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HomeMy WebLinkAboutRS_Preliminary_Techical_Information_Report_Revision_180122_v2 PRELIMINARY TECHNICAL INFORMATION REPORT FOR SINGH SHORT PLAT CITY OF RENTON IN KING COUNTY, WASHINGTON Project Manager: Lafe Hermansen Prepared by: Sheri Murata, P.E. First Submittal: August 21, 2017 Revised: January 22, 2018 Core No.: 17001 1/22/18 Core Design, Inc. SINGH SHORT PLAT i Singh Short Plat Table of Contents 1 PROJECT OVERVIEW ..................................................................................................................... 1 Figure 1-1: Vicinity Map ..................................................................................................... 2 2 CONDITIONS AND REQUIREMENTS SUMMARY ........................................................................... 3 2.1 Core Requirements ............................................................................................................... 3 2.1.1 Core Requirement #1: Discharge at the Natural Location ............................................ 3 2.1.2 Core Requirement #2: Offsite Analysis .......................................................................... 3 2.1.3 Core Requirement #3: Flow Control .............................................................................. 3 2.1.4 Core Requirement #4: Conveyance System .................................................................. 3 2.1.5 Core Requirements #5: Erosion and Sediment Control ................................................. 3 2.1.6 Core Requirement #6: Maintenance and Operations ................................................... 3 2.1.7 Core Requirement #7: Financial Guarantees and Liability ............................................ 3 2.1.8 Core Requirement #8: Water Quality ............................................................................ 3 2.2 Special Requirement #1: Other Adopted Area-Specific Requirements ................................ 4 2.2.1 Critical Drainage Areas ................................................................................................... 4 2.2.2 Master Drainage Plan .................................................................................................... 4 2.2.3 Basin Plans ..................................................................................................................... 4 2.2.4 Salmon Conservation Plans (SCPs) ................................................................................. 4 2.2.5 Stormwater Compliance Plans (SWCPs) ........................................................................ 4 2.2.6 Lake Management Plans (LMPs) .................................................................................... 4 2.2.7 Flood Hazard Reduction Plan Updates (FHRPs) ............................................................. 4 2.2.8 Shared Facility Drainage Plans (SFDPs) .......................................................................... 4 2.3 Special Requirement #2: Floodplain / Floodway Delineation ............................................... 4 2.4 Special Requirement #3: Flood Protection Facilities ............................................................ 4 2.5 Special Requirement #4: Source Controls ............................................................................. 4 2.6 Special Requirement #5: Oil Control ..................................................................................... 4 3 OFFSITE ANALYSIS ......................................................................................................................... 5 TASK 1 Study Area Definition and Maps ..................................................................................... 5 TASK 2 Resource Review ............................................................................................................. 5 Core Design, Inc. SINGH SHORT PLAT ii TASK 3 Field Investigation ........................................................................................................... 6 Figure 3-1: Upstream Drainage Area ............................................................................... 11 Figure 3-2: Downstream Drainage Exhibit....................................................................... 12 TASK 4 Drainage System Description and Problem Description ............................................... 13 TASK 5 Mitigation of Existing and Potential Problems .............................................................. 13 4 FLOW CONTROL AND WATER QUALITY DESIGN ........................................................................ 16 4.1 Predeveloped Site Hydrology .............................................................................................. 16 4.2 Developed Site Hydrology ................................................................................................... 16 Figure 4-1: Existing Conditions Exhibit ............................................................................ 20 Figure 4-2: Developed Conditions Exhibit ....................................................................... 21 4.3 Performance Standards....................................................................................................... 22 4.4 Flow Control System ........................................................................................................... 23 4.5 Water Quality Calculations ................................................................................................. 27 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN .......................................................................... 28 5.1 Rational Method ................................................................................................................. 28 5.2 King County Backwater Analysis ......................................................................................... 30 Figure 5-1: Catch Basin Areas Exhibit .............................................................................. 32 6 SPECIAL REPORTS AND STUDIES ................................................................................................. 33 7 OTHER PERMITS .......................................................................................................................... 34 8 ESC ANALYSIS AND DESIGN ........................................................................................................ 35 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ...................... 36 9.1 Bond Quantities .................................................................................................................. 36 9.2 Facility Summaries .............................................................................................................. 36 9.3 Declaration of Covenant ..................................................................................................... 36 10 OPERATIONS AND MAINTENANCE ........................................................................................... 37   Core Design, Inc. SINGH SHORT PLAT  iii  Appendix A – Parcel & Basin Information     King County Parcel Report (0007200196)    Flow Control Map  Appendix B – Resource Review & Off‐site Analysis Documentation    Aquifer Protection Zone    FIRM Map    Coal Mine Hazard Map   Erosion Hazard Map    Slide Hazard Map    Steep Slopes Map    Drainage Complaints Exhibit  Appendix C – Conveyance Calculations    KCBW Results         Core Design, Inc. SINGH SHORT PLAT Page 1 1 PROJECT OVERVIEW The project site is located in the Black River drainage basin, on the west side of Renton Avenue S, in between S 9th Street and S 10th Street in the City of Renton, King County. Specifically, the project is in the northeast quarter of the northwest quarter of Section 20, Township 23 North, Range 5 East, W.M. It is bordered by single family residential on the north and east, a critical areas tract owned by WSDOT on the west and a transmission line corridor owned by Puget Sound Energy on the south. The King County tax parcel ID numbers for the existing parcel is shown in Table 1 below (refer to the King County Parcel Reports included in Appendix A). Table 1: Parcel Information KC Parcel # Site Address Site Area (SF) 0007200196 N/A 140,723 The total project site is 3.23 acres in size and currently completely forested. The site drains to the west at a slope ranging between 10 and 40 percent. Upstream flow from the residential developments to the east are piped across Renton Avenue S and discharge into three drainage channels on site. Proposed development of the property will include constructing six new lots and the associated roads, driveways, utilities and stormwater vault. Frontage improvements include 13 feet of pavement with curb, gutter, an 8-foot planter and 5-foot sidewalk on the west side of Renton Avenue S. See Figure 1-1: Vicinity Map, provided below. The project will be designed using the guidelines and requirements established in the 2017 City of Renton Surface Water Design Manual (2076 RSWDM). The project required to match forested site conditions (or a Conservation Flow Control) and Basic Water Quality treatment. The drainage analysis for detention and water quality treatment was completed using MGSFlood. Core Design, Inc. SINGH SHORT PLAT Page 2 Figure 1-1: Vicinity Map Core Design, Inc. SINGH SHORT PLAT Page 3 2 CONDITIONS AND REQUIREMENTS SUMMARY The proposed project is classified as requiring “Full Drainage Review” per the 2016 KCSWDM. Therefore, all eight core requirements and five special requirements will be addressed per Section 1.1 of the 2016 KCSWDM). 2.1 Core Requirements 2.1.1 Core Requirement #1: Discharge at the Natural Location The project will maintain the natural discharge location on the west side of the parcel to a drainage course having a confluence with the existing drainage courses through the site within a quarter mile of the site. 2.1.2 Core Requirement #2: Offsite Analysis This core requirement is addressed in Section 3 of this report. 2.1.3 Core Requirement #3: Flow Control The detention vault is designed to match the forested condition or Conservation Flow Control. This requires that the developed condition discharge durations match the existing condition durations from 50% of the 2-year to the 50-year storm events and that the developed 2-year and 10-year peak discharge rates do not exceed the existing 2-year and 10-year peak discharge rates, respectively. 2.1.4 Core Requirement #4: Conveyance System A backwater analysis using King County Backwater (KCBW) has been provided in Section 5 to show that the proposed conveyance system provides sufficient capacity for the 25-year storm as calculated by the Rational Method. 2.1.5 Core Requirements #5: Erosion and Sediment Control Erosion and sediment control will be provided through catch basin protection, interceptor swales, rock check dams, silt fencing and a construction access entrance. 2.1.6 Core Requirement #6: Maintenance and Operations The City of Renton will be responsible for the maintenance and operations of the stormwater facility located in Tract B. An Operations and Maintenance Manual will be provided in Section 10 during the Utility Permit process. 2.1.7 Core Requirement #7: Financial Guarantees and Liability A bond quantities worksheet will be provided in Section 9 as part of the Utility Permit. 2.1.8 Core Requirement #8: Water Quality Basic water quality treatment will be provided dead storage in the detention vault. Core Design, Inc. SINGH SHORT PLAT Page 4 2.2 Special Requirement #1: Other Adopted Area-Specific Requirements 2.2.1 Critical Drainage Areas Per the City’s Aquifer Protection Zone map, the project is not in an aquifer protection zone. 2.2.2 Master Drainage Plan Not applicable. 2.2.3 Basin Plans There are no basin plans for this project. 2.2.4 Salmon Conservation Plans (SCPs) There are no salmon conservation plan for this project. 2.2.5 Stormwater Compliance Plans (SWCPs) Not applicable. 2.2.6 Lake Management Plans (LMPs) Not applicable. 2.2.7 Flood Hazard Reduction Plan Updates (FHRPs) This project is not within a floodplain (see FEMA map included in Appendix B) and is not within an area with an applicable Flood Hazard Reduction Plan. Therefore, additional requirements from a Flood Hazard Reduction Plan do not apply. 2.2.8 Shared Facility Drainage Plans (SFDPs) Not applicable. 2.3 Special Requirement #2: Floodplain / Floodway Delineation This project is not located within the 100-year floodplain (see FEMA Map included in Appendix B). 2.4 Special Requirement #3: Flood Protection Facilities As this project is not located within a 100-year floodplain there are no levees, revetments or berms within the project. 2.5 Special Requirement #4: Source Controls These requirements are not applicable as the project is not a commercial, industrial or multi- family development. 2.6 Special Requirement #5: Oil Control This requirement does not apply because the project is not a commercial or industrial development nor is it expected to have more than 15,000 vehicles per day. Core Design, Inc. SINGH SHORT PLAT Page 5 3 OFFSITE ANALYSIS TASK 1 Study Area Definition and Maps The proposed project contains parcel number 0007200196. A map of the downstream can be found in Figure 3-1 Downstream Drainage Exhibit. TASK 2 Resource Review Basin Reconnaissance Summary Reports: No Basin Reconnaissance Summary Reports appear to be available for the area that is within one mile of this project site. FEMA Maps: A FEMA map dated May 16, 1995 number 53033C0977F was reviewed. The site is not located within a floodplain as it is covered by “Zone X – Outside of 500-year floodplain. The FEMA Map is included in Appendix B. Sensitive Areas Folio: The City of Renton Sensitive Areas Maps, this project is located in a moderate coal mine hazard, erosion hazard, moderate landslide hazard, and steep slopes. Soils The Geotechnical Report was completed by the Riley Group on March 14, 2017. It was determined that the “soils encountered during field exploration include loose to medium dense silty sand with varying amounts of gravel over medium dense to very dense and very stiff to hard weathered bedrock comprised of silty sand and sandy silt.” Downstream Drainage Complaints Drainage complaints were researched within the study area. King County does not list any complaints within a quarter mile of the downstream discharge point. There is one drainage compliant just beyond a quarter mile, but it was closed in 1996. See the Drainage Complaint Exhibit in Appendix B. Restrictive Well Covenant There is no existing well onsite. Core Design, Inc. SINGH SHORT PLAT Page 6 TASK 3 Field Investigation Upstream Tributary Area The residential developments to the east drain to three piped connections crossing Renton Avenue N and drain into three drainage channels onsite. See Figure 3-1 Upstream Drainage Area at the end of this section. Field Investigation Downstream Analysis A Level 1 downstream analysis was completed on March 10, 2017. The weather was cloudy and raining. The project site lies within Black River drainage basin. See Figure 3-2 Downstream Drainage Exhibit at the end of this section. Runoff on site generally drains to the south and west on-site. Runoff leaves the site through two small channels, one to the north and one to the south. The channel to the north leaves the site heading west (Point A) and then turns and heads southwest after leaving the project site. The channel to the south becomes a deeper ravine that runs southwest across the project site and continues southwest after leaving the project site (Point B). The channel to the north heads generally southwest through heavy brush and grass for approximately 400 feet after leaving the project site. It then flows onto a green plastic bedding material (Point C) which continues for about 100 feet before reaching a very steep drop off. The stream flows over the drop off through a rock lined spillway and enters Thunder Hills Creek at the bottom of the hill just east of I-405 (Point D). The channel on the south side of the project site leaves flowing southwest and flows through thick brush for approximately 200 feet. It then flows over a dirt access road (Point E) and continues heading southwest through thick brush for another 150 feet. The runoff then reaches the steep drop off. This channel also flows over the drop off and down into Thunder Hills Creek just east of I-405 (Point F). Thunder Hills Creek collects both small channels leaving the project site. Thunder Hills Creek flows to the northwest toward I-405. Based on an as-built schematic from a WSDOT report titled “Final Hydraulic Report I-405/I-5 to SR 169 Stage 2 and SR 515 Interchange Project”, Thunder Hills Creek enters a large culvert (Point G) approximately 36-inches in diameter and crosses under I-405 and Benson Rd South. The culvert continues to head northwest and outlets just east of the parking lot behind a store called Sam’s Club (Point H). At this point, the stream flows into a concrete channel and flows southwest along the edge of the Sam’s Club parking lot. The stream flows in the concrete channel for about 850 feet still heading southwest. The concrete channel then transitions to a grass and dirt lined stream which runoff reaches the ¼ mile downstream point in, near the southern exit to the Sam’s Club parking lot (Point I). Core Design, Inc. SINGH SHORT PLAT Page 7 Based on King County iMap, beyond the quarter mile downstream point runoff enters a wetland area just east of Talbot Road and south of the Sam’s Club parking lot. After leaving the wetland area, runoff eventually makes its way west to the Black River. The Black River flows north and then turns west where it joins the Green River to create the Duwamish River. The Duwamish River flows northwest and eventually outlets into Puget Sound. Level 2 Downstream Analysis: After preliminary review by the City of Renton, a Level 2 downstream was requested. The Level 2 downstream analysis was completed on January 19, 2018. The weather was cloudy with light rain and the temperature was approximately 50 degrees. According to the 2016 KCSWDM section 1.2.2.1, a Level 2 downstream analysis requires a rough quantitative analysis of the drainage components including non-survey field data and uniform flow analysis. During the site visit on January 19, 2018 dimension data was collected on Thunder Hills Creek where the onsite channels flow into the creek before entering the culvert under I-405. Dimension data was also collected on the channel on the west side of I-405 that Thunder Hills Creek drains to after crossing under I-405 and Rolling Hills Creek that the concrete channel drains into. See tables below for dimension data and the Downstream Drainage Exhibit for locations that dimension data was taken. A uniform flow analysis has been completed below for the flow capacity at each point the dimension data was taken. The uniform flow analysis was completed using Manning’s Equation per section 4.4.1.2 of the 2017 RSWDM. Core Design, Inc. SINGH SHORT PLAT Page 8 Point 1: Thunder Hills Creek Creek Top Width 5’ Creek Bottom Width 3’ Creek Depth 3’ Creek Side Slope 1:3 Approximate Slope 3% Bed Lining Medium Rocks Manning’s “n” 0.050 Q =1.49n A R23 S 12 A = Area = 12 ft2 S = Slope = 0.03 ft/ft R = Hydraulic Radius = 12/9.7 = 1.24 ft Flow Capacity Q = 71.38 CFS 1 3 3’ 5’ Core Design, Inc. SINGH SHORT PLAT Page 9 Point 2: Concrete Rectangular Channel Channel Width 4’ Channel Depth 3’ Approximate Slope 2% Bed Lining Concrete Manning’s “n” 0.018 Q =1.49n A R23 S 12 A = Area = 12 ft2 S = Slope = 0.02 ft/ft R = Hydraulic Radius = 12/10 = 1.2 ft Flow Capacity Q = 158.6 CFS 3’ 4’ Core Design, Inc. SINGH SHORT PLAT Page 10 Point 3: Rolling Hills Creek Creek Top Width 6’ Creek Bottom Width 4’ Creek Depth 2’ Creek Side Slope 1:2 Approximate Slope 2% Bed Lining Grass/Dirt Manning’s “n” 0.04 Q =1.49n A R23 S 12 A = Area = 11 ft2 S = Slope = 0.02 ft/ft R = Hydraulic Radius = 11/8.48 = 1.30 Flow Capacity Q = 69.02 CFS 1 2 4’ 6’ 4,000 333 Upstream Drainage Area This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. 7/5/2017 Legend 2270 113 THIS MAP IS NOT TO BE USED FOR NAVIGATION Feet Notes 227 WGS_1984_Web_Mercator_Auxiliary_Sphere City and County Boundary Other City of Renton Parcels 100' Primary 100' Intermediate 20' Primary 20' Intermediate 5' Primary 5' Intermediate 2' Primary 2' Intermediate Network Structures Inlet Manhole Utility Vault Unknown Structure Control Structure Pump Station Discharge Point Water Quality Detention Facilities Pond Tank Vault Wetland FIGURE 3-1 Core Design, Inc. SINGH SHORT PLAT Page 13 TASK 4 Drainage System Description and Problem Description See the Drainage Complaints Map and drainage complaint request in Appendix B. TASK 5 Mitigation of Existing and Potential Problems Downstream Drainage Problems Requiring Special Attention Type 1 – Conveyance System Nuisance Problems There are no known, reported or observed current downstream conveyance nuisance problems. Type 2 – Severe Erosion Problems There are no known, reported or observed current downstream severe erosion problems. Type 3-Severe Flooding Problems There are no known, reported or observed current downstream severe flooding problems. Downstream Water Quality Problems Requiring Special Attention Type 1 – Bacteria Problems There are no known or reported downstream bacteria problems. Type 2 – Dissolved Oxygen (DO) Problems There are no known or reported downstream dissolved oxygen problems. Type 3 – Temperature Problems There are no known or reported downstream temperature problems. Type 4 – Metals Problems There are no known or reported downstream metals problems. Type 5 – Phosphorous Problems There are no known or reported downstream phosphorous problems. Type 6 – Turbidity Problems There are no known or reported downstream turbidity problems. Core Design, Inc. SINGH SHORT PLAT Page 14 Type 7 – High pH Problems There are no known or reported downstream high pH problems. Bioassessment Rolling Hills Creek is a Category 5 for bioassessment. Core Design, Inc. SINGH SHORT PLAT Page 15 Drainage Adjustments There are no proposed drainage adjustments. Core Design, Inc. SINGH SHORT PLAT Page 16 4 FLOW CONTROL AND WATER QUALITY DESIGN 4.1 Predeveloped Site Hydrology The project area is approximately 1.63 acres. The project site and upstream area (from Figure 3-1) drain to two existing drainage courses that discharge from the west portion of the site into Thunder Hills Creek with a quarter mile of the site. The entire site is completely forested and drains to the west at slope ranging between 10 to 40 percent. Upstream drainage area shown consisting of about 17.9 acres drains through three 12-inch pipes crossing Renton Avenue S between S 9th Street and S 10th Street and discharge into drainage courses on site. Historic site conditions are assumed for all existing onsite areas per Section 1.2.3.1 of the 2016 KCSWDM (page 1-43) and are modeled as Till Forest, except for the existing pavement on Renton Avenue S that is west of the ROW centerline. The predeveloped areas are summarized in Table 4-1 below and Figure 4-1 Predeveloped Conditions. Table 4-1 Predeveloped Conditions Areas GROUND COVER AREA (acres) Till-Forest 1.45 Existing Peak Flows Predeveloped Scenario from MGSFlood and peak flow rates: 4.2 Developed Site Hydrology In the developed condition, the two existing drainage courses conveying the upstream area will be combined into one drainage course located in between lots 4 and 5, which will continue to discharge to Thunder Hill Creek. Lots 1-4 will be captured drain directly to the vault. Due to topographical constraints, the lower pads of lots 5 and 6 are unable to drain to the vault and existing impervious area on Renton Avenue S will be detained in lieu of the lower roofs of Lots 5 and 6. The proposed detention vault will discharge west to an existing drainage course near the west property line. This drainage course continues west through the WSDOT mitigation area where the channel of the creek has been reinforced with chicken wire, rip rap, and geotextile matting. See photo below. Core Design, Inc. SINGH SHORT PLAT Page 17 Looking downstream at the drainage course from the southwest corner of the WSDOT property Table 4-2 Developed Area for Lots 5 and 6 Lot Total Area Land Use Area Total Impervious Effective Impervious Pervious (Grass) sf acre sf acre sf acre sf acre 5 8,675 0.20 4,000 0.09 3,913 0.09 4,762 0.11 6 8,507 0.20 4,000 0.09 3,915 0.09 4,592 0.11 TOTAL 17,182 0.39 8,000 0.18 7,828 0.18 9,354 0.21 Effective Impervious Area from Lots 5 and 6 = 7,828 square feet Existing Impervious Area on Renton Avenue S = 3,345 square feet (assumed to be equal to Roof Area of Lower Pads) Roof Area of Upper Pads = 4,483 square feet Therefore, the impervious area draining to the vault in Table 4-3 below from Lots 5 and 6 is 4,483 square feet. Frontage improvements include 13 feet of pavement with curb, gutter, an 8-foot planter and 5-foot sidewalk on the west side of Renton Avenue S. The developed condition areas are summarized in Table 4-3 below and Figure 4-2 Developed Conditions Map. Core Design, Inc. SINGH SHORT PLAT Page 18 Table 4-3 Developed Conditions Areas (to Vault) Lot Total Area Land Use Area Total Impervious Effective2 Impervious Pervious (Grass) sf acre sf acre sf acre sf acre 1 7,827 0.18 4,000 0.09 3,922 0.09 3,905 0.09 2 7,825 0.18 4,000 0.09 3,922 0.09 3,903 0.09 3 7,824 0.18 4,000 0.09 3,922 0.09 3,902 0.09 4 9,996 0.23 4,000 0.09 3,900 0.09 6,096 0.14 51 3,954 0.09 2,242 0.05 2,242 0.05 1,712 0.04 61 4,833 0.11 2,242 0.05 2,242 0.05 2,591 0.06 ROW 8,070 0.08 3,657 0.08 3,657 0.08 4,413 0.10 Ex Upstream 3,345 0.08 3,345 0.08 3,345 0.08 0 0.00 Tract C 5,413 0.12 387 0.01 387 0.01 5,026 0.12 Offsite 4,236 0.10 1,259 0.03 1,259 0.03 2,977 0.07 TOTAL to Vault 63,323 1.45 29,131 0.67 28,796 0.66 34,527 0.79 1 Total area for lots 5 and 6 is the area draining to the vault, NOT the actual lot area. The impervious area for each lot was calculated as follows: (Effective Impervious Area – Ex Upstream Area)/2 = (7,828 sf – 3,345)/2 = 2,242 sf per lot 2 The effective impervious area was calculated assuming that basic dispersion would be applied to each lot to meet the minimum 10% lot BMP requirement. For example, on Lot 1: (0.10 x 7,827 sf) = 783 sf (0.10 x 783 sf) = 78 sf  Per Table 1.2.9.A, Basic Dispersion is modeled as 90% impervious, 10% grass 7,827 sf – 78 sf = 3,922 sf Developed Peak Flows The Developed scenario from MGSFlood is shown below: Core Design, Inc. SINGH SHORT PLAT Page 19 Core Design, Inc. SINGH SHORT PLAT Page 22 4.3 Performance Standards All stormwater facilities will be designed in accordance with the 2016 KCSWDM with Conservation Flow Control Standards. The proposed water quality treatment system will meet requirements from the Basic Water Quality Protection Menu. Flow Control: Conservation Flow Control Standard The Conservation Flow Control Standard requires maintaining the durations of high flows at their pre- development levels for all flows greater than one-half of the 2-year peak flow through the 50-year peak flow. The pre-development peak flow rates for the 2-year and 10-year runoff events must also be maintained under this requirement. Conveyance Capacity: The proposed conveyance system has been designed with sufficient capacity to convey and contain the 25-year peak flow as determined by the Rational Method. It will also be verified that the 100-year peak flow will not create or aggravate a severe flooding or erosion problem per Section 1.2.2. Water Quality: Basic Water Quality Menu The Basic Water Quality Menu includes one pollutant removal targets: • Total Suspended Solids = 80% reduction The Basic Water Quality Menu, described in detail in Section 6.1.1 of the 2016 KCSWDM (page 6-4), provides eight options to meet the pollutant removal targets listed above. • Option 1: Biofiltration Swale • Option 2: Filter Strip • Option 3: Wetpond • Option 4: Wetvault • Option 5: Stormwater Wetland • Option 6: Combined Detention and Wetpool Facilities • Option 7: Sand Filter • Option 8: StormFilter The project proposes to apply Option 4, a Wetvault. More detailed discussion and preliminary sizing calculations of the flow control and water quality treatment facility proposed for this project follows later in this section. More detailed discussion and preliminary sizing calculations of the flow control and water quality treatment facility proposed for this project follows later in this section. Core Design, Inc. SINGH SHORT PLAT Page 23 4.4 Flow Control System Calculation of Lot Impervious Area The impervious area per lot applied to the developed basin time series file was determined using the criteria in the 2016 KCSWDM page 3-27. The proposed development is urban residential. The site is zoned R-8 (see parcel information in Appendix A). The minimum impervious area per lot per the 2016 KCSWDM (page 3-27) would either be 4,000 square feet or the maximum impervious area based on zoning, whichever is less. The maximum impervious surface allowed in the R-8, zone in the City of Renton, is 70%. Small Lot BMP Requirements If the proposed project is on a site/lot smaller than 22,000 square feet, then flow control BMPs must be applied as specified in the requirements below or the project must demonstrate compliance with the LID Performance Standard (described in Section 1.2.9.1.B, p. 1-83) using an approved continuous runoff model. This project is not in compliance with the LID performance standard and has evaluated the following BMPs in order of precedence: 1. Full Dispersion – A native flowpath of 100 feet and no steeper than 20% per the requirements of Appendix C, Section C2.1.1 cannot be met so full dispersion is infeasible. The project site is also located in an erosion and landslide hazard area. 2. Full Infiltration of Roof Runoff – Full infiltration is not feasible because the project is located in an erosion and landslide hazard area. 3. All target surfaces not mitigated by requirements 1 and 2 above, must be mitigated to the maximum extent feasible using one or more of the BMPs from the following list: • Full Infiltration, Limited Infiltration, Bioretention and Permeable Pavement are also infeasible because the project is located in an erosion and landslide hazard area. 4. All target surfaces not mitigated by requirements 1, 2 and 3 above, must be mitigated to the maximum extent feasible using basic dispersion. The project site is located in an erosion and landslide hazard area so the application of basic dispersion must be approved by a geotechnical engineer. The use of basic dispersion on each will be confirmed at the time of building permits. 5. BMPs must be implemented, at a minimum for an impervious area equal to at least 10% of the site/lot for site/lots up to 11,000 square feet and at least 20% of the site/lot for site/lot sizes between 11,000 and 22,000 square feet. If these minimum areas are not mitigated using feasible BMPs from Requirements 1, 2, 3 and 4 above either a fee in lieu of the required minimum BMPs must be paid (requires that the City has established a program for determining Core Design, Inc. SINGH SHORT PLAT Page 24 and utilizing the fees for stormwater focused retrofit projects) or one or more of the BMPs from the following list are required to be implemented to achieve compliance. • Reduced Impervious Surface Credit – A reduced impervious surface credit will be applied to the remaining area not covered by basic dispersion to meet the minimum 10 percent lot BMP area. • Native Grown Protection Credit – It is not anticipated that a native growth protection credit will be used. 6. The soil moisture capacity of new pervious surfaces must be protected in accordance with the City’s standards. The soil moisture capacity of the developed pervious surfaces will be protected per the City’s standards. 7. Any proposed connection of roof downspouts to the local drainage system must be via a perforated pipe connection. Perforated pipe connections are not proposed because the site is located in an erosion and landslide hazard drainage area. Small Road Improvement and Urban Road Improvement Projects BMP Requirements If the proposed project is a road improvement project that is within the UGA or is on a site/parcel less than 5 acres in size, then flow control BMPs must be applied as specified in the requirements below: 1. Full Dispersion – A native flowpath of 100 feet and no steeper than 20% per the requirements of Appendix C, Section C2.1.1 cannot be met so full dispersion is infeasible. The project site is also located in an erosion and landslide hazard area. 2. All target surfaces not mitigated by requirements 1 and 2 above, must be mitigated to the maximum extent feasible using one or more of the BMPs from the following list: • Full Infiltration, Limited Infiltration, Bioretention and Permeable Pavement are also infeasible because the project is located in an erosion and landslide hazard area. 3. All target surfaces not mitigated by requirements 1, and 2 above, must be mitigated to the maximum extent feasible using basic dispersion. Basic Dispersion for the road has been determined to be infeasible because the project is located in an erosion and landslide hazard drainage area. Core Design, Inc. SINGH SHORT PLAT Page 25 Flow Control A 64’x31’ detention vault will be located in Tract B, with access off of Cedar Avenue S. The detention vault summary is located below and the full report has been included in Appendix C. MGS Flood Pond Calculation Link Name: Vault Link Type: Structure Downstream Link: None Prismatic Pond Option Used Pond Floor Elevation (ft) : 216.50 Riser Crest Elevation (ft) : 227.00 Max Pond Elevation (ft) : 227.50 Storage Depth (ft) : 10.50 Pond Bottom Length (ft) : 64.0 Pond Bottom Width (ft) : 30.0 Pond Side Slopes (ft/ft) : L1= 0.00 L2= 0.00 W1= 0.00 W2= 0.00 Bottom Area (sq-ft) : 1920. Area at Riser Crest El (sq-ft) : 1,920. (acres) : 0.044 Volume at Riser Crest (cu-ft) : 20,160. (ac-ft) : 0.463 Area at Max Elevation (sq-ft) : 1920. (acres) : 0.044 Vol at Max Elevation (cu-ft) : 21,504. (ac-ft) : 0.494 Massmann Infiltration Option Used Hydraulic Conductivity (in/hr) : 0.00 Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 18.00 Common Length (ft) : 0.000 Riser Crest Elevation : 227.00 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 216.50 Diameter (in) : 0.38 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type : Circular Orifice Core Design, Inc. SINGH SHORT PLAT Page 26 Control Elevation (ft) : 223.50 Diameter (in) : 0.62 Orientation : Horizontal Elbow : Yes ---Device Number 3 --- Device Type : Circular Orifice Control Elevation (ft) : 225.00 Diameter (in) : 0.94 Orientation : Horizontal Elbow : Yes The proposed detention vault includes a three-orifice control structure. The first orifice is 3/8 inches in diameter and is at the bottom of the riser. The second orifice is at elevation 223.50 and is 9/16 inches in diameter. The third orifice is at elevation 225.00 and is 15/16 inches in diameter. The 100-year water surface elevation is 226.87. ********** Link: Vault ********** Link WSEL Stats WSEL Frequency Data(ft) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) WSEL Peak (ft) ====================================== 1.05-Year 219.853 1.11-Year 220.124 1.25-Year 220.995 2.00-Year 222.851 3.33-Year 223.880 5-Year 224.531 10-Year 225.548 25-Year 226.178 50-Year 226.484 100-Year 226.870 The flow duration plot below indicates that the vault passes the flow control performance criteria with no positive excursions. Core Design, Inc. SINGH SHORT PLAT Page 27 The vault will discharge with outlet projection to an existing drainage course . 4.5 Water Quality Calculations Option 4 of the Basic Water Quality Protection Menu is a wetvault. Wetvault Wetvaults are sized with a volume equal to the 91% treatment volume and meets the Basic Water Quality goal of 80% TSS removal. The MGSFlood modeling results below show that the required water quality treatment volume is 4,011 cubic feet. ********** Link: Vault ********** Basic Wet Pond Volume (91% Exceedance): 4011. cu-ft Computed Large Wet Pond Volume, 1.5*Basic Volume: 6016. cu-ft The dead storage provided in the vault is as follows: Cell 1 – 64’ x 15.5’ x 4’ = 3,968 cf Cell 2 – 64’ x 15.5’ x 3’ = 2,976 cf Total Volume = 6,944 cf provided Core Design, Inc. SINGH SHORT PLAT Page 28 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The onsite conveyance system has been analyzed using the King County Back Water (KCBW) program per the requirements described in Chapter 4 of the 2017 RSWDM. The KCBW program applies the Manning equation in the Backwater Analysis Method described in Section 4.2.1.2 (page 4-21) of the 2017 RSWDM. Refer to Figure 5-1: Tributary CB Areas located at the end of this Section to aid in the following discussion. 5.1 Rational Method The conveyance system has been designed to provide sufficient capacity to convey and contain, at a minimum, the 25-year peak developed condition flow as determined by the Rational Method. Section 3.2.1 of the 2017 RSWDM outlines the process for determining QR for the project site area. The peak 25-year flow is determined by the following equation: Equation 3-1 𝑄𝑄𝑅𝑅=𝐶𝐶𝐶𝐶𝐼𝐼𝑅𝑅𝐴𝐴 Where: QR = peak flow for a storm of return frequency R CC = composite estimated runoff coefficient (0.55, see “C” Value Calculation below) IR = peak rainfall intensity for a storm of return frequency R (varies, see “IR” Peak Rainfall Intensity Calculation below) A = drainage subbasin area “C” Value Calculation The allowable runoff coefficients to be used in the Rational Method are shown in Table 3.2.1.A of the 2017 RSWDM (page 3-13) by type of land cover. The composite “C” value, CC, is determined by the following equation: Equation 3-2 𝐶𝐶𝐶𝐶=(𝐶𝐶1 𝐴𝐴1 +𝐶𝐶2 𝐴𝐴2 +⋯+𝐶𝐶𝑛𝑛𝐴𝐴𝑛𝑛)/𝐴𝐴𝑇𝑇 Where: AT = total area (1.45 acres) A1,2,…n = areas of land cover types (acres, see table below) C1, 2,…n = runoff coefficients for each land cover type ( see table below) Table 5-1 Composite “C” Value Cover Type C A Lawns / landscaping 0.25 0.79 Pavement and roofs 0.90 0.66 CC = 0.55 AT = 1.45 Core Design, Inc. SINGH SHORT PLAT Page 29 “IR” Peak Rainfall Intensity Calculation The peak rainfall intensity, IR, for the specified design storm of return frequency R (25-year) is determined using the following equations: Equation 3-3 𝐼𝐼𝑅𝑅=(𝑃𝑃𝑅𝑅)(𝑖𝑖𝑅𝑅) Equation 3-4 𝑖𝑖𝑅𝑅=(𝑎𝑎𝑅𝑅)(𝑇𝑇𝑐𝑐)−𝑏𝑏𝑅𝑅 Where: IR = peak rainfall intensity PR = total precipitation at the project site for the 24-hour, 25-year storm (3.4 in, Figure 3.2.1.C, page 3-16) iR = unit peak rainfall intensity factor (0.80 in/hr, Equation 3-4) Tc = time of concentration (6.3 minutes at furthest catch basin upstream, see “Tc” Time of Concentration Calculation below) aR, bR = Table 3.2.1.B (25-year) adjustment coefficients 2.66 and 0.65 respectively) “Tc” Time of Concentration Calculation The time of concentration is defined as “…the time it takes runoff to travel overland (from the onset of precipitation) from the most hydraulically distant location in the drainage basin to the point of discharge.” The value for time of concentration, Tc, used in equation 3-4 above is the sum total of the time of concentration for each overland flowpath segment, Tt. The equations for calculating Tc, therefore, are as follows: Equation 3-5 𝑇𝑇𝑐𝑐=𝑇𝑇1 +𝑇𝑇2 +⋯+𝑇𝑇𝑛𝑛 Equation 3-6 𝑇𝑇1,2,…𝑛𝑛=𝐿𝐿60𝑉𝑉 Where: T1, 2,…n = travel time (6.3 minutes, see calculation and discussion below) L = distance of flow across a given segment V = average velocity across the land cover =𝑘𝑘𝑅𝑅�𝑠𝑠0 ) kR = time of concentration velocity factor (per Table 3.2.1.C, page 3-13) s0 = slope of flowpath A minimum time of concentration of 6.3 minutes was used at the furthest catch basin upstream. With each progression downstream the time of concentration was recalculated to include the travel time in the pipe per equation 3-6. Core Design, Inc. SINGH SHORT PLAT Page 30 Tributary Flow, Q Calculation The time of concentration increases as you progress downstream, so therefore the intensity, I decreases as you progress downstream. At each catch basin the peak flow rate is calculated from the ∑(A*C) x Tc x IR. Qratio Calculation The Q Ratio is the ratio of new flow introduced at the pipe section to the main flow or cumulative flow in the system. For example, the Q Ratio at CB 1: = (QLateral + Qgrate)/QCB2 = (0.0cfs + 0.27 cfs)/1.45 cfs = 0.18 The areas and corresponding catchment flow rates summarized in Table 5-2 below and are graphically represented on Figure 5-1: Tributary CB Areas. Table 5-2 - Catch Basin Areas CB Area (ac) Q Q Q25 Grate Lateral New Cum Qratio CB1 0.18 0.27 0.27 1.72 0.18 CB2 0.36 0.54 0.54 1.45 0.58 CB3 0.23 0.34 0.34 0.92 0.59 CB4 0.00 0.00 0.00 0.58 0.00 CB5 0.12 0.19 0.19 0.58 0.48 CB6 0.26 0.39 0.39 0.39 5.2 King County Backwater Analysis The King County Backwater Program was used to analyze the conveyance system. The total cumulative flow for each pipe section is input as the discharge flow analyzed (minimum and maximum, 1 cfs increments), with the overflow elevation set to the rim elevation for the catch basin at the upper end of the pipe run. The KCBW results are included at the end of this section. Core Design, Inc. SINGH SHORT PLAT Page 31 The KCBW input file (.bwx) is shown below: 8 MainMenu:Perform Backwater on PIPES 17001.bwp Pipe Filename F broad-crested weir at Intermediate junctions F UTW:Use HW/TW File for Tailwater 226.87 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTW=True] 1.72000 Minimum discharge 1.72000 Maximum discharge 1.00000 discharge Increment 17001 Documentation Filename (Specify) for NONE 1 1=Standard,2=Condensed,3=Expanded output 1 1=no weir,2=Broad,3=Sharp 285.75 Overflow Elevation 2.00000 Weir Length [used only for Broad/Sharp weirs] 0.000000 Weir Height above overflow [used only for Broad/Sharp weirs] T UVF:Upstream Velocity Fixed? 3.00000 Upstream Velocity [used only for UVF=True] 3.00000 Channel Width [used only for UVF=False] 0 Return to Main Menu 15 MainMenu:Exit KCBW Program The starting tailwater for the west line was set at the maximum water surface elevation of the vault. All conveyance systems are designed to safely convey the 25-year storm event per Core Requirement #4 in the 2017 RSWDM. Tables 5-3 below shows the calculated freeboard at each catch basin analyzed. During the 25-year storm event, the minimum height of freeboard provided will 1.94 feet at CB 3. Table 5-3 KCBW Results CB HGL Rim Freeboard CB1 256.96 263.77 6.81 CB2 257.54 262.68 5.15 CB3 259.76 261.81 1.94 CB4 259.91 264.05 4.10 CB5 279.58 285.86 6.28 CB6 283.48 285.75 2.27 Core Design, Inc. SINGH SHORT PLAT Page 33 6 SPECIAL REPORTS AND STUDIES  Geotechnical Report Prepared by: Kristina Weller Dated: March 14, 2017 Riley Group 17522 Bothell Way NE Bothell, WA 98011  Critical Areas Report Prepared by: Habitat Technologies Dated: April 22, 2017 P.O. Box 1088 Puyallup, WA 98371  Arborist Report Prepared by: Daniel Maple Dated: June 29, 2017 A.B.C. Consulting Arborist LLC 12402 N Division #294 Spokane, WA 99218 Core Design, Inc. SINGH SHORT PLAT Page 34 7 OTHER PERMITS  Utilities Permit  Building Permits  ROW Use Permit  NPDES Permit Core Design, Inc. SINGH SHORT PLAT Page 35 8 ESC ANALYSIS AND DESIGN The site will utilize Appendix D of the 2017 RSWDM for the erosion and sedimentation control design to reduce the discharge of sediment-laden runoff from the site. Clearing limits will be established prior to any earthwork on the project site. Perimeter protection will be provided by silt fencing as shown on the erosion control plans to limit the downstream transport of sediment to neighboring properties. A temporary construction entrance will be used to reduce the amount of sediment transported onto paved roads by construction vehicles and, if required dust control will be provided by a water truck. The permanent detention vault will be used as a temporary sediment pond and calculations will be provided during the Construction Permit. Core Design, Inc. SINGH SHORT PLAT Page 36 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 Bond Quantities A Site Improvement Bond Quantity Worksheet to be provided with the Construction Permit. 9.2 Facility Summaries A facility summary sheet will be provided with the submittal of the final plat. 9.3 Declaration of Covenant Not applicable. Core Design, Inc. SINGH SHORT PLAT Page 37 10 OPERATIONS AND MAINTENANCE The operations and maintenance information will be provided with the Utilities Permit through select portions from Appendix A of the 2016 KCSWDM and Site Development Permit plan set. Appendix A Fair, Equitable, and Understandable Property Valuations You're in: Assessor >> Look up Property Info >> eReal Property Department of Assessments 500 Fourth Avenue, Suite ADM- AS-0708, Seattle, WA 98104 Office Hours: Mon - Fri  8:30 a.m. to 4:30 p.m. TEL: 206- 296-7300 FAX: 206- 296-5107 TTY: 206- 296-7888 Send us mail ADVERTISEMENT New Search Property Tax Bill Map This Property Glossary of Terms Area Report Print Property Detail   PARCEL DATA Parcel 000720-0196 Name SOUND & STEVE LLC Site Address   Residential Area 030-002 (SW Appraisal District) Property Name Jurisdiction RENTON Levy Code 2100 Property Type R Plat Block / Building Number Plat Lot / Unit Number Quarter-Section-Township- Range NW-20-23-5 Legal Description TOBIN H H-D C # 37 POR OF D C SLY OF LOTS 4 & 5 HIGHLAND ADD WLY OF W LN RENTON ST PROD S ELY OF C/L CEDAR ST PROD S & NLY OF PSP & L R/W  PLat Block:  Plat Lot: LAND DATA   Highest & Best Use As If Vacant SINGLE FAMILY Highest & Best Use As Improved (unknown) Present Use Vacant(Single-family) Land SqFt 140,341 Acres 3.22 Percentage Unusable 0 Unbuildable NO Restrictive Size Shape NO Zoning R-8 Water WATER DISTRICT Sewer/Septic (none) Road Access PUBLIC Parking Street Surface PAVED Views Waterfront Rainier Territorial AVERAGE Olympics AVERAGE Cascades Seattle Skyline Puget Sound Lake Washington Lake Sammamish Lake/River/Creek Other View Waterfront Location Waterfront Footage 0 Lot Depth Factor 0 Waterfront Bank Tide/Shore Waterfront Restricted Access Waterfront Access Rights NO Poor Quality NO Proximity Influence NO Designations Nuisances Historic Site Current Use (none) Nbr Bldg Sites   Adjacent to Golf Fairway NO Adjacent to Greenbelt NO Other Designation NO Deed Restrictions NO Development Rights Purchased NO Easements NO Native Growth Protection Easement NO DNR Lease NO   Topography YES Traffic Noise MODERATE Airport Noise   Power Lines YES Other Nuisances NO Problems Water Problems NO Transportation Concurrency NO Other Problems NO Environmental Environmental NO BUILDING   TAX ROLL HISTORY Account Valued Year Tax Year Omit Year Levy Code Appraised Land Value ($) Appraised Imps Value ($) Appraised Total Value ($) New Dollars ($) Taxable Land Value ($) Taxable Imps Value ($) Taxable Total Value ($) Tax Value Reason 000720019603 2016 2017 2100 143,000 0 143,000 0 143,000 0 143,000 000720019603 2015 2016 2100 143,000 0 143,000 0 143,000 0 143,000 000720019603 2014 2015 2100 137,000 0 137,000 0 137,000 0 137,000 ADVERTISEMENT Reference Links: King County Tax Links Property Tax Advisor Washington State Department of Revenue (External link) Washington State Board of Tax Appeals (External link) Board of Appeals/Equalization Districts Report iMap Recorder's Office  Scanned images of surveys and other map documents Scanned images of plats   Search Kingcounty.gov Home How do I... Services About King County Departments  King County Department of Assessments Information for... Residents Businesses Job seekers Volunteers King County employees Do more online Trip Planner Property tax information & payment Jail inmate look up Parcel viewer or iMap Public records More online tools... Get help Contact us  Customer service Phone list Employee directory Stay connected! View King County social media     © King County, WA 2016 Privacy Accessibility Terms of use 000720019603 2013 2014 2100 125,000 0 125,000 0 125,000 0 125,000 000720019603 2012 2013 2100 125,000 0 125,000 0 125,000 0 125,000 000720019603 2011 2012 2100 125,000 0 125,000 0 125,000 0 125,000 000720019603 2010 2011 2100 17,000 0 17,000 0 17,000 0 17,000 000720019603 2009 2010 2100 17,000 0 17,000 0 17,000 0 17,000 000720019603 2008 2009 2100 17,000 0 17,000 0 17,000 0 17,000 000720019603 2007 2008 2110 17,000 0 17,000 0 17,000 0 17,000 000720019603 2006 2007 2110 17,000 0 17,000 0 17,000 0 17,000 000720019603 2005 2006 2110 17,000 0 17,000 0 17,000 0 17,000 000720019603 2004 2005 2110 16,000 0 16,000 0 16,000 0 16,000 000720019603 2003 2004 2110 16,000 0 16,000 0 16,000 0 16,000 000720019603 2002 2003 2110 6,000 0 6,000 0 6,000 0 6,000 000720019603 2001 2002 2110 6,000 0 6,000 0 6,000 0 6,000 000720019603 2000 2001 2110 6,000 0 6,000 0 6,000 0 6,000 000720019603 1999 2000 2110 6,000 0 6,000 0 6,000 0 6,000 000720019603 1998 1999 2110 6,000 0 6,000 0 6,000 0 6,000 000720019603 1997 1998 2110 0 0 0 0 6,000 0 6,000 000720019603 1996 1997 2110 0 0 0 0 68,500 0 68,500 000720019603 1994 1995 2110 0 0 0 0 68,500 0 68,500 000720019603 1992 1993 2110 0 0 0 0 85,700 0 85,700 000720019603 1990 1991 2110 0 0 0 0 72,600 0 72,600 000720019603 1988 1989 2110 0 0 0 0 58,800 0 58,800 000720019603 1986 1987 2110 0 0 0 0 65,300 0 65,300 000720019603 1984 1985 2110 0 0 0 0 72,500 0 72,500 000720019603 1982 1983 2110 0 0 0 0 72,500 0 72,500 SALES HISTORY Excise Number Recording Number Document Date Sale Price Seller Name Buyer Name Instrument Sale Reason 2758145 20150928000657 9/15/2015 $145,000.00 RAFEL LAW GROUP PLLC SOUND & STEVE LLC Statutory Warranty Deed None 2652884 20140210000443 2/7/2014 $0.00 DEFOOR TERRY MARK+GWC INC RAFEL LAW GROUP PLLC Statutory Warranty Deed Foreclosure 2164485 20051026001112 9/29/2005 $270,000.00 KAO WEI KANG+CHIU-CHU TUAN ET AL GWC INC Statutory Warranty Deed None 1107586 198912291919 12/27/1989 $0.00 KAO WEI- KANG+CHIU CHU TUAN TENG LENG SHENG+HSU MEI-YU Quit Claim Deed Settlement REVIEW HISTORY PERMIT HISTORY HOME IMPROVEMENT EXEMPTION New Search Property Tax Bill Map This Property Glossary of Terms Area Report Print Property Detail ADVERTISEMENT Updated: March 17, 2016  Share   Tweet   Email   Print Information for...Do more online Get help §¨¦405 ¬«167 ¬«169 Ginger CreekSpringbrook CreekGarrison CreekKennyda l e C r e e k Rolling Hills CreekMadsen Creek J o h n s C r e e k Maple wood Creek May Creek Gypsy C r e e k Mo l a s s e s C r e e k Panther CreekC e d a r R i v e r Mola s se s C ree kThunder H i l l s C r eekGreen RiverMay C r e e k Ma d s e n C r e e k Ho n e y C r e e k Mill CreekBig S o o s C r e e k Ce d a r R i v e rSpringbrook CreekBig Soos CreekMad s en C r e e k S p r i n g b r o o k C r e e k Panther CreekBN Inc RdSR 167Cedar Riv S 135th S t Rain ier AveGreen River TrlSW 27th St Sidn e y A v e N Jones Ave NEoa l M i n e R d S S 132n d S t Industry DrSE 196th D r 89th Ave S66 t h L n S N 33rd Pl N 35th St 75th A ly S Fir Ln Puget Dr SEL a k e Y o u n g s T r a i l W a l k143rd Pl SES E 1 7 1 s t W a y SE J o n e s R d SE 8 3 r d P l 183rd Ave SESE 160th PlLake Washington TrlLogan Ave NSE 132nd St SE 91st St 110th Ave SESE SE 64th St SE 20 NE 27th S t S o o s C r e e k T r lSR 515SE Carr RdCostco Dr Nile Ave NES 32nd St 72nd Ave S77th Ave SEWo o d s i d e D r S E S 77th PlSE 68th St SE 3rd Pl 98th Pl S183rd Way SE113th Pl SES 129th St M e a d o w L n 99th Pl S120th Ave SE118th Pl SE83rd Ave SES 23rd St SE 100 th S t S Taft St Gl e n w o o d A v e S E SE 187th St S 196th St 184th Pl SE 103rd Pl SES 45th Pl Lake Youngs Service RdS 36th Pl 0th St N 41st Pl161st Pl SESE 179th Pl SE 133rd St94th Ave SESE 72nd Pl S 1 1 6 t h P l S 126th St 166th Pl SES 55th St N 38th St Rosario Pl NES 112th St Renton Ave SNE 7th St NE 9th St 87th Ave S105th Ave SEN 8th St SE 123rd Pl SE 82nd St 125th Ave SERipley Ln NInterurban TrlSE 188th Way N 31st St90th Ave SE SW 34th St Mo n t e r e y P l NE S 48th St 174th Ave SE129th Ave SEFor e s t A v e S NE 4th St61st Ave SS 75th Pl1 7 1 s t A v e S E SE 180th St S 119th St63rd Ave SSE 141st St S 199th Pl 80th Pl SBenson Rd SAndover Park E184th Ave SE16 9 t h A v e S E 111th Ave SES E 8 9 t h P l 157th Pl SEDuvall Ave NES 113th St S 115th St 178th Ave SESE 159th Pl 163rd Pl SESW 41st St S 117th Pl Renton Maple Valley Rd SE 10 106th Ave SESE 128th S 136th Pl SESE 191st StMain Ave SSE 2nd St121st Ave SESE 170th Lind Ave SWNE 21st St West Valley Hwy132nd Ave SENE 8th St122nd Ave SE77th Ave SHard ie Ave SW SW 19th St 68th Ave SSE 95th Wa y SE 200th St SE 160th St 118th Pl 116th Ave SEAvalon Dr173rd A ve SE177th Ave SESE 102n SE 120th St SE 72nd St SE 208th St117th Ave SE85th Pl SEMonster R d S W Forest Dr SE NE 5th S t 76th Ave SSE 121st Pl 96th Ave SNE 25th St 166th Ave SEB e a c o n W a y S 1 4 3 r d A v e SES 123rd St84th Ave S80th Ave SES 184th StSE 79th Pl113th Ave SE24th St S 116th St SE 204th Pl SE 139th Pl NE 24th StNE 23rd Pl NE 2nd St NE 16th St 164th Ave SESE 168th St SE 186th St nd Ave SE112th Ave SESE 172nd Pl 108th Ave SEPark Ave NNewcast l e G o l f C l u b R d S 3rd St 118th Ave SE148th Pl SE124th Ave SES 2nd St SE 63rd St S E 1 7 0 t h P l ai n i e r A v e S 66th Ave SPie rce Ave SE SE M a y V a l l e y R d SE 192nd D r N 4th St 109th Ave SESW Grady W a y 151st Ave SE d S 128th St SE P e t r o v i t s k y R d S Tobin St SE 190th St S 212th Way156th Ave SEMonroe Ave NE1 5 9 t h A v e SEE Mercer WayNE 20th Pl Aberdeen Ave NESE 201st Pl 168th Pl SE SE 116th StNE 10th St 168th Ave SES 188th St SE 112th St 138th Ave SE80th Ave SS 130th St 92nd Ave SSW 39th StMaule Ave S134th Ave SE65th Ave SMap l e V a l l e y H w y SE 184th St 140 t h W a y S E t Lakemont Blv164th Pl SE13 6 t h A v e S E NE 6th Pl Boeing AcRd S 190th St Lind Ave NW129th P l SE180th Ave SE181st Ave SE142nd Ave SESE SE 1 6 1 s t P l S 121st St S 114th St 135th P l SE148th Ave SES 194th St 84th Ave SP e d e s t r i a n W a l k 183rd Ave SEI-405 Ram p 116th Ave SESR 515 N E 2 7 t h S t NE 7th St East Valley Rdwy SE 188th St S 132nd St NE 3rd St Talbot Rd SSE May V a l l e y R d 110th Ave SE1 7 1 s t A v e S E 148th Ave SEI-4SE 82n d St SE 120th St 174 th A ve SEstrian WalkSE Jones Rd 80th Ave SS 116th P l Private RdPedestrian WalkLak e Young s T ra i l Wa l k SE Jones R d SR 167SE 208th St Ra i n i e r A v e S eek TrlS 190th St 116th Ave SEPri v a t e R dSunset Blvd NESE 159th PlSR 167S 200th St Flow Control Standards Peak Rate Flow Control Standard (Existing Site Conditions) Flow Control Duration Standard (Existing Site Conditions) Flow Control Duration Standard (Forested Conditions) Renton City Limits Potential Annexation Area ± 012Miles Flow Control Application Map Printed 1/14/2010 Reference 11-A Appendix B LAKE WASHINGTON Big Soos CreekLAKE WASHINGTON M a y C r e e k Cedar RiverCedar River Cedar RiverLAKE YOUNGS PANTHER LAKE LAKE WASHINGTON Soos CreekLAKE WASHINGTONLAKE WASHINGTON 60003000 k k k k k k k k k k k k k k k k k k k k k k k k k k k kk k k k k k k k k k k k k k k k k k k k HoquiamAveNEE Valley Hwy84thAveSNEParkD r SW 7th St SE 128th St SE 192nd StLindAveSWMainAveSS 132nd St Factory PlN Talbot Rd SN 3rd St RainierAveS 164thAveSETukwila Pk w y SPuget Dr NE 4th St S 3rd St S 1 2 9 th S t68thAveSSWSunsetBlvd SW 16th St 116thAveSEN 4th St I n t e r u r b a n Av e S WilliamsAveNBronsonW a y N NE7thSt 124thAveSES 7th St SERenton IssaquahRd Rai ni er AveNNewcastle Way CoalCr e e k PkwySESW 41st St T a ylo r P l N WNESunsetBlvdWellsAveNUnionAveNEN E 3 rd S tHa r die A v eSWS180th St Maple Valley Hwy 140thAveSES G ra d yWayS 2 1 s tSt BensonRdSRe nt o n AveS87thAveS128thAveSE148thAveSESW 43rd St SEC arrR d SE 168th St Beaco n A v e S 68thAveSLoganAveN108thAveSEForestDr SE S2ndSt 141 s tAve S ERainierAveS 156thAveSES E 183rd StBenson Dr SS 124th StS 43rd St Airport Way S W G radyW a y S E J o n e s RdSunsetBlvdN Puget Dr SESE 204th W aySW 34th StMo n s ter RdSW S E 1 4 2 n d P lWestValleyHwySSEMay ValleyRd SunsetBlvdNS C a r r RdHouserWayNNewcastle GolfClubRd S 133rd St WilliamsAveSWellsAveSEMercerWay154thPlSEDuvallAveNELoganAveSMonroeAveNESunsetBlvdNEEdmondsAveNEStevens AveNWRai ni er AveSTalbotRdSOakesdaleAveSWTaylorAveNW164thAveSERainierAveSWestVal leyHwyWestValleyHwyParkAveN108thAveSE6 6 t h Av e SWMercerWayWMercer W ay LakemontBlvdSE132ndAve SELakeWashingtonBlvdNE140thWaySE East Valley Rd68thAveS³City of RentonSensitive Areas 0 0.5 10.25 Miles Information Technology - GISmapsupport@rentonwa.govPrinted on: 11/12/2014 Data Sources: City of Renton, King County This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Renton City Limits k Education Fire Station K Valley Medical Center Coal Mine Hazards Severity HIGH MODERATE UNCLASSIFIED Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN k k k k k k k k k k k k k k k k k k k k k k k k k k k kk k k k k k k k k k k k k k k k k k k k HoquiamAveNEE Valley Hwy84thAveSNEParkD r SW 7th St SE 128th St SE 192nd StLindAveSWMainAveSS 132nd St Factory PlN Talbot Rd SN 3rd St RainierAveS 164thAveSETukwila Pk w y SPuget Dr NE 4th St S 3rd St S 1 2 9 th S t68thAveSSWSunsetBlvd SW 16th St 116thAveSEN 4th St I n t e r u r b a n Av e S WilliamsAveNBronsonW a y N NE7thSt 124thAveSES 7th St SERenton IssaquahRd Rai ni er AveNNewcastle Way CoalCr e e k PkwySESW 41st St T a ylo r P l N WNESunsetBlvdWellsAveNUnionAveNEN E 3 rd S tHa r die A v eSWS180th St Maple Valley Hwy 140thAveSES G ra d yWayS 2 1 s tSt BensonRdSRe nt o n AveS87thAveS128thAveSE148thAveSESW 43rd St SEC arrR d SE 168th St Beaco n A v e S 68thAveSLoganAveN108thAveSEForestDr SE S2ndSt 141 s tAve S ERainierAveS 156thAveSES E 183rd StBenson Dr SS 124th StS 43rd St Airport Way S W G radyW a y S E J o n e s RdSunsetBlvdN Puget Dr SESE 204th W aySW 34th StMo n s ter RdSW S E 1 4 2 n d P lWestValleyHwySSEMay ValleyRd SunsetBlvdNS C a r r RdHouserWayNNewcastle GolfClubRd S 133rd St WilliamsAveSWellsAveSEMercerWay154thPlSEDuvallAveNELoganAveSMonroeAveNESunsetBlvdNEEdmondsAveNEStevens AveNWRai ni er AveSTalbotRdSOakesdaleAveSWTaylorAveNW164thAveSERainierAveSWestVal leyHwyWestValleyHwyParkAveN108thAveSE6 6 t h Av e SWMercerWayWMercer W ay LakemontBlvdSE132ndAve SELakeWashingtonBlvdNE140thWaySE East Valley Rd68thAveS³City of RentonSensitive Areas 0 0.5 10.25 Miles Information Technology - GISmapsupport@rentonwa.govPrinted on: 11/12/2014 Data Sources: City of Renton, King County This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Renton City Limits k Education Fire Station K Valley Medical Center Erosion Hazard Severity High Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN k k k k k k k k k k k k k k k k k k k k k k k k k k k kk k k k k k k k k k k k k k k k k k k k HoquiamAveNEE Valley Hwy84thAveSNEParkD r SW 7th St SE 128th St SE 192nd StLindAveSWMainAveSS 132nd St Factory PlN Talbot Rd SN 3rd St RainierAveS 164thAveSETukwila Pk w y SPuget Dr NE 4th St S 3rd St S 1 2 9 th S t68thAveSSWSunsetBlvd SW 16th St 116thAveSEN 4th St I n t e r u r b a n Av e S WilliamsAveNBronsonW a y N NE7thSt 124thAveSES 7th St SERenton IssaquahRd Rai ni er AveNNewcastle Way CoalCr e e k PkwySESW 41st St T a ylo r P l N WNESunsetBlvdWellsAveNUnionAveNEN E 3 rd S tHa r die A v eSWS180th St Maple Valley Hwy 140thAveSES G ra d yWayS 2 1 s tSt BensonRdSRe nt o n AveS87thAveS128thAveSE148thAveSESW 43rd St SEC arrR d SE 168th St Beaco n A v e S 68thAveSLoganAveN108thAveSEForestDr SE S2ndSt 141 s tAve S ERainierAveS 156thAveSES E 183rd StBenson Dr SS 124th StS 43rd St Airport Way S W G radyW a y S E J o n e s RdSunsetBlvdN Puget Dr SESE 204th W aySW 34th StMo n s ter RdSW S E 1 4 2 n d P lWestValleyHwySSEMay ValleyRd SunsetBlvdNS C a r r RdHouserWayNNewcastle GolfClubRd S 133rd St WilliamsAveSWellsAveSEMercerWay154thPlSEDuvallAveNELoganAveSMonroeAveNESunsetBlvdNEEdmondsAveNEStevens AveNWRai ni er AveSTalbotRdSOakesdaleAveSWTaylorAveNW164thAveSERainierAveSWestVal leyHwyWestValleyHwyParkAveN108thAveSE6 6 t h Av e SWMercerWayWMercer W ay LakemontBlvdSE132ndAve SELakeWashingtonBlvdNE140thWaySE East Valley Rd68thAveS³City of RentonSensitive Areas 0 0.5 10.25 Miles Information Technology - GISmapsupport@rentonwa.govPrinted on: 11/12/2014 Data Sources: City of Renton, King County This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Renton City Limits k Education Fire Station K Valley Medical Center Landslide HazardSeverityVery HighHighModerateUnclassified Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN k k k k k k k k k k k k k k k k k k k k k k k k k k k kk k k k k k k k k k k k k k k k k k k k HoquiamAveNEE Valley Hwy84thAveSNEParkD r SW 7th St SE 128th St SE 192nd StLindAveSWMainAveSS 132nd St Factory PlN Talbot Rd SN 3rd St RainierAveS 164thAveSETukwila Pk w y SPuget Dr NE 4th St S 3rd St S 1 2 9 th S t68thAveSSWSunsetBlvd SW 16th St 116thAveSEN 4th St I n t e r u r b a n Av e S WilliamsAveNBronsonW a y N NE7thSt 124thAveSES 7th St SERenton IssaquahRd Rai ni er AveNNewcastle Way CoalCr e e k PkwySESW 41st St T a ylo r P l N WNESunsetBlvdWellsAveNUnionAveNEN E 3 rd S tHa r die A v eSWS180th St Maple Valley Hwy 140thAveSES G ra d yWayS 2 1 s tSt BensonRdSRe nt o n AveS87thAveS128thAveSE148thAveSESW 43rd St SEC arrR d SE 168th St Beaco n A v e S 68thAveSLoganAveN108thAveSEForestDr SE S2ndSt 141 s tAve S ERainierAveS 156thAveSES E 183rd StBenson Dr SS 124th StS 43rd St Airport Way S W G radyW a y S E J o n e s RdSunsetBlvdN Puget Dr SESE 204th W aySW 34th StMo n s ter RdSW S E 1 4 2 n d P lWestValleyHwySSEMay ValleyRd SunsetBlvdNS C a r r RdHouserWayNNewcastle GolfClubRd S 133rd St WilliamsAveSWellsAveSEMercerWay154thPlSEDuvallAveNELoganAveSMonroeAveNESunsetBlvdNEEdmondsAveNEStevens AveNWRai ni er AveSTalbotRdSOakesdaleAveSWTaylorAveNW164thAveSERainierAveSWestVal leyHwyWestValleyHwyParkAveN108thAveSE6 6 t h Av e SWMercerWayWMercer W ay LakemontBlvdSE132ndAve SELakeWashingtonBlvdNE140thWaySE East Valley Rd68thAveS³City of RentonSensitive Areas 0 0.5 10.25 Miles Information Technology - GISmapsupport@rentonwa.govPrinted on: 11/12/2014 Data Sources: City of Renton, King County This document is a graphic representation, not guaranteedto survey accuracy, and is based on the best informationavailable as of the date shown. This map is intended forCity display purposes only. Renton City Limits k Education Fire Station K Valley Medical Center Steep Slopes Percent Range >15% & <=25% >25% & <=40% >40% & <=90% >90% Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 FeetProjection: Lambert Conformal ConicDatum: North American 1983 HARN King C ou n ty Dow nstre am D rainage Complai nts Date: 7 /5/201 7 Notes: ±Th e infor matio n in clu de d on t his map has been comp ile d b y Kin g Count y staf f from a variety of source s an d is su bject to cha ng ewithout n otice. Kin g Co unt y makes no re present ations o r wa rra nties, exp re ss o r im plied , a s to accu ra cy, complet en ess, t ime lin ess,or rig hts to the use of such informa tion . This d ocu me nt is not intended for u se as a survey pr od uct. King Cou nty shall n ot be lia blefor a ny g en er al, sp ecial, indirect, incide ntal, o r conse qu en tial damag es including , but not limited to , lost revenu es or lo st profitsresulting from th e use or m isu se of t he info rmat ion cont aine d on this map . An y sale of this map or in formation o n t his map isprohibited except by written p er mission of King County. Appendix C BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:17001.bwp Surcharge condition at intermediate junctions Tailwater Elevation:226.87 feet Discharge Range:1.72 to 1.72 Step of 1. [cfs] Overflow Elevation:285.75 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 120 LF - 12"CP @ 25.98% OUTLET: 225.00 INLET: 256.17 INTYP: 1 JUNC NO. 1: OVERFLOW-EL: 263.77 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.18 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.72 0.79 256.96 * 0.012 0.56 0.20 1.87 1.87 0.56 ***** 0.79 PIPE NO. 2: 99 LF - 12"CP @ 0.60% OUTLET: 256.17 INLET: 256.76 INTYP: 1 JUNC NO. 2: OVERFLOW-EL: 262.68 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.58 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 1.46 0.78 257.54 * 0.012 0.52 0.50 0.79 0.79 0.52 ***** 0.78 PIPE NO. 3: 105 LF - 12"CP @ 2.30% OUTLET: 256.76 INLET: 259.18 INTYP: 1 JUNC NO. 3: OVERFLOW-EL: 261.81 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.59 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.92 0.58 259.76 * 0.012 0.41 0.27 0.78 0.78 0.41 ***** 0.58 PIPE NO. 4: 25 LF - 12"CP @ 0.88% OUTLET: 259.18 INLET: 259.40 INTYP: 1 JUNC NO. 4: OVERFLOW-EL: 264.05 BEND: 45 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.58 0.51 259.91 * 0.012 0.32 0.28 0.58 0.58 0.35 0.51 0.44 PIPE NO. 5: 120 LF - 12"CP @ 16.51% OUTLET: 259.40 INLET: 279.21 INTYP: 1 JUNC NO. 5: OVERFLOW-EL: 285.86 BEND: 45 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.48 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.58 0.37 279.58 * 0.012 0.32 0.14 0.51 0.51 0.32 ***** 0.37 PIPE NO. 6: 24 LF - 12"CP @ 16.71% OUTLET: 279.21 INLET: 283.22 INTYP: 1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.39 0.26 283.48 * 0.012 0.26 0.11 0.37 0.37 0.26 ***** 0.14