 2022 May 4th, 2022 14900 Interurban Ave. S, Suite 279 Seattle, WA 98168-4635 Ph: 206.674.4659 www.patrickharron.com Engineering & Planning DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx TABLE OF CONTENTS 1. PROJECT OVERVIEW .................................................................................... 1 2. CONDITIONS AND REQUIREMENTS SUMMARY ................................ 10 3. OFF-SITE ANALYSIS ..................................................................................... 11 Task 1: Study Area Definition ................................................................................................11 Task 2: Resource Review .......................................................................................................11 Task 3: Site Description .........................................................................................................11 Task 4: Upstream Drainage System Description ...................................................................14 Task 5: Downstream Drainage System Description and Existing and Potential Problems ...14 4. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN.................................................................................................... 16 Drainage Concept ...................................................................................................................16 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN ............................... 19 6. SPECIAL REPORTS AND STUDIES ........................................................... 21 7. OTHER PERMITS ........................................................................................... 21 8. CSWPPP ANALYSIS AND DESIGN ............................................................. 21 9. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF COVENANT ............................................................................................... 21 10. OPERATIONS AND MAINTENANCE MANUAL ..................................... 21 LIST OF APPENDICES Appendix A – Stormwater Site Plans Appendix B – Storm Calculations Appendix C – Operations & Maintenance Manual Appendix D – Geotechnical Report Appendix E – CSWPPP Appendix F – City of Renton Bond Quantity Worksheet LIST OF FIGURES Figure 1 Drainage Review Flowchart ............................................................................................. 2 Figure 2 TIR Worksheet .................................................................................................................. 3 Figure 3 Vicinity Map ..................................................................................................................... 8 Figure 4 Proposed Conditions Exhibit ............................................................................................ 9 Figure 5 Aerial Photograph ........................................................................................................... 11 Figure 6 Existing Site Condition ................................................................................................... 12 Figure 7 NRCS Soil Description ................................................................................................... 13 Figure 8 Downstream Flow Path ................................................................................................... 15 Figure 9 Pipe Capacity .................................................................................................................. 18 Figure 10 Flow Frequency .............................................................................................................. 19 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 1 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx 1. PROJECT OVERVIEW This Preliminary Technical Information Report (TIR) is submitted in support of the Short Plat and Building Permits for the construction of two new residences with attached garages and driveways. Roadway extension and frontage improvements along Queen Ave NE are also proposed as a part of this project. Project Data: Address: 1157 Queen Ave NE Renton, WA 98056 Parcel Number: 106570-0100 Lot Area Total: 14,560 SF (0.334 Acres) after ROW dedication Zoning: R-8 (Residential, 8 Units/Acre) Drainage Basin: May Creek (Cedar River / Lake Washington Watershed) This analysis was completed using the format set forth in the 2017 City of Renton Surface Water Design Manual (RSWDM). The project requires a Full Drainage Review as specified in Fig. 1.1.2.A of the RSWDM (See following page, Figure 1). Core requirements 1-9 and special requirements 1-6 have been addressed accordingly. Project Description: Please refer to Figure 2 – Vicinity Map and Figure 3 – Proposed Conditions Exhibit on the following pages to aid in the project description. The project proposes to remove two on-site trees in the north half of the property and divide the property into two parcels (B to the north and A to the south) of approximately equal size while dedicating about 23’ along the west edge of the property to the right-of-way. Two new single- family residences are to be constructed, with attached garages and driveways accessing Pierce Ave NE to the west. The project site is located within the Peak Rate Flow Control Standard Area, and a detention system is proposed to manage site runoff accordingly within a stormwater tract along the eastern edge of the properties. Offsite discharge of stormwater from the system will be directed into a new piped conveyance system along the west side of Queen Ave NE. This system will connect to an existing storm system at the south end of Queen Ave NE. See Section 4 and Appendix B for details. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 2 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 1 – Drainage Review Flowchart DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 3 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 2 – TIR Worksheet DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 4 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 5 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 6 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 7 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 8 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 3 – Vicinity Map More generally the site is located within the NE quarter of Section 9, Township 23 North, Range 5 East, Willamette Meridian. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 9 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 4 – Proposed Conditions Exhibit DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 10 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx 2. CONDITIONS AND REQUIREMENTS SUMMARY CORE REQUIREMENT #1: Discharge at the Natural Location Stormwater runoff from the undeveloped site flows to a low spot within the southeast portion of the property. Runoff leaving the site flows to the southeast, entering the Queen Ave NE storm system. See Section 3, Task 5 for details. Post development, stormwater will be collected and directed to a detention system within a stormwater tract along the eastern edge of the properties, with outflow into the Queen Ave NE storm system via a new piped conveyance system along the west site of Queen Ave NE. This system will connect to an existing storm system at the south end of Queen Ave NE. CORE REQUIREMENT #2: Offsite Analysis There is potential for minor upstream tributary runoff from Pierce Ave NE to the west. Detailed downstream analysis is provided. See Section 3, Task 5 for details. Bypass areas within the Queen Ave NE and Pierce Ave NE frontages are to be offset by collecting Queen Ave NE roadway and frontage runoff to the maximum extent feasible. See Appendix B for details. CORE REQUIREMENT #3: Flow Control Facilities The project site is located within the Peak Rate Flow Control Standard Area, requiring no increase of peak site flows in the 2-year, 10-year, and 100-year storm conditions. A detention system consisting of underground washed rock surrounding 3’ diameter pipes is proposed to manage site runoff accordingly. See Appendix B. CORE REQUIREMENT #4: Conveyance System Conveyance capacity will be provided to carry peak flows from the 100-year storm event. See Section 5 for details. CORE REQUIREMENT #5: Erosion and Sediment Control See Section 8. CORE REQUIREMENT #6: Operations and Maintenance An Operations and Maintenance Manual is provided in Appendix C of this report. CORE REQUIREMENT #7: Financial Guarantees and Liability Bond and liability assurances will be provided by the Owner or the Contractor and provided with final engineering. CORE REQUIREMENT #8: Water Quality Facilities The proposed area of Pollution Generating Impervious Surfaces (PGIS) is less than 5,000 sf. No water quality treatment is required. CORE REQUIREMENT #9: On-Site BMPs The project proposes more than 2,000 sf of new plus replaced impervious surfaces, and so requires flow control BMPs taken from the Large Lot BMP Requirements. See Section 4. SPECIAL REQUIREMENT #1: Other Adopted Area-Specific Requirements Not applicable. SPECIAL REQUIREMENT #2: Flood Hazard Area Delineation This property is not identified as a flood zone per FEMA flood analysis and King County iMap. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 11 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx SPECIAL REQUIREMENT #3: Flood Protection Facilities Not applicable. SPECIAL REQUIREMENT #4: Source Controls Not applicable. SPECIAL REQUIREMENT #5: Oil Control Not applicable. SPECIAL REQUIREMENT #5: Aquifer Protection Area The project site is not located within an Aquifer Protection Zone. 3. OFF-SITE ANALYSIS Task 1: Study Area Definition The study area covered consisted of the project site and upstream and downstream drainage areas near the development property. Task 2: Resource Review The project site is located within the May Creek drainage basin within the Cedar River / Lake Washington watershed and the site is not located in a critical drainage area. No erosion hazard or landslide hazard areas, or seismic hazards are located on or near the site. The soils on the site have been classified as Alderwood Material by the NRCS (See Figure 5) and as Vashon Till by the project Geotech (See Appendix D for Geotech Report). Task 3: Site Description Please refer to Figure 3 - Aerial Photograph, Figure 4 - Existing Site Conditions, and Figure 5 – NRCS Soil Description below to aid in the following description. Figure 5 – Aerial Photograph DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 12 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 6 – Existing Site Conditions Existing Conditions The existing property area is 17,174 sf (0.394 ac) and is currently undeveloped with medium to large trees along the north and west edges. residence in the center of the property. To the east of the property, there is a gravel parking area along the side of Queen Ave NE. The site topography slopes gently to the west, at an average slope of approximately 2%. The site is fronted by Pierce Ave NE to the west, Queen Ave NE to the east, and is bordered by other single-family residences to the north and south. The site soil map and description per the National Resources Conservation Service (NRCS) are included below. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 13 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 7 – NRCS Soil Description DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 14 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Task 4: Upstream Drainage System Description Generally, the site slopes to the west, with Queen Ave NE located upstream of the site. Currently, a small amount of runoff from Queen Ave NE presumably enters the site during storm events. The proposed frontage improvements along Queen Ave NE include a curb and gutter, directing runoff into the existing storm system within Queen Ave further south of the property. Task 5: Downstream Drainage System Description and Existing and Potential Problems In the current condition, site surface runoff generally gathers at a low point in the southeast corner of the property, and potentially leaves the property to the southeast, entering the Queen Ave NE storm system. Runoff travels south for approximately 330 feet before turning east at a cul-de-sac and traveling about 160 feet within a residential property. It then travels another 830 feet south before reaching the ¼-mile downstream point, crossing NE 10th Court and NE 10th Lane. No drainage issues are known to exist within the area, and no drainage issues are anticipated from the proposed development. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 15 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 8 – Downstream Flow Path DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 16 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx 4. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Drainage Concept The project site is located within the Peak Rate Flow Control Standard Area. A detention system is proposed to manage flow rates accordingly and will consist of a storage trench with two 3-foot diameter pipes in the center, with the remainder filled with washed rock (Detention Trench). See Appendix B. Per the RSWDM (pg. 1-74 through 1-79, Section 1.2.9.1), since the project site is larger than 22,000 sf Large Lot BMPs must be utilized to manage on-site runoff. Refer to feasibility review of BMPs in the following section. Flow Control & BMP Requirements The project site/lot is larger than 22,000 sf (total project area = 23,467 sf), and therefore requires stormwater management in accordance with the Large Lot BMP Requirements menu as provided in the table below. Please refer to Appendix A – Storm Plan and the Proposed Areas Summary Table to aid in the following feasibility analysis. Large Lot BMP Requirements (Section C.1.2.9.2.2 of the 2017 RSWDM) BMP Rank BMP Infeasibility Description 1 Full Dispersion Inadequate space for flow path on site. 2 Full Infiltration Infiltration is not recommended per Geotech Report (See Appendix D) 3 Limited Infiltration Infiltration is not recommended per Geotech Report (See Appendix D) 4 Bioretention Infiltration is not recommended per Geotech Report (See Appendix D) 5 Permeable Pavement Infiltration is not recommended per Geotech Report (See Appendix D) 6 Basic Dispersion Inadequate space for flow path on site. * BMPs are required to manage a minimum of 47% of Impervious Area (47% Impervious coverage proposed) Proposed detention system is designed to manage full project site. Detention Volume Provided = 2,712 CF to meet Peak Rate Flow Control Standards (See Appendix B). 7 Reduced Impervious Credit Not viable, not enough pervious vegetation, and perf. pipe not permitted. 8 Native Growth Retention Credit Not viable, not enough space for required pervious vegetation. 9 Tree Retention Credit Not viable, trees not retainable for proposed development. * Soil Amendment for New Pervious Surfaces Applied to all replaced pervious surfaces * Perforated Pipe Connection Infiltration is not recommended per Geotech Report (See Appendix D) DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 17 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Existing Areas Summary Table: See Areas Exhibit in Appendix B to aid in review of the following information. * Existing Pollution Generating Impervious Surface (PGIS) = 1,679 sf Proposed Areas Summary Table: *Proposed New + Replaced Pollution Generating Impervious Surface (PGIS) = 4,918 sf 4,918 < 5,000 OK Roof Sidewalk Parking Roadway C&G Sub-Total Forested Pasture Sub-Total Lot A 0 0 0 0 0 0 961 6,326 7,287 7,287 0 Lot B 0 0 0 0 0 0 4,330 2,943 7,273 7,273 0 Sub-Total 0 0 0 0 0 0 5,291 9,269 14,560 14,560 0 Pierce 0 0 0 275 0 275 2,807 1 2,808 3,083 275 Queen 0 0 1,404 0 1,404 247 5,577 5,824 5,824 1,404 Sub-Total 0 0 1,404 275 0 1,679 3,054 5,578 8,632 8,907 1,679 Total 0 1,404 0 1,679 8,345 14,847 23,192 23,467 1,679 Offsite (Frontage) PGIS* Onsite Impervious Pervious Total Area Roof Sidewalk Driveway Roadway C&G Sub-Total Forested Lawn Sub-Total Lot A 2,361 0 331 0 0 2,692 757 2,394 3,151 5,843 331 Lot B 2,361 0 333 0 0 2,694 781 2,580 3,361 6,055 333 Tract A 0 0 0 0 0 0 165 2,497 2,662 2,662 0 Sub-Total 4,722 0 664 0 0 5,386 1,703 7,471 9,174 14,560 664 Site Coverage (%) 37% 63% 100% Pierce 0 682 445 250 63 1,440 1,643 0 1,643 3,083 758 Queen 0 804 0 3,299 197 4,300 116 1,408 1,524 5,824 3,496 Sub-Total 0 1,486 445 3,549 260 5,740 1,759 1,408 3,167 8,907 4,254 Total 4,722 1,486 1,109 3,549 260 11,126 3,462 8,879 12,341 23,467 4,918 Callout I-A I-B I-C I-D I-E P-A P-B *Road, Driveways, Curb & Gutter. < 5,000 sf ==> No Water Quality Treatment Required Offsite (Frontage) Onsite PGIS*Impervious Pervious Total Area DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 18 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Bypass Areas Frontage areas along Pierce Ave NE and Queen Ave NE will not be directed to the proposed detention system, and so will be considered bypass areas. Per Section 1.2.3.2.E of the RSWSDM: On some sites, topography may make it difficult or costly to collect all target surface runoff for discharge to the onsite flow control facility. Therefore, some project runoff subject to flow control may bypass required onsite flow control facilities provided that all of the following conditions are met: 1. The point of convergence for runoff discharged from the bypassed target surfaces and from the project’s flow control facility must be within a quarter-mile downstream of the facility’s project site discharge point, AND Response: Yes. 2. The increase in the existing site conditions 100-year peak discharge from the area of bypassed target surfaces must not exceed 0.4 cfs, AND Response: The increase does not exceed the threshold. 100-yr Flow Rate of Impervious Runoff = 0.775 cfs/acre (per modeling, see Appx. B) Proposed Frontage Area within Project Site = 0.20 acres 0.204 ac * 0.775 cfs/ac = 0.158 cfs 0.158 < 0.40 cfs OK 3. Runoff from the bypassed target surfaces must not create a significant adverse impact to downstream drainage systems, salmonid habitat, or properties as determined by CED, AND Response: No adverse impact is anticipated. 4. Water quality requirements applicable to the bypassed target surfaces must be met, AND Response: Water quality is not required per Surface Area Exemption. 4,918 sf new + replaced pollution-generating impervious surface is proposed within the frontage area. 5. Compensatory mitigation by a flow control facility must be provided so that the net effect at the point of convergence downstream is the same with or without the bypass. This mitigation may be waived if the existing site conditions 100-year peak discharge from the area of bypassed target surfaces is increased by no more than 0.15 cfs (modeled using 15 minute time steps) and on-site BMPs as detailed in Appendix C are applied to all impervious surfaces within the area of bypassed target surfaces. One or combination of the following methods may be used to provide compensatory mitigation by a flow control facility subject to permission/approvals from other parties as deemed necessary by CED: a) Design the project’s flow control facility or retrofit an existing offsite flow control facility as needed to achieve the desired effect at the point of convergence, OR b) Design the project’s flow control facility or provide/retrofit an offsite flow control facility to mitigate an existing developed area (either onsite or offsite) that has runoff characteristics (i.e., peak flow and volume) equivalent to those of the bypassed target surfaces but is currently not mitigated or required to be mitigated to the same flow control performance requirement as the bypassed target surfaces. Consideration of an offsite area to be mitigated for must take into DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 19 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx account the likelihood of that area redeveloping in the future. Those areas determined by the City to have a high likelihood of future redevelopment that will provide its own mitigation may not be used as compensatory mitigation. Response: Compensatory Mitigation is provided per method (b). The maximum amount of offsite runoff from the Queen Ave roadway and frontage is directed to the proposed detention system (7,890 sf). The total offsite area within the project area is 8,907 sf. This leaves an equivalent of 1,017 square feet bypassing the detention system. Conservatively modeling this bypass area as roadway in conjunction with output from the detention system results in no increase in the 2-year, 10-yr, or 100-yr discharge from the project area. See Appendix B for details. 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN Conveyance capacity of proposed storm system outflow is 0.458 cfs for a 6” diameter pipe at 0.5% minimum allowable slope. Flows estimated for the 100-year peak developed flows for the total proposed impervious area is 0.198 cfs (See Figures 9 & 10 below). Adequate capacity is provided with the proposed outflow system, as shown below. Figure 9 – Pipe Capacity Using Hydraflow Express: *Pipe Capacity = 0.458 cfs DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 20 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx Figure 10 – Flow Frequency Refer to Appendix B for Storm Calculation details. Using Western Washington Hydrology Model 2012 (WWHM12): * Peak flow rates are presented for 1 acre of Predeveloped 100% Forested condition and 1 acre of Developed (Mitigated) 100% Impervious condition to establish a flow rate per acre (cfs/ac). Peak flow rates are calculated by pro-rating actual tributary areas multiplied by cfs/ac. 100-year, 1 Acre Impervious Runoff = 0.775 cfs/ac Total Proposed Impervious = 11,126 sf (0.255 ac) 100-yr Outflow for Proposed Impervious = 0.775*0.255 = 0.198 cfs Outflow Pipe Capacity > 100-year Outflow 0.458 cfs > 0.198 cfs OK DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum Short Plat Technical Information Report PHA Project#: 21807 Page 21 of 21 P:\2021\21807_Shum Residence - Renton\Text\Storm Reports\21807_Shum Residence_TIR.docx 6. SPECIAL REPORTS AND STUDIES Geotechnical Report (See Appendix D). 7. OTHER PERMITS Demolition Permit Building Permit Right-of-Way Permit 8. CSWPPP ANALYSIS AND DESIGN See Appendix E. 9. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF COVENANT Bond and liability assurances will be provided by the Owner or the Contractor. Bond Quantities, Facility Summaries, and Declaration of Covenant will be provided at time of final engineering. 10. OPERATIONS AND MAINTENANCE MANUAL An Operations and Maintenance Manual is included in Appendix C of this report. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix A Stormwater Site Plans DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E xxx x x xxN87°59'46"W 114.15'N00°15'00"W 20.02'N87°59'46"W 20.02'111.09'131.11'WVWV 24"F 18"F 26"F S 26"F 30"F 16"DEC 30"F 10"M EM WV TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP5' TALL CLF 5' TALL CLF VERTICAL CURB6"DEC(3) SHED ON CONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPOPOPOPOPOPOPOP~SSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL SSMH TOP 434.25 8" PVC (W), 8" CONC (N), 8" CONC (S) CENTER CHANNEL ELEV. 425.43 CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E) CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS~SD SDSD430.5429.8432.7430.3432.2432.8430.1430.6432.1432.5430.1431.84432.46432.17432.92433.15433.82434.04433.84433.41433.39433.51432.44430.0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.1432.0N87°59'50"W 134.14' FENCE 0.3' W. OF P/L FENCE 0.5' W. OF P/L 1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)SS~PARCEL A KING COUNTY BOUNDARY LINE ADJUSTMENT REC.NO. 9802099012 FENCE CROSSES P/L FENCE 0.2' S. OF P/L TBM 1 TOP REBAR/CAP EL = 434.36' FENCE CROSSES P/L FENCE 0.2' S. OF P/L TBM 2 TOP REBAR/CAP EL = 430.64'PIERCEAVE NEQUEENAVE NELOT B LOT A TRACT A xx xN87°59'46"W 114.15'N00°15'00"W 20.02'N87°59'46"W 20.02'111.09'131.11'WVWV 18"F 26"F S 26"F 30"F 16"DEC 30"F 10"M TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 OPOPOPOPOPOPOPOP5' TALL CLF 5' TALL CLF VERTICAL CURBCONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPSSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL 8" PVC (W), 8" CONC (N), CENTER CHANNEL CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E) CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSD 430.5429.8432.7430.1430.6432.1432.5432.46432.17432.92433.15433.82434.04433.84433.41433.39433.51432.44430.0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.0N87°59'50"W 134.14' FENCE 0.5' W. OF P/L W(D)W(D)W(D)W(D)W(D)~PARCEL A KING COUNTY BOUNDARY LINE ADJUSTMENT REC.NO. 9802099012 FENCE CROSSES P/L FENCE 0.2' S. OF P/L FENCE CROSSES P/L FENCE 0.2' S. OF P/L TBM 2 TOP REBAR/CAP EL = 430.64' LOT B LOT A TRACT A PROJECT INFORMATION: PROJECT TEAM: LEGAL DESCRIPTION: REFERENCES: 0 20 40 SITE CALLOUTS: SEWER & WATER CALLOUTS: STORM CALLOUTS: DATUM: Proposed Surface Area (Including Frontage) Description Area (sf)Area (ac) Project Area 23,467 0.539 Driveway (Onsite)664 0.015 Rooftop 4,722 0.108 Sidewalk (Frontage)1,486 0.034 Roadway (Frontage)3,549 0.081 Curb & Gutter (Frontage)260 0.006 Driveway Entrance (Frontage)445 0.010 New + Replaced Hard Surface (Property)5,386 0.124 New + Replaced Hard Surface (Frontage)5,740 0.132 Total Pervious Surface (Lawn)12,341 0.283 AREA INVENTORY: PROJECT SITE N COVER SHEET & SITEPLANCSP1.0 1 N SITE PLAN VICINITY MAP DEDICATION PLAN N DEDICATION LEGEND: Sheet List OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION PROPERTY AREA INVENTORY: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E SITE DETAILSCSP1.1 2 101 102 104.3 110.1 101.1 103 OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E LOT B LOT APIERCE AVE NEQUEEN AVE NExxxxxxx x x x x x x x xxN87°59'46"W 114.15'N00°15'00"W 20.02'N87°59'46"W 20.02'111.09'131.11'WV WV 24"F 18"F 26"F S 26"F 30"F 16"DEC 30"F 10"M WV TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 xxOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP5' TALL CLF x5' TALL CLF VERTICAL CURBSHED ON CONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP~SSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL SSMH TOP 434.25 8" PVC (W), 8" CONC (N), 8" CONC (S) CENTER CHANNEL ELEV. 425.43 CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E) CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS~SD SD SD SDSDSD430.5429.8432.7430.3430.1430.6432.1432.5432.46432.17432.92433.15433.82434.04433.84433.41433.39433.51432.44430.0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.1432.0N87°59'50"W 134.14' FENCE 0.5' W. OF P/L 1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)SSSS~FENCE CROSSES P/L FENCE 0.2' S. OF P/L FENCE CROSSES P/L FENCE 0.2' S. OF P/L TREE CANOPY LINE (TYP)5' TALL CLFDEMOLITION & TESCPLANCSP2.0 3 TESC LEGEND: DEMOLITION & TESC PLAN DEMOLITION & TESC NOTES: DEMOLITION & TESC CALLOUTS: 0 10 20 N OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E TESC DETAILSCSP2.1 4 213.40214.00 215.10216.30 OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E xxxxxxx x x x x x x x xxN87°59'46"W 114.15'N00°15'00"W 20.02'N87°59'46"W 20.02'111.09'131.11'WV WV 24"F 18"F 26"F S 26"F 30"F 16"DEC 30"F 10"M WV TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 xxOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP5' TALL CLF x5' TALL CLF VERTICAL CURBSHED ON CONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP~SSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL SSMH TOP 434.25 8" PVC (W), 8" CONC (N), 8" CONC (S) CENTER CHANNEL ELEV. 425.43 CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E) CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS~SD SD SD SDSDSD430.5429.8432.7430.3430.1430.6432.1432.5432.46432.17432.92433.15433.82434.04433.84433.41433.39433.51432.44430.0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.1432.0N87°59'50"W 134.14' FENCE 0.5' W. OF P/L 1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)SSSS~PARCEL A KING COUNTY BOUNDARY LINE ADJUSTMENT REC.NO. 9802099012 FENCE CROSSES P/L FENCE 0.2' S. OF P/L TBM 1 TOP REBAR/CAP EL = 434.36' FENCE CROSSES P/L FENCE 0.2' S. OF P/L TBM 2 TOP REBAR/CAP EL = 430.64'PIERCE AVE NEQUEEN AVE NELOT B LOT A GRADING & STORMDRAINAGE PLANCSP3.0 5 GRADING & STORM DRAINAGE PLAN STORM DRAINAGE NOTES: STORM DRAINAGE CALLOUTS: SEWER & WATER CALLOUTS: 0 10 20 N DETENTION SECTION A QUEEN AVE NE SECTION A A B B OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E GRADING & STORMDRAINAGE DETAILSCSP3.1 6 200.00 201.00 403.1 237.00 DETENTION TRENCH 200.30 OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E xxx131.11' 30"F WVTJRWMSFOUND 1/2" REBAR ANDCAP IN 5" X 5" CONC"MHT 9470"E. 0.1'09-02-21xxOP OP OP OP OP OP OP OP OP OP OP OP OP OP OP OP OP OP OPOP OP OP OP OP OP 6' TALL BF 5' TALL CLF432 SSMHTOP 432.03IE 427.63 (8" PVC (OUT-N)BOTTOM STRUCTUREELEV. 427.66NO CHANNELSS SS SS SS SS SS SS SS SS SS SS SS 4 3 2 . 8 4 3 3 . 1 3 4 3 2 . 1 4 3 2 . 1 4 3 0 . 3 4 3 1 . 7 4 3 0 . 3 4 3 0 . 3 4 3 2 . 6432.14 3 2 . 0 FENCE 0.3'W. OF P/LFENCE 0.5'W. OF P/LW(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D) LEVATION (FT) STATION 420 14+00 430 440 450 13+00 12+00 11+00 10+00 420 430 440 450 STORM EXTENSIONPLAN & PROFILECSP3.2 7 STORM EXTENSION PLAN & PROFILE 0 10 20N 0 10 20N OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E xxxxxxx x x x x x x x xxN87°59'46"W 114.15'N00°15'00"W 20.02'N87°59'46"W 20.02'111.09'131.11'WV WV 24"F 18"F 26"F S 26"F 30"F 16"DEC 30"F 10"M WV TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 xxOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP5' TALL CLF x5' TALL CLF VERTICAL CURBSHED ON CONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP~SSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL SSMH TOP 434.25 8" PVC (W), 8" CONC (N), 8" CONC (S) CENTER CHANNEL ELEV. 425.43 CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E) CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS~SD SD SD SDSDSD430.5429.8432.7430.3430.1430.6432.1432.5432.46432.17432.92433.15433.82434.04433.84433.41433.39433.51432.44430.0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.1432.0N87°59'50"W 134.14' FENCE 0.5' W. OF P/L 1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)SSSS~FENCE CROSSES P/L FENCE 0.2' S. OF P/L FENCE CROSSES P/L FENCE 0.2' S. OF P/LPIERCE AVE NEQUEEN AVE NELOT B LOT A LOT B LOT A UTILITY PLANCSP4.0 8 UTILITY PLAN STORM DRAINAGE CALLOUTS: SEWER & WATER CALLOUTS: 0 10 20 N WATER NOTES: ELECTRICAL CALLOUTS: OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E UTILITY DETAILSCSP4.1 9 200.00 320.1 403.1 406.1 OF SCALE: DATE: DRAWING NO. CHK. BY:DWN. BY: PROJ. NO.DSN. BY:R#DATEBYDESCRIPTIONCivil Engineering & PlanningWeb : patrickharron.com14900 Interurban Ave. S, Suite 279, Seattle, WA 98168Phone : 206.674.4659 21807 SC SC 9SHUM PRELIMINARYSHORT PLATHOI-FUNG SHUM1157 QUEEN AVE NERENTON, WA 98056SHUM PRELIMINARY SHORT PLAT NW 1/4 , NE 1/4, SEC 09, T 23 N, R 05 E, W. M.CITY OF RENTON - PRELIMINARYSHORT PLATCC AS SHOWN 5/4/22 NOT FOR CONSTRUCTION DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix B Storm Calculations DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E TREE CANOPYLINE (TYP)5' TALL CLFx xWVWV24"F18"F26"FS26"F30"F16"DEC30"F10"MEMWVTJRWMS8"DEC(2)FOUND 1/2" REBAR ANDCAP AT GRADE"MHT 9470"E. 0.1'09-02-21FOUND 1/2" REBAR ANDCAP IN 5" X 5" CONC"MHT 9470"E. 0.1'09-02-21FOUND BARE 1/4"REBARW. 0.5'09-02-21OPOPOPOPOPOPOPOP5' TALL CLF5' TALL CLFVERTICAL CURB6"DEC(3)SHED ONCONC SLABTREE CANOPYLINE (TYP)TREE CANOPYLINE (TYP)5' TALL CLFGATE 5' TALL CLFCEDAR HEDGEOPOPOPOPOPOP~SSMHTOP 432.03IE 427.63 (8" PVC (OUT-N)BOTTOM STRUCTUREELEV. 427.66NO CHANNELSSMHTOP 434.258" PVC (W), 8" CONC (N),8" CONC (S)CENTER CHANNELELEV. 425.43CATCH BASINTOP 433.616" CONC IE 432.30 (OUT-E)CATCH BASINTOP 433.336" CONC IE 432.30 (IN-W)8" CMP IE 431.28 (OUT-S)SS SS SS SS SS SS SSSSSSSSSS~SDFENCE 0.3'W. OF P/LFENCE 0.5'W. OF P/L1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)~PARCEL AKING COUNTY BOUNDARY LINE ADJUSTMENTREC.NO. 9802099012FENCE CROSSES P/LFENCE 0.2' S. OF P/LTBM 1TOP REBAR/CAPEL = 434.36'FENCE CROSSES P/LFENCE 0.2' S. OF P/LTBM 2TOP REBAR/CAPEL = 430.64'xxWVWV24"F18"F26"FS26"F30"F16"DEC30"F10"MEMWVTJRWMS8"DEC(2)FOUND 1/2" REBAR ANDCAP AT GRADE"MHT 9470"E. 0.1'09-02-21FOUND 1/2" REBAR ANDCAP IN 5" X 5" CONC"MHT 9470"E. 0.1'09-02-21FOUND BARE 1/4"REBARW. 0.5'09-02-21OPOPOPOPOPOPOPOP5' TALL CLF5' TALL CLFVERTICAL CURB6"DEC(3)SHED ONCONC SLABTREE CANOPYLINE (TYP)TREE CANOPYLINE (TYP)5' TALL CLFGATE 5' TALL CLFCEDAR HEDGEOPOPOPOPOPOP~SSMHTOP 432.03IE 427.63 (8" PVC (OUT-N)BOTTOM STRUCTUREELEV. 427.66NO CHANNELSSMHTOP 434.258" PVC (W), 8" CONC (N),8" CONC (S)CENTER CHANNELELEV. 425.43CATCH BASINTOP 433.616" CONC IE 432.30 (OUT-E)CATCH BASINTOP 433.336" CONC IE 432.30 (IN-W)8" CMP IE 431.28 (OUT-S)SS SS SS SS SS SS SSSSSSSSSS~SDFENCE 0.3'W. OF P/LFENCE 0.5'W. OF P/L1.5'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)~PARCEL AKING COUNTY BOUNDARY LINE ADJUSTMENTREC.NO. 9802099012FENCE CROSSES P/LFENCE 0.2' S. OF P/LTBM 1TOP REBAR/CAPEL = 434.36'FENCE CROSSES P/LFENCE 0.2' S. OF P/LTBM 2TOP REBAR/CAPEL = 430.64'LOT BLOT ATREE CANOPYLINE (TYP)5' TALL CLF 04080NOTES:Civil Engineering & Planning14900 Interurban Ave. S,Suite 279, Seattle, WA 98168Phone : 206.674.4659AREAS EXHIBITSHUM RESIDENCENEXISTING CONDITIONSPROPOSED CONDITIONSDocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E DETENTION FACILITY Performance Standards The site is located within a Peak Rate Flow Control Area, which requires discharge rates from the site to not exceed the 2-year, 10-year, or 100-year Existing Flow Rates. FACILITY SIZING WWHM12 Output Hydrologic analysis was performed using continuous modeling with the Western Washington Hydrologic Modeling Version 12 (WWHM12) program. WWHM12 output is provided within the following sections. Onsite: The Natural Resource Conservation Service (NRCS) classifies site soils as Alderwood Material and the Geotech classifies site soils as Vashon Till, with a slope of approximately 2%. Conservatively, the site was modeled using C Soils. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Existing vs Proposed Basin Model Project Areas: Existing Proposed (Within Project Area) * Offsite area collected within Queen Ave = 0.193 ac (8,425 sf) * Total offsite area within the project site = 0.204 ac 0.009 ac Net Bypass Area WWHM Model Layout: Roof Sidewalk Parking Roadway C&G Sub-Total Forested Pasture Sub-Total Lot A 0.000 0.000 0.000 0.000 0.000 0.000 0.022 0.145 0.167 0.167 0.000 Lot B 0.000 0.000 0.000 0.000 0.000 0.000 0.099 0.068 0.167 0.167 0.000 Sub-Total 0.000 0.000 0.000 0.000 0.000 0.000 0.121 0.213 0.334 0.334 0.000 Pierce 0.000 0.000 0.000 0.006 0.000 0.006 0.064 0.000 0.064 0.071 0.006 Queen 0.000 0.000 0.069 0.000 0.000 0.069 0.006 0.059 0.065 0.134 0.069 Sub-Total 0.000 0.000 0.069 0.006 0.000 0.075 0.070 0.059 0.129 0.204 0.075 Total 0.000 0.000 0.069 0.006 0.000 0.075 0.192 0.272 0.464 0.539 0.075 Existing Areas Impervious Pervious PGIS* Onsite Offsite (Frontage) Total Area Roof Sidewalk Driveway Roadway C&G Sub-Total Forested Lawn Sub-Total Lot A 0.054 0.000 0.008 0.000 0.000 0.062 0.017 0.055 0.072 0.134 0.008 Lot B 0.054 0.000 0.008 0.000 0.000 0.062 0.018 0.059 0.077 0.139 0.008 Tract A 0.000 0.000 0.000 0.000 0.000 0.000 0.004 0.057 0.061 0.061 0.000 Sub-Total 0.108 0.000 0.015 0.000 0.000 0.124 0.039 0.172 0.211 0.334 0.015 Pierce 0.000 0.016 0.010 0.006 0.001 0.033 0.038 0.000 0.038 0.071 0.017 Queen 0.000 0.018 0.000 0.076 0.005 0.099 0.003 0.032 0.035 0.134 0.080 Sub-Total 0.000 0.034 0.010 0.081 0.006 0.132 0.040 0.032 0.073 0.204 0.098 Total 0.108 0.034 0.025 0.081 0.006 0.255 0.079 0.204 0.283 0.539 0.113 Proposed Areas Impervious Pervious Total Area PGIS* Onsite DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Existing Basin: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Proposed Tributary to Detention System: Queen Ave Frontage & Roadway Area directed to detention system = 8,425 SF Total Offsite Area = 8,907 SF Net Bypass Area (total offsite - collected area) = 482 SF DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Bypass Area: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Detention System Specifications: Volume Required = 21 x 21 x 5 = 2,205 CF Volume Proposed = Pipe Vol. + Rock Void Vol. = 1,160 CF + 1,552 CF = 2,712 CF 2,712 CF > 2,205 CF OK (23% FS) DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Flow Frequency: Flow Control Threshold: 100-yr Peak Flows (Unmitigated Developed Flow Rate – Existing Flow Rate) 0.2432 – 0.1049 = 0.1383 cfs 0.1383 < 0.15 cfs Flow Control (Detention) not required, but is provided Peak Rate Flow Control Standard: Existing vs. Mitigated Developed Peak Flows (Detention) 2-year Peak Flows: 0.0383 cfs > 0.0291 cfs 10-year Peak Flows: 0.0639 cfs > 0.0541 cfs 100-year Peak Flows: 0.1049 cfs > 0.1043 cfs No Peak Flow Increases Flow Control Standards Met DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E WWHM Project Report: WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: 21807_Det. Vault_Peaks_& Bypass Site Name: Shum Residence Site Address: 1157 Queen Ave NE City : Renton, WA Report Date: 3/30/2022 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2021/08/18 Version : 4.2.18 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Existing Basin Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat .192 C, Pasture, Flat .272 Pervious Total 0.464 Impervious Land Use acre ROADS FLAT 0.006 PARKING FLAT 0.069 Impervious Total 0.075 Basin Total 0.539 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Name : Prop. Tributary to Det. Sys. Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .204 C, Forest, Flat .079 Pervious Total 0.283 Impervious Land Use acre ROADS FLAT 0.065 ROOF TOPS FLAT 0.109 DRIVEWAYS FLAT 0.025 SIDEWALKS FLAT 0.034 Impervious Total 0.233 Basin Total 0.516 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Detention System Detention System ___________________________________________________________________ Name : Detention System Width : 21 ft. Length : 21 ft. Depth: 6 ft. Discharge Structure Riser Height: 5 ft. Riser Diameter: 12 in. Orifice 1 Diameter: 0.75 in. Elevation: 0 ft. Orifice 2 Diameter: 0.65 in. Elevation: 3 ft. Orifice 3 Diameter: 0.5 in. Elevation: 4 ft. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Vault Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.010 0.000 0.000 0.000 0.0667 0.010 0.000 0.003 0.000 0.1333 0.010 0.001 0.005 0.000 0.2000 0.010 0.002 0.006 0.000 0.2667 0.010 0.002 0.007 0.000 0.3333 0.010 0.003 0.008 0.000 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 0.4000 0.010 0.004 0.009 0.000 0.4667 0.010 0.004 0.010 0.000 0.5333 0.010 0.005 0.011 0.000 0.6000 0.010 0.006 0.011 0.000 0.6667 0.010 0.006 0.012 0.000 0.7333 0.010 0.007 0.013 0.000 0.8000 0.010 0.008 0.013 0.000 0.8667 0.010 0.008 0.014 0.000 0.9333 0.010 0.009 0.014 0.000 1.0000 0.010 0.010 0.015 0.000 1.0667 0.010 0.010 0.015 0.000 1.1333 0.010 0.011 0.016 0.000 1.2000 0.010 0.012 0.016 0.000 1.2667 0.010 0.012 0.017 0.000 1.3333 0.010 0.013 0.017 0.000 1.4000 0.010 0.014 0.018 0.000 1.4667 0.010 0.014 0.018 0.000 1.5333 0.010 0.015 0.018 0.000 1.6000 0.010 0.016 0.019 0.000 1.6667 0.010 0.016 0.019 0.000 1.7333 0.010 0.017 0.020 0.000 1.8000 0.010 0.018 0.020 0.000 1.8667 0.010 0.018 0.020 0.000 1.9333 0.010 0.019 0.021 0.000 2.0000 0.010 0.020 0.021 0.000 2.0667 0.010 0.020 0.021 0.000 2.1333 0.010 0.021 0.022 0.000 2.2000 0.010 0.022 0.022 0.000 2.2667 0.010 0.022 0.023 0.000 2.3333 0.010 0.023 0.023 0.000 2.4000 0.010 0.024 0.023 0.000 2.4667 0.010 0.025 0.024 0.000 2.5333 0.010 0.025 0.024 0.000 2.6000 0.010 0.026 0.024 0.000 2.6667 0.010 0.027 0.024 0.000 2.7333 0.010 0.027 0.025 0.000 2.8000 0.010 0.028 0.025 0.000 2.8667 0.010 0.029 0.025 0.000 2.9333 0.010 0.029 0.026 0.000 3.0000 0.010 0.030 0.026 0.000 3.0667 0.010 0.031 0.029 0.000 3.1333 0.010 0.031 0.031 0.000 3.2000 0.010 0.032 0.032 0.000 3.2667 0.010 0.033 0.033 0.000 3.3333 0.010 0.033 0.034 0.000 3.4000 0.010 0.034 0.035 0.000 3.4667 0.010 0.035 0.036 0.000 3.5333 0.010 0.035 0.037 0.000 3.6000 0.010 0.036 0.037 0.000 3.6667 0.010 0.037 0.038 0.000 3.7333 0.010 0.037 0.039 0.000 3.8000 0.010 0.038 0.040 0.000 3.8667 0.010 0.039 0.040 0.000 3.9333 0.010 0.039 0.041 0.000 4.0000 0.010 0.040 0.042 0.000 4.0667 0.010 0.041 0.044 0.000 4.1333 0.010 0.041 0.045 0.000 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 4.2000 0.010 0.042 0.046 0.000 4.2667 0.010 0.043 0.047 0.000 4.3333 0.010 0.043 0.048 0.000 4.4000 0.010 0.044 0.049 0.000 4.4667 0.010 0.045 0.050 0.000 4.5333 0.010 0.045 0.051 0.000 4.6000 0.010 0.046 0.052 0.000 4.6667 0.010 0.047 0.053 0.000 4.7333 0.010 0.047 0.054 0.000 4.8000 0.010 0.048 0.054 0.000 4.8667 0.010 0.049 0.055 0.000 4.9333 0.010 0.049 0.056 0.000 5.0000 0.010 0.050 0.057 0.000 5.0667 0.010 0.051 0.240 0.000 5.1333 0.010 0.052 0.568 0.000 5.2000 0.010 0.052 0.966 0.000 5.2667 0.010 0.053 1.378 0.000 5.3333 0.010 0.054 1.744 0.000 5.4000 0.010 0.054 2.021 0.000 5.4667 0.010 0.055 2.200 0.000 5.5333 0.010 0.056 2.362 0.000 5.6000 0.010 0.056 2.502 0.000 5.6667 0.010 0.057 2.635 0.000 5.7333 0.010 0.058 2.761 0.000 5.8000 0.010 0.058 2.882 0.000 5.8667 0.010 0.059 2.997 0.000 5.9333 0.010 0.060 3.109 0.000 6.0000 0.010 0.060 3.216 0.000 6.0667 0.010 0.061 3.320 0.000 6.1333 0.000 0.000 3.421 0.000 ___________________________________________________________________ Name : Bypass Area Bypass: Yes GroundWater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROADS FLAT 0.023 Impervious Total 0.023 Basin Total 0.023 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.464 Total Impervious Area:0.075 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.283 Total Impervious Area:0.256 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.038322 5 year 0.052991 10 year 0.0639 25 year 0.079108 50 year 0.091514 100 year 0.104879 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.029055 5 year 0.042727 10 year 0.054065 25 year 0.071374 50 year 0.086697 100 year 0.104341 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.055 0.027 1950 0.050 0.029 1951 0.046 0.051 1952 0.028 0.023 1953 0.024 0.023 1954 0.032 0.022 1955 0.037 0.036 1956 0.035 0.029 1957 0.043 0.030 1958 0.029 0.026 1959 0.026 0.023 1960 0.047 0.046 1961 0.036 0.024 1962 0.023 0.020 1963 0.034 0.024 1964 0.031 0.024 1965 0.040 0.025 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 1966 0.029 0.023 1967 0.054 0.032 1968 0.040 0.025 1969 0.035 0.027 1970 0.036 0.025 1971 0.039 0.029 1972 0.048 0.038 1973 0.027 0.022 1974 0.037 0.022 1975 0.047 0.033 1976 0.035 0.025 1977 0.024 0.019 1978 0.032 0.027 1979 0.041 0.021 1980 0.068 0.036 1981 0.036 0.027 1982 0.063 0.055 1983 0.035 0.027 1984 0.027 0.023 1985 0.031 0.026 1986 0.046 0.045 1987 0.045 0.047 1988 0.024 0.022 1989 0.030 0.018 1990 0.117 0.060 1991 0.070 0.054 1992 0.031 0.025 1993 0.023 0.023 1994 0.020 0.017 1995 0.032 0.027 1996 0.063 0.046 1997 0.047 0.055 1998 0.032 0.025 1999 0.075 0.036 2000 0.037 0.025 2001 0.031 0.023 2002 0.047 0.045 2003 0.049 0.021 2004 0.061 0.139 2005 0.040 0.032 2006 0.037 0.029 2007 0.097 0.062 2008 0.082 0.137 2009 0.051 0.040 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1167 0.1395 2 0.0970 0.1371 3 0.0816 0.0621 4 0.0749 0.0599 5 0.0696 0.0554 6 0.0678 0.0551 7 0.0630 0.0541 8 0.0627 0.0506 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 9 0.0607 0.0471 10 0.0555 0.0464 11 0.0537 0.0460 12 0.0510 0.0454 13 0.0505 0.0448 14 0.0490 0.0399 15 0.0479 0.0376 16 0.0475 0.0361 17 0.0474 0.0357 18 0.0470 0.0356 19 0.0468 0.0331 20 0.0460 0.0322 21 0.0455 0.0315 22 0.0454 0.0298 23 0.0433 0.0290 24 0.0408 0.0286 25 0.0402 0.0286 26 0.0400 0.0285 27 0.0398 0.0275 28 0.0393 0.0273 29 0.0372 0.0272 30 0.0371 0.0271 31 0.0370 0.0268 32 0.0369 0.0266 33 0.0364 0.0258 34 0.0364 0.0255 35 0.0355 0.0253 36 0.0353 0.0253 37 0.0351 0.0253 38 0.0345 0.0251 39 0.0345 0.0251 40 0.0335 0.0251 41 0.0322 0.0245 42 0.0321 0.0244 43 0.0319 0.0240 44 0.0318 0.0239 45 0.0313 0.0235 46 0.0312 0.0232 47 0.0310 0.0232 48 0.0307 0.0231 49 0.0303 0.0229 50 0.0287 0.0229 51 0.0286 0.0226 52 0.0277 0.0223 53 0.0271 0.0221 54 0.0265 0.0220 55 0.0256 0.0219 56 0.0244 0.0214 57 0.0242 0.0210 58 0.0239 0.0196 59 0.0232 0.0191 60 0.0232 0.0179 61 0.0202 0.0171 ___________________________________________________________________ Stream Protection Duration POC #1 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E The Facility FAILED Facility FAILED duration standard for 1+ flows. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0192 4235 10239 241 Fail 0.0199 3769 8825 234 Fail 0.0206 3335 7548 226 Fail 0.0214 2975 6427 216 Fail 0.0221 2676 5561 207 Fail 0.0228 2400 4825 201 Fail 0.0235 2171 4119 189 Fail 0.0243 1954 3482 178 Fail 0.0250 1743 2941 168 Fail 0.0257 1563 2462 157 Fail 0.0265 1426 2040 143 Fail 0.0272 1270 1787 140 Fail 0.0279 1133 1625 143 Fail 0.0287 1046 1506 143 Fail 0.0294 946 1423 150 Fail 0.0301 849 1359 160 Fail 0.0309 765 1291 168 Fail 0.0316 679 1233 181 Fail 0.0323 610 1183 193 Fail 0.0330 553 1120 202 Fail 0.0338 491 1062 216 Fail 0.0345 457 983 215 Fail 0.0352 422 919 217 Fail 0.0360 381 849 222 Fail 0.0367 338 788 233 Fail 0.0374 306 735 240 Fail 0.0382 282 682 241 Fail 0.0389 257 636 247 Fail 0.0396 231 580 251 Fail 0.0404 208 520 250 Fail 0.0411 190 470 247 Fail 0.0418 178 423 237 Fail 0.0425 163 372 228 Fail 0.0433 149 343 230 Fail 0.0440 131 310 236 Fail 0.0447 123 276 224 Fail 0.0455 112 256 228 Fail 0.0462 101 231 228 Fail 0.0469 95 214 225 Fail 0.0477 88 200 227 Fail 0.0484 79 180 227 Fail 0.0491 71 171 240 Fail 0.0499 67 156 232 Fail 0.0506 62 147 237 Fail 0.0513 54 135 250 Fail 0.0520 50 122 244 Fail 0.0528 47 114 242 Fail 0.0535 44 105 238 Fail 0.0542 39 96 246 Fail 0.0550 36 92 255 Fail 0.0557 31 80 258 Fail 0.0564 29 74 255 Fail DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 0.0572 28 67 239 Fail 0.0579 25 57 228 Fail 0.0586 22 52 236 Fail 0.0594 21 47 223 Fail 0.0601 20 43 215 Fail 0.0608 18 38 211 Fail 0.0615 17 34 200 Fail 0.0623 16 31 193 Fail 0.0630 14 31 221 Fail 0.0637 12 31 258 Fail 0.0645 12 30 250 Fail 0.0652 12 29 241 Fail 0.0659 12 28 233 Fail 0.0667 12 27 225 Fail 0.0674 12 27 225 Fail 0.0681 11 26 236 Fail 0.0689 9 26 288 Fail 0.0696 9 26 288 Fail 0.0703 8 26 325 Fail 0.0711 8 25 312 Fail 0.0718 7 25 357 Fail 0.0725 7 25 357 Fail 0.0732 7 25 357 Fail 0.0740 7 25 357 Fail 0.0747 7 25 357 Fail 0.0754 6 25 416 Fail 0.0762 6 25 416 Fail 0.0769 6 25 416 Fail 0.0776 6 25 416 Fail 0.0784 5 25 500 Fail 0.0791 5 23 460 Fail 0.0798 5 23 460 Fail 0.0806 5 23 460 Fail 0.0813 5 23 460 Fail 0.0820 3 20 666 Fail 0.0827 3 20 666 Fail 0.0835 3 20 666 Fail 0.0842 3 20 666 Fail 0.0849 3 20 666 Fail 0.0857 2 20 1000 Fail 0.0864 2 19 950 Fail 0.0871 2 19 950 Fail 0.0879 2 18 900 Fail 0.0886 2 18 900 Fail 0.0893 2 18 900 Fail 0.0901 2 18 900 Fail 0.0908 2 17 850 Fail 0.0915 2 17 850 Fail _____________________________________________________ The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. ___________________________________________________________________ DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. ___________________________________________________________________ LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Detention System POC N 50.96 N 0.00 Total Volume Infiltrated 50.96 0.00 0.00 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Failed ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2022; All Rights Reserved. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 1-Acre Model for Pipe Capacity: Forested 1-Acre: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Impervious 1-Acre: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Flow Frequency: DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix C Operations & Maintenance DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix D Geotechnical Report DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Gary A. Flowers, PLLC Geological & Geotechnical Consulting 5205 23rd Avenue W Everett, WA 98203 Gary A. Flowers, PLLC. 5205 23rd Avenue W Everett, Washington 98203 206-819-4304 1 October 27, 2021 Project No. 21021 Xiao Zhang 440 Maple Ave SW Apt. B201 Renton, WA 98057-2801 Subject: Geotechnical Services Report Shum Short Plat 1157 Queen Ave NE Renton, Washington This report summarizes the results of our geological and infiltration evaluation of the property located at the above noted address in Renton, WA. Infiltration testing was provided in general accordance with the 2017 Renton Storm Water Design Manual. EXISTING CONDITIONS The property is currently undeveloped and is flat lying with a barely discernible downward slope from west to east. Overall relief is on the order of 2 feet. The site is primarily vegetated with tall field grass, an area of blackberry bushes in the southeast corner, a cedar hedge along the south property line and a few deciduous trees. At the time of our study there was no evidence of standing or flowing water on the parcel. Subsurface Exploration In order to confirm subsurface conditions on th e property a series of 3 exploration pits were excavated on October 13, 2021. Logs of the exploration pits are attached with this report. Generally, medium dense to very dense silty sand with gravel was observed on the site. This sediment is interpreted to be Vashon age lodgement till. Lodgement till is a nonhomogeneous mixture of sand and gravel in a silt/clay matrix. This material was deposited in front of the advancing ice sheet on the order of 13,500 years ago and subsequently overrun by the ice which is thought to have been in excess of 3,000 feet thick in this area. The result is a densely consolidated soil with high strength and low permeability characteristics. Ground water seepage was not observed in any of the exploration pits and no caving conditions were observed within the sidewalls of the exploration pits. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum 2 Lot Short Plat Geotechnical Services Report 1157 Queen Avenue NE, Renton, Washington Gary A. Flowers, PLLC. 5205 23rd Avenue W Everett, Washington 98203 206-819-4304 2 Mappings According to the Geologic Map of King County, Washington, by Booth, Troost and Wisher, March 2007, the site is mapped as Vashon age glacial till (Qvt). Our explorations are in agreement with the published geology map of the area. Infiltration of Storm Water We understand that infiltration of storm water on-site was to be considered for the project. Our subsurface explorations were located in order to encompass both potential building sites should the short plat be granted. In order to verify whether or not there was any infiltration potential within the observed sediments an infiltration test was performed on these soils. Testing was completed in general accordance with City of Renton 2017 Storm Water Design Manual and Reference 6-A for a small scale pilot infiltration test (PIT). Based on our current understanding storm water would be infiltrated into one or more infiltration trenches approximately 3 feet below existing grade. As such, the infiltration testing was completed at a depth which included the planned receptor soils. The pit was excavated to a depth of 3.1 feet and the bottom measured 4.7 feet long and 4.1 feet wide for a total area of 19.27 square feet. Presoaking and testing was completed using a garden hose running into an 4-foot long, 4-inch diameter, perforated, pvc pipe with a cap for a splash plate on the bottom end. The pvc pipe was marked in half-inch increments as required. Water was then added to the pit for the pre-soak period and maintained at a depth of 12 to 14 inches for 6 hours. It should be noted that little to no water flow was required in order to maintain the water depth. In fact, at the lowest water flow setting attainable with the available equipment the water level continued to rise throughout the soak period. Following the pre-soak, the water flow was shut off to allow the water level to adjust to the required 6-inch head. After 2 hours the water level had only reduced by less than 1 inch. Due to the conditions detailed above, the constant head test was not performed. The falling head test was then performed for an hour. During the falling head test the water level reduced by approximately .5 inches in one hour even with a 12-inch head instead of a 6-inch head. Based on the results of our explorations that encountered glacial till sediments at shallow depth, the measured infiltration rate and the required correction factors for testing, geometry and plugging, it is our opinion that the design infiltration rate is nil and no consideration should be given to infiltration of storm water on this property. This is typical for sites that are underlain by glacial till sediments. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum 2 Lot Short Plat Geotechnical Services Report 1157 Queen Avenue NE, Renton, Washington Gary A. Flowers, PLLC. 5205 23rd Avenue W Everett, Washington 98203 206-819-4304 3 SUMMARY Our findings and recommendations provided in this report were prepared in accordance with generally accepted principles of engineering geology and geotechnical engineering as practiced in the Puget Sound area at the time this report was submitted. We make no other warranty, either express or implied. Thank you for the opportunity to be of service. Should you have any questions please do not hesitate to contact our office. Respectfully submitted, Gary A. Flowers, P.G., P.E.G. Principal Engineering Geologist Attachments: Exploration Pit Logs Site & Exploration Plan DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Shum 2 Lot Short Plat Geotechnical Services Report 1157 Queen Avenue NE, Renton, Washington Gary A. Flowers, PLLC. 5205 23rd Avenue W Everett, Washington 98203 206-819-4304 4 EXPLORATION PIT LOGS Shum 2 Lot Short Plat 1157 Queen Avenue NE Renton, WA EP-1 Approximate elevation 432 feet 0.0’ – 1.0’ Loose, moist, grayish-black, silty SAND (topsoil) and grass sod 1.0’ – 2.5’ Medium dense, light brown, silty sand with gravel (glacial till) [SM] 2.5’ – 4.0’ Very dense, light brown, silty sand with gravel (glacial till) [SM] Bottom of pit at 4.0 feet on 10/13/2021. No ground water. No caving. EP-2 Approximate elevation 432 feet 0.0’ – 1.0’ Loose, moist, grayish-black, silty SAND (topsoil) and grass sod 1.0’ – 2.5’ Medium dense, light brown, silty sand with gravel (glacial till) [SM] 2.5’ – 4.0’ Very dense, light brown, silty sand with gravel (glacial till) [SM] Bottom of pit at 4.0 feet on 10/13/2021. No ground water. No caving. EP-3 Approximate elevation 431 feet 0.0’ – 1.0’ Loose, moist, grayish-black, silty SAND (topsoil) and grass sod 1.0’ – 2.5’ Medium dense, light brown, silty sand with gravel (glacial till) [SM] 2.5’ – 4.0’ Very dense, light brown, silty sand with gravel (glacial till) [SM] Bottom of pit at 4.0 feet on 10/13/2021. No ground water. No caving. IP-1 Approximate elevation 430 feet 0.0’ – 1.0’ Loose, moist, grayish-black, silty SAND (topsoil) and grass sod 1.0’ – 2.5’ Medium dense, light brown, silty sand with gravel (glacial till) [SM] 2.5’ – 3.1’ Very dense, light brown, silty sand with gravel (glacial till) [SM] Bottom of pit at 4.0 feet on 10/13/2021. No ground water. No caving. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E 30.02'30.02'NE 12TH STREET N87°59'46"W 2,625.71'(M)(R1)210.16'210.16'N00°15'00"W 240.18'S00°15'59"E 240.18'1,506.81'(C)(R1) 134.07'(C)(R1) W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D) FOUND PUNCH ON 1 1/2" BRASS DISK IN IN CASE DOWN 0.7' 08-30-21 UNION AVE. NEFOUND 1/8" PIN IN CONC MON IN CASE DOWN 1.5' 08-30-21MONROE AVE. NE805.92'(C)(R1) FOUND TACK IN CONC MON IN CASE DOWN 2.1' 08-30-21 MONROE AVE. NE178.91'(R1) 178.92'(M) TREE CANOPY/DRIP LINE FENCE LINE (TYPE AS NOTED)x BUILDING LINE TELEPHONE RISERTJR MONUMENT (FOUND AS NOTED) SIGN DECIDUOUS TREE CONIFEROUS TREE WATER VALVE FIRE HYDRANT HOSE BIB STORM DRAIN MANHOLE STORM CATCH BASIN SEWER MANHOLE POWER POLE/LIGHT POLE GUY ANCHOR GAS METER S D GM WV POWER OVERHEAD LINEOP SANITARY SEWER PIPESS STORM DRAIN PIPESD CONCRETE PAVING ASPHALT PAVING REBAR (FOUND AS NOTED) POST OR BOLLARD GAS VALVEGV F FIR TREE M MAPLE TREE LEGEND LEGEND (C) (M) P/L CLF CALCULATED DIMENSION MEASURED DIMENSION PROPERTY LINE CHAIN LINK FENCE WATER LINE PER RECORD DATAW(D)xxxxxxxxxxxxxxxxxxxxxxxx x x x x x x x x xxxxxxxxxxxxxxxxxxxN00°15'00"W 20.02'N87°59'46"W 20.02'QUEEN AVEWV WV 18"F 20"F 14"F 30"F 26"F 30"F S 32"F 26"F 30"F 60"MA 12"DEC 16"DEC 30"F 10"M WV TJR WMS 8"DEC(2) FOUND 1/2" REBAR AND CAP AT GRADE "MHT 9470" E. 0.1' 09-02-21 FOUND 1/2" REBAR AND CAP IN 5" X 5" CONC "MHT 9470" E. 0.1' 09-02-21 FOUND BARE 1/4" REBAR W. 0.5' 09-02-21 xxOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP5' TALL CLF x5' TALL CLF VERTICAL CURB5' TALL CLFCONC SLAB TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP) TREE CANOPY LINE (TYP)5' TALL CLFGATE5' TALL CLFCEDAR HEDGE 430 43243 2 432OPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOPOP ~PIERCE AVE NEPARCEL A KING COUNTY BOUNDARY LINE ADJUSTMENT REC.NO. 9802099012 SSMH TOP 432.03 IE 427.63 (8" PVC (OUT-N) BOTTOM STRUCTURE ELEV. 427.66 NO CHANNEL SSMH TOP 434.25 8" PVC (W), 8" CONC (N), 8" CONC (S) CENTER CHANNEL ELEV. 425.43 CATCH BASIN TOP 433.33 6" CONC IE 432.30 (IN-W) 8" CMP IE 431.28 (OUT-S)SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS~SD SD SD SDSDSDSDTBM 1 TOP REBAR/CAP EL = 434.36'430.5429.8432.7430.1430.6432.1432.5432.46432.17432.9 2433.15433.82434.04433.84433.41433.39433.51432.44430. 0431.3433.4434.7432.6431.6429.7430.3431.7430.3430.3432.6432.0N87°59'50"W 134.14'(C) 134.13'(R1) N87°59'46"W 114.15'S00°15'59"E 131.11'S00°15'00"E 111.09'430 4324344344344304 3 0 432430430 5' TALL CLF0.5' 0.6' FENCE CROSSES P/L FENCE 0.1' S. OF P/LFENCE 0.2' S. OF P/L 1.8' CONC DRIVECONC WALKTBM 2 TOP REBAR/CAP EL = 430.64' 4.8' 30.00' 30.00'W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D)W(D) CATCH BASIN TOP 433.61 6" CONC IE 432.30 (OUT-E)SSSS~30.00' 30.00' 3.3' 10.7' 9.8'REVISIONOFSHEET NO.DRAWING FILE:PROJECT NUMBER:NUMBER: SCALE: DATE:DESIGN:DRAWN:CHECKED: REVISIONS:APPD.SV-TP-OWDV01880001.dwgSave Date: Plot Date: 9/21/2021 2:46 PM 9/24/2021 10:35 AM By: Arj P:\O\OWDV01880001\0400CAD\SV\BASES\SV-TP-OWDV01880001.dwg Aaron JenningsBy: File: POR. NW 1/4, NE 1/4, SEC. 9, TWP. 23 N., RGE. 5 E., W.M. TOPOGRAPHIC SURVEY FOR SHUM PROPERTY HOI-FUNG SHUM 17723 110TH PLACE SE, RENTON, WA 98055SEPTEMBER 24, 2021ARJ1"=10'OWDV0188-0000111® 20300 Woodinville Snohomish Rd. NE, Ste A Woodinville Washington 98072 Phone: 425.415.2000 NORTH 1. INSTRUMENTATION FOR THIS SURVEY WAS A TRIMBLE TOTAL STATION. PROCEDURES USED IN THIS SURVEY WERE FIELD TRAVERSE, MEETING OR EXCEEDING STANDARDS SET BY WAC 332-130-090. 2. PRIMARY CONTROL POINTS AND ACCESSIBLE MONUMENT POSITIONS WERE FIELD MEASURED UTILIZING GLOBAL POSITIONING SYSTEM (GPS) SURVEY TECHNIQUES USING TRIMBLE EQUIPMENT. MONUMENT POSITIONS THAT WERE NOT DIRECTLY OBSERVED USING GPS SURVEY TECHNIQUES WERE TIED INTO THE CONTROL POINTS UTILIZING TRIMBLE ELECTRONIC TOTAL STATIONS FOR THE MEASUREMENT OF BOTH ANGLES AND DISTANCES. THIS SURVEY MEETS OR EXCEEDS THE STANDARDS SET BY WAC 332-130-090. 3. THE INFORMATION DEPICTED ON THIS MAP REPRESENTS THE RESULTS OF A SURVEY MADE ON SEPTEMBER 3, 2021 AND CAN ONLY BE CONSIDERED AS INDICATING THE GENERAL CONDITION EXISTING AT THAT TIME. 4. NO EASEMENTS, RESTRICTIONS OR RESERVATION OF RECORD WHICH WOULD BE DISCLOSED BY TITLE REPORT ARE SHOWN. 5. CONTOUR INTERVAL: 2 FOOT PARCEL A OF KING COUNTY BOUNDARY LINE ADJUSTMENT, RECORDED UNDER RECORDING NO. 9802099012, RECORDS OF KING COUNTY, WASHINGTON. NAVD 88 BASED ON GPS OBSERVATIONS. SITE BENCH MARKS: TBM 1: TOP OF REBAR AND CAP, SET IN ASPH DRIVE, 46'± SW OF SW CORNER OF SUBJECT PROPERTY ON SITE AS SHOWN ELEVATION = 434.36' TBM 2: TOP OF REBAR AND CAP, SET IN MIDDLE OF SUBJECT PROPERTY AS SHOWN ELEVATION = 430.64' EROF GI E OY DU Call: TOLL FREE 1-800-424-5555CLLABCALL BEFORE YOU DIG 1. KING COUNTY BOUNDARY LINE ADJUSTMENT, RECORDED UNDER RECORDING NO. 9802099012, RECORDS OF KING COUNTY, WASHINGTON. 09-24-21 GARY A. FLOWERS, PLLC PROJECT NO. 21021 SHUM PARCEL - 1157 QUEEN AVE NE IP-1 EP-3 EP-2EP-1 DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix E Construction Stormwater Pollution Prevention Plan (CSWPPP) DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E CESCL REQUIREMENT A Certified Erosion and Sediment Control Specialist shall be identified in the Construction SWPPP and shall be onsite or oncall at all times. Certification may be obtained by an approved training program that meets the erosion and sediment control training criteria established by Ecology. If a preconstruction meeting is held, this person shall attend. See attached BMPC160 Certified Erosion and Sediment Control Lead (CESCL) CESCL___________________TBD____________ 24hr Contact number:______ TBD____________ Fax number:______________ TBD____________ Address:_________________ TBD_________ __ _________________________________________ _________________________________________ ELEMENT 1: MARK CLEARING LIMITS Prior to beginning land disturbing activities, including clearing and grading, all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area should be clearly marked, both in the field and on the plans, to prevent damage and offsite impacts. Plastic, metal, or stake wire fence may be used to mark the clearing limits. The duff layer, native topsoil, and natural vegetation shall be retained in an undisturbed state to the maximum extent practicable. If it is not practicable to retain the duff layer in place, it should be stockpiled onsite, covered to prevent erosion, and replaced immediately upon completion of the ground disturbing activities. Element #1 BMP Description X C101 Preserving Natural Vegetation X C102 Buffer Zones X C103 High Visibility Plastic or Metal Fence X C104 Stake and Wire Fence Construction and silt fencing will be used to delineate the limits of clearing for the project. ELEMENT 2: ESTABLISH CONSTRUCTION ACCESS Construction vehicle access and exit shall be limited to one route if possible. Access points shall be stabilized with quarry spalls or crushed rock to minimize the tracking of sediment onto public roads. Wheel wash or tire baths should be located onsite, if applicable. Public roads shall be cleaned thoroughly as needed to protect stormwater infrastructure and downstream water resources. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area. Street washing will be allowed only after sediment is removed in this manner. Street wash wastewater shall be controlled by pumping back onsite, or otherwise be prevented from discharging untreated into systems tributary to state surface waters. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Element #2 BMP Description X C105 Stabilized Construction Entrance C106 Wheel Wash C107 Construction Road/Parking Area Stabilization The proposed construction accesses will be on Pierce Ave NE, on the western side of the property. ELEMENT 3: CONTROL FLOW RATES Properties and waterways downstream from development sites shall be protected from erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from the project site, as required by local plan approval authority. Downstream analysis is necessary if changes in flows could impair or alter conveyance systems, stream banks, bed sediment or aquatic habitat. See Chapter 3 for offsite analysis guidance. Where necessary to comply with Minimum Requirement #7, stormwater retention/detention facilities shall be constructed as one of the first steps in grading. Detention facilities shall be functional prior to construction of site improvements (e.g. impervious surfaces). The local permitting agency may require pond designs that provide additional or different stormwater flow control if necessary to address local conditions or to protect properties and waterways downstream from erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from the project site. If permanent infiltration ponds are used for flow control during construction, these facilities shall be protected from siltation during the construction phase and plans made for restoration after construction. Element #3 BMP Description C240 Sediment Trap C241 Temporary Sediment Pond The project area is less than 1 acre, and silt fencing will be utilized. ELEMENT 4: INSTALL SEDIMENT CONTROLS Prior to leaving a construction site, or prior to discharge to an infiltration facility, stormwater runoff from disturbed areas shall pass through a sediment pond or other appropriate sediment removal BMP. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Element #3, bullet #1. Full stabilization means concrete or asphalt paving; quarry spalls used as ditch lining; or the use of rolled erosion products, a bonded fiber matrix product, or vegetative cover in a manner that will fully prevent soil erosion. The local permitting authority should inspect and approve DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E areas stabilized by means other than pavement or quarry spalls. Sediment ponds, vegetated buffer strips, sediment barriers or filters, dikes, and other BMP’s intended to trap sediment onsite shall be constructed as one of the first steps in grading. These BMP’s shall be functional before other land disturbing activities take place. Earthen structures such as dams, dikes, and diversions shall be seeded and mulched according to the timing indicated in Element #5. BMPs intended to trap sediment on site must be located in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages, often during nonstorm events, in response to rain event changes in stream elevation or wetted area. Element #4 BMP Description C230 Straw Bale Barrier C231 Brush Barrier C232 Gravel Filter Berm X C233 Silt Fence C234 Vegetated Strip C235 Straw Wattles C240 Sediment Trap C241 Temporary Sediment Pond C250 Construction Stormwater Chemical Treatment C251 Construction Stormwater Filtration The proposed sediment control measures are provided on Sheet C2.0 – Demolition and TESC Plan. At minimum, the project will be required to have downstream protection (compost socks, silt fencing, or equivalent), inlet protection, and appropriate cover measures. The proposed plan is intended as guidance and the Contractor shall be responsible for implementing and maintaining appropriate sediment controls based on changing site conditions. ELEMENT 5: STABILIZE SOILS All exposed and unworked soils shall be stabilized by application of effective BMPs that protect the soil from the erosive forces of raindrop impact, flowing water, and wind. Soils shall be stabilized as outlined below, where downstream water resources or stormwater infrastructure may be negatively affected by sediments (i.e., runoff discharges off the development site). From October 1 through April 30, no soils shall remain exposed and unworked for more than 2 days. From May 1 to September 30, no soils shall remain exposed and unworked for more than 7 days. This condition applies to all onsite soils, whether at final grade or not. The local permitting authority may adjust these time limits if it can be shown that a development site's erosion or runoff potential justifies a different standard. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Applicable practices include, but are not limited to, compost addition, temporary and permanent seeding, sodding, mulching, plastic covering, soil application of polyacrylamide (PAM), early application of gravel base on areas to be paved, and dust control. Soil stabilization measures selected should be appropriate for the time of year, site conditions, estimated duration of use, and potential water quality impacts that stabilization agents may have on downstream waters or ground water. Soil stockpiles must be stabilized from erosion, protected with sediment-trapping measures, and located away from storm drains, waterways, or drainage channels. Work on linear construction sites and activities, including right-of-way and easement clearing, roadway development, pipelines, and trenching for utilities, shall not exceed the capability of the individual contractor for his portion of the project to install the bedding materials, roadbeds, structures, pipelines, and/or utilities, and to re-stabilize the disturbed soils, in compliance with the applicable 2-day or 7-day criterion listed above. Element #5 BMP Description C120 Temporary and Permanent Seeding C121 Mulching C122 Nets and Blankets X C123 Plastic Covering C124 Sodding C125 Topsoiling C126 Polyacrylamide for Soil Erosion Protection C130 Surface Roughening C131 Gradient Terraces C140 Dust Control X C180 Small Project Construction Stormwater Pollution Prevention Temporary and permanent cover measures shall be provided based upon plans and Contractor’s discretion per site conditions during construction. ELEMENT 6: PROTECT SLOPES Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Consider soil type and its potential for erosion. Reduce slope runoff velocities by reducing the continuous length of slope with terracing and diversions, reduce slope steepness, and roughen slope surface. Offsite stormwater (run-on) shall be diverted away from slopes and disturbed areas with interceptor dikes and swales. Offsite stormwater should be managed separately from stormwater generated on the site. To prevent erosion, at the top of slopes collect drainage in pipe slope drains or protected channels. Temporary pipe slope drains shall handle the peak flow from a 10-year, 24- hour event; permanent slope drains shall be sized for a 25-year, 24-hour event. Check DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E dams shall be used within channels that are cut down a slope. Provide drainage to remove ground water intersecting the slope surface of exposed soil areas. Stabilize soils on slopes, as specified in Element #5. Element #6 BMP Description C120 Temporary and Permanent Seeding C130 Surface Roughening C131 Gradient Terraces C200 Interceptor Dike and Swale C201 Grass-Lined Channels C204 Pipe Slope Drains C205 Subsurface Drains C206 Level Spreader C207 Check Dams C208 Triangular Silt Dike The Contractor shall be responsible for protecting and stabilizing site slopes as required. ELEMENT 7: PROTECT DRAIN INLETS As needed to protect stormwater infrastructure and downstream water resources, all storm drain inlets made operable during construction shall be protected so that stormwater runoff shall not enter the conveyance system without first being filtered or treated to remove sediment. All approach roads shall be kept clean, and all sediment and street wash water shall not be allowed to enter storm drains without prior and adequate treatment, unless treatment is provided before the storm drain discharges to waters of the State. Element #7 BMP Description X C220 Storm Drain Inlet Protection Both existing and proposed drain inlets shall be protected as required. ELEMENT 8: STABILIZE CHANNELS AND OUTLETS All temporary onsite conveyance channels shall be designed, constructed and stabilized to prevent erosion from the peak 10-minute flow velocity from a Type 1A 10-year 24- hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream reaches shall be provided at the outlets of all conveyance systems. Element #8 BMP Description C202 Channel Lining C209 Outlet Protection None required. 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. Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and non-inert wastes present on the site (see Chapter 173-304 WAC for the definition of inert waste). Onsite fueling tanks shall include secondary containment. Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff must be conducted using spill prevention measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Report all spills to 911. Emergency repairs may be performed onsite using temporary plastic placed beneath and, if raining, over the vehicle. Wheel wash, or tire bath wastewater, shall be discharged to a separate onsite treatment system or to the sanitary sewer if allowed by the local wastewater authority. Application of agricultural chemicals, including fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers' label recommendations shall be followed for application rates and procedures. Management of pH-modifying sources shall prevent contamination of runoff and stormwater collected on the site. These sources include, but are not limited to, bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, and concrete pumping and mixer washout waters. Construction sites with significant concrete work shall adjust the pH of stormwater if necessary to prevent violations of water quality standards. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Element #9 BMP Description X C151 Concrete Handling X C152 Sawcutting and Surfacing Pollution Prevention The Contractor shall be responsible for controlling pollutants from construction activities off the project site. ELEMENT 10: CONTROL DE-WATERING All foundation, vault, and trench de-watering water, which has similar characteristics to stormwater runoff at the site, shall be discharged into a controlled conveyance system, prior to discharge to a sediment trap or sediment pond. Channels must be stabilized, as specified in Element #8. Clean, non-turbid de-watering water, such as well-point ground water, can be discharged to systems tributary to state surface waters, as specified in Element #8, provided the de- watering flow does not cause erosion or flooding of the receiving waters. These clean waters should not be routed through sediment ponds with stormwater. Highly turbid or otherwise contaminated dewatering water, such as from construction equipment operation, clamshell digging, concrete tremie pour, or work inside a cofferdam, shall be handled separately from stormwater at the site. Other disposal options, depending on site constraints, may include: 1) infiltration, 2) transport offsite in vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters, 3) onsite treatment using chemical treatment or other suitable treatment technologies, or 4) sanitary sewer discharge with local sewer district approval. The Contractor shall be responsible for discharging de-watering water in an appropriate manner. ELEMENT 11: MAINTAIN BMP’S All temporary and permanent erosion and sediment control BMP’s shall be maintained and repaired as needed to assure continued performance of their intended function. All maintenance and repair shall be conducted in accordance with BMP’s. Sediment control BMP’s shall be inspected weekly or after a runoff-producing storm event during the dry season and daily during the wet season. All temporary erosion and sediment control BMP’s shall be removed within 30 days after final site stabilization is achieved or after the temporary BMP’s are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal of BMP’s or vegetation shall be permanently stabilized. The Contractor shall be responsible for maintaining BMPs to assure performance of their intended function. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E ELEMENT 12: MANAGE THE PROJECT Phasing of Construction - Development projects shall be phased where feasible in order to prevent soil erosion and, to the maximum extent practicable, the transport of sediment from the project site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities for any phase. Clearing and grading activities for developments shall be permitted only if conducted pursuant to an approved site development plan (e.g., subdivision approval) that establishes permitted areas of clearing, grading, cutting, and filling. When establishing these permitted clearing and grading areas, consideration should be given to minimizing removal of existing trees and minimizing disturbance/compaction of native soils except as needed for building purposes. These permitted clearing and grading areas and any other areas required to preserve critical or sensitive areas, buffers, native growth protection easements, or tree retention areas as may be required by local jurisdictions, shall be delineated on the site plans and the development site. All plats shall include lot-specific grading plans, including information specified by the local permitting authority such as finished grades, finished floor elevations, buildable areas, and identified drainage outlets. This information would normally be submitted with the construction drawings, but may be required prior to preliminary plat approval. 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 construction site through a combination of the following: 1. Site conditions including existing vegetative coverage, slope, soil type and proximity to receiving waters; and 2. Limitations on activities and the extent of disturbed areas; and 3. 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. If, during the course of any construction activity or soil disturbance during the seasonal limitation period, silt-laden runoff leaving the construction site causes a violation of the surface water quality standard or if clearing and grading limits or erosion and sediment control measures shown in the approved plan are not maintained, the local permitting authority may take enforcement action, including but not limited to a notice of violation, administrative order, fine/penalty, stop-work order, or correction notice. The following activities are exempt from the seasonal clearing and grading limitations: 1. Routine maintenance and necessary repair of erosion and sediment control BMP’s; 2. Routine maintenance of public facilities or existing utility structures that do not (a) expose the soil or (b) result in the removal of the soil's vegetative cover; and Self- contained project sites, where there is complete infiltration of the water quality design event runoff within the site. 3. Local governments may restrict clearing and grading activities where site conditions may present a significant risk of impact to property or critical areas. Contact the local permitting authority for information on specific site restrictions. In Olympia, except where approved chemical treatment, full dispersion or infiltration is practiced, clearing, grading, and other soil disturbing activities are prohibited in all watersheds November through February, and in Green Cove, Percival, Woodard, and Ellis Creek watersheds between October through April. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Coordination with Utilities and Other Contractors The primary project proponent shall evaluate, with input from utilities and other contractors, the stormwater management requirements for the entire project, including the utilities, when preparing the Construction SWPPP. Inspection and Monitoring All BMP’s 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. The person shall have the skills to (1) assess site conditions and construction activities that could impact stormwater runoff quality, and (2) assess erosion and sediment control measure effectiveness. A Certified Erosion and Sediment Control Specialist shall be identified in the construction SWPPP and shall be onsite or on-call at all times. Certification may be obtained an approved training program that meets the erosion and sediment control training criteria established by Ecology. If a pre-construction meeting is held, this person shall attend. Sampling and analysis of the stormwater discharges from a construction site may be necessary on a case-by-case basis to ensure compliance with standards. Monitoring and reporting requirements may be established by the local permitting authority when necessary. The following discharge standard applies: Runoff leaving the construction site shall be free of settle able solids, as measured with an Imhoff Cone and in accordance with Standard Methods for the Examination of Water and Wastewater, most recent edition, American Water Works Association. "Free of settle able solids" shall be defined as measuring less than 2.5 mL/L/hr, for storms up to the water quality design event.1 The following surface water standard applies: 1. For storms up to the water quality design event, turbidity downstream of a construction site may not increase more than 5 NTU, if upstream turbidity is 50 NTU or less, and may not increase more than 10 percent, if upstream turbidity is over 50 NTU. To the extent practicable, samples should be taken far enough downstream so that the construction site discharge has been well-mixed with the surface water. 2. Whenever inspection and/or monitoring reveals that the BMP’s identified in the Construction SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMP’s or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP - The SWPPP shall be retained onsite or within reasonable access to the site. The SWPPP shall be updated within 7 days to reflect any significant changes in the design, construction, operation, or maintenance at the construction site that have, or could have, a significant effect on the discharge of pollutants to waters of the state. The SWPPP shall be updated within 7 days if during inspections or investigations by site staff or local or state officials, it is determined that the SWPPP is ineffective in controlling pollutants such that applicable discharge or surface water standards violations are apparent. The objective is to control erosion and prevent sediment and other pollutants from leaving the site during the construction phase of a project. The Contractor shall be responsible for managing the construction phase of the project within reasonable applications of the guidelines of this section and the SWPPP. DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E Appendix F City of Renton Bond Quantity Worksheet (Not included with this submittal) DocuSign Envelope ID: B58AD446-584F-46BF-8420-90761B7E491E