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Home My WebLink AboutTIR-4230 FINAL TECHNICAL INFORMATION REPORT FOR Cyprus Lane Plat CITY OF RENTON, WASHINGTON Prepared by: Andrew Oh, E.I.T Date: August 1, 2022 Revised: January 2023, April 2023 Core No.: 20134 4/27/23 DEVELOPMENT ENGINEERING NJanders 06/07/2023 SURFACE WATER UTILITY jfarah 06/07/2023 Core Design, Inc. CYPRUS LANE PLAT i Cyprus Lane Plat Table of Contents 1. PROJECT OVERVIEW ............................................................................................................................. 3 Figure 1-1 Vicinity Map ........................................................................................................................ 3 2. CONDITIONS AND REQUIREMENTS SUMMARY ................................................................................... 5 2.1 Core Requirements ............................................................................................................................. 6 2.1.1 Core Requirement #1: Discharge at the Natural Location ......................................................... 6 2.1.2 Core Requirement #2: Offsite Analysis ....................................................................................... 6 2.1.3 Core Requirement #3: Flow Control............................................................................................ 6 2.1.4 Core Requirement #4: Conveyance System ................................................................................ 6 2.1.5 Core Requirements #5: Erosion and Sediment Control .............................................................. 6 2.1.6 Core Requirement #6: Maintenance and Operations ................................................................. 6 2.1.7 Core Requirement #7: Financial Guarantees and Liability .......................................................... 6 2.1.8 Core Requirement #8: Water Quality ......................................................................................... 6 2.1.9 Core Requirement #9: On-Site BMPs .......................................................................................... 6 2.2 Special Requirements ......................................................................................................................... 6 2.2.1 Special Requirement #1: Other Adopted Area Specific Requirements ....................................... 6 2.2.2 Special Requirement #2: Flood Hazard Area Delineation ........................................................... 7 2.2.3 Special Requirement #3: Flood Protection Facilities ................................................................... 7 2.2.4 Special Requirement #4: Source Control .................................................................................... 7 2.2.5 Special Requirement #5: Oil Control ........................................................................................... 7 2.2.6 Special Requirement #6: Aquifer Protection Area ...................................................................... 7 3. OFFSITE ANALYSIS ................................................................................................................................ 8 Task 1 Study Area Definition and Maps .................................................................................................... 8 Task 2 Resource Review ........................................................................................................................... 8 Sensitive Areas Folio............................................................................................................................. 8 Task 3 Field Investigation ......................................................................................................................... 8 Task 4 Drainage System Description and Problem Description ............................................................... 8 4. FLOW CONTROL AND WATER QUALITY ANALYSIS ............................................................................. 10 4.1 Predeveloped Site Hydrology ........................................................................................................... 10 West Basin .......................................................................................................................................... 10 Core Design, Inc. CYPRUS LANE PLAT ii Table 4.1-1 West Basin Predeveloped Conditions ............................................................................. 10 South Basin ......................................................................................................................................... 10 Table 4.1-2 South Basin Predeveloped Conditions ............................................................................ 10 4.2 Developed Site Hydrology ................................................................................................................ 11 West Vault .......................................................................................................................................... 11 Table 4.2-1 Developed Conditions ..................................................................................................... 11 South Vault ......................................................................................................................................... 12 Table 4.2-2 Developed Conditions ..................................................................................................... 12 4.3 Flow Control System ......................................................................................................................... 14 West Vault .......................................................................................................................................... 14 South Vault ......................................................................................................................................... 14 4.4 BMP Feasibility ................................................................................................................................. 18 4.5 Water Quality Treatment Analysis and Design ................................................................................. 21 South Basin ......................................................................................................................................... 21 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN .................................................................................. 22 6. SPECIAL REPORTS AND STUDIES ........................................................................................................ 25 7. OTHER PERMITS ................................................................................................................................. 26 8. ESC ANALYSIS AND DESIGN ................................................................................................................ 27 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT ................................ 1 10. OPERATIONS AND MAINTENANCE ....................................................................................................... 2 Appendix A .................................................................................................................................................... 3 Appendix B .................................................................................................................................................... 4 • MGS Flood Report Core Design, Inc. CYPRUS LANE PLAT 3 1. PROJECT OVERVIEW The proposed Cyprus Lane project is located at 5816 NE 4th Place, Renton, WA and 510 Nile Avenue NE, Renton, WA. See Vicinity Map below. Figure 1-1 Vicinity Map The site is composed of parcels #1123059023, #1123059021, and #1123059031 with an area of approximately 4.92 acres. The site is bordered by NE 4th Place to the south, Nile Avenue to the west, and single-family residential homes to the north and east. The south two parcels were previously developed with a single story residential home and detached garage. The north parcel was previously developed with a single story residential home. The rest of the site was left as forest. The site generally slopes at 5-10% from northeast to southwest. Proposed development of the property will include the demolition of all existing structures and the construction of 14 single family residences, access road, public alley, utilities, and frontage improvements. Core Design, Inc. CYPRUS LANE PLAT 4 The subject project’s drainage facilities were designed using the guidelines and requirements established in the 2017 City of Renton Surface Water Design Manual (RSWDM).Flow Control Duration Standard (Forested Site Conditions) and Basic Water Quality Treatment are required for this project. Core Design, Inc. CYPRUS LANE PLAT 5 2. CONDITIONS AND REQUIREMENTS SUMMARY The proposed project is classified as requiring “Full Drainage Review” per the 2017 RSWDM. Therefore, all nine core requirements and six special requirements will be addressed per Section 1.2 and 1.3 of the 2017 RSWDM. Core Design, Inc. CYPRUS LANE PLAT 6 2.1 Core Requirements 2.1.1 Core Requirement #1: Discharge at the Natural Location The project has two natural discharge locations. Both are to the City’s conveyance system. The west vault discharge location is along Nile Avenue NE and the south vault discharge location is on NE 4th Place. The discharge from the two vaults are within the same basin and will converge within a ¼ mile. There is a small portion of forest located at the southeast corner of the site that is a part of a separate basin that will be discharged with the rest of the site in the developed conditions. A drainage adjustment has been submitted for this. 2.1.2 Core Requirement #2: Offsite Analysis See Section 3 of this Report for the downstream drainage path. 2.1.3 Core Requirement #3: Flow Control The site falls within the City’s Flow Control Duration Standard (Forested Site Conditions). See City’s Flow Control Application Map in Appendix A. This flow control standard requires matching forested conditions for the 2, 10, and 100-year peak rate runoffs. See Section 4 of this report for a detailed Flow Control Analysis. 2.1.4 Core Requirement #4: Conveyance System See Section 5 of this report for a detailed conveyance system analysis for the 25-year and 100-year storm events. The proposed conveyance system will be designed to convey and contain the 25-year peak flow. The conveyance system may overtop for runoff events exceeding the 25-year design capacity provided that overflow from the 100-year runoff event does not create or aggravate a severe flooding or erosion problem. See section 1.2.4.1 of the 2017 RSWDM for conveyance system requirements. 2.1.5 Core Requirements #5: Erosion and Sediment Control See Section 8 of this report for ESC analysis and design. 2.1.6 Core Requirement #6: Maintenance and Operations See Section 10 of this report for the Maintenance and Operations manual. 2.1.7 Core Requirement #7: Financial Guarantees and Liability A City of Renton Bond Quantity Worksheet has been provided in Section 9 of this report. 2.1.8 Core Requirement #8: Water Quality The project is required to provide basic water quality treatment if the new plus replaced pollution generating impervious surface exceeds 5,000 SF. See section 4.5 for details. 2.1.9 Core Requirement #9: On-Site BMPs See Section 4.3 of this Report for discussion on how this Core Requirement is addressed. 2.2 Special Requirements 2.2.1 Special Requirement #1: Other Adopted Area Specific Requirements There are no known additional requirements for the subject project. Core Design, Inc. CYPRUS LANE PLAT 7 2.2.2 Special Requirement #2: Flood Hazard Area Delineation Not applicable since the project does not contain nor is adjacent to a flood hazard area. 2.2.3 Special Requirement #3: Flood Protection Facilities Not applicable since the project does not rely on an existing flood protection facility or plans to modify or construct a new flood protection facility. 2.2.4 Special Requirement #4: Source Control Not applicable. 2.2.5 Special Requirement #5: Oil Control Not applicable since the project is not a high use site. The expected average daily traffic is less than 100 vehicles per 1,000 square feet of gross building area. 2.2.6 Special Requirement #6: Aquifer Protection Area Not applicable since the project is not in an Aquifer Protection Area. Core Design, Inc. CYPRUS LANE PLAT 8 3. OFFSITE ANALYSIS Task 1 Study Area Definition and Maps The proposed project is located within the Lower Cedar River drainage basin. Task 2 Resource Review Sensitive Areas Folio Renton GIS was reviewed for sensitive areas. The proposed project site does not fall within the following sensitive area; coal mines, erosion hazard, flood hazard, floodway, channel migration zone, landslide, seismic hazard, regulated stream, wetland, or wellhead protection. Task 3 Field Investigation There is negligible upstream tributary area. Downstream Drainage Path West Basin This downstream route description begins at the catch basin located along the east side of Nile Avenue NE right at the southwest corner of the project site. This catch basin captures runoff from the site and directs flow south until the intersection with NE 4th Street. At this point the runoff is redirected west along the north side of NE 4th Street. This concludes the ¼ mile analysis just before the runoff crosses to the south side of NE 4th Street near 401 Lyons Avenue NE. The drainage will continue to follow this path until it is discharged into a stream tributary to Lake Washington. The other downstream route for the west basin begins at the catch basin located along the south side of NE 4th Place, approximately 100 feet west of the site. This catch basin captures runoff from the site and directs flow south into an existing storm control facility. This facility then discharges flows to the west at which point it merges with the flow from the other downstream route within a ¼ mile. South Basin This downstream route description begins at the two catch basins located along the south side of NE 4th Place, one at the west side and the other at the east side of the site. The two catch basins combine at the next manhole and flow south along Orcas Place NE until it meets NE 4th Street. The storm system directs runoff to the west along NE 4th Street for approximately 800 ft at which point the ¼ mile analysis ends near 5514 NE 4th Street. The West and South Basin combine 1,600 feet downstream of the west basin and 1,900 feet downstream of the South Basin so the project has two separate drainage basins. Task 4 Drainage System Description and Problem Description Drainage complaints were researched within a quarter mile of the project site. City of Renton does not list any current complaints along the project’s downstream route. 2,257376 City of Renton Storm 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. THIS MAP IS NOT TO BE USED FOR NAVIGATIONWGS_1984_Web_Mercator_Auxiliary_Sphere Notes None 01/17/2023 Legend 256 0 128 256 Feet Information Technology - GIS RentonMapSupport@Rentonwa.gov City and County Labels Addresses Parcels City and County Boundary <all other values> Renton Renton Fire Hydrant Control Valve Water Gravity Pipe Water Main Water Main - Other System Network Structures Access Riser Inlet Manhole Utility Vault Clean Out Unknown Control Structure Pump Station Discharge Point Water Quality Detention Facilities Pond Tank Vault Bioswale Wetland Other Surface Water Main Culvert Open Drains Virtual Drainline Facility Outline Private Network Structures Access Riser Inlet Manhole Clean Out Utility Vault Unknown Private Control Structure Private Pump Station Private Discharge Point Private Water Quality Private Detention Facilities Tank, No Stormwater Wetland, No; Natural Wetland, No Filter Strip, No Infiltration Trench, No Vault, No Pond, No; Pond, Unknown Bioswale, No Stormtech Chamber, No Other, No Private Pipe Private Culvert WEST BASIN SOUTH BASIN 1/4 MILE ENDS 1/4 MILE ENDS EXISTING SOUTH BASIN DISCHARGE 1,600 LF 1,900 LF BASINS COMBINE 1,600 LF DOWNSTREAM OF THE WEST BASINA ND 1,900 LF DOWNSTREAM OF THE SOUTH BASIN WHICH IS GREATER THAN 1/4 MILE AND THEREFORE THE PROJECT HAS TWO SEPARATE DRAINAGE BASINS WEST BASINS CONVERGE 520 LF (SITE TO WEST BASIN CONVERGENCE) 450LF (SITE TO WEST BASIN CONVERGENCE) Core Design, Inc. CYPRUS LANE PLAT 10 4. FLOW CONTROL AND WATER QUALITY ANALYSIS Two flow control facilities are proposed for the project. See section 4.1 below for details. A water quality treatment facility is proposed in the south basin as the project is not exempt from water quality treatment as delineated in Section 4.2 of this Report. The drainage analysis was modeled using MGS Flood software. 4.1 Predeveloped Site Hydrology The site was previously developed with two single story residential homes and detached garage. The rest of the site was left as forest. The total project area is approximately 4.92 acres and includes the site as well as frontage improvements. As per the flow control standard designated for the site, the entire project area will be modeled as Till Forest in MGS Flood. The site has two existing basins that are shown in the table below. West Basin The existing impervious in the west basin is from the existing impervious on Nile Avenue NE that will be grinded and overlayed. This area would not be considered a targeted area for mitigation and as it will drain into the vault due to the crown of the road, we will be modeling it in its existing condition as impervious in the developed conditions. Table 4.1-1 West Basin Predeveloped Conditions Ground Cover Area (acres) Till Forest 4.66 Ex. Impervious 0.06 Total Basin 4.72 South Basin Existing forested area located at the south east corner of the site. This area is not included in the predeveloped conditions in the flow control model, but will be detained with the rest of the site flows in the developed conditions. A basin adjustment has been submitted for this area. Table 4.1-2 South Basin Predeveloped Conditions Ground Cover Area (acres) Till Forest 0.20 Total Basin 0.20 Core Design, Inc. CYPRUS LANE PLAT 11 4.2 Developed Site Hydrology Proposed development of the property will include the demolition of all existing structures and the construction of 14 single family residences, access road, utilities, and frontage improvements along NE 4th Place and Nile Avenue NE. Flow control BMP credit has been taken into account for modeling for future flow control BMPs. A max impervious area per lot of 4,000 SF was found per the guideline of 4,000 SF or max impervious based on zoning, whichever is less. The project is split into two vaults to capture flows from different areas of the site (West/South), although they are all in the same basin. The developed conditions are shown below. West Vault Table 4.2-1 Developed Conditions Total Area (SF) Impervious (SF) Pervious (SF) Lot 9 9,335 4,000 5,335 Lot 10 10,819 4,000 6,819 Lot 11 10,515 4,000 6,515 Tract D 5,872 0 5,872 Tract E 8,134 0 8,134 Right of Way 5,967 4,690 1,277 Total (SF) 50,642 16,690 33,952 Total (Acres) 1.16 0.38 0.78 Core Design, Inc. CYPRUS LANE PLAT 12 South Vault Table 4.2-2 Developed Conditions Total Area (SF) Impervious (SF) Pervious (SF) Lot 1 10,978 4,000 6,978 Lot 2 9,017 4,000 5,017 Lot 3 9,005 4,000 5,005 Lot 4 9,015 4,000 5,015 Lot 5 10,014 4,000 6,014 Lot 6 10,818 4,000 6,818 Lot 7 9,100 4,000 5,100 Lot 8 9,032 4,000 5,032 Lot 12 12,788 4,000 8,788 Lot 13 9,308 4,000 5,308 Lot 14 9,367 4,000 5,367 Right of Way 36,636 27,919 8,717 Right of Way Connection 667 667 0 Alley 6,985 5,946 1,039 Open Space Tract A 10,846 0 10,846 Total (SF) 163,576 78,532 85,044 Total (Acres) 3.76 1.80 1.95 NE 4TH PLACENILE PLACE NE ORCAS PLACE NE NILE AVENUE NE DESIGNE N G I N E E R I N G P L A N N I N G S U R V E Y I N G12100 NE 195th St, Suite 300Bothell, Washington 98011425.885.7877 Fax 425.885.796320134 NE 4TH PLACENILE PLACE NE ORCAS PLACE NE 53' NILE AVENUE NE 139,308± SFTR. ASTORM/ OP. SP.10,846± SF89,032± SF110,978± SF29,017± SFROW6.5' ROW DED.1,070± SF39,005± SFTR. CTREE306± SFTR. BTREE248± SFTR. ITREE740± SFTR. HTREE950± SFTR. FTREE1,051± SFTR. GTREE799± SF149,367± SF99,335± SF49,015± SF1010,819± SFROW36,636± SFTR. DOPEN SPACE5,872± SF1212,788± SF610,818± SF79,100± SF510,014± SFALLEY (PUBLIC)6,985± SFTR. ESTORM8,134± SF1110,515± SFDESIGNE N G I N E E R I N G P L A N N I N G S U R V E Y I N G12100 NE 195th St, Suite 300Bothell, Washington 98011425.885.7877 Fax 425.885.796320134 Core Design, Inc. CYPRUS LANE PLAT 14 4.3 Flow Control System West Vault Using the predeveloped and developed areas above, a 40’x30’ with 5.1’ of live storage was sized. The vault will be providing 6,120 CF of storage at riser crest. Below are the vault details and the flow rates. The full MGS Flood report can be found in Appendix B. South Vault Using the predeveloped and developed areas above, a 58’ x 88’ vault with 10’ of live storage was sized. The vault will be providing 51,040 CF of storage at riser crest. Below are the tank details and the flow rates. The full MGS Flood report can be found in Appendix B Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 0.130 2-Year 7.816E-02 5-Year 0.213 5-Year 0.118 10-Year 0.276 10-Year 0.179 25-Year 0.370 25-Year 0.213 50-Year 0.468 50-Year 0.256 100-Year 0.501 100-Year 0.306 200-Year 0.780 200-Year 0.333 500-Year 1.154 500-Year 0.368 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals **** Flow Duration Performance **** Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): -3.8% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%): -3.8% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -11.4% PASS Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS Core Design, Inc. CYPRUS LANE PLAT 15 Core Design, Inc. CYPRUS LANE PLAT 16 Link Name: North Vault Link Type: Structure Downstream Link Name: New Copy Lnk3 Prismatic Pond Option Used Pond Floor Elevation (ft) : 0.00 Riser Crest Elevation (ft) : 5.10 Max Pond Elevation (ft) : 6.10 Storage Depth (ft) : 5.10 Pond Bottom Length (ft) : 40.0 Pond Bottom Width (ft) : 30.0 Pond Side Slopes (ft/ft) : Z1= 0.00 Z2= 0.00 Z3= 0.00 Z4= 0.00 Bottom Area (sq-ft) : 1200. Area at Riser Crest El (sq-ft) : 1,200. (acres) : 0.028 Volume at Riser Crest (cu-ft) : 6,120. (ac-ft) : 0.140 Area at Max Elevation (sq-ft) : 1200. (acres) : 0.028 Vol at Max Elevation (cu-ft) : 7,320. (ac-ft) : 0.168 Hydraulic Conductivity (in/hr) : 0.00 Massmann Regression Used to Estimate Hydralic Gradient Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 5.10 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 0.00 Diameter (in) : 0.81 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type : Circular Orifice Control Elevation (ft) : 2.50 Diameter (in) : 1.19 Orientation : Horizontal Elbow : Yes ---Device Number 3 --- Device Type : Circular Orifice Control Elevation (ft) : 3.85 Diameter (in) : 0.62 Orientation : Horizontal Elbow : Yes Core Design, Inc. CYPRUS LANE PLAT 17 Link Name: South Vault Link Type: Structure Downstream Link Name: New Copy Lnk3 Prismatic Pond Option Used Pond Floor Elevation (ft) : 0.00 Riser Crest Elevation (ft) : 10.00 Max Pond Elevation (ft) : 10.50 Storage Depth (ft) : 10.00 Pond Bottom Length (ft) : 100.0 Pond Bottom Width (ft) : 58.0 Pond Side Slopes (ft/ft) : Z1= 0.00 Z2= 0.00 Z3= 0.00 Z4= 0.00 Bottom Area (sq-ft) : 5800. Area at Riser Crest El (sq-ft) : 5,800. (acres) : 0.133 Volume at Riser Crest (cu-ft) : 58,000. (ac-ft) : 1.331 Area at Max Elevation (sq-ft) : 5800. (acres) : 0.133 Vol at Max Elevation (cu-ft) : 60,900. (ac-ft) : 1.398 Hydraulic Conductivity (in/hr) : 0.00 Massmann Regression Used to Estimate Hydralic Gradient Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 10.00 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 0.00 Diameter (in) : 0.81 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type : Circular Orifice Control Elevation (ft) : 5.67 Diameter (in) : 0.87 Orientation : Horizontal Elbow : Yes ---Device Number 3 --- Device Type : Circular Orifice Control Elevation (ft) : 7.10 Diameter (in) : 1.13 Orientation : Horizontal Elbow : Yes Core Design, Inc. CYPRUS LANE PLAT 18 4.4 BMP Feasibility Per Section 1.2.9.1 in the RSWDM, projects subject to Core Requirement #9 must apply flow control BMPs to either supplement the flow mitigation provided by required flow control facilities or provide flow mitigation where flow control facilities are not required. Flow control BMPs must be implemented per the requirements and approach detailed in Sections 1.2.9.2 and 1.2.9.3 for individual lots and subdivisions or road improvement projects, respectively. The Section applicable to this project is Section 1.2.9.2. Per Section 1.2.9.2, projects on individual sites/lots, flow control BMPs must be selected and applied according to the individual lot BMP requirements. The category of requirements applicable to the subject project is the Small Lot BMP Requirements (for sites/lots <22,000 square feet). 1. The feasibility and applicability of full dispersion as detailed in Appendix C, Section C.2.1 must be evaluated for all target impervious surfaces. If feasible and applicable, full dispersion must be implemented as part of the proposed project. Typically, small lot full dispersion will be applicable only in subdivisions where enough forest was preserved by tract, easement, or covenant to meet the minimum requirements for full dispersion in Appendix C, Section C.2.1.1 Full dispersion is not feasible since there is no forested area. 2. Where full dispersion of target impervious roof areas is not feasible or applicable, or will cause flooding or erosion impacts, the feasibility and applicability of full infiltration as detailed in Appendix C, Section C.2.2 must be evaluated (note, this will require a soils report for the site/lot). If feasible and applicable, full infiltration of roof runoff must be implemented as part of the proposed project. As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” 3. All target impervious surfaces not mitigated by Requirements 1 and 2 above, must be mitigated to the maximum extent feasible using one or more BMPs from the following list. Use of a given BMP is subject to evaluation of its feasibility and applicability as detailed in Appendix C. Feasible BMPs are required to be implemented. The BMPs listed below may be located anywhere on the site/lot subject to the limitations and design specifications for each BMP. These BMPs must be implemented as part of the proposed project. • Full Infiltration per Appendix C, Section C.2.2, or per Section 5.2, whichever is applicable As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” • Limited Infiltration per Appendix C, Section C.2.3, As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” Core Design, Inc. CYPRUS LANE PLAT 19 • Rain Gardens per Appendix C, Section C.2.12, sized as follows: As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” • Bioretention per Appendix C, Section C.2.6, sized as follows: o SeaTac regional scale factor equals 1.0: In till soils, provide bioretention volume based on 0.6 inches of equivalent storage depth; in outwash soils provide bioretention volume based on 0.1 inches of equivalent storage depth, o SeaTac regional scale factor greater than 1.0: In till soils, provide bioretention volume based on 0.8 inches of equivalent storage depth; in outwash soils, provide bioretention volume based on 0.4 inches of equivalent storage depth, As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” • Permeable Pavement per Appendix C, Section C.2.7 As per the Geotechnical report by Cobalt Geosciences dated February 2, 2021, “Infiltration is not feasible due to the presence of dense fine-grained soil deposits, which act as an aquitard.” 4. All target impervious surfaces not mitigated by Requirements 1, 2 and 3 above, must be mitigated to the maximum extent feasible using the Basic Dispersion BMP described below. Use of Basic Dispersion is subject to evaluation of its feasibility and applicability as detailed in Appendix C. Feasible BMPs are required to be implemented. Basic Dispersion BMPs may be located anywhere on the site/lot subject to the limitations and design specifications cited in Appendix C. The BMP must be implemented as part of the proposed project. • Basic Dispersion per Appendix C, Section C.2.4, Basic Dispersion will be implemented for walkways. The minimum required BMP area will be met with basic dispersion through sheetflow dispersion, splash blocks, or dispersion trenches. These BMPs will be evaluated with the building permits. 5. BMPs must be implemented, at minimum, for an impervious area equal to at least 10% of the site/lot for site/lot sizes 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. For projects located in Zone 1 of the Aquifer Protection Area, these impervious area amounts must be doubled. Doubling of the minimum impervious area required for BMP implementation in Zone 1 of the Aquifer Protection Area is not required for projects located within 200 feet of a steep slope hazard area, landslide hazard, or erosion hazard area. If these minimum areas are not mitigated using feasible BMPs from Requirements 1, 2, 3, and 4 above, one or more BMPs from the following list are required to be implemented to achieve compliance. These BMPs must be implemented as part of the proposed project. • Reduced Impervious Surface Credit per Appendix C, Section C.2.9, Core Design, Inc. CYPRUS LANE PLAT 20 • Native Growth Retention Credit per Appendix C, Section C.2.10. • Tree Retention Credit per Appendix C, Section C.2.14 Reduced impervious surface credit is not feasible due to the insufficient lot area/space to provide applicable compliance levels and maintain required setbacks while having reasonable use of the lot. The native grown retention credit is not feasible because there is no native vegetation on this site to maintain. 6. The soil moisture holding capacity of new pervious surfaces (target pervious surfaces) must be protected in accordance with the soil amendment BMP as detailed in Appendix C, Section C.2.13. Soil amendment will be incorporated for disturbed areas not covered with hard surfaces. 7. Any proposed connection of roof downspouts to the local drainage system must be via a perforated pipe connection as detailed in Appendix C, Section C.2.11. Perforated pipe connections will be provided for any proposed connection of roof downspouts to the local drainage system. Core Design, Inc. CYPRUS LANE PLAT 21 4.5 Water Quality Treatment Analysis and Design West Basin Water quality will be provided through dead storage in the detention vault. The snip below from MGS Flood shows that the vault will need a minimum of 2,956 CF of dead storage to achieve basic water quality treatment. The proposed vault will provide 4,800 CF of dead storage (40’x30’x4’). Therefore, basic water quality treatment has been met. South Basin Water quality will be provided through dead storage in the detention vault. The snip below from MGS Flood shows that the vault will need a minimum of 11,270 CF of dead storage to achieve basic water quality treatment. The proposed vault will provide 15,200 CF of dead storage in two out of the three cells (100’x38’x4’). Therefore, basic water quality treatment has been met. Core Design, Inc. CYPRUS LANE PLAT 22 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The conveyance system was designed for the 25-year, 24-hour and 100-year, 24-hour storm events. A conveyance spreadsheet was generated for basin using the rational method to calculate flows for the area collected by each catch basin. The precipitation rates for the 25-year, 24-hour and 100-year, 24- hour storm events are 3.4 inches and 3.9 inches respectively. The flows generated from the conveyance system spreadsheets for both storm events were input into backwater analysis spreadsheets to confirm adequate sizing. The backwater analysis was performed to ensure that during the 25-year, 24-hour storm event, the headwater elevation in each structure did not overtop any of the rims. For the 100-year, 24-hour storm event, structures are allowed to overtop, but all runoff must be safely conveyed to ensure that overflowing runoff or ponding would not cause structural damage. These requirements are found in section 1.2.4 of the 2016 KCSWDM. Weighted C values for basin was used in the rational method spreadsheet. Impervious area has a C value of 0.9 and grass area has a C value of 0.25. These values along with the impervious area and grass area of the developed basin was used to calculate the weighted C values. See calculations provided below. ((2.09 x 0.25)+ (1.88 x 0.9))/3.96 =0.56 =C The tailwater elevations within the vault were derived from the MGS Flood report. See the MGS Flood generated reports provided in Section 4. Tailwater elevations for the 25-year storm event and the 100- year storm event are provided in the table below. Storm Year Tailwater Elevation 25-year 483.29 100-year 484.05 During the 25-year storm all headwater elevations remained below the rim elevations of all catch basins. During the 100-year storm all headwater elevations also remained below the rim elevations of all catch basins. Therefore, the conveyance system meets the requirements of the 2016 KCSWDM. See conveyance and backwater spreadsheets for the 25 and 100-year storms below. A Conveyance Exhibit is also provided showing the area assumed to drain to each catch basin on the following pages. Core Design, Inc. CYPRUS LANE PLAT 23 A conveyance analysis has been completed to verify if the 18-inch pipe of CB 21 has adequate capacity to convey runoff. The pipe capacity analysis will be for a 18” pipe. The slope for this pipe is 5%. Using the nomograph above, the flow capacity of the 18” pipe at 5% slope is roughly 25 CFS. CB 21 is taking in roughly 1.06 CFS at the 100-year storm, which is significantly under the max capacity of 25 CFS. Q = 25 cfs (25 cfs >> 1.06 cfs) Therefore, the proposed pipes will convey the 100-year peak flows. Core Design, Inc. CYPRUS LANE PLAT 24 A conveyance analysis has been completed to verify if the 12-inch pipes of CB 20 and 25 have adequate capacity to convey runoff. The pipe capacity analysis will be for a 12” pipe. The project is using a conservative 0.5% slope. Using the nomograph above, the flow capacity of a 12” pipe at 0.5% slope is roughly 2.6 CFS. CB 20 is taking in roughly 0.12 CFS at the 100-year storm and the mitigated flows from the vault into CB25 is 0.11 CFS, which are both significantly under the max capacity of 2.6 CFS. Q = 2.6 cfs (2.6cfs >> 0.12 & 0.11 cfs) Therefore, the proposed pipes will convey the 100- year peak flows. NE 4TH PLACEPASCO PLACE NE 53' NILE AVENUE NE DESIGNE N G I N E E R I N G P L A N N I N G S U R V E Y I N G12100 NE 195th St, Suite 300Bothell, Washington 98011425.885.7877 Fax 425.885.796320134 RATIONAL METHOD CONVEYANCE SYSTEM DESIGN LOCATION: KING COUNTY PR (24-HR RAINFALL):3.4 INCHES PROJECT NAME: Cyprus Lane PROJECT NUMBER: 20134 PREPARED BY: AO DESIGN STORM: 25 YEAR SUBBASIN PIPE PIPE PIPE ACTUAL TRAVEL PIPE CAPACITY SUMMARY LOCATION AREA SUM OF Tc IR QR MANNING'S SIZE SLOPE LENGTH VELOCITY (VR)TIME Q(FULL) V(FULL) QR/Q(FULL) FROM TO (AC) "C" (A * C) (A * C) (MIN) (IN/HR) (CFS) "n" (IN) (%) (FT) (FT/SEC) (MIN) (CFS) (FT/SEC) (%) 14 13 0.270 0.56 0.151 0.151 6.30 2.73 0.413 0.012 12 0.530 19 2.49 0.13 2.810 3.58 14.7% 13 12 0.060 0.56 0.034 0.185 6.43 2.70 0.499 0.012 12 1.700 57 3.88 0.25 5.032 6.41 9.9% 12 11 0.240 0.56 0.134 0.319 6.67 2.63 0.841 0.012 12 0.500 25 3.02 0.14 2.729 3.47 30.8% 11 10 0.060 0.56 0.034 0.353 6.81 2.60 0.917 0.012 12 1.760 62 4.73 0.22 5.120 6.52 17.9% 10 8 0.040 0.56 0.022 0.375 7.03 2.55 0.955 0.012 12 2.790 54 5.70 0.16 6.447 8.21 14.8% 17 16 0.070 0.56 0.039 0.039 6.30 2.73 0.107 0.012 12 6.720 46 3.89 0.20 10.005 12.74 1.1% 16 15 0.030 0.56 0.017 0.056 6.50 2.68 0.150 0.012 12 9.580 98 4.64 0.35 11.946 15.21 1.3% 15 9 0.760 0.56 0.426 0.482 6.85 2.59 1.247 0.012 12 3.110 23 6.54 0.06 6.807 8.67 18.3% 9 8 0.100 0.56 0.056 0.538 6.91 2.58 1.384 0.012 12 2.100 25 5.84 0.07 5.593 7.12 24.8% 8 6 0.040 0.56 0.022 0.935 7.19 2.51 2.347 0.012 12 2.320 65 6.96 0.16 5.879 7.49 39.9% 7 6 0.260 0.56 0.146 0.146 6.30 2.73 0.398 0.012 12 1.000 25 3.10 0.13 3.860 4.91 10.3% 6 3 0.330 0.56 0.185 1.266 7.34 2.47 3.132 0.012 12 2.630 179 7.97 0.37 6.259 7.97 50.0% 2 1 0.830 0.56 0.465 0.465 6.30 2.73 1.271 0.012 12 0.500 19 3.41 0.09 2.729 3.47 46.6% 1 3 0.020 0.56 0.011 0.476 6.39 2.71 1.289 0.012 12 0.500 32 3.41 0.16 2.729 3.47 47.2% 3 Vault 0.11 0.56 0.062 2 7.717 2.40 4.321 0.012 12.000 55.600 29 25.47 0.02 28.780 36.64 15.0% RATIONAL METHOD CONVEYANCE SYSTEM DESIGN LOCATION: KING COUNTY PR (24-HR RAINFALL):3.9 INCHES PROJECT NAME: Cyprus Lane PROJECT NUMBER: 20134 PREPARED BY: AO DESIGN STORM: 100 YEAR SUBBASIN PIPE PIPE PIPE ACTUAL TRAVEL PIPE CAPACITY SUMMARY LOCATION AREA SUM OF Tc IR QR MANNING'S SIZE SLOPE LENGTH VELOCITY (VR)TIME Q(FULL) V(FULL) QR/Q(FULL) FROM TO (AC) "C" (A * C) (A * C) (MIN) (IN/HR) (CFS) "n" (IN) (%) (FT) (FT/SEC) (MIN) (CFS) (FT/SEC) (%) 14 13 0.270 0.56 0.151 0.151 6.30 3.19 0.483 0.012 12 0.530 19 2.59 0.12 2.810 3.58 17.2% 13 12 0.060 0.56 0.034 0.185 6.42 3.15 0.583 0.012 12 1.700 57 4.04 0.24 5.032 6.41 11.6% 12 11 0.240 0.56 0.134 0.319 6.66 3.08 0.984 0.012 12 0.500 25 3.18 0.13 2.729 3.47 36.1% 11 10 0.060 0.56 0.034 0.353 6.79 3.05 1.075 0.012 12 1.760 62 5.05 0.20 5.120 6.52 21.0% 10 8 0.040 0.56 0.022 0.375 6.99 2.99 1.122 0.012 12 2.790 54 5.95 0.15 6.447 8.21 17.4% 17 16 0.070 0.56 0.039 0.039 6.30 3.19 0.125 0.012 12 6.720 46 3.89 0.20 10.005 12.74 1.3% 16 15 0.030 0.56 0.017 0.056 6.50 3.13 0.175 0.012 12 9.580 98 4.64 0.35 11.946 15.21 1.5% 15 9 0.760 0.56 0.426 0.482 6.85 3.03 1.459 0.012 12 3.110 23 6.72 0.06 6.807 8.67 21.4% 9 8 0.100 0.56 0.056 0.538 6.91 3.01 1.620 0.012 12 2.100 25 6.09 0.07 5.593 7.12 29.0% 8 6 0.040 0.56 0.022 0.935 7.14 2.95 2.758 0.012 12 2.320 65 7.34 0.15 5.879 7.49 46.9% 7 6 0.260 0.56 0.146 0.146 6.30 3.19 0.465 0.012 12 1.000 25 3.27 0.13 3.860 4.91 12.0% 6 3 0.330 0.56 0.185 1.266 7.29 2.91 3.685 0.012 12 2.630 179 8.29 0.36 6.259 7.97 58.9% 2 1 0.830 0.56 0.465 0.465 6.30 3.19 1.484 0.012 12 0.500 19 3.54 0.09 2.729 3.47 54.4% 1 3 0.020 0.56 0.011 0.476 6.39 3.16 1.506 0.012 12 0.500 32 3.54 0.15 2.729 3.47 55.2% 3 Vault 0.11 0.56 0.062 2 7.652 2.82 5.093 0.012 12.000 55.600 29 26.57 0.02 28.780 36.64 17.7% BACKWATER CALCULATIONS PROJECT NAME: Cyprus Lane PREPARED BY: AO PROJECT NUMBER: 20134 DESIGN STORM: 25 YEAR ENTRANCE ENTRANCE EXIT OUTLET INLET APPROACH BEND JUNCTION PIPE PIPE MANNING'S OUTLET INLET PIPE FULL VELOCITY TAILWATER FRICTION HGL HEAD HEAD CONTROL CONTROL VELOCITY HEAD HEAD HEADWATER RIM FROM TO Q LENGTH SIZE "n" ELEVATION ELEVATION AREA VELOCITY HEAD ELEVATION LOSS ELEVATION LOSS LOSS ELEVATION ELEVATION HEAD LOSS LOSS ELEVATION ELEVATION FREEBOARD CB CB (CFS) (FT) (IN) VALUE (FT) (FT) (SQ FT) (FT/SEC) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) 3 vault 4.33 29 12 0.012 472.50 484.79 0.79 5.52 0.47 483.29 0.36 485.79 0.24 0.47 486.50 486.46 0.25 0.62 0.14 487.01 489.62 2.61 1 3 1.29 32 12 0.012 484.79 484.95 0.79 1.64 0.04 487.01 0.04 487.05 0.02 0.04 487.11 485.95 0.04 0.05 0.00 487.13 488.97 1.84 2 1 1.27 19 12 0.012 484.95 485.07 0.79 1.62 0.04 487.13 0.02 487.15 0.02 0.04 487.21 486.07 0.00 0.05 0.00 487.26 489.35 2.09 6 3 3.13 179 12 0.012 484.79 489.50 0.79 3.98 0.25 487.01 1.16 490.50 0.12 0.25 490.87 490.79 0.14 0.33 0.03 491.09 493.77 2.68 7 6 0.40 25 12 0.012 489.50 489.75 0.79 0.51 0.00 491.09 0.00 491.09 0.00 0.00 491.10 490.75 0.00 0.01 0.00 491.10 493.77 2.67 8 6 2.34 65 12 0.012 489.50 491.00 0.79 2.98 0.14 491.09 0.24 492.00 0.07 0.14 492.21 492.00 0.05 0.00 0.06 492.22 495.23 3.01 9 8 1.38 25 12 0.012 491.00 491.15 0.79 1.76 0.05 492.22 0.03 492.25 0.02 0.05 492.33 492.15 0.04 0.06 0.00 492.35 495.18 2.83 15 9 1.25 23 12 0.012 491.15 492.95 0.79 1.59 0.04 492.35 0.02 493.95 0.02 0.04 494.01 493.95 0.00 0.00 0.00 494.01 496.95 2.94 16 15 0.15 98 12 0.012 492.95 501.28 0.79 0.19 0.00 494.01 0.00 502.28 0.00 0.00 502.28 502.28 0.00 0.00 0.00 502.28 505.28 3.00 17 16 0.11 46 12 0.012 501.28 503.86 0.79 0.14 0.00 502.28 0.00 504.86 0.00 0.00 504.86 504.86 0.00 0.00 0.00 504.86 507.86 3.00 10 8 0.95 54 12 0.012 491.00 492.50 0.79 1.21 0.02 492.22 0.03 493.50 0.01 0.02 493.53 493.50 0.02 0.01 0.00 493.52 496.64 3.12 11 10 0.92 62 12 0.012 492.50 493.50 0.79 1.17 0.02 493.52 0.03 494.50 0.01 0.02 494.53 494.50 0.02 0.00 0.00 494.52 497.75 3.23 12 11 0.84 25 12 0.012 493.50 493.62 0.79 1.07 0.02 494.52 0.01 494.62 0.01 0.02 494.65 494.62 0.01 0.02 0.00 494.66 497.81 3.15 13 12 0.50 57 12 0.012 493.62 494.51 0.79 0.63 0.01 494.66 0.01 495.51 0.00 0.01 495.52 495.51 0.00 0.00 0.00 495.52 498.97 3.45 14 13 0.41 19 12 0.012 494.51 494.63 0.79 0.53 0.00 495.52 0.00 495.63 0.00 0.00 495.64 495.63 0.00 0.00 0.00 495.64 499.05 3.41 PIPE SEGMENT BACKWATER CALCULATIONS PROJECT NAME: Cyprus Lane PREPARED BY: AO PROJECT NUMBER: 20134 DESIGN STORM: 100 YEAR ENTRANCE ENTRANCE EXIT OUTLET INLET APPROACH BEND JUNCTION PIPE PIPE MANNING'S OUTLET INLET PIPE FULL VELOCITY TAILWATER FRICTION HGL HEAD HEAD CONTROL CONTROL VELOCITY HEAD HEAD HEADWATER RIM FROM TO Q LENGTH SIZE "n" ELEVATION ELEVATION AREA VELOCITY HEAD ELEVATION LOSS ELEVATION LOSS LOSS ELEVATION ELEVATION HEAD LOSS LOSS ELEVATION ELEVATION FREEBOARD CB CB (CFS) (FT) (IN) VALUE (FT) (FT) (SQ FT) (FT/SEC) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) (FT) 3 vault 5.11 29 12 0.012 472.50 484.79 0.79 6.50 0.66 484.05 0.50 485.79 0.33 0.66 486.78 486.93 0.34 0.87 0.19 487.65 489.62 1.97 1 3 1.50 32 12 0.012 484.79 484.95 0.79 1.91 0.06 487.65 0.05 487.69 0.03 0.06 487.78 485.95 0.06 0.08 0.00 487.80 488.97 1.17 2 1 1.48 19 12 0.012 484.95 485.07 0.79 1.89 0.06 487.80 0.03 487.83 0.03 0.06 487.91 486.07 0.00 0.07 0.00 487.98 489.35 1.37 6 3 3.68 179 12 0.012 484.79 489.50 0.79 4.68 0.34 487.65 1.61 490.50 0.17 0.34 491.01 491.03 0.19 0.45 0.04 491.33 493.77 2.44 7 6 0.46 25 12 0.012 489.50 489.75 0.79 0.59 0.01 491.33 0.00 491.34 0.00 0.01 491.35 490.75 0.00 0.01 0.00 491.35 493.77 2.42 8 6 2.75 65 12 0.012 489.50 491.00 0.79 3.51 0.19 491.33 0.33 492.00 0.10 0.19 492.29 492.15 0.07 0.00 0.08 492.31 495.23 2.92 9 8 1.62 25 12 0.012 491.00 491.15 0.79 2.06 0.07 492.31 0.04 492.35 0.03 0.07 492.45 492.15 0.05 0.09 0.00 492.48 495.15 2.67 15 9 1.46 23 12 0.012 491.15 492.95 0.79 1.86 0.05 492.48 0.03 493.95 0.03 0.05 494.03 493.95 0.00 0.01 0.00 494.04 496.95 2.91 16 15 0.18 98 12 0.012 492.95 501.28 0.79 0.22 0.00 494.04 0.00 502.28 0.00 0.00 502.28 502.28 0.00 0.00 0.00 502.28 505.28 3.00 17 16 0.13 46 12 0.012 501.28 503.86 0.79 0.16 0.00 502.28 0.00 504.86 0.00 0.00 504.86 504.86 0.00 0.00 0.00 504.86 507.86 3.00 10 8 1.12 54 12 0.012 491.00 492.50 0.79 1.43 0.03 492.31 0.05 493.50 0.02 0.03 493.55 493.50 0.03 0.01 0.00 493.53 496.64 3.11 11 10 1.07 62 12 0.012 492.50 493.50 0.79 1.37 0.03 493.53 0.05 494.50 0.01 0.03 494.54 494.50 0.02 0.01 0.00 494.52 497.75 3.23 12 11 0.98 25 12 0.012 493.50 493.62 0.79 1.25 0.02 494.52 0.02 494.62 0.01 0.02 494.66 494.62 0.01 0.03 0.00 494.68 497.81 3.13 13 12 0.58 57 12 0.012 493.62 494.51 0.79 0.74 0.01 494.68 0.01 495.51 0.00 0.01 495.52 495.51 0.01 0.00 0.00 495.52 498.97 3.45 14 13 0.48 19 12 0.012 494.51 494.63 0.79 0.61 0.01 495.52 0.00 495.63 0.00 0.01 495.64 495.63 0.00 0.00 0.00 495.64 499.05 3.41 PIPE SEGMENT Core Design, Inc. CYPRUS LANE PLAT 25 6. SPECIAL REPORTS AND STUDIES The following reports and assessments are provided under separate cover for reference and informational purposes only. Core Design takes no responsibility or liability for these reports, assessments or designs as they were not completed under the direct supervision of Core Design. ➢ Geotechnical Evaluation February 2, 2021 Cobalt Geosciences, LLC P.O Box 82243 Kenmore, WA 98028 206-331-1097 ➢ Arborist Report June 21, 2021 Greenforest Inc 4547 S. Lucile Street Seattle, WA 98118 206-723-0656 Core Design, Inc. CYPRUS LANE PLAT 26 7. OTHER PERMITS • Civil Construction Permit • NPDES Permit • Building Permit (Vaults) • Franchise Permits • Electrical Permits Core Design, Inc. CYPRUS LANE PLAT 27 8. ESC ANALYSIS AND DESIGN This project will comply with Section 1.2.5 and Appendix D of the 2016 KCSWDM. This project will also comply with the 13 Elements presented in the 2014 Washington State Department of Ecology Stormwater Management Manual for Western Washington. Part A: ESC Plan Analysis and Design The following ESC measure have been considered for this project. A brief discussion of each measure is also provided below. Additional information on ESC measures can be found in the SWPPP Report provided under separate cover. 1. Clearing Limits: Clearing Limits will be marked with orange construction fencing or silt fence where shown on the TESC Plans. 2. Cover Measures: Plastic covering will be used to cover exposed soils. 3. Perimeter Protection: Perimeter protection will be provided using silt fence. 4. Traffic Area Stabilization: Traffic Area Stabilization will be provided by a stabilized construction entrance. 5. Sediment Retention: Sediment Retention will be completed using silt fence and temporary sediment ponds. Temporary sediment ponds will be in the permanent detention facility. Sizing is below. West Temporary Sediment Pond See undetained developed flow rates for area draining to the proposed detention vault during construction from MGS Flood Below. Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 5.244E-02 2-Year 0.235 5-Year 8.526E-02 5-Year 0.328 10-Year 0.107 10-Year 0.410 25-Year 0.140 25-Year 0.531 50-Year 0.179 50-Year 0.701 100-Year 0.194 100-Year 0.882 200-Year 0.288 200-Year 0.892 500-Year 0.416 500-Year 0.900 Runoff from the site will sheet flow across cleared areas into temporary interceptor swales and into the proposed temporary sediment pond within the proposed detention vault. The Temporary Sediment Pond was sized using the 10-year storm event. Unmitigated Developed 10-year Storm, 15-min interval: Q10 = 0.410 CFS Temporary Sediment Pond minimum surface area, SA, is determined by the following equation: Core Design, Inc. CYPRUS LANE PLAT 28 SA = 2080 sf/cfs * (Total Q10-Developed) SA = 852.8 SF The total design surface areas of the proposed detention vault is 1,200 SF which is more than enough to provide adequate erosion and sedimentation control. South Temporary Sediment Pond See undetained developed flow rates for area draining to the proposed detention vault during construction from MGS Flood Below. Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 8.539E-02 2-Year 0.924 5-Year 0.137 5-Year 1.218 10-Year 0.178 10-Year 1.505 25-Year 0.245 25-Year 1.897 50-Year 0.308 50-Year 2.518 100-Year 0.327 100-Year 3.123 200-Year 0.523 200-Year 3.164 500-Year 0.786 500-Year 3.197 Runoff from the site will sheet flow across cleared areas into temporary interceptor swales and into the proposed temporary sediment pond within the proposed detention vault. The Temporary Sediment Pond was sized using the 10-year storm event. Unmitigated Developed 10-year Storm, 15-min interval: Q10 = 1.51 CFS Temporary Sediment Pond minimum surface area, SA, is determined by the following equation: SA = 2080 sf/cfs * (Total Q10-Developed) SA = 3,140.8 SF The total design surface areas of the proposed detention vault is 5,800 SF which is more than enough to provide adequate erosion and sedimentation control. Core Design, Inc. CYPRUS LANE PLAT 29 6. Surface Water Collection: Surface water collection will be done using interceptor swales. 7. Dewatering Control: No dewatering is anticipated to be required. If any dewatering does need to occur, water will be discharged through a stabilized channel to the proposed Temporary Sediment Pond. 8. Dust Control: Dust control will be provided using a water truck as needed. 9. Flow Control: Flow control will be provided using check dams and the temporary sediment pond. The sediment ponds will be properly sized with the 10-year unmitigated developed conditions. 10. Control Pollutants: Pollutants will be controlled as needed using Best Management Practices. See the SWPPP report for more detailed information on controlling pollutants. 11. Protect Existing and Proposed Flow Control BMPs: No flow control BMPs are proposed. 12. Maintain BMPs: BMPs will be maintained in order to provide adequate erosion and sediment control. 13. Manage the Project: Project will be managed to provide adequate erosion and sediment control during construction. See the SWPPP report for more information on managing the project. Core Design, Inc. CYPRUS LANE PLAT 30 Part B: SWPPS Plan Design Refer to the SWPPP Report provided under separate cover for information on anticipated pollutants and BMPs to address pollutants of concern. See Section 3, Task 5, for a discussion of the downstream receiving waters. This section discusses all 7 types of downstream water quality problems requiring special attention Core Design, Inc. CYPRUS LANE PLAT Page 1 9. BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT See the following page for the bond quantities worksheet. 1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 Date Prepared: Name: PE Registration No: Firm Name: Firm Address: Phone No. Email Address: Project Name: Project Owner: CED Plan # (LUA): Phone: CED Permit # (C):Address: Site Address: Street Intersection: Addt'l Project Owner: Parcel #(s): Phone: Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:YES Water Service Provided by: If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: Abbreviated Legal Description: SW1/4, SW1/4, SEC. 11, TWP. 23 N., RGE. 5 E., W.M. 5816 NE 4th Place PO Box 2170,22-001966 21-000287 206.714.6707 4/27/2023 Prepared by: FOR APPROVALProject Phase 1 shm@coredesigninc.com Sheri Murata 41846 Core Design Inc. 12100 NE 195th St, Suite #300, Bothell, WA 98011 425.885.7877 SITE IMPROVEMENT BOND QUANTITY WORKSHEET PROJECT INFORMATION KC WATER DISTRICT 90 CITY OF RENTON Engineer Stamp Required (all cost estimates must have original wet stamp and signature) Clearing and Grading Utility Providers FPP not Required Project Location and Description Project Owner Information Cyprus Lane Renton, WA 98056 1123059023;1123059021;1123059031 Tuscany Construction Page 1 of 14 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 10.1% Total Estimated Construction Costs E A + B + C + D 1,459,987.66$ Estimated Civil Construction Permit - Construction Costs2 Stormwater (Erosion Control + Drainage)C 688,298.96$ As outlined in City Ordinance No. 4345, 50% of the plan review and inspection fees are to be paid at Permit Submittal. The balance is due at Permit Issuance. Significant changes or additional review cycles (beyond 3 cycles) during the review process may result in adjustments to the final review fees. Roadway (Transportation)D 441,575.87$ Water A -$ Wastewater (Sanitary Sewer)B 330,112.83$ 2 All prices include labor, equipment, materials, overhead, profit, and taxes. City of Renton Sales Tax is: 1 Select the current project status/phase from the following options: For Approval - Preliminary Data Enclosed, pending approval from the City; For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout - Final Costs and Quantities Enclosed for Project Close-out Submittal Page 2 of 14 Ref 8-H Bond Quantity Worksheet SECTION I PROJECT INFORMATION Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Unit Reference #Price Unit Quantity Cost Backfill & compaction-embankment ESC-1 7.50$ CY Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 90.00$ Each Catch Basin Protection ESC-3 145.00$ Each 22 3,190.00 Crushed surfacing 1 1/4" minus ESC-4 WSDOT 9-03.9(3)110.00$ CY Ditching ESC-5 10.50$ CY Excavation-bulk ESC-6 2.30$ CY 250 575.00 Fence, silt ESC-7 SWDM 5.4.3.1 5.00$ LF 1568 7,840.00 Fence, Temporary (NGPE)ESC-8 1.75$ LF Geotextile Fabric ESC-9 3.00$ SY Hay Bale Silt Trap ESC-10 0.60$ Each Hydroseeding ESC-11 SWDM 5.4.2.4 0.90$ SY Interceptor Swale / Dike ESC-12 1.15$ LF Jute Mesh ESC-13 SWDM 5.4.2.2 4.00$ SY Level Spreader ESC-14 2.00$ LF Mulch, by hand, straw, 3" deep ESC-15 SWDM 5.4.2.1 2.90$ SY Mulch, by machine, straw, 2" deep ESC-16 SWDM 5.4.2.1 2.30$ SY Piping, temporary, CPP, 6"ESC-17 13.75$ LF Piping, temporary, CPP, 8"ESC-18 16.00$ LF Piping, temporary, CPP, 12"ESC-19 20.50$ LF Plastic covering, 6mm thick, sandbagged ESC-20 SWDM 5.4.2.3 4.60$ SY Rip Rap, machine placed; slopes ESC-21 WSDOT 9-13.1(2)51.00$ CY Rock Construction Entrance, 50'x15'x1'ESC-22 SWDM 5.4.4.1 2,050.00$ Each Rock Construction Entrance, 100'x15'x1'ESC-23 SWDM 5.4.4.1 3,675.00$ Each Sediment pond riser assembly ESC-24 SWDM 5.4.5.2 2,525.00$ Each Sediment trap, 5' high berm ESC-25 SWDM 5.4.5.1 22.00$ LF Sed. trap, 5' high, riprapped spillway berm section ESC-26 SWDM 5.4.5.1 80.00$ LF Seeding, by hand ESC-27 SWDM 5.4.2.4 1.15$ SY Sodding, 1" deep, level ground ESC-28 SWDM 5.4.2.5 9.20$ SY Sodding, 1" deep, sloped ground ESC-29 SWDM 5.4.2.5 11.50$ SY TESC Supervisor ESC-30 125.00$ HR 40 5,000.00 Water truck, dust control ESC-31 SWDM 5.4.7 160.00$ HR 40 6,400.00 Unit Reference #Price Unit Quantity Cost 8.00$ LF 1535 12,280.00 EROSION/SEDIMENT SUBTOTAL:35,285.00 SALES TAX @ 10.1%3,563.79 EROSION/SEDIMENT TOTAL:38,848.79 (A) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR EROSION & SEDIMENT CONTROL Description No. (A) Tree Protection Fence WRITE-IN-ITEMS Page 3 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.a EROSION_CONTROL Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost GENERAL ITEMS Backfill & Compaction- embankment GI-1 7.00$ CY 500 3,500.00 Backfill & Compaction- trench GI-2 10.25$ CY 72 738.00 111 1,137.75 Clear/Remove Brush, by hand (SY)GI-3 1.15$ SY Bollards - fixed GI-4 275.00$ Each Bollards - removable GI-5 520.00$ Each Clearing/Grubbing/Tree Removal GI-6 11,475.00$ Acre 0.87 9,983.25 3.86 44,293.50 Excavation - bulk GI-7 2.30$ CY 500 1,150.00 Excavation - Trench GI-8 5.75$ CY 72 414.00 111 638.25 Fencing, cedar, 6' high GI-9 23.00$ LF Fencing, chain link, 4'GI-10 44.00$ LF Fencing, chain link, vinyl coated, 6' high GI-11 23.00$ LF Fencing, chain link, gate, vinyl coated, 20' GI-12 1,600.00$ Each Fill & compact - common barrow GI-13 28.75$ CY 340 9,775.00 Fill & compact - gravel base GI-14 31.00$ CY Fill & compact - screened topsoil GI-15 44.75$ CY Gabion, 12" deep, stone filled mesh GI-16 74.50$ SY Gabion, 18" deep, stone filled mesh GI-17 103.25$ SY Gabion, 36" deep, stone filled mesh GI-18 172.00$ SY Grading, fine, by hand GI-19 2.90$ SY Grading, fine, with grader GI-20 2.30$ SY Monuments, 3' Long GI-21 1,025.00$ Each Sensitive Areas Sign GI-22 8.00$ Each Sodding, 1" deep, sloped ground GI-23 9.25$ SY Surveying, line & grade GI-24 975.00$ Day Surveying, lot location/lines GI-25 2,050.00$ Acre Topsoil Type A (imported)GI-26 32.75$ CY Traffic control crew ( 2 flaggers )GI-27 137.75$ HR 40 5,510.00 Trail, 4" chipped wood GI-28 9.15$ SY Trail, 4" crushed cinder GI-29 10.25$ SY Trail, 4" top course GI-30 13.75$ SY Conduit, 2"GI-31 5.75$ LF Wall, retaining, concrete GI-32 63.00$ SF Wall, rockery GI-33 17.25$ SF SUBTOTAL THIS PAGE:6,662.00 9,983.25 60,494.50 (B)(C)(D)(E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) Page 4 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) ROAD IMPROVEMENT/PAVEMENT/SURFACING AC Grinding, 4' wide machine < 1000sy RI-1 34.50$ SY AC Grinding, 4' wide machine 1000-2000sy RI-2 18.25$ SY 1231 22,465.75 AC Grinding, 4' wide machine > 2000sy RI-3 11.50$ SY AC Removal/Disposal RI-4 40.00$ SY Barricade, Type III ( Permanent )RI-5 64.25$ LF Guard Rail RI-6 34.50$ LF Curb & Gutter, rolled RI-7 19.50$ LF Curb & Gutter, vertical RI-8 14.25$ LF 443 6,312.75 1168 16,644.00 Curb and Gutter, demolition and disposal RI-9 20.50$ LF Curb, extruded asphalt RI-10 6.25$ LF Curb, extruded concrete RI-11 8.00$ LF Sawcut, asphalt, 3" depth RI-12 3.00$ LF 1093 3,279.00 Sawcut, concrete, per 1" depth RI-13 5.00$ LF Sealant, asphalt RI-14 2.25$ LF Shoulder, gravel, 4" thick RI-15 17.25$ SY Sidewalk, 4" thick RI-16 43.50$ SY 200 8,700.00 720 31,320.00 Sidewalk, 4" thick, demolition and disposal RI-17 37.00$ SY Sidewalk, 5" thick RI-18 47.00$ SY 125 5,875.00 Sidewalk, 5" thick, demolition and disposal RI-19 46.00$ SY Sign, Handicap RI-20 97.00$ Each Striping, per stall RI-21 8.00$ Each Striping, thermoplastic, ( for crosswalk )RI-22 3.50$ SF Striping, 4" reflectorized line RI-23 0.55$ LF Additional 2.5" Crushed Surfacing RI-24 4.15$ SY HMA 1/2" Overlay 1.5" RI-25 16.00$ SY HMA 1/2" Overlay 2"RI-26 20.75$ SY 1273 26,414.75 HMA Road, 2", 4" rock, First 2500 SY RI-27 32.25$ SY 2500 80,625.00 HMA Road, 2", 4" rock, Qty. over 2500SY RI-28 24.00$ SY 78 1,872.00 HMA Road, 4", 6" rock, First 2500 SY RI-29 51.75$ SY HMA Road, 4", 6" rock, Qty. over 2500 SY RI-30 42.50$ SY HMA Road, 4", 4.5" ATB RI-31 43.50$ SY Gravel Road, 4" rock, First 2500 SY RI-32 17.25$ SY Gravel Road, 4" rock, Qty. over 2500 SY RI-33 11.50$ SY Thickened Edge RI-34 10.00$ LF SUBTOTAL THIS PAGE:67,172.25 136,336.00 (B)(C)(D)(E) Page 5 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR STREET AND SITE IMPROVEMENTS Quantity Remaining (Bond Reduction) (B)(C) PARKING LOT SURFACING No. 2" AC, 2" top course rock & 4" borrow PL-1 24.00$ SY 2" AC, 1.5" top course & 2.5" base course PL-2 32.00$ SY 4" select borrow PL-3 5.75$ SY 1.5" top course rock & 2.5" base course PL-4 16.00$ SY SUBTOTAL PARKING LOT SURFACING: (B)(C)(D)(E) LANDSCAPING & VEGETATION No. Street Trees LA-1 220.00$ EA 8 1,760.00 23 5,060.00 Median Landscaping LA-2 45.00$ SY Right-of-Way Landscaping LA-3 45.00$ SY Wetland Landscaping LA-4 SUBTOTAL LANDSCAPING & VEGETATION:1,760.00 5,060.00 (B)(C)(D)(E) TRAFFIC & LIGHTING No. Signs TR-1 100.00$ 16 1,600.00 Street Light System ( # of Poles)TR-2 8,000.00$ EA 14 112,000.00 Traffic Signal TR-3 Traffic Signal Modification TR-4 SUBTOTAL TRAFFIC & LIGHTING:113,600.00 (B)(C)(D)(E) WRITE-IN-ITEMS SUBTOTAL WRITE-IN ITEMS: STREET AND SITE IMPROVEMENTS SUBTOTAL:75,594.25 264,979.25 60,494.50 SALES TAX @ 10.1%7,635.02 26,762.90 6,109.94 STREET AND SITE IMPROVEMENTS TOTAL:83,229.27 291,742.15 66,604.44 (B)(C)(D)(E) Page 6 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.b TRANSPORTATION Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost DRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/D D-1 30.00$ SY * (CBs include frame and lid) Beehive D-2 103.00$ Each Through-curb Inlet Framework D-3 460.00$ Each CB Type I D-4 1,725.00$ Each 3 5,175.00 15 25,875.00 CB Type IL D-5 2,000.00$ Each CB Type II, 48" diameter D-6 3,500.00$ Each 2 7,000.00 for additional depth over 4' D-7 550.00$ FT CB Type II, 54" diameter D-8 4,075.00$ Each for additional depth over 4'D-9 570.00$ FT CB Type II, 60" diameter D-10 4,225.00$ Each for additional depth over 4'D-11 690.00$ FT CB Type II, 72" diameter D-12 6,900.00$ Each for additional depth over 4'D-13 975.00$ FT CB Type II, 96" diameter D-14 16,000.00$ Each for additional depth over 4'D-15 1,050.00$ FT Trash Rack, 12"D-16 400.00$ Each Trash Rack, 15"D-17 470.00$ Each Trash Rack, 18"D-18 550.00$ Each Trash Rack, 21"D-19 630.00$ Each Cleanout, PVC, 4"D-20 170.00$ Each Cleanout, PVC, 6"D-21 195.00$ Each 11 2,145.00 15 2,925.00 Cleanout, PVC, 8"D-22 230.00$ Each Culvert, PVC, 4" D-23 11.50$ LF Culvert, PVC, 6" D-24 15.00$ LF 663 9,945.00 644 9,660.00 Culvert, PVC, 8" D-25 17.00$ LF Culvert, PVC, 12" D-26 26.00$ LF 443 11,518.00 1245 32,370.00 Culvert, PVC, 15" D-27 40.00$ LF Culvert, PVC, 18" D-28 47.00$ LF Culvert, PVC, 24"D-29 65.00$ LF Culvert, PVC, 30" D-30 90.00$ LF Culvert, PVC, 36" D-31 150.00$ LF Culvert, CMP, 8"D-32 22.00$ LF Culvert, CMP, 12"D-33 33.00$ LF SUBTOTAL THIS PAGE:23,693.00 70,335.00 12,585.00 (B)(C)(D)(E) Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Page 7 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES DRAINAGE (Continued) Culvert, CMP, 15"D-34 40.00$ LF Culvert, CMP, 18"D-35 47.00$ LF Culvert, CMP, 24"D-36 64.00$ LF Culvert, CMP, 30"D-37 90.00$ LF Culvert, CMP, 36"D-38 150.00$ LF Culvert, CMP, 48"D-39 218.00$ LF Culvert, CMP, 60"D-40 310.00$ LF Culvert, CMP, 72"D-41 400.00$ LF Culvert, Concrete, 8"D-42 48.00$ LF Culvert, Concrete, 12"D-43 55.00$ LF Culvert, Concrete, 15"D-44 89.00$ LF Culvert, Concrete, 18"D-45 100.00$ LF Culvert, Concrete, 24"D-46 120.00$ LF Culvert, Concrete, 30"D-47 145.00$ LF Culvert, Concrete, 36"D-48 175.00$ LF Culvert, Concrete, 42"D-49 200.00$ LF Culvert, Concrete, 48"D-50 235.00$ LF Culvert, CPE Triple Wall, 6" D-51 16.00$ LF Culvert, CPE Triple Wall, 8" D-52 18.00$ LF Culvert, CPE Triple Wall, 12" D-53 27.00$ LF Culvert, CPE Triple Wall, 15" D-54 40.00$ LF Culvert, CPE Triple Wall, 18" D-55 47.00$ LF Culvert, CPE Triple Wall, 24" D-56 64.00$ LF Culvert, CPE Triple Wall, 30" D-57 90.00$ LF Culvert, CPE Triple Wall, 36" D-58 149.00$ LF Culvert, LCPE, 6"D-59 69.00$ LF Culvert, LCPE, 8"D-60 83.00$ LF Culvert, LCPE, 12"D-61 96.00$ LF Culvert, LCPE, 15"D-62 110.00$ LF Culvert, LCPE, 18"D-63 124.00$ LF Culvert, LCPE, 24"D-64 138.00$ LF Culvert, LCPE, 30"D-65 151.00$ LF Culvert, LCPE, 36"D-66 165.00$ LF Culvert, LCPE, 48"D-67 179.00$ LF Culvert, LCPE, 54"D-68 193.00$ LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) Page 8 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES DRAINAGE (Continued) Culvert, LCPE, 60"D-69 206.00$ LF Culvert, LCPE, 72"D-70 220.00$ LF Culvert, HDPE, 6"D-71 48.00$ LF Culvert, HDPE, 8"D-72 60.00$ LF Culvert, HDPE, 12"D-73 85.00$ LF Culvert, HDPE, 15"D-74 122.00$ LF Culvert, HDPE, 18"D-75 158.00$ LF Culvert, HDPE, 24"D-76 254.00$ LF Culvert, HDPE, 30"D-77 317.00$ LF Culvert, HDPE, 36"D-78 380.00$ LF Culvert, HDPE, 48"D-79 443.00$ LF Culvert, HDPE, 54"D-80 506.00$ LF Culvert, HDPE, 60"D-81 570.00$ LF Culvert, HDPE, 72"D-82 632.00$ LF Pipe, Polypropylene, 6"D-83 96.00$ LF Pipe, Polypropylene, 8"D-84 100.00$ LF Pipe, Polypropylene, 12"D-85 100.00$ LF Pipe, Polypropylene, 15"D-86 103.00$ LF Pipe, Polypropylene, 18"D-87 106.00$ LF Pipe, Polypropylene, 24"D-88 119.00$ LF Pipe, Polypropylene, 30"D-89 136.00$ LF Pipe, Polypropylene, 36"D-90 185.00$ LF Pipe, Polypropylene, 48"D-91 260.00$ LF Pipe, Polypropylene, 54"D-92 381.00$ LF Pipe, Polypropylene, 60"D-93 504.00$ LF Pipe, Polypropylene, 72"D-94 625.00$ LF Culvert, DI, 6"D-95 70.00$ LF Culvert, DI, 8"D-96 101.00$ LF Culvert, DI, 12"D-97 121.00$ LF Culvert, DI, 15"D-98 148.00$ LF Culvert, DI, 18"D-99 175.00$ LF Culvert, DI, 24"D-100 200.00$ LF Culvert, DI, 30"D-101 227.00$ LF Culvert, DI, 36"D-102 252.00$ LF Culvert, DI, 48"D-103 279.00$ LF Culvert, DI, 54"D-104 305.00$ LF Culvert, DI, 60"D-105 331.00$ LF Culvert, DI, 72"D-106 357.00$ LF SUBTOTAL THIS PAGE: (B)(C)(D)(E) Page 9 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES Specialty Drainage Items Ditching SD-1 10.90$ CY Flow Dispersal Trench (1,436 base+)SD-3 32.00$ LF French Drain (3' depth)SD-4 30.00$ LF Geotextile, laid in trench, polypropylene SD-5 3.40$ SY Mid-tank Access Riser, 48" dia, 6' deep SD-6 2,300.00$ Each Pond Overflow Spillway SD-7 18.25$ SY Restrictor/Oil Separator, 12"SD-8 1,320.00$ Each Restrictor/Oil Separator, 15"SD-9 1,550.00$ Each Restrictor/Oil Separator, 18"SD-10 1,950.00$ Each Riprap, placed SD-11 48.20$ CY Tank End Reducer (36" diameter)SD-12 1,375.00$ Each Infiltration pond testing SD-13 143.00$ HR Permeable Pavement SD-14 Permeable Concrete Sidewalk SD-15 Culvert, Box __ ft x __ ft SD-16 SUBTOTAL SPECIALTY DRAINAGE ITEMS: (B)(C)(D)(E) STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch) Detention Pond SF-1 Each Detention Tank SF-2 Each Detention Vault SF-3 Each Infiltration Pond SF-4 Each Infiltration Tank SF-5 Each Infiltration Vault SF-6 Each Infiltration Trenches SF-7 Each Basic Biofiltration Swale SF-8 Each Wet Biofiltration Swale SF-9 Each Wetpond SF-10 Each Wetvault SF-11 Each Sand Filter SF-12 Each Sand Filter Vault SF-13 Each Linear Sand Filter SF-14 Each Proprietary Facility SF-15 Each Bioretention Facility SF-16 Each SUBTOTAL STORMWATER FACILITIES: (B)(C)(D)(E) Page 10 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Quantity Remaining (Bond Reduction) (B)(C) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR DRAINAGE AND STORMWATER FACILITIES WRITE-IN-ITEMS (INCLUDE ON-SITE BMPs) Detention Vault West WI-1 12.50$ CF 12120 151,500.00 Detention Vault South WI-2 6.50$ CF 51040 331,760.00 WI-3 WI-4 WI-5 WI-6 WI-7 WI-8 WI-9 WI-10 WI-11 WI-12 WI-13 WI-14 WI-15 SUBTOTAL WRITE-IN ITEMS:483,260.00 DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:23,693.00 553,595.00 12,585.00 SALES TAX @ 10.1%2,392.99 55,913.10 1,271.09 DRAINAGE AND STORMWATER FACILITIES TOTAL:26,085.99 609,508.10 13,856.09 (B) (C) (D) (E) Page 11 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.c DRAINAGE Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Connection to Existing Watermain W-1 3,400.00$ Each Ductile Iron Watermain, CL 52, 4 Inch Diameter W-2 58.00$ LF Ductile Iron Watermain, CL 52, 6 Inch Diameter W-3 65.00$ LF Ductile Iron Watermain, CL 52, 8 Inch Diameter W-4 75.00$ LF Ductile Iron Watermain, CL 52, 10 Inch Diameter W-5 80.00$ LF Ductile Iron Watermain, CL 52, 12 Inch Diameter W-6 145.00$ LF Gate Valve, 4 inch Diameter W-7 1,225.00$ Each Gate Valve, 6 inch Diameter W-8 1,350.00$ Each Gate Valve, 8 Inch Diameter W-9 1,550.00$ Each Gate Valve, 10 Inch Diameter W-10 2,100.00$ Each Gate Valve, 12 Inch Diameter W-11 2,500.00$ Each Fire Hydrant Assembly W-12 5,000.00$ Each Permanent Blow-Off Assembly W-13 1,950.00$ Each Air-Vac Assembly, 2-Inch Diameter W-14 3,050.00$ Each Air-Vac Assembly, 1-Inch Diameter W-15 1,725.00$ Each Compound Meter Assembly 3-inch Diameter W-16 9,200.00$ Each Compound Meter Assembly 4-inch Diameter W-17 10,500.00$ Each Compound Meter Assembly 6-inch Diameter W-18 11,500.00$ Each Pressure Reducing Valve Station 8-inch to 10-inch W-19 23,000.00$ Each WATER SUBTOTAL: SALES TAX @ 10.1% WATER TOTAL: (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR WATER Quantity Remaining (Bond Reduction) (B)(C) Page 12 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.d WATER Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 CED Permit #:22-001966 Existing Future Public Private Right-of-Way Improvements Improvements (D) (E) Description No. Unit Price Unit Quant.Cost Quant.Cost Quant.Cost Quant.Cost Clean Outs SS-1 1,150.00$ Each 15 17,250.00 Grease Interceptor, 500 gallon SS-2 9,200.00$ Each Grease Interceptor, 1000 gallon SS-3 11,500.00$ Each Grease Interceptor, 1500 gallon SS-4 17,200.00$ Each Side Sewer Pipe, PVC. 4 Inch Diameter SS-5 92.00$ LF Side Sewer Pipe, PVC. 6 Inch Diameter SS-6 110.00$ LF 650 71,500.00 Sewer Pipe, PVC, 8 inch Diameter SS-7 120.00$ LF 254 30,480.00 930 111,600.00 Sewer Pipe, PVC, 12 Inch Diameter SS-8 144.00$ LF Sewer Pipe, DI, 8 inch Diameter SS-9 130.00$ LF Sewer Pipe, DI, 12 Inch Diameter SS-10 150.00$ LF Manhole, 48 Inch Diameter SS-11 6,900.00$ Each 2 13,800.00 8 55,200.00 Manhole, 54 Inch Diameter SS-13 6,800.00$ Each Manhole, 60 Inch Diameter SS-15 7,600.00$ Each Manhole, 72 Inch Diameter SS-17 10,600.00$ Each Manhole, 96 Inch Diameter SS-19 16,000.00$ Each Pipe, C-900, 12 Inch Diameter SS-21 205.00$ LF Outside Drop SS-24 1,700.00$ LS Inside Drop SS-25 1,150.00$ LS Sewer Pipe, PVC, ____ Inch Diameter SS-26 Lift Station (Entire System)SS-27 LS SANITARY SEWER SUBTOTAL:44,280.00 166,800.00 88,750.00 SALES TAX @ 10.1%4,472.28 16,846.80 8,963.75 SANITARY SEWER TOTAL:48,752.28 183,646.80 97,713.75 (B) (C) (D) (E) SITE IMPROVEMENT BOND QUANTITY WORKSHEET FOR SANITARY SEWER Quantity Remaining (Bond Reduction) (B)(C) Page 13 of 14 Ref 8-H Bond Quantity Worksheet SECTION II.e SANITARY SEWER Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 1055 South Grady Way – 6 th Floor | Renton, WA 98057 (425) 430-7200 Date: Name: Project Name: PE Registration No: CED Plan # (LUA): Firm Name:CED Permit # (C): Firm Address: Site Address: Phone No. Parcel #(s): Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal (a) Existing Right-of-Way Improvements Subtotal (b) (b)131,981.55$ Future Public Improvements Subtotal (c)475,388.95$ Stormwater & Drainage Facilities (Public & Private) Subtotal (d) (d)649,450.17$ (e) (f) Site Restoration Civil Construction Permit Maintenance Bond 251,364.14$ Bond Reduction 2 Construction Permit Bond Amount 3 Minimum Bond Amount is $10,000.00 1 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering. 2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% will cover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering. * Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton. ** Note: All prices include labor, equipment, materials, overhead, profit, and taxes. EST1 ((b) + (c) + (d)) x 20% -$ MAINTENANCE BOND */** (after final acceptance of construction) 38,848.79$ 131,981.55$ 847,422.50$ 38,848.79$ -$ 649,450.17$ -$ 886,271.28$ P (a) x 100% SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS 4/27/2023 Sheri Murata 41846 Core Design Inc. R ((b x 150%) + (d x 100%)) S (e) x 150% + (f) x 100% Bond Reduction: Existing Right-of-Way Improvements (Quantity Remaining)2 Bond Reduction: Stormwater & Drainage Facilities (Quantity Remaining)2 T (P +R - S) Prepared by: Project Information CONSTRUCTION BOND AMOUNT */** (prior to permit issuance) 425.885.7877 shm@coredesigninc.com Cyprus Lane 21-000287 5816 NE 4th Place 1123059023;1123059021;1123059031 FOR APPROVAL 22-001966 12100 NE 195th St, Suite #300, Bothell, WA 98011 Page 14 of 14 Ref 8-H Bond Quantity Worksheet SECTION III. BOND WORKSHEET Unit Prices Updated: 01/07/2022 Version: 01/07/2022 Printed 4/27/2023 Core Design, Inc. CYPRUS LANE PLAT Page 2 10. OPERATIONS AND MAINTENANCE See the following pages for the operations and maintenance manual. APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 3 – DETENTION TANKS AND VAULTS Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Tank or Vault Storage Area Trash and debris Any trash and debris accumulated in vault or tank (includes floatables and non-floatables). No trash or debris in vault. Sediment accumulation Accumulated sediment depth exceeds 10% of the diameter of the storage area for ½ length of storage vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ½ length of tank. All sediment removed from storage area. Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-5 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 3 – DETENTION TANKS AND VAULTS Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-6 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damage T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-7 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (If Applicable) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-8 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 5 – CATCH BASINS AND MANHOLES Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism Not Working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to Remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual – Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 – CONVEYANCE PIPES AND DITCHES Maintenance Component Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If Applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 17 – WETVAULT Maintenance Component Defect or Problem Condition When Maintenance is Needed Results Expected When Maintenance is Performed Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from facility site. Treatment Area Trash and debris Any trash and debris accumulated in vault (includes floatables and non-floatables). No trash or debris in vault. Sediment accumulation Sediment accumulation in vault bottom exceeds the depth of the sediment zone plus 6 inches. No sediment in vault. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks, vault does not retain water or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Baffles damaged Baffles corroding, cracking, warping and/or showing signs of failure or baffle cannot be removed. Repair or replace baffles or walls to specifications. Ventilation Ventilation area blocked or plugged. No reduction of ventilation area exists. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally. Valve won’t seal Valve does not seal completely. Valve completely seals closed. Access Manhole Access cover/lid damaged or difficult to open Access cover/lid cannot be easily opened by one person. Corrosion/deformation of cover/lid. Access cover/lid can be opened by one person. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Access doors/plate has gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. 2016 Surface Water Design Manual – Appendix A 4/24/2016 A-23 Core Design, Inc. CYPRUS LANE PLAT Page 3 Appendix A United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for King County Area, Washington Cyprus Lane Short Plat Natural Resources Conservation Service September 9, 2020 6 Custom Soil Resource Report Soil Map 525987052598805259890525990052599105259920525993052599405259950525996052599705259980525999052600005260010525987052598805259890525990052599105259920525993052599405259950525996052599705259980525999052600005260010564660 564670 564680 564690 564700 564710 564720 564730 564740 564750 564760 564660 564670 564680 564690 564700 564710 564720 564730 564740 564750 564760 47° 29' 25'' N 122° 8' 30'' W47° 29' 25'' N122° 8' 24'' W47° 29' 20'' N 122° 8' 30'' W47° 29' 20'' N 122° 8' 24'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 35 70 140 210 Feet 0 10 20 40 60 Meters Map Scale: 1:720 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 16, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 1, 2019—Jul 25, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 7 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AgC Alderwood gravelly sandy loam, 8 to 15 percent slopes 2.2 100.0% Totals for Area of Interest 2.2 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 8 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 9 King County Area, Washington AgC—Alderwood gravelly sandy loam, 8 to 15 percent slopes Map Unit Setting National map unit symbol: 2t626 Elevation: 50 to 800 feet Mean annual precipitation: 20 to 60 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 160 to 240 days Farmland classification: Prime farmland if irrigated Map Unit Composition Alderwood and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting Landform:Ridges, hills Landform position (two-dimensional):Shoulder Landform position (three-dimensional):Nose slope, talf Down-slope shape:Linear, convex Across-slope shape:Convex Parent material:Glacial drift and/or glacial outwash over dense glaciomarine deposits Typical profile A - 0 to 7 inches: gravelly sandy loam Bw1 - 7 to 21 inches: very gravelly sandy loam Bw2 - 21 to 30 inches: very gravelly sandy loam Bg - 30 to 35 inches: very gravelly sandy loam 2Cd1 - 35 to 43 inches: very gravelly sandy loam 2Cd2 - 43 to 59 inches: very gravelly sandy loam Properties and qualities Slope:8 to 15 percent Depth to restrictive feature:20 to 39 inches to densic material Drainage class:Moderately well drained Capacity of the most limiting layer to transmit water (Ksat):Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table:About 18 to 37 inches Frequency of flooding:None Frequency of ponding:None Available water capacity:Very low (about 2.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: B Forage suitability group: Limited Depth Soils (G002XN302WA), Limited Depth Soils (G002XF303WA), Limited Depth Soils (G002XS301WA) Other vegetative classification: Limited Depth Soils (G002XN302WA), Limited Depth Soils (G002XF303WA), Limited Depth Soils (G002XS301WA) Custom Soil Resource Report 10 Hydric soil rating: No Minor Components Indianola Percent of map unit:5 percent Landform:Kames, terraces, eskers Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Hydric soil rating: No Everett Percent of map unit:5 percent Landform:Kames, eskers, moraines Landform position (two-dimensional):Shoulder, footslope Landform position (three-dimensional):Crest, base slope Down-slope shape:Convex Across-slope shape:Convex Hydric soil rating: No Shalcar Percent of map unit:3 percent Landform:Depressions Landform position (three-dimensional):Dip Down-slope shape:Concave Across-slope shape:Concave Hydric soil rating: Yes Norma Percent of map unit:2 percent Landform:Drainageways, depressions Landform position (three-dimensional):Dip Down-slope shape:Linear, concave Across-slope shape:Concave Hydric soil rating: Yes Custom Soil Resource Report 11 Core Design, Inc. CYPRUS LANE PLAT Page 4 Appendix B ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.58 Program License Number: 200210008 Project Simulation Performed on: 01/17/2023 1:29 PM Report Generation Date: 01/17/2023 1:29 PM ————————————————————————————————— Input File Name: Single POC Model.fld Project Name: North Vault Analysis Title: Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Full Period of Record Available used for Routing Climatic Region Number: 16 Precipitation Station : 96004405 Puget East 44 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961044 Puget East 44 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 3 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 4.720 4.920 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 4.720 4.920 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : West Basin ---------- -------Area (Acres) -------- Till Forest 4.660 Impervious 0.060 ---------------------------------------------- Subbasin Total 4.720 Core Design, Inc. CYPRUS LANE PLAT Page 5 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 ---------- Subbasin : West Vault Basin ---------- -------Area (Acres) -------- Till Grass 0.780 Impervious 0.380 ---------------------------------------------- Subbasin Total 1.160 ---------- Subbasin : South Vault Basin ---------- -------Area (Acres) -------- Till Grass 1.960 Impervious 1.800 ---------------------------------------------- Subbasin Total 3.760 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 3 ------------------------------------------ Link Name: North Vault Link Type: Structure Downstream Link Name: New Copy Lnk3 Prismatic Pond Option Used Pond Floor Elevation (ft) : 0.00 Riser Crest Elevation (ft) : 5.10 Max Pond Elevation (ft) : 6.10 Storage Depth (ft) : 5.10 Pond Bottom Length (ft) : 40.0 Pond Bottom Width (ft) : 30.0 Pond Side Slopes (ft/ft) : Z1= 0.00 Z2= 0.00 Z3= 0.00 Z4= 0.00 Bottom Area (sq-ft) : 1200. Area at Riser Crest El (sq-ft) : 1,200. (acres) : 0.028 Core Design, Inc. CYPRUS LANE PLAT Page 6 Volume at Riser Crest (cu-ft) : 6,120. (ac-ft) : 0.140 Area at Max Elevation (sq-ft) : 1200. (acres) : 0.028 Vol at Max Elevation (cu-ft) : 7,320. (ac-ft) : 0.168 Hydraulic Conductivity (in/hr) : 0.00 Massmann Regression Used to Estimate Hydralic Gradient Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 5.10 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 0.00 Diameter (in) : 0.81 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type : Circular Orifice Control Elevation (ft) : 2.50 Diameter (in) : 1.19 Orientation : Horizontal Elbow : Yes ---Device Number 3 --- Device Type : Circular Orifice Control Elevation (ft) : 3.85 Diameter (in) : 0.62 Orientation : Horizontal Elbow : Yes ------------------------------------------ Link Name: South Vault Link Type: Structure Downstream Link Name: New Copy Lnk3 Prismatic Pond Option Used Pond Floor Elevation (ft) : 0.00 Riser Crest Elevation (ft) : 10.00 Max Pond Elevation (ft) : 10.50 Storage Depth (ft) : 10.00 Pond Bottom Length (ft) : 100.0 Core Design, Inc. CYPRUS LANE PLAT Page 7 Pond Bottom Width (ft) : 58.0 Pond Side Slopes (ft/ft) : Z1= 0.00 Z2= 0.00 Z3= 0.00 Z4= 0.00 Bottom Area (sq-ft) : 5800. Area at Riser Crest El (sq-ft) : 5,800. (acres) : 0.133 Volume at Riser Crest (cu-ft) : 58,000. (ac-ft) : 1.331 Area at Max Elevation (sq-ft) : 5800. (acres) : 0.133 Vol at Max Elevation (cu-ft) : 60,900. (ac-ft) : 1.398 Hydraulic Conductivity (in/hr) : 0.00 Massmann Regression Used to Estimate Hydralic Gradient Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 10.00 ft Hydraulic Structure Geometry Number of Devices: 3 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 0.00 Diameter (in) : 0.81 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type : Circular Orifice Control Elevation (ft) : 5.67 Diameter (in) : 0.87 Orientation : Horizontal Elbow : Yes ---Device Number 3 --- Device Type : Circular Orifice Control Elevation (ft) : 7.10 Diameter (in) : 1.13 Orientation : Horizontal Elbow : Yes ------------------------------------------ Link Name: New Copy Lnk3 Link Type: Copy Downstream Link: None Core Design, Inc. CYPRUS LANE PLAT Page 8 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 Number of Links: 3 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: West Basin 886.518 Link: New Copy Lnk1 0.000 _____________________________________ Total: 886.518 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: West Vault Basin 100.461 Subbasin: South Vault Basin 252.440 Link: North Vault Not Computed Link: South Vault Not Computed Link: New Copy Lnk3 0.000 _____________________________________ Total: 352.901 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 5.611 ac-ft/year, Post Developed: 2.234 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** 2-Year Discharge Rate : 0.130 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.09 cfs Off-line Design Discharge Rate (91% Exceedance): 0.05 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 597.30 Core Design, Inc. CYPRUS LANE PLAT Page 9 Inflow Volume Including PPT-Evap (ac-ft): 597.30 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 597.30 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 3 ********** Link: New Copy Lnk3 ********** 2-Year Discharge Rate : 0.078 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 999.00 cfs Off-line Design Discharge Rate (91% Exceedance): 999.00 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 1767.00 Inflow Volume Including PPT-Evap (ac-ft): 1767.00 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 1767.00 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk3 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 0.130 2-Year 7.816E-02 5-Year 0.213 5-Year 0.118 10-Year 0.276 10-Year 0.179 25-Year 0.370 25-Year 0.213 50-Year 0.468 50-Year 0.256 100-Year 0.501 100-Year 0.306 200-Year 0.780 200-Year 0.333 500-Year 1.154 500-Year 0.368 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals **** Flow Duration Performance **** Core Design, Inc. CYPRUS LANE PLAT Page 10 Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): -3.8% PASS Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%): -3.8% PASS Maximum Excursion from Q2 to Q50 (Must be less than 10%): -11.4% PASS Percent Excursion from Q2 to Q50 (Must be less than 50%): 0.0% PASS ------------------------------------------------------------------------------------------------- MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS -------------------------------------------------------------------------------------------------