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SWP272737
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REQUEST FOR PROJECT# Prelim.Plat (PP# CAG# ) To: Technical Services Date loll q 8 WO# Green# LUR -c�1-JB-j From: Plan Review/Project Manager 3{ }{t•t-TiZkC k(- Project Name SQUA&E CONc2Io►titNl U►-&S (70 characters max) Description of Project: �02 Cot-.r Circle Size of Waterline: 8" 10" 12" Circle One: ew or Extension Circle Size of Seweriine: 8" 10" 12" Circle One: ew or Extension Circle Size of Stormline: 12" 15" 18" 24" Circle One: New or Extension Address or Street Name(s) v5) 0 5 ST S �8*k ST 6P-At-,T- AV S Dvlpr/Contractor/Owner/Cnslt:: SQuRP-Z- ASSUctW-rES LL-C- A-*�kL--W l+oµt S (70 chamacrs max) Check each discipline involved in Project Ltr Drwg #of sheets per discipline Ga' Trans-Storm 7 (Roadway/Drainagc) (off site impmYc=nts)(include basin name) (include TESC sheets) O' Transportation (Signaliiation•Channclization•Lighting) ca- 8' (2" Wastewater Sanitary Scwcr Main(include basin name)Water (Mains.Valves,Hydcants) `�' 1 D, ----- — (Includc composi(e i Horizontal Ctrl Sheen) CV Suface Water 3 Improvements (CP NLY)(includc basin name) TS Use Only 4o ',27 37 R-2-73-7 —� 41-2-7 T-2 73.7 frJwP-27-27 I 5 r27?2`7 WV--27-2737 w ,278 •7 �— Swp -2 7-27�7 -2737 -- 2�3 SQUARE City of Renton, Washington Storm Drainage Report Prepared By: 1 Brett K. Pudists Reviewed By. Mark A. Reeves, P.E. CITY OF RENTO N _ DECEIVED JUL 2 Z 1998 Vim 6Q4-.0 ING DIVISION ' TRIAD ASSOCIATES 1 July 17 1998 Triad Job No . 96 - 358 1 SQUARE City of Renton, Washington Storm Drainage Report ENGINEER'S STAMP NOT VALID ' Prepared By: UNLESS SIGNED. AND DATED Brett K. Pudists �P�OVAW s l`s a Reviewed By: Mark A. Reeves, P.E. F � Q1STE����,�� SS10NAI. EXPIRES: 4/26/7 M � t TRIAD ASSOCIATES July 175 1998 Triad Job No . 96 - 358 1 ' TABLE OF CONTENTS INTRODUCTION.................................................................................................................................. 1 VICINITYMAP.....................................................................................................................................2 ' DRAINAGE CONCEPT........................................................................................................................3 DOWNSTREAMANALYSIS................................................................................................................4 ' DETENTION CALCULATIONS..........................................................................................................5 DETENTIONVAULT........................................................................................................................6 ExistingCondition Hydrographs..................................................................................................... 6 ' Allowable Release Rates...........................................................................................................................7 DevelopedCondition Hydrographs................................................................................................. 7 DetainedArea...........................................................................................................................................7 BypassArea..............................................................................................................................................8 ' Level Pool Routing......................................................................................................................... 9 Theoretical................................................................................................................................................9 OutflowControl Structure.........................................................................................................................10 ' Actual.......................................................................................................................................................11 LiveStorage.................................................................................................................................. 12 WaterQuality............................................................................................................................... 12 OverflowRiser.............................................................................:................................................ 13 ' CONVEYANCE CALCULATIONS................................................................................................... 14 VAULTINFLOW SYSTEM..................................................................................................................... 15 ' VAULT OUTFLOW SYSTEM.................................................................................................................. 15 EROSION CONTROL CALCULATIONS......................................................................................... 16 1 ' APPENDIX Existing Condition Map Developed Condition Map ' Soils Map Table 3.5.213 —W. Washington Runoff Curve Numbers 2, 10, 100-year Isopluvial Maps ' Water Works Output Figure 4.4.7-J Riser Inflow Curves (Detention Vault) Pipe Tributary Area Map ' HGL Calculations TESC Tributary Area Map TESC Flow Estimates ' Figure 4.4.7-J Riser Inflow Curves (TESC) STORM DRAINAGE REPORT FOR HERITAGE SQUARE - Page i 1 ' INTRODUCTION The proposed project is the construction of multifamily apartment units and associated parking areas on approximately four acres of land. The site is located northeast of the ' intersection of SE 18'h Street and Grant Avenue South in the City of Renton. The site lies within Section 20, Township 23 North, Range 5 East, in King County, Washington (please reference the Vicinity Map on the following page). Refer to the Existing Condition Map and Developed Condition Map, located in the appendix, to aid in the following discussion. An onsite loop road will provide access to the site from SE 18'' Street. In addition to onsite road improvements, SE 18'' Street will be improved to provide a sidewalk and 32' of pavement as a part of this project. A sidewalk will also be constructed on the east side of Grant Avenue South along the site's frontage. ' The eastern portion of the site is covered with a variety of trees and brush while the ' western portion consists mainly of tall grasses. The site currently contains an abandoned house in addition to two out buildings. In general, the site drains westerly at slopes from ' 20% - 4% towards Grant Avenue South. According to the SCS Soil Survey for King County the site is underlain with Alderwood soils. These soils belong to the SCS type `C' ' hydrologic soil group. Refer to the Soils Map, located in the Appendix, for soil type delineation. The site is bordered by apartments to the north, single family residences to the east, and tpaved streets to the south and west. The apartments and houses connect into a tightline conveyance system located in the street therefore there is no upstream area tributary to the ' site. Currently, runoff sheet flows west across the site to Grant Avenue South. At this point, runoff enters an existing tightline conveyance system. 1 1 STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 1 405 �. ,SITE SE 18 TH j Z (s� ' TALBOT z S PUG-ET DR RO S ) Z a 713 cn v, Qn ' Vicinity Map Not To Scale ' STORM DRAINAGE REPORT FOR Pa—HERITAGES SQUARE e 2 Q g ' DRAINAGE CONCEPT ' The storm drainage system for the proposed project was designed with reference to standards found within the 1994 updates to the 1990 King County Surface Water Design Manual (KCSWDM). The onsite drainage system will convey runoff, via a tightline conveyance system, from the developed site to an underground detention vault located in ' the western portion of the site (see Developed Conditions Map). The detention vault will provide live storage for stream bank erosion control and dead storage for water quality enhancement. Detained storm water will ultimately discharge to an existing tightline conveyance system located in Grant Avenue South. Refer to the previously submitted ' Level One Downstream Analysis (8/14/97 by Triad Associates) for a description of the offsite downstream drainage route. 1 Due to grade constraints, a portion of the site's runoff will not be conveyed to the ' detention vault. Specifically, runoff from the frontage improvements along SE 18"' Street ' will be collected and discharged to an existing tightline system located on the north side of SE 18"' Street. Runoff from this area was treated as "bypass" consequently the outflow ' rates from the onsite detention vault were reduced. Please note that runoff from the bypass area combines with runoff from the detention vault approximately 40 feet downstream of ' the site therefore stormwater diversion is not an issue. ' The detention facility was designed to provide peak rate runoff control for the 2, 10, and 100-year, 24-hour storm events. The facility was designed such that the post-developed ' peak runoff rates are attenuated to the pre-developed peak runoff rates for each of the 2, 10, and 100-year, 24-hour storm events. A 30-percent volume correction factor (factor of ' safety) was applied to the live storage volume. ' Water quality was provided through the use of dead storage. The volume of water quality storage required is equal to the runoff generated by the 24-hour design storm event using a ' rainfall precipitation equal to 33%of the 2-year, 24-hour design storm precipitation. STORM DRAINAGE REPORT FOR HERITAGE SQUARE —Page 3 DOWNSTREAM ANALYSIS Runoff from the site is collected and conveyed to an existing tightline conveyance system located in Grant Avenue South. The conveyance system consists of a network of catch ' basins and pipes that discharge to an open channel drainage course on the west side of Grant Avenue South. Refer to the previously submitted Level One Downstream Anal (8/14/97 by Triad Associates) for a detailed description of the offsite downstream drainage route. 1 t STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 4 ' DETENTION CALCULATIONS ' In the post-developed condition, runoff from the majority of the site (referred to as the Detained Area) will be conveyed to the proposed detention vault located in the western ' portion of the site near proposed buildings C and D. Runoff from the remainder of the site (referred to as the Bypass Area) will discharge directly to an'existing tightline conveyance system. ' The detention calculations were performed using Engenious Systems Inc.'s hydrology program Water Works. Hydrographs were developed using S.B.U.H. methodology with a King County Type I-A (User 1) 24-hour rainfall distribution. Separate S.C.S. curve numbers were used for the impervious and pervious portions of the site. Using the onsite existing condition hydrographs, the allowable release rates were determined for the site in accordance with City of Renton standards. Specifically, the ' facility was designed such that the post-developed peak runoff rates are attenuated to the pre-developed peak runoff rates for each of the 2, 10, and 100-year, 24-hour storm events. ' The onsite developed condition h dro ra hs were then routed through a theoretical p Y g p g ' structure to determine the theoretical volume of live storage. The theoretical volume of live storage was then increased by a 30-percent volume correction factor (factor of safety) to determine the actual volume of live storage required. Please refer to the Existing and Developed Condition exhibits as well as Table 3.S.2B — S.C.S. Western Washington Runoff Curve Numbers located in the appendix of this report. ' Based on King County isopluvial maps (see appendix) the total precipitation for the 2, 10, and 100-year, 24-hour storm events are 2.00", 2.90", and 3.90" respectively. A summary ' of the detention calculations is provided below. Refer to the appendix for actual Water Works Output. STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 5 ' DETENTION VAULT As designed, the vault provides 16,328 cubic feet (104' long x 20' wide x 7.85' deep) of live storage volume. The vault was fitted with a 15" diameter overflow riser, with 0.5' of available head, which was sized to convey the 100-year un-detained flow of 2.98 cfs. As designed, the vault provides 4,020 cubic feet (67' long x 20' wide x 3' deep) of dead storage. In addition to the dead storage, and additional one foot of depth was provided in the vault for sediment storage area. ' Existing Condition Hydrographs The existing condition area consists of approximately 4.02 acres and includes the area associated with the frontage improvements. Based on field observations, approximately ' one-half of the site consists of tall grasses while the remainder of the site consists of a ' mixture of trees and brush. Refer to the Existing Condition Map, located in the appendix, to aid in the following discussion. ' Total Area=4.02 Ac Impervious Area = 0.05 Ac @ CN= 98 (existing house and shed) ' Pervious Area = 3.97 Ac @ CN,,= 83 (weighted) Grasses/Meadow- 1.99 Ac @ CN= 85 ' Trees w/Brush- 1.98 Ac @ CN= 81 CN — 1.99x85+1.98x81 —83 ' w 3.97 Time of Concentration = 44.40 minutes ' Reach 1: 130 ft Sheet Flow @ 15.0%, `n'=0.40 (treesibrush) Reach 2: 170 ft Sheet Flow @ 6.1%, `n'= 0.40 (trees/brush) Reach 3: 100 ft Shallow Concentrated Flow @ 6.0%,`ks'=5 (trees/brush) ' Reach 4: 150 ft Shallow Concentrated Flow @ 11.3%,`ks'=5 (trees/brush) Existing Condition Hydro ra h Summaries 1 Storm Precip. Peak Flow Volume Time of Peak Event in] [cfs] [ft3 min. 2-Year 2.00 0.314 10340 490 ' 10-Year 2.90 0.745 20177 490 100-Year 1 3.90 1.298 1 32364 490 STORM DRAINAGE REPORT FOR HERITAGE SQUARE —Page 6 ' Allowable Release Rates Using the existing condition hydrographs, the allowable release rates for the detention ' vault were determined in accordance with City of Renton Standards. These release rates were then used to calculate the required detention volume. The allowable release rates are ' as follows: 2-Year Allowable Release Rate = 2-yr Pre-developed flow = 0.31 cfs 10-Year Allowable Release Rate = 10-yr Pre-developed flow = 0.75 cfs 100-Year Allowable Release Rate= 100-yr Pre-developed flow= 1.30 cfs ' Developed Condition Hvdrographs The impervious area for the post-developed condition was calculated based on the current site plan. The pervious area was assumed to be a mixture of lawn and landscaping. 1 In the post developed condition, runoff from approximately 0.68 acres will not be ' conveyed to the detention vault due to grade limitations. This area will be treated as "bypass" consequently the outflow rates from the onsite detention vault were reduced. ' The developed basin was therefore divided into two basins, namely the "Detained Area" and the `Bypass Area". A summary of the hydrographs for.each area is provided below. ' Refer to the Developed Conditions Map, located in the appendix, to aid in the following discussion. Detained Area ' Total Area= 3.34 Ac Impervious Area = 2.10 Ac @ CN= 98 (pavement, roofs) 0.85 Ac—loop road pavement including parking and garages 1.06 Ac—buildings 0.19 Ac— sidewalks ' Pervious Area = 1.24 Ac @ CN= 86 (landscaping, lawns) tTime of Concentration= 5.00 minutes (assumed) STORM DRAINAGE REPORT FOR HERITAGE SQUARE —Page 7 ' Detained Area Hydrograph Summaries Storm Precip. Peak Flow Volume Time of Peak ' Event in cfs ft3 min. 2-Year 2.00 1.305 17347 470 10-Year 2.90 2.088 27442 470 100-Year 3.90 2.984 38995 470 Water Quality , 0.67 0.283 3892 470 Bypass Area ' Total Area= 0.68 Ac Impervious Area = 0.34 Ac @ CN= 98 (pavement, sidewalks) ' 0.20 Ac— SE 18t` Street 0.14 Ac— sidewalks Pervious Area = 0.34 Ac @ CN= 86 (landscaping, lawns) ' Time of Concentration = 5.00 minutes (assumed) Bypass Area Hydrograph Summaries ' Storm Precip. Peak Flow Volume Time of Peak Event in] I&I ft' min. ' 2-Year 2.00 0.239 3238 470 10-Year 2.90 0.396 5240 470 100-Year 3.90 1 0.577 7555 470 STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 8 Level Pool Routing ' Theoretical The outflow rates from the vault were reduced so that the peak rates obtained by adding ' the vault outflow hydrographs to the bypass area hydrographs (the sum represents the total release from the site in the post developed condition) are less than the allowable ' release rates for the site. Refer to the hydrograph summary table below for a summary of the hydrograph additions. HYDROGRAPH SUMMARY DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 YEAR DETAINABLE AREA(DEV.) 4 1.305 470 17347 3.34 10 YEAR DETAINABLE AREA(DEV.) 5 2.088 470 27442 3.34 100 YEAR DETAINABLE AREA(DEV.) 6 2.984 470 38995 3.34 2 YEAR BYPASS (DEV.) 7 0.239 470 3238 0.68 10 YEAR BYPASS (DEV.) 8 0.396 470 5240 0.68 100 YEAR BYPASS(DEV.) 9 0.577 470 7555 0.68 2 YEAR THEORETICAL OUTFLOW 12 0.119 1450 15233 3.34 10 YEAR THEORETICAL OUTFLOW 13 0.453 650 25295 3.34 ' 100 YEAR THEORETICAL OUTFLOW 14 1.107 510 36837 3.34 2 YR TOTAL RELEASE(HYD 7+HYD 12) 18 **0.305 470 18471 4.02 10 YR TOTAL RELEASE(HYD 8+HYD 13) 19 **0.541 640 30536 4.02 100 YR TOTAL RELEASE(HYD 9+HYD 14) 20 **1.292 510 44392 4.02 2 YEAR ACTUAL OUTFLOW 15 0.107 1460 14075 3.34 10 YEAR ACTUAL OUTFLOW 16 0.378 770 22669 3.34 ' 100 YEAR ACTUAL OUTFLOW 1 17 1 0.676 1 550 34208 3.34 **The vault outflow hydrographs were added to the bypass area hydrographs to compute the total release from the site in the developed condition. Please note, in all cases,the total release from the site is less than ' the allowable release rate for each of the storm events. ' A theoretical detention vault was sized to determine the required depth and theoretical volume of live storage for the site. The following level pool table summary represents the ' results of routing the onsite developed area 2, 10, and 100-year hydrographs through a theoretical detention structure. Please refer to the Water Works output located in the ' appendix for actual program output. ' STORM DRAINAGE REPORT FOR Pa—HERITAGES SQUARE 9 Q Page ' THEORETICAL LEVEL POOL TABLE SUMMARY Description Inflow Storage Dischrg P. Stage Volume Outflow P. Time CFS ID ID FT CF] [CFS] [Min ' 2 Yr. Theoretical Vault Outflow 1.31 THEO O 319.08 10130 0.119 1450 10 Yr. Theoretical Vault Outflow 2.09 THEO O 319.26 10418 0.453 650 100 Yr. Theoretical Vault Outflow 2.98 1 THEO O 320.45 *12281 1.107 510 ' *Theoretical volume of live storage= 12,281 cubic-feet. Outflow Control Structure Multiple Orifice: ID No. O ' Description: Orifice discharge from vault Outlet Elev: 312.60 Elev: 310.60 ft Orifice 1 Diameter: 1.3125 in. Elev: 319.10 ft Orifice 2 Diameter: 5.5625 in. ' THEORETICAL STAGE/STORAGE/DISCHARGE TABLE ' RECTANGULAR VAULT ID No. THEO Description: THEORETICAL VAULT Length: 78.20 ft. Width: 20.00 ft. ' STAGE STORAGE STORAGE DISCHARGE FT CF] [Ac-FT] [CFS ' 312.60 0 0.0000 0.0000 313.00 625 0.0144 0.0295 313.50 1408 0.0323 0.0443 314.00 2190 0.0503 0.0553 ' 314.50 2972 0.0682 0.0644 315.00 3754 0.0862 0.0724 315.50 4536 0.1041 0.0795 316.00 5318 0.1221 0.0861 316.50 6100 0.1400 0.0922 317.00 6882 0.1580 0.0980 ' 317.50 7664 0.1759 0.1034 318.00 8446 0.1939 0.1085 318.50 9228 0.2118 0.1135 ' 319.00 10010 0.2298 0.1182 319.50 10792 0.2477 0.6537 320.00 11574 0.2657 0.9235 320.40 12199 0.2801 1.0876 ' 1 320.50 12356 1 0.2836 1.1246 STORM DRAINAGE REPORT FOR HERITAGE SQUARE-Page 10 Actual The following level pool table summary represents the results of routing the developed ' area 2, 10, and 100-year hydrographs through the actual detention structure. For the actual detention structure, the plan view dimensions of the theoretical vault were increased ' in order to accommodate extra volume associated with the 30% factor of safety. ' ACTUAL LEVEL POOL TABLE SUMMARY Description Inflow Storage Dischrg P. Stage Volume Outflow P. Time CFS ID ID FT CF] [CFS] [Min t 2 Year Actual Vault Outflow 1.31 ACT O 317.86 10935 0.107 1460 10 Year Actual Vault Outflow 2.09 ACT O 319.20 13723 0.378 770 100 Year Actual Vault Outflow 1 2.98 1 ACT 1 O 1 319.53 1 14424 1 0.676 1 550 ' ACTUAL STAGE/STORAGE/DISCHARGE TABLE RECTANGULAR VAULT ID No. ACT ' Description: ACTUAL VAULT Length: 104.00 ft. Width: 20.00 ft. ' STAGE STORAGE STORAGE DISCHARGE FT CF] [Ac-FT CFS 312.60 0 0.0000 0.0000 ' 313.00 832 0.0191 0.0295 313.50 1872 0.0430 0.0443 314.00 2912 0.0669 0.0553 ' 314.50 3952 0.0907 0.0644 315.00 4992 0.1146 0.0724 315.50 6032 0.1385 0.0795 ' 316.00 7072 0.1624 0.0861 316.50 8112 0.1862 0.0922 317.00 9152 0.2101 0.0980 ' 317.50 10192 0.2340 0.1034 318.00 11232 0.2579 0.1085 318.50 12272 0.2817 0.1135 ' 319.00 13312 0.3056 0.1182 319.50 14352 0.3295 0.6537 320.00 15392 0.3534 0.9235 320.50 16432 0.3772 1.1246 ' 321.00 17472 0.4011 1.2926 321.40 18304 0.4202 1.4117 321.50 1 18512 0.4250 1.4399 ' STORM DRAINAGE REPORT FOR HERITAGE SQUARE -Page 11 1 ' Live Storage ' In accordance with City of Renton standards, a 30% volume correction factor was applied to the theoretical live storage volume to determine the required live storage volume. The ' theoretical live storage volume for the detention vault is 12,281 cubic-feet (see Level Pool Routing section of this report). The actual detention volume required is therefore ' 15,966 cubic feet (1.30x 12,281). ' A construction factor of safety was also added to the live storage volume to account for inaccuracies which may occur during construction of the detention structure. As designed, ' the detention vault provides 16,328 cubic feet (104'x 20'x 7.85') of live storage. Water Quality Water quality will be provided through the use of dead storage. According to King ' County standards, the required water quality volume is equal to the total runoff from the developed condition 24-hour design storm event using 33% of the 2-year, 24-hour precipitation. (0.33)(P2y,) _ (0.33)(2.00 in) = 0.67 inches Water Quali H dro ra h Summa ' Storm Precip. Peak Flow Volume Time of Peak Event in cfs ft3 min. Water Quality 0.67 0.283 3892 470 ' The required volume to be used for water quality storage is 3,892 cubic feet. As designed, the detention vault provides 4,020 cubic feet (67'x 20'x 3) of water quality ' storage. In addition to the fore mentioned water quality volume, and additional one foot of depth is provided in the vault for sediment storage- STORM ' DRAINAGE REPORT FOR HERITAGES SQUARE —Page 12 Q g ' Overflow Riser ' The overflow riser was sized to convey the 100-year un-detained flow of 2.98 cfs (see Detainable Area Hydrograph Summary table). The riser was designed assuming 0.5 feet of available head. Please reference the calculation below as well as Figure 4.4.7 J located in the appendix. Qo,ifi,e = 3.782(D2)(H)1r2 2.98 = 3.782(D2)(0.5)'/2 ' D = 1.06 feet = 12.72 inches ' The overflow riser was chosen to be 15 inches in diameter. 1 STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 13 ' CONVEYANCE CALCULATIONS ' In accordance with City of Renton Standards and the King County Surface Water Design Manual, the conveyance system is required to provide a minimum of six inches of ' freeboard within each catch basin for the 25-year, 24-hour design storm event. As designed, the tightline conveyance system provides a minimum of six inches of freeboard ' within each catch basin for the 100-year, 24-hour design storm event The hydraulic grade line calculations were performed using Eagle Point Software's computer program Storm Sewers. The program determines the flow rate in each pipe and ' then performs a standard step hydraulic analysis on the pipe network. The methodology used for non-uniform flow analysis is the standard step energy balance. This procedure is used to determine the hydraulic grade line throughout the pipe network and is identical to ' that used for any open channel water surface profile. The steady state energy equation (Bernoulli equation) is used between upstream and downstream sections of each pipe in ' the network. The friction slope is then calculated by applying Manning's equation at the upstream and downstream ends and averaging the slope between them. The program then ' performs three iterations to pinpoint the hydraulic grade line. Computations begin at the most downstream pipe and continue in an upward direction. The rational method of analysis, with an initial time of concentration equal to 6.3 minutes ' (conservative), was used to find the flow rate in each pipe based on the area tributary to each catch basin. Please reference the Pipe Tributary Area Map located in the appendix of this report. A weighted runoff coefficient, respective of the impervious (C=0.90 — pavement/roofs) and pervious (C = 0.25 — lawn/landscaping) areas tributary to the conveyance system, was ' used in the Rational Method flow calculations. STORM DRAINAGE REPORT FOR HERITAGE SQUARE—Page 14 ' Tables summarizing the amount of freeboard available in each structure are included below. Please reference the HGL Calculations exhibit, in the appendix of this report, for ' actual computer output (including flow estimates). ' VAULT INFLOW SYSTEM The following table represents a summary of the hydraulic grade line calculations for the pipe system conveying runoff to the proposed detention vault. 100 Year Freeboard Table Catch Basin Rim Elev. HGL Elev. Freeboard CB 5 323.94 321.19 2.75 ' CB 6 326.42 323.30 3.12 CB 7 330.47 324.64 5.83 CB 8 337.45 334.00 3.44 ' CB 9 339.02 335.25 3.77 CB 10 343.55 339.62 3.93 VAULT OUTFLOW SYSTEM ' The following table represents a summary of the hydraulic grade line calculations for the pipe system conveying runoff from the proposed detention vault. 100 Year Freeboard Table ' Catch Basin Rim Elev. HGL Elev. Freeboard CB 1 322.00 312.55 9.45 CB 2 323.00 312.75 10.25 ' CB 3 328.20 312.89 15.31 CB 4 326.80 313.07 13.73 C.O. 3 324.00 312.66 11.34 STORM DRAINAGE REPORT FOR HERITAGE SQUARE -Page 15 t ' EROSION CONTROL CALCULATIONS ' The temporary erosion and sedimentation control plan was designed to reduce the discharge of sediment laden runoff from the site. The plan is comprised of temporary ' measures (rock entrance, filter fence, etc.) as well as permanent measures (hydroseeding, landscaping). In general, runoff from the site will sheet flow across cleared areas into ' temporary interceptor swales and be conveyed to a sediment retention facility. ' The sediment retention facility was designed in accordance with Appendix D (Section D.4.5.2) of the 1996 King County Surface Water Design Manual (Draft). Specifically, the surface area of the sediment pond was designed to settle out the design particle (medium silt) at a 10-year inflow rate. Once the proposed storm water detention vault for this project is constructed, the site's runoff will be directed to the vault and the sediment retention pond removed. A summary of the surface area calculations, as well capacity ' calculations for the outflow structures, for the sediment retention facility is provided on ' the pages that follow. ' Flows used in the following erosion control calculations were estimated using the Santa ' Barbara Urban Hydrograph method with a User 1 (King County type IA) rainfall file. Refer to the TESC Tributary Area Map, located in the appendix, for area delineation. ' According to King County isopluvial maps (see Appendix), the 10 and 100-year / 24-hour rainfall precipitation values are 2.9 and 3.9 inches respectively. STORM DRAINAGE REPORT FOR HERITAGE SQUARE —Page 16 ' Pond Surface Area The surface area of the sediment pond was designed to settle out the design particle (medium silt) at a 10-year inflow rate assuming the entire site is cleared. ' Flow Estimate Tributary Area= 4.02 Ac @ CN= 87 (bare dirt) Time of Concentration= 5 minutes (conservative) ' TESC Hydrograph Summary Precip. I Peak Flow I Volume Time of Peak t Storm rinl I [CFS1Ac-ft min 10-Year 2.90 1 1.77 0.55 470 Surface Area Calculation Required Surface Area= 2 x(Q 10)/ 0.00096 Required Surface Area= 2 x(1.77) / 0.00096 ' Required Surface Area =3,688 square feet ' The sedimentation pond was designed to provide a surface area of 4,050 square feet at the maximum water surface elevation. STORM DRAINAGE REPORT FOR HERITAGE SQUARE —Page 17 ' Dewatering Orifice The dewatering orifice was sized based on the equations found in Section 4.5.2 of Appendix D of the 1996 King County Surface Water Design Manual (Draft). ' Calculate Area of Orifice AS(2h)os A. 10.6 x 3600Tg" Where: ' A. = orifice area (square feet) Ae = 4,050 SF (pond surface area) h = 4.0 ft (head of water above orifice) ' T = 24 hr (dewatering time) g = 32.2 ft/sec2 (acceleration of gravity) A. = 0.00220 SF Convert Area of Orifice to Orifice Diameter ' rAD=24x ' D = 0.64 inches ; 1.0 inch minimum The dewatering orifice will be 1.0 inch in diameter and connect to perforated tubing that is 4.0 inches in diameter. ' Overflow Riser ' The overflow riser was sized to convey the peak rate of runoff(1.77 cfs) from the 10-year / 24-hour design storm event assuming the entire site is cleared. As designed, there is 1.0 ' feet of available head between the top of the riser pipe and the crest of the emergency overflow spillway. Refer to Figure 4.4.7J—Riser Inflow Curves located in the appendix. Q°,.;f°e = 3.782 x D2 x H'12 1.77 = 3.782 x D2 x 1.01/2 D = 0.68 feet = 8.2 inches ' The overflow riser was conservatively selected to be 12 inches in diameter. STORM DRAINAGE REPORT FOR HERITAGE SQUARE — Page 18 ' Emergency Overflow Spillway The overflow spillway was designed to convey the peak rate of runoff from the 100-year/ ' 24-hour design storm event assuming the entire site is developed. A summary of the flow estimate as well as the spillway sizing calculations is provided below. Flow Estimate ' Tributary Area= 4.02 Ac Impervious Area (60%) = 2.41 acres @ CN = 98 (roofs/pavement) ' Pervious Area(40%) = 1.61 acres @ CN= 86 (lawns/landscaping) Time of Concentration= 5 minutes (conservative) TESC H dro ra h Summary Precip. Peak Flow Volume Time of Peak ' Storm in CFS Ac-ft min 100-Year 3.90 3.55 1.07 470 ' Spillway Sizing The spillway was designed with a flow depth of 0.25 feet. 1 L = Q'oo - 2AH12 or 6 feet minimum 3.21 H3i2 ' Where: Qioo = 3.55 cfs (100-year peak) H = 0.25 ft (flow depth) L = length of weir = 7.65 feet ' The emergency overflow spillway was designed to be 10 feet long, with 3:1 side slopes and one foot of available flow depth. t STORM DRAINAGE REPORT FOR HERITAGES e 19 SQUARE —Page g F� A W TRIAD ASSOCIATES \ cht bad W�RoNy `t L.&W bdr IW{111111R R EAis4 4 Y061--0u WdKMAW t 4&mjdt M ft.Maim :....'::,.:.., AND .v:• .. � ems' � � ; ' /: •r r"fir ' � ;� { { W SCALE: i " = so' EIS TING BA SIN - 4..0'2 : A f` a tq ' 0 25 50 100 - hPIPER V/OUS = 0..05 AC r o ' f'FR V/O US A RrA = 3.97-l'A,c 7`IrIE OF C ONC. _ 44;40` MINN ., _ ,. 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"`"�r�",�.' a� t � �• MT ?1� _ e �p' c' ail }e r • �'` I 77 I• � g. �� < ¢t � . { \ 'J�Ind �Illt"I� J • n e� �° .i 'I:+:dI K 7 ; ,~ rr' �_ f�tY�1�., t a�7�_ �ryi...�..J SOIL LEGEND The first capitol letter is the initial one of the soil none. A second capital letter, ' A. B, C, D, E, or F, indicates the class of slope. Symbols without o slope letter are those of nearly level soils. SYMBOL NAME AgB Aldetwood gravelly sandy loom,0 to 6 percent slopes AgC Alderwood gravelly sandy loam,6 to 15 percent slopes AgD Alderwood gravelly sandy loam, 15 to 30 percent slopes AkF Alderwood and Kitsop soils, very steep ' Am8 Arents,Alderwood material,0 to 6 percent slopes a AmC Arents,Alderwood material,6 to 15 percent slopes r An Arents, Everett material* BeC Beausite gravelly sandy loom,6 to 15 percent slopes ' BeD Beausite gravelly sandy loam, 15 to 30 percent slopes BeF Beausite gravellys4rdy4oam,-A0-to its percc at mlcx� Bh Bellingham silt loam Or .BrIscot silt loam Bu Buckley silt loam t Cb Coastal Beaches Ea Earlmont silt loam Ed Edgewick fine sandy loam EvB Everett gravelly sandy loom,0 to 5 percent slopes ' EvC Everett gravelly sandy loam,5 to 15 percent slopes EvD Everett gravelly sandy loam, 15 to 30 percent slopes E-C Everett-Alderwood gravelly sandy looms,6 to 15 percent slopes InA Indianola loamy fine sand, 0 to 4 percent slopes ' InC Indianola loamy fine sand,4 to 15 percent slopes InD Indianola loamy fine sand, 15 to 30 percent slopes KPB Kitsap silt loam,2 to 8 percent slopes KpC Kitsap silt loam,8 to 15 percent slopes KpD Kitsap silt loam, 15 to 30 percent slopes ' KsC Klaus gravelly loamy sand,6 to 15 percent slopes Ma Mixed alluvial land NeC Neilton very gravelly loamy sand,2 to 15 percent slopes Ng Newberg silt loam Nk Nooksack silt loom No Norm sandy loam Or Orcas peat Os Oridia silt loam ' OvC Ovall gravelly loam,0 to 15 percent slopes OvD Ovall gravelly loam, 15 to 25 percent slopes OvF Ovall gravelly loom, 40 to 75 percent slopes Pc Pilchvck loamy fine sand Pk Pilchuck fine sandy loam Pu Puget silty clay loam Py Puyallup fine sandy loam RoC Rognar fine sandy loam,6 to 15 percent slopes RoD Ragnar fine sandy loam, 15 to 25 percent slopes RdC Ragnar-Indianolaassoc lotion,sloping i2dE Rognor-Indianola association,moderately steep• Re Renton silt loam. Rh Riverwosh ' Sa Salol silt loam Sh Sammmish silt loam Sk Seattle muck Sm Shalca,muck Sn SI silt loam So Snohomish silt loam Sr Snohomish silt loam,thick surface variant Su Sultan silt loam Tu Tukwila muck ' Ur Urban land Wo Woodinville silt loam The composition of these units Is more variable than that of the others In the area,but It has been controlled well enough to interpret for the expected use of the soils. ' KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 ' CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE:3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS IN KING COUNTY 1 HYDROLOGIC HYDROLOGIC ' SOIL GROUP GROUP* SOIL GROUP GROUP* Alderwood Orr-as Peat D Arents, Alderwood Material Oridia D ' Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B ' Buckley D Ragnar B Coastal Beaches Variable Renton D Earimont Silt Loam D Riverwash Variable Edgewick C Salal C ' Everett A/B °Sammamish D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D ' Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL GROUP CLASSIFICATIONS ' A. (Low runoff potential). Soils havinghigh infiltration rates even when thoroughly 9 o oughly wetted, and consisting chiefly of deep, well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of ' water transmission. CO (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately ' fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a ' hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. * From SCS, TR-55, Second Edition, June 1986, Exhibit A-1. Revisions made from SCS, Soil Interpretation ' Record, Form #5, September 19M. ' K I N G COU N "I' )', WAS If I N G "I' O N, S U RIFACE W A 'I' E R DESIGN MAN UAL TABLE 3_5.2B-SCS %N'ESTERN 1VASI11N(;'FON RUNOFF CURVE NUMBERS ' SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. ' CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 ' Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second growth 42 64 81 Wood or forest land: young second growth or brush 55 72 81 86 ' Orchard: with cover crop 81 88 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 68 80 O 90 fair condition: grass cover on 50% ' to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 ' Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number ' 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin t 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 ' 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and industrial areas. ' (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. ' (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 11/92 1 • UK grj cm F Not olfo Alr ,�. • WO coil � � �►� hilt .� �� �' ,a ,�►.� � �._ � •�-fir , -� _ o • . MA law Sa Me 1 _ - r ' r •'� I �t � ate FROM WIN 111. r , . • . • WA fit>�i �� m a � �♦� � ���i(��� m. aq -Cr pq INK pr g I�mvqij' MF ail/�����isi*1� �� �`��fj,�= • •� � . .�t �,� Heritage Square BASIN SUMMARY ' BASIN ID: Al NAME: 2 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs ' RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 3.97 Acres TIME INTERVAL..: 10.00 min CN..: 83.00 TIME OF CONC..: 44.40 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.05 Acres CN..: 98.00 TcReach-Sheet L: 130.00 ns:0.4000 p2yr:2.00 s:0.1500 TcReach-Sheet L: 170.00 ns:0.4000 p2yr: 2.00 s:0.0610 TcReach-Shallow L: 100.00 ks:5.00 s:0.0600 ' TcReach-Shallow L: 150.00 ks:5.00 s:0.1130 PEAK RATE: 0.31 cfs VOL: 0.24 Ac-ft TIME: 490 min BASIN ID: A2 NAME: 10 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA ' PRECIPITATION..: 2.90 inches AREA..: 3.97 Acres TIME INTERVAL..: 10.00 min CN..: 83.00 TIME OF CONC... 44.40 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.05 Acres ' CN..: 98.00 TcReach-Sheet L: 130.00 ns:0.4000 p2yr:2.00 s:0.1500 TcReach-Sheet L: 170.00 ns:0.4000 p2yr: 2.00 s:0.0610 ' TcReach-Shallow L: 100.00 ks:5.00 s:0.0600 TcReach-Shallow L: 150.00 ks:5.00 s:0.1130 PEAK RATE: 0.74 efs VOL: 0.46 Ac-ft TIME: 490 min BASIN ID: A3 NAME: 100 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs ' RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.90 inches AREA..: 3.97 Acres TIME INTERVAL..: 10.00 min CN..: 83.00 ' TIME OF CONC..: 44.40 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.05 Acres CN... 98.00 TcReach-Sheet L: 130.00 ns:0.4000 p2yr:2.00 s:0.1500 TcReach-Sheet L: 170.00 ns:0.4000 p2yr:2.00 s:0.0610 TcReach-Shallow L: 100.00 ks:5.00 s:0.0600 ' TcReach-Shallow L: 150.00 ks:5.00 s:0.1130 PEAK RATE: 1.30 cfs VOL: 0.74 Ac-ft TIME: 490 min File: 963580UT Detention Vault Water Works Output ' Heritage Square BASIN SUMMARY ' BASIN ID: B 1 NAME:2 YEAR DETAINED AREA SBUH METHODOLOGY ' TOTAL AREA..: 3.34 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION... 2.00 inches AREA..: 1.24 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 ' TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 2.10 Acres CN..: 98.00 ' PEAK RATE: 1.31 cfs VOL: 0.40 Ac-ft TI ME: 470 min ' BASIN ID: B2 NAME: 10 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA... 3.34 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA ' PRECIPITATION..: 2.90 inches AREA..: 1.24 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 2.10 Acres ' CN..: 98.00 PEAK RATE: 2.09 cfs VOL: 0.63 Ac-ft TIME: 470 min BASIN ID:B3 NAME: 100 YEAR DETAINED AREA SBUH METHODOLOGY ' TOTAL AREA..: 3.34 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.90 inches AREA..: 1.24 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 ' TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 2.10 Acres CN..: 98.00 PEAK RATE: 2.98 cfs VOL: 0.90 Ac-ft TIME: 470 min 1 ' File: 963580UT Detention Vault Water Works Output ' Heritage Square BASIN SUNIMARY BASIN ID: CI NAME: 2 YEAR BYPASS AREA SBUH METHODOLOGY TOTAL AREA..: 0.68 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 0.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF . 0.20 AREA... 0.34 Acres CN..: 98.00 PEAK RATE: 0.24 cfs VOL: 0.07 Ac-ft TIME: 470 min BASIN ID: C2 NAME: 10 YEAR BYPASS AREA SBUH METHODOLOGY TOTAL AREA..: 0.68 Acres BASEFLOWS 0.00 cfs ' RAINFALL TYPE-: USER1 PERVIOUS AREA PRECIPITATION..: 2.90 inches AREA..: 0.34 Acres TIME INTERVAL... 10.00 min CN... 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ' ABSTRACTION COEFF : 0.20 AREA..: 0.34 Acres CN..: 98.00 ' PEAK RATE: 0.40 cfs VOL: 0.12 Ac-ft TIME: 470 min ' BASIN ID: C3 NAME: 100 YEAR BYPASS AREA SBUH METHODOLOGY ' TOTAL AREA..: 0.68 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.90 inches AREA..: 0.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF . 0.20 AREA... 0.34 Acres CN..: 98.00 PEAK RATE: 0.58 cfs VOL: 0.17 Ac-ft TIME: 470 min File: 96358OUT Detention Vault Water Works Output ' Heritage Square ' BASIN SUMMARY BASIN ID: WQ NAME: WATER QUALITY SBUH METHODOLOGY ' TOTAL AREA..: 3.34 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION-: 0.67 inches AREA..: 1.24 Acres ' TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF . 0.20 AREA... 2.10 Acres CN..: 98.00 PEAK RATE: 0.28 cfs VOL: 0.09 Ac-ft TIME: 470 min HYDROGRAPH SUMMARY ' DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 YEAR EXISTING 1 0.314 490 10340 4.02 ' 10 YEAR EXISTING 2 0.745 490 20177 4.02 100 YEAR EXISTING 3 1.298 490 32364 4.02 2 YEAR DETAINABLE AREA(DEV.) 4 1.305 470 17347 3.34 10 YEAR DETAINABLE AREA(DEV.) 5 2.088 470 27442 3.34 100 YEAR DETAINABLE AREA(DEV.) 6 2.984 470 38995 3.34 2 YEAR BYPASS (DEV.) 7 0.239 470 3238 0.68 10 YEAR BYPASS(DEV.) 8 0.396 470 5240 0.68 ' 100 YEAR BYPASS (DEV.) 9 0.577 470 7555 0.68 WATER QUALITY 10 0.283 470 *3892 3.34 2 YEAR THEORETICAL OUTFLOW 12 0.119 1450 15233 3.34 10 YEAR THEORETICAL OUTFLOW 13 0.453 650 25295 3.34 100 YEAR THEORETICAL OUTFLOW 14 1.107 510 36837 3.34 2 YEAR ACTUAL OUTFLOW 15 0.107 1460 14075 3.34 ' 10 YEAR ACTUAL OUTFLOW 16 0.378 770 22669 3.34 100 YEAR ACTUAL OUTFLOW 17 0.676 550 34208 3.34 2 YR TOTAL RELEASE(HYD 7+HYD 12) 18 **0.305 470 18471 4.02 10 YR TOTAL RELEASE(HYD 8+HYD 13) 19 **0.541 640 30536 4.02 ' 100 YR TOTAL RELEASE(HYD 9+HYD 14) 20 **1.292 510 44392 4.02 *Required water quality volume=3,892 cubic-feet. ' **The vault outflow hydrographs were added to the bypass area hydrographs to compute the total release from the site in the developed condition. Please note, in all cases, the total release from the site is less than the allowable release rates. ' Allowable Release Rates 2-Year Allowable Release = 0.31 cfs 10 Year Allowable Release = 0.75 cfs I00-Year Allowable Release = 1.30 cfs OUTFLOW CONTROL STRUCTURE MULTIPLE ORIFICE ID No. O ' Description: Orifice discharge from vault Outlet Elev: 312.60 Elev: 310.60 ft Orifice 1 Diameter: 1.3125 in. ' Elev: 319.10 ft Orifice 2 Diameter: 5.5625 in. File: 963580UT Detention Vault Water Works Output ' Heritage Square ' THEORETICAL STAGE/STORAGE/DISCHARGE TABLE RECTANGULAR VAULT ID No. THEO Description:THEORETICAL VAULT ' Length: 78.20 ft. Width: 20.00 ft. STAGE STORAGE STORAGE DISCHARGE ' FT CF Ac-FT CFS 312.60 0 0.0000 0.0000 313.00 625 0.0144 0.0295 313.50 1408 0.0323 0.0443 314.00 2190 0.0503 0.0553 314.50 2972 0.0682 0.0644 315.00 3754 0.0862 0.0724 315.50 4536 0.1041 0.0795 316.00 5318 0.1221 0.0861 316.50 6100 0.1400 0.0922 317.00 6882 0.1580 0.0980 317.50 7664 0.1759 0.1034 318.00 8446 0.1939 0.1085 ' 318.50 9228 0.2118 0.1135 319.00 10010 0.2298 0.1182 319.50 10792 0.2477 0.6537 320.00 11574 0.2657 0.9235 320.40 12199 0.2801 1.0876 320.50 12356 0.2836 1.1246 ' THEORETICAL LEVEL POOL TABLE SUMMARY Description Inflow Storage Dischrg P. Stage Volume Outflow P. Time CFS ID ID FT CF CFS Min 2 Yr.Theoretical Vault Outflow 1.31 THEO O 319.08 10130 0.119 1450 10 Yr.Theoretical Vault Outflow 2.09 THEO O 319.26 10418 0.453 650 100 Yr. Theoretical Vault Outflow 2.98 THEO O 320.45 *12281 1.107 510 *Theoretical volume of live storage= 12,281 cubic-feet. File: 96358OUT Detention Vault Water Works Output Heritage Square ' ACTUAL STAGE/STORAGE/DISCHARGE TABLE ' RECTANGULAR VAULT ID No. ACT Description: ACTUAL VAULT Length: 104.00 ft. Width: 20.00 ft. STAGE STORAGE STORAGE DISCHARGE FT CF Ae-FT CFS ' 312.60 0 0.0000 0.0000 313.00 832 0.0191 0.0295 313.50 1872 0.0430 0.0443 314.00 2912 0.0669 0.0553 314.50 3952 0.0907 0.0644 315.00 4992 0.1146 0.0724 315.50 6032 0.1385 0.0795 316.00 7072 0.1624 0.0861 316.50 8112 0.1862 0.0922 317.00 9152 0.2101 0.0980 ' 317.50 10192 0.2340 0.1034 318.00 11232 0.2579 0.1085 318.50 12272 0.2817 0.1135 ' 319.00 13312 0.3056 0.1182 319.50 14352 0.3295 0.6537 320.00 15392 0.3534 0.9235 ' 320.50 16432 0.3772 1.1246 321.00 17472 0.4011 1.2926 321.40 18304 0.4202 1.4117 321.50 18512 0.4250 1.4399 ACTUAL LEVEL POOL TABLE SUMMARY ' Description Inflow Storage Dischrg P. Stage Volume Outflow P. Time CFS ID ID FT CF] [CFS] [Min 2 Year Actual Vault Outflow 1.31 ACT O 317.86 10935 0.107 1460 ' 10 Year Actual Vault Outflow 2.09 ACT O 319.20 13723 0.378 770 100 Year Actual Vault Outflow 2.98 1 ACT O 319.53 14424 0.676 550 File: 963580UT Detention Vault Water Works Output KI NG COUNTY, W AS 1-1 1 N GT 11 N, S U R FAC' E WATER DESIGN MANUAL FIGURE 4.4.7J RISER INI+LOW CURVES Weir Flow ' Orifice Flow ------ 100 -- 36 — 33 30 C 27 U N 24 n 21 c - 18 T 0 ' a 15 tr . 12 ' 10 10 0.1 1.0 — O.5 10.0 HEAD IN FEET (measured from crest of riser) ' SOURCE: USDA-SCS ' QWIER = 9.739 DH32 QORIFICE - 3.782 D2H112 ' Q in cfs, D and H in feet 4.4.7-10 1/9() FIGURE 4.4.7J (VAULT) I , r AIL=. ■ � 1 • �� n�,i(i/ ■ummua �.= �� �unnnn/ /uonmiv`�= � ±'�: �ni�u/ �m� •� � 1 • • •• �► �_ ��a�i+�l�I�iaii��� �sr�►�s�Ir !�'�el�l®®�►a`�r�►�S�i�i..r®�®,•r�••�rr��� � I � �►�� � �uuu+ii I 1 r uunlo ♦ A R R AL � , ' //�/ ��,•• ,'����t�►�as�i+lr� f���" i�1�i����p�NlAeAi��i9�1" r m�e�..;' � - � ®� � O ; � � ■� © � , ,a �Muii ��� i , •':Illi 'll'IiN:I' •a�� '�� �,�ar�■�®►�,�>e�.�►�. �®��■ram®�la���►`�� ruffill mom„����■���®•►rem ►.ter.:. —.._._.... ;. • r r r 1 u ' 07/16/98 STORM SEWER SUMMARY REPORT 100 YEAR DESIGN FILE: 96358ONS.STM RAINFALL FILE: RENTON98.RND 100 YEAR DESIGN STORM I - 10.180/ ( Tc + 0.000) ^ 0.630 LINE/I DESCRIPTION IINC ARIRUNOFFCIINLTIMEIINLT IIINC CIA) INPUTQ I UNIFORM I SIZE/I INVERT (PIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINEI ITOT ARIWEIGHTDI Tc ITOTL IITOT CIA) TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN ' I I (ac) I C I (min) I (in/h) I (cfs) i (cfs) I (cfs) l(in) I (ft) l(ft) I(ft/ft) 1 (ft/ft)I (ft) I (ft/3) I I I I I I I I I I I i I I I 1 I CB 5 1 0.41 0.701 6.301 3.191 0.941 0.001 I 12D1 319.001 111 0.0121 0.0071 320.531 5.85 1 DNLN = 0 1 2.51 0.701 8.321 2.681 4.601 4.601 21.11 12D1 315.701 1 0.3001 1.25 1 320.451 5.85 I I 2 CB 6 0.2I 0.70I 6.30I 3.19I 0.42I 0.001 I 12DI 321.99I 82i 0.0121 0.0201 322.83I 5.54 1 DNLN = 1 1 2.01 0.701 8.061 2.731 3.881 3.881 7.41 12D1 319.001 1 0.0361 1.00 1 321.191 4.95 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB 7 1 0.81 0.701 6.301 3.191 1.851 0.001 1 12D1 323.501 921 0.0121 0.0111 324.311 5.32 I DNLN = 2 1 1.81 0.701 7.751 2.801 3.611 3.611 4.91 12D1 321.991 1 0.0161 0.75 1 323.301 4.60 I I I I I I I 1 I I I I I i I 9 I CB 8 I 0.51 0.701 6.301 3.191 1.101 0.001 I 12D1 333.111 1551 0.0121 0.0591 333.731 4.16 1 DNLN - 3 1 1.01 0.701 7.001 2.991 2.111 2.111 9.61 12D1 323.501 1 0.0621 1.00 1 324.641 2.69 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 I CB 9 I 0.11 0.70I 6.301 3.191 0.18I 0.001 I 12D1 334.641 341 0.0121 0.0321 335.091 3.27 I DNLN 4 I 0.51 0.701 6.761 3.051 1.111 1.111 8.21 12D1 333.111 1 0.0451 1.00 1 334.001 1.51 I I I I I I I I 1 I I I I I 1 6 I CB 10 1 0.41 0.701 6.301 3.191 0.981 0.001 1 12D1 339.051 701 0.0121 0.0621 339.621 3.14 1 DNLN - 5 1 0.41 0.701 6.301 3.191 0.901 0.981 9.71 12D1 334.641 1 0.0631 1.00 1 335.251 1.95 STORM SEWER CUSTOM REPORT ' 100 YEAR DESIGN Catch Basin Rim Elev. HGL Elev. Freeboard CB 5 323.94 321.19 2.75 ' CB 6 326.42 323.30 3.12 CB 7 330.47 324.64 5.83 CB 8 337.45 334.00 3.44 ' CB 9 339.02 335.25 3.77 CB 10 343.55 339.62 3.93 1 FILE: 93358VINSMRY VAULT INFLOW SYSTEM HGL CALCULATIONS ' 07/16/98 STORM SEWER SUMMARY REPORT 100 YEAR DESIGN FILE: 96358VLT.STM ' RAINFALL FILE: RENTON98.RND 100 YEAR DESIGN STORM I - 10.180/ ( Tc + 0.000) ^ 0.630 LINE/I DESCRIPTION ]INC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN ' I I (ac) I C i (min) I (in/h) I (cfs) I (cfs) I (cfs) 1(in) I (ft) l(ft) I(ft/ft) 1 (ft/ft) I (ft) I (ft/s) I I I 1 1 CB 1 1 0.31 0.701 6.301 3.191 0.781 0.001 1 15D1 305.701 211 0.0121 0.0021 312.341 3.23 1 DNLN - 0 1 0.51 0.701 8.791 2.591 0.981 3.961 5.71 15D1 305.561 1 0.0071 1.25 1 312.311 3.23 1 I 2 I CB 2 I 0.01 0.70I 6.301 3.19i 0.00I 0.00I I 15Di 306.19I 97I 0.0121 0.001I 312.631 2.43 DNLN - 1 1 0.01 0.001 7.341 2.901 0.001 2.981 5.01 15D1 305.701 1 0.0051 1.25 1 312.551 2.43 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB 3 1 0.01 0.701 6.301 3.191 0.001 0.001 1 15D1 306.481 591 0.0121 0.0011 312.801 2.43 I DNLN e 2 1 0.01 0.001 6.931 3.011 0.001 2.981 5.01 15D1 306.181 1 0.0051 1.00 1 312.751 2.43 I I I I I I I I I I I I I 1 1 4 1 CB 4 1 0.01 0.701 6.301 3.191 0.001 2.981 1 15D1 307.401 921 0.0121 0.0021 313.071 2.43 1 DNLN 3 1 0.01 0.001 6.301 3.191 0.001 2.981 7.01 15D1 306.481 1 0.0101 1.00 1 312.891 2.43 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 I C.O. 3 I 0.21 0.701 6.301 3.191 0.421 0.001 1 8D1 310.001 1821 0.0121 0.0011 312.661 1.22 ' I DNLN _ 1 I 0.21 0.701 6.301 3.191 0.421 0.421 2.01 8D1 305.701 1 0.0241 1.00 1 312.551 1.22 ' STORM SEWER CUSTOM REPORT 100 YEAR DESIGN ' Catch Basin Rim Elev. HGL Elev. Freeboard CB 1 322.00 312.55 9.45 CB 2 323.00 312.75 10.25 CB 3 328.20 312.89 15.31 CB 4 326.80 313.07 13.73 C.O. 3 324.00 312.66 11.34 1 t FILE: 96358 VOUTSMRY VAULT OUTFLOW SYSTEM HGL CALCULATIONS ................. ...................... ----------- - c/) A-- ............... ............... ........ :� 01 0 'No'-7 7.1 �4 , 4!k X, ...... b ............... Y Z ................... A ................ r I%I m 0-Ij k ..................... q% -uV 'JI .......... ........... ........... ........... V1. Al"WIM :.;a A X' .......... 00 —71 > 7 > loft 0 M. Din MMON ET C1 TESC TRIBUTARY AREA MAP to ?) HERITAGE SQUARE fill CITY OF RENTON, WA SHIMGTOM BASIN SUMMARY ' BASIN ID: T1 NAME:2 YEAR TESC-BARE DIRT SBUH METHODOLOGY TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA ' PRECIPITATION..: 2.00 inches AREA..: 4.02 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ' ABSTRACTION COEFF : 0.20 AREA..: 0.00 Acres CN..: 98.00 ' PEAK RATE: 0.87 cfs VOL: 0.30 Ac-ft TIME: 480 min BASIN ID: T2 NAME: 10 YEAR TESC-BARE DIRT SBUH METHODOLOGY t TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.90 inches AREA..: 4.02 Acres ' TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF . 0.20 AREA... 0.00 Acres CN..: 98.00 1 PEAK RATE: 1.77 cfs VOL: 0.55 Ac-ft TIME: 470 min 1 BASIN ID: T3 NAME: 100 YR TESC-DEVELOPED ' SBUH METHODOLOGY TOTAL AREA..: 4.02 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.90 inches AREA..: 1.61 Acres ' TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 2.41 Acres CN..: 98.00 PEAK RATE: 3.55 cfs VOL: 1.07 Ac-ft TIME: 470 min ' FILE: 963580UT HERITAGE SQUARE TESC FLOW ESTIMATES 1 KING COUNTY, WASH INGTON, SU RFA (' E WATER DESIGN MANUAL FIGURE 4.4.7J RISER INFLOW CURVES Weir Flow 1 — Orifice Flow — ----- 100 36 1 _ 33 30 C: 27 - 1 0 24 = � U a 21 C 1 - EHE U U 18 E 7 � U Q 1 a 15 it 12 1 10 10 1 77Cx�; 1 0.1 11_0 — 10.0 1 HEAD IN FEET (measured from crest of riser) 1 SOURCE: USDA-SCS 1 QWIER = 9.739 DH312 QORIFICE = 3.782 D2H12 1 Q in cfs, D and H in feet 1 1 4.4.7-10 1 FIGURE 4.4.7J (TESC)