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Home My WebLink AboutStudies APPLICANT 1/27/2023Preliminary Stormwater Report Marcola Apartments Prepared for: Paradigm Properties Prepared by: Mark Reyes, PE Project Engineer: Matt Keenan, PE January 2023 1 KPFF Project#2200316 KPFF'S COMMITMENT TO SUSTAINABILITY As a member of the US Green Building Council, a sustaining member of Oregon Natural Step, and a member of the Sustainable Products Purchasers Coalition, KPFF is committed to the practice of sustainable design and the use of sustainable materials in our work. When hardcopy reports are provided by KPFF, they are prepared using recycled and recyclable materials, reflecting KPFF's commitment to using sustainable practices and methods in all of our products. NO MO WiNmMte Street, SURe 400, Eugene, OR 9)401 rl-r f 541-664-09021 w kPp.c -p y Table of Contents ProjectOverview and Description.....................................................................................................................2 ProjectSize and Location...............................................................................................................................2 Existing vs. Proposed Conditions....................................................................................................................2 ProjectNarrative................................................................................................................................................2 Proposed Stormwater System........................................................................................................................3 Water Quality Facilitie Engineering Conclusions Tables and Figures Table 1: Pre -Development vs. Post -development Flows...................................................................................3 Table 2: 24 -Hour Precipitation for Eugene, OR (NOAA Atlas 2, Volume X) ......................................................5 Table 3: Catchment and Facility Table (See Exhibit 2, Appendix 1)...................................................................5 Appendices Appendix Basin Maps Appendix 2 Stormwater Plans Appendix 3 Existing Runoff Calculations Appendix 4 Proposed Runoff, Water Quality, and Calculations Proje Name I OFF Comuhing Engineers REPORTME Project Overview and Description Project Size and Location The Marcola Apartments development is to be constructed on the 4.72 -acre project site located long Marcola Road. The project is bounded by Marcola Road to the north, 22n° street and a residential development to the east, HWy 126 to the south and a commercial and residential development to the west. The project development consists of 6 multi -family buildings. Watershed and Soil Description Springfield's stormwater basins are part of the larger Upper Willamette Basin. The site itself is located within the City of Springfield's West Springfield Q Street Basin, per the City's 2010 Stormwater Management Plan. The proposed stormwater system will connect to the City's stormwater system. The site has been identified as having type C and D soils. Soil types C and D have poor infiltration rates and no stormwater runoff will be infiltrated on site. Existing vs. Proposed Conditions Existing Conditions The site currently an undeveloped grassyfield with a few groupings of trees on the north half of the site. The site is relatively flat with site slopes generally being in the 1%-2%range. Grades across the site vary 1'-2' with the exception of the berm located on the south boundary of the site. There are no existing stormwater facilities or current connections to any City public storm main. Proposed Conditions The proposed conditions will include 6 multi -family structures, and a community center/gym. In addition, the development will include connecting drive aisles, sidewalks, covered an uncovered parking spots, tennis court and a garage building. The project will treat site runoff according to City design standards Chapter 3 Stormwater Quality. Vehicle impervious surfaces will be treated with a combination of vegetated facilities and mechanical treatment (filters) with no more than 50% of the vehicle impervious area being treated through mechanical means. Additionally, catch basins within the vehicle areas will feature pre-treatment prior to conveying runoff to mechanical treatment. The site as been identified by the City as not needing detention. The proposed site includes 126,187 square feet of impervious area and 78,082 square feet of pervious area. Of the 125,822 square feet of impervious area 56,615 square feet is from structures, 19,936 square feet from pedestrian hardscape and 49,271 square feet from vehicle pavement. Project Narrative The City of Springfield stormwater quality design criteria set forth in Chapter 4 calls for a water quality design storm of 0.83 inch in 24 hours rain event. Proje Name I OFF Comuhing Engineers REMRTWLE Proposed Stormwater System The impervious area on site is divided between the building roof areas, asphalt parking, asphalt drive aisles and site hardscape. See Appendix 1 for the drainage basin areas. Vegetative filtration facilities and mechanical treatment has been selected for water quality treatment. On- site new impervious surfaces from vehicle pavement such as drive aisles and parking spaces will be treated through either a filtration planter or through a mechanical treatment structure. Per City design standards, no more than 50% of the vehicle pavement will be treated through mechanical treatment. All facilities will be designed per City of Springfield standards. The filtration planters will have an open storage at the surface ranging from 8 inches to 12 inches deep with a minimum of 2 inches of freeboard. The planters will have 18 inches of growing media with landscaping planting for the water quality management, and 12 -inch minimum of rock storage depth below the facility. The filtration planters will treat the water quality storm and an overflow will collect larger storm events to convey to the stormwater system. The mechanical treatment will be a filter product such as BayFilter or Stormfilter. The product used will be sized in accordance with the manufacturers recommended. Table 1: Pre- a elopment vs. Postdewlopment Flows Development CFS CF CFS CF L -Tear DTorm 5 -Tear DTorm lu-Iea KeDTorm rflow _Overflow Overflow Over Development CFS CF CFS CF CFS CF CFS CF Existing Conditions 0.01 261.356 0.35 4,745 0.44 5,869 0.53 7,022 Proposed 0,34 5,446 2.20 28,057 2.55 32,696 2.90 37,322 Conditions Development CFS CF CFS CF Existing Conditions 0.63 8,196 0.71 9,148 Proposed Conditions 3.24 41,975 3.52 45,722 Water quality Facilities Basin 1 encompasses the buildings and the pedestrian hardscape not adjacent to the parking bays and drive aisle. Run-off from the buildings will be collected via roof drains and downspouts and the run-off from the pedestrian hardscape will be collected by area drains. Run-off will then be conveyed through the on-site storm drainage system and discharged into the City system at the main located in 22n° Street. Basin 2 encompasses the north section of the parking lot, drive aisle and associated sidewalk that is adjected to the parking bays. Run-off will sheet flow North where it will be captured by two catch basins. Project Name I OFF Conuhing Engineers REMRTWLE These catch basins will filtered to satisfy the pre-treatment requirement before sending run-off to a vault where mechanical treatment via filtration (BayFilter, StormFilter or approved equal) where water quality treatment will take place. After treatment run-off will be conveyed through the on-site storm system and discharge at the connection point in 22n° Street. The treated vehicle pavement area is approximately 43 percent of the total vehicle pavement area. Basin 3 encompasses a portion of the parking bays, drive aisle and adjacent sidewalk located in the middle of the site. Run-off will sheet flow to the filtration planter located in the middle of the site via curb cut. The planter will provide treatment via filtration and overflow run-off will be routed to the on-site storm system via an overflow inlet. Treated run-off will be conveyed to the on-site stormwater system and then to the connection point in 22n° street. Basin 3 encompasses a portion of the parking bays, drive aisle and adjacent sidewalk located on the south side of the site. Run-off will sheet flow to the filtration planter via curb cut. The planter will provide treatment via filtration and overflow run-off will be routed to the on-site storm system via an overflow inlet. Treated run-off will be conveyed to the on-site stormwater system and then to the connection point in 22n° street. Flow Control Per City of Springfield Stormwater Scoping sheet, no detention required for the project site. Source Control Source control is required for facilities that are highly likely to generate pollutants that are not addressed through the implementation of vegetated stormwater facilities. There are a variety of trash areas located throughout the development that will require source control measures. To meet these requirements, heavy- duty sanitary drains located in the trash areas will be trapped, auto -primed, vented and connected to the sanitary sewer system and will not convey to the storm drainage system. Additionally, trash areas will be covered and hydraulically isolated from the stormwater system. Analysis Water Quality Facilities The runoff for the impervious areas has been calculated and the planters and rain garden have been sized to meet or exceed the City of Springfield requirements. The calculations determine runoff using the Santa Barbara Urban Hydrograph (SBUH) Method and NRCS 24 -Hour Type 3A Hyetograph as outlined Chapter 4 of the Engineering Design Standards & Procedures Manual. The facility capacity is based on the requirements and facility details found in City of Eugene Stormwater Design Manual. For analysis purposes, each basin required the following information as input data for the computer model: • Impervious Area (Ai), in acres • Curve Number (CNi), impervious • Travel Time (Tc) • Total Precipitation Proje Name I OFF Comuhing Engineers REPORTTITLE Precipitation data for the respective City of Albany design storms are shown in Table 2 below. Table 2: 24 -Hour Precipitation for Springfield, OR INOAA Alas 1, Volume xl Ped 63,145 1.45 ]3,489 1.69 136,634 - WQ Hardsrape ear 3.3 5 Year 10 -Year 4.3 25 -Year 0.62 2,243 100 -Year 5.2 Basin 1 Ped 63,145 1.45 ]3,489 1.69 136,634 - j Hardsrape Basin 2 (Example) 26,931 0.62 2,243 0.05 29,1]4 MT -1 B ample) 0 -1 Basin (Example) 22,425 0.51 -22,425 -0.51 0 FTP -2 To size each planter, the following information was needed: • Bottom area, in square feet • Bottom perimeter length or bottom width, in feet • Storage depth, in inches All the water quality facilities meet the City of Springfield water quality requirements. For full calculations and results, see Appendix 4. Engineering Conclusions Based on the requirements of the Engineering Design Standards & Procedures Manual the facilities and conveyance components have enough capacity to handle the required storm events and should be approved as designed. Project Name I OFF Consuhing Engineers REPORTTRLE Appendix Basin Maps Proje Name I OFF muhing Engineers REPORTME 5 I I I T r._. J t s EXISTING AREA=205,565 SF 10"SS ° 10"55 10"55_ I J SHEET LEGEND - - PROPERTY �_____ UNE STORMWATE �.....L ............. ® EXISTING STORMWATER BASIN MAP 2 BASIN 4 AREA=23,962 SF IMPERVIOUS AREA=22,425 SF STORMWATER BASIN MAP Appendix 2 Stormwater Plans Proje Name I OFF muhing Engineers REPORTME CONNECT TO EXISTING 10" SANITARY LINE�r S Co -4 IE 10" IN=457.37 (E) S -10' PVC IE 6- IN457.37 (W) S - 6- PVC FIELD VERIFY POINT OF CONNECTION C I L/ 10.00' EWEB WATER TRANSMISSION EASEMENT. EWES SHALL BE PRESENT WITH EXCAVATION OR INSTALLING UTILITIES WITHIN EWEB'S EASEMENT. COORDINATE WITH EWEB. RG FH 11 CONNECT TO EXISTING STORM STRUCTURE O RG RG I +6 II I p IE IN=456.95(N) EX. 60" ar. IE IN=458.84(E)EX 24" MARCOI-A ROAD a v FIELD VERIFY POINT P OF CONNECTION I =RM!�I�IIlI 55 10"55 10"55 10"55 0 89LF-15"SD— _97LF-1S'SO O CONNECT TO EXISTING 10" SANITARY LINE�r S Co -4 IE 10" IN=457.37 (E) S -10' PVC IE 6- IN457.37 (W) S - 6- PVC FIELD VERIFY POINT OF CONNECTION C I L/ 10.00' EWEB WATER TRANSMISSION EASEMENT. EWES SHALL BE PRESENT WITH EXCAVATION OR INSTALLING UTILITIES WITHIN EWEB'S EASEMENT. COORDINATE WITH EWEB. i _ s 11 CONNECT TO EXISTING STORM STRUCTURE I I I �� RG I +6 II I p IE IN=456.95(N) EX. 60" ar. IE IN=458.84(E)EX 24" o IE OUT=456.66 (S) EX. 72" i FIELD VERIFY POINT P OF CONNECTION I =RM!�I�IIlI 55 10"55 10"55 10"55 0 89LF-15"SD— _97LF-1S'SO O RSTRET 5=0.50°h S�.50% 1 – W METER �-� CONNECT TO EXISTING 10" SANITARY LINE�r S Co -4 IE 10" IN=457.37 (E) S -10' PVC IE 6- IN457.37 (W) S - 6- PVC FIELD VERIFY POINT OF CONNECTION C I L/ 10.00' EWEB WATER TRANSMISSION EASEMENT. EWES SHALL BE PRESENT WITH EXCAVATION OR INSTALLING UTILITIES WITHIN EWEB'S EASEMENT. COORDINATE WITH EWEB. 19:1 I RG k 9 �+ o _ s 11 CONNECT TO EXISTING STORM STRUCTURE I I I �� RG I N II I p IE IN=456.95(N) EX. 60" ar. 19:1 I RG k 9 �+ o 11 CONNECT TO EXISTING STORM STRUCTURE �� IE 15" IN=456.84 (W) N II -" p IE IN=456.95(N) EX. 60" Q�N IE IN=458.84(E)EX 24" o IE OUT=456.66 (S) EX. 72" i FIELD VERIFY POINT P OF CONNECTION 55 10"55 10"55 10"55 0 89LF-15"SD— _97LF-1S'SO O RSTRET 5=0.50°h S�.50% 1 – W METER �-� J N ISD MH -1 i RIM=465.89 f IE 10" IN=460.14 (N) IE 10' IN=460.14 (S) I 15' OUT=459.77 (E)15" OUT=459.77 (E) _IE RG o o FTWl P- i j I J N lWl� m O/W1�/1_y�11 6\FH NOTSURVEYED 0 UTILITY KEY NOTES NOTE DESCRIPTION DETAIL REF. 1 CONNECT TO EXISTING 10" SANITARY LINE. FIELD VERIFY PIPE SIZE, INVERT ELEVATION AND LOCATION. 2 CONNECT TO EXISTING 24" STORM LINE. FIELD VERIFY PIPE SIZE, INVERT ELEVATION AND LOCATION. TAP TO EXISTING 8" WATER MAIN. COORDINATE CONNECTION TO EXISTING MAIN WITH SUB. SUB TO PERFORM TAP, INSTALL FIRE PROTECTION TO 3 PROPERTY, AND INSTALL BOX AND METER. CONTRACTOR TO COORDINATE SCHEDULE AND EXACT LOCATION IN FIELD. CONTRACTOR TO POTHOLE PRIOR TO CONSTRUCTION. BWV BACKFLOW PREVENTION VAULT FH FIRE HYDRANT FTP FLOW-THROUGH PLANTER RG RAIN GARDEN II UTILITY CROSSING. PROVIDE 12" MIN. CLEARANCE, U.N.O. UTILITY LABEL LEGEND STRUCTURE LABEL FFFUTILITY TYPE (SD=STORM DRAINAGE) STRUCTURE TYPE CALLOUT ID NUMBER (WHERE APPLICABLE) XX XX -XX X+XX.X RT X.X'—LOCATION (WHERE APPLICABLE) RIM= IE IN III: XX.X^STRUCTURE INFO (WHERE APPLICABLE) IE OUT = XX.X PIPE LABEL UTILITY LENGTH UTILITY SIZE UTILITY TYPE XXLF-XX" XX S=X.XX% SLOPE (WHERE APPLICABLE) SHEET LEGEND FP FIRE PROTECTION LINE S SANITARY SEWER LINE SD STORM WATER LINE W CF UNL9X"91[H4791I�:7�ICI � SCALE 1 INCH = 40 FEET 40 0 40 80 1Tff 800 Willamette Street, Suite 400 Eugene, OR 97401 0: 541.684.4902 F: 541.684.4909 www.koffcom 0 Paradigm < �S� Revision Schedule No. I Description I Date PRINT DATE THIS SET 1/27/20231'44:23 PM ISSUE DATES Pricing Pennit - Construction - Revision - Misc. - 11M DUSTRUD architecture 1622 Pearl Street Eugene, Oregon 97401 541.338.8544 d ustru darc hitecture. com m o m ry � N CONY, Fj 02 N r' 0 �Y8�o`o Ado3« m c 2> T E c m a E$ n Q rnan no p % 41 c °Ci af°i = o w . U w g E0_ m E d Te o o E w d o f w m E$F �aSn DRAWN BY: FU CHECKED BY: MR O U � �a SHEET TITLE UTILITY PLAN SHEET NO. C-200 Appendix 3 Existing Runoff Calculations Proje Name I OFF muhing Engineers REPORTME SBUH Calculation Worksheet for City of Springfield Storm Events k l j j Project Name: Marcola Apartments Date: 1/26/2023 Designer: MAR Basin: Ex. 1 User -Supplied Data Pervious Area Impervbus Area Pervious Area, SF Pervious Area, Acres Pervious Area Cu rve Num her, CNpery Time of Con centratinn, TQ minutes 30,893 Impervious Area, SF Impervious Area, Acres 0.00 I mpervious Area Cu rve Nu mher, CN imp 98 Note: minimum Tc isfive minutes 0.71 85 5 CIN of Eugene 24Hour Rainfall Depths (NRCS Type 1Adlstrlbutlon) Recurrence Interval WQ 1 2 1 5 30 1 25 50 1 100 Inches 1 0.83 1 3.3 1 3.8 1 4.3 1 4.8 1 1 5.2 Calculated Data l Project Area, Acres 0]3 Total Project Area, Square Feet 30,893 urrence Interval WQ 2 5 10 25 50 100 k Flo. Rate, Qpeak, as I OA0.35OA0.53 —WQ 0.63 0.00 0.71 l RunoffVolume, V, cubic feet 26 4,745 5,86 7,022 8,196 0 9148e to Peak Runoff, hours 2A. 7.931 7331 7.83 783 0.00 7$3 Runoff Hydrogroph 0.80 —WQ —2 -Year 0.74 —S -Year —10 -Year 0.60 —25 -Year —50 -Year 0.50 —100 -Year 0.40 e 7 rc 0.30 0.20 0.10 0.08 0 500 1000 1500 2000 2500 Time, mintMea 8[0Willamem,Su,t,5uu,4O Eugen,()R ] 1 511.f$4.4902 kpff. m Appendix 4 Proposed Runoff, Water Quality, and Calculations Proje Name I OFF muhing Engineers REPORTME SBUH Calculation Worksheet for City of Springfield Storm Events kpff Project Name: Marcola Apartments Date: 1/26/2023 Designer: MAR Basin:1 User -Supplied Data PerviousArea Im ervbus Area Pervious Area, SF Pervious Area, Acres Pervious Area Cu rve Num ber, CNpery Time of Con centratir Ta, minutes Impervious Area, SF 48,695 Impervious Area, Acres 1.12 I mpervious Area Cu rve No miner, CN imp 98 Note: minimum Tc isfive minutes 0.00 90 5 oru 4ur Rainfall Depths NRC6Trip bne —WQ Total Project Area, Square Feet 4$695 erfeEnceIt WQ 2 -Yr I 51r I 10 -Yr 1 25 -Yr 1 50 -Yr 1 100 -Yr Inches 1 0.83 1 3.3 1 3.8 1 4.3 1 4.8 1 1 5.2 Calculated Data Total Proj ect Area, Acres 1.121 —WQ Total Project Area, Square Feet 4$695 Recurrence Interval WQ 2 Y 5 -Yr 10 -Yr 25 -Yr 50 -Yr 10D -Yr Peak Flo. Rate, Qpeak, cis Ru noff Vol ume, V, cu bic feet Time to Peak Runoff, hours 0.20 0.96 1.11 1.26 SAS 0.00 1.53Total 2,544 12,446 14,46 16,493 18,518 0 20,139 783 7.83 783 7.83 783 0.00 7$3 Runoff Hydmgmph 1.80 —WQ —2 -Year 1.60 —5 -Year 1.40 —10 -Year —25 -Year 1.20 —50 -Year 100 —100 -Year V Zy g 0.80 K 0.60 0.40 0.20 0.00 0 500 1000 ism 2000 2500 Time, minxMe s 8WWilbmUeSr,tSuu,400 Eurn,O89]01 XL W09@ kpff. m SBUH Calculation Worksheet for City of Springfield Storm Events kpff Project Name: Marcola Date: 1/26/2023 Designer: MAR Basin:2 User -Supplied Data PerviousArea InnipentiousArea Pervious Area, SF Pervious Area, Acres Pervious Area Curve Num ber,CNpery Time of Con centratir Ta, minutes Impervious Area, SF 26,931 Impervious Area, Acres 0.62 Impervious Area Curve Number CNimp 98 Note: minimum Tc isfive minutes 0.00 90 5 CI of Eu ne 24Hour Rainfall Depths NRC6T eSAdlstrlbutbn —WQ Total Project Area, Square Feet RequrrenceI It WQ 2 -Yr I 51r I 10 -Yr 1 25 -Yr 1 50 -Yr 1 100 -Yr Inches 1 0.83 1 3.3 1 3.8 1 4.3 1 4.8 1 1 5.2 Calculated Data Total Project Area, Acres 0.621 —WQ Total Project Area, Square Feet 26,931 Recurrence Interval WQ I 2 -Yr I 5 -Yr I 10 -Yr I 25 -Yr I 50 -Yr I 100 -Yr Peak Flow Rate, Qpeak, cis 0.111 O.S31 0.611 0.70 0.7 O.ODI 085 Total Ru noff vol ume, V, cu bic feet 1,40 6,883 8,00 9,InJ 10,2421 01 11,138 Time to Peak Runoff, hours 783 7.83 783 7.83 783 0.1 783 Runoff Hydrogroph 0.90 —WQ —2 -Year 0.80 —S -Year 0.70 —10 -Year —25 -Year 0.69 —50 -Year 0.50 —100 -Year V Zy g 0.40 K 0.30 0.20 0.10 0.00 0 500 1000 ism 2DDO 2500 rrEe, n:nulea 80]Willa eru,Sr,tSuite4 Eurn,OP9]01 XL W09@ kpff. m SBUH Calculation Worksheet for City of Springfield Storm Events l J j j Project Name: Marcola Date: 1/26/2023 Designer: MAR Basin:3 User -Supplied Data PerviousArea InnipentiousArea Pervious Area, SF Pervious Area, Acres Pervious Area Curve Number, CNpery Time of Con centratir Tr, minutes Impervious Area, SF 13,686 Impervious Area, Acres 0.31 Impervious Area Curve Number CNimp 98 Note: minimum Tc isfive minutes 0.00 8o 5 CI of Eu ne 24Hour Rainfall Depths NRC6T eSAdlstrlbutbn —WQ Total Project Area, Square Feet 13,686 RequrrenceI It WQ 2 -Yr I 51r I 10 -Yr 1 25 -Yr 1 50 -Yr 1 100 -Yr Inches 1 0.83 1 3.3 1 3.8 1 4.3 1 4.8 1 1 5.2 Calculated Data Total Project Area, Acres 0.311 —WQ Total Project Area, Square Feet 13,686 Recurrence Interval WQ 1 2 Y I 5 -Yr I 17"_50 -Yr 10D -Yr Peak Flo. Rate, Qpeak, ch Total Runoff Volume,V, cubic feet Time to Peak Runoff, hours 0.06 0.27 031 0.35 OAO.ODI 0.40 OA3 735 3,4991 4,06 4,MSI 5,2051 01 5,660 7$3 7.83 7331 7.83 7$3 O.W1 7$3 Runoff Hydrogroph 0.50 —WQ —2 -Year 0.45 —5 -Year 0.40 —10 -Year 0.35 —25 -Year —50 -Year 0.30 —100 -Year C" V 0.25 L J K 0.20 0.15 0.10 0.05 0.00 0 500 1000 ism 2000 2500 rrEe, n:nulea 8WWHlam to Sr,tSuu,400 Eurn,O89]01 XL W09@ kpff. m Stormwater Facility Calculator Instructions: 1. Choose Facility Type 2. Choose shape 3. Complete information in highlighted cells Facility Planter Shape Amoeba Bottom Area: 262 sf Bottom Perimeter: 68 ft Vertical Sides 3,380 Storage Depth: MYrinrltration volume (co: Growing Media: �in 18 in Surface Storage Capacity 131 cf Infiltration Area 262 sf GM Infiltration Rate 2.5 in/hr Infiltration Capacity (avg) 0.015 cfs Results Below -Grade WATER QUALITY EVENT PASS ROCK CAPACITY N/A SURFACE CAPACITY 62% Recurrance Peak Flow Interval (cfs) Volume (cf) Rock Capacity Meets Infiltration? WQ 0.0152 634 N/A Filtration Only 2 -Yr 0.2701 3,380 N/A MYrinrltration volume (co: 5 -Yr 0.3125 3,947 N/A 10 -Yr 0.3548 4,506 N/A N/A 25 -Yr 0.3971 5,091 N/A 50 -Yr 0.0000 0 N/A 100-Yrl 0.43081 5,541 N/A 1201 Oak Street, Suite 100 Eu,ene,01197401 541.664.4902 kpa.cum lqj f Proje Name: Marw6 Basin:3 Date: 1/26/2023 Impermeable Liner Water quality Event Surface Facility Modeling 0.0600 0.0500 0.0400 N u 0.0300 0 0 c Ic o.ozoo 0.0100 O.Wro ; I I� 0 500 1000 1500 Time, minutes kpff Project Name: Marcola l3asin:3 Date: 1/26/2023 I% Surface Inflow 0% --— Infiltration Capacity 0% Percolation to Subsurface 0% iOX --- Overflow Surface Capacity 0% 80% 90% 100% 2000 2500 800 Willamette Street, Suite 400 EWene,OR97401 541.684.4902 kpa.wm SBUH Calculation Worksheet for City of Springfield Storm Events kpff Project Name: Marcola Date: 1/26/2023 Designer: MAR Basin:4 User -Supplied Data PerviousArea InnipentiousArea Pervious Area, SF Pervious Area, Acres Pervious Area Curve Num ber,CNpery Time of Con centratir Ta, minutes Impervious Area, SF 22,425 Impervious Area, Acres 0.51 Impervious Area Curve Number CNimp 98 Note: minimum Tc isfive minutes 0.00 RO 5 CI of Eu ne 24Hour Rainfall Depths NRCST eSAdlstrlbutbn —WQ Total Project Area, Square Feet 22,429 RequrrenceI It WQ 2 -Yr I 51r I 10 -Yr 1 25 -Yr 1 50 -Yr 1 100 -Yr Inches 1 0.83 1 3.3 1 3.8 1 4.3 1 4.8 1 1 5.2 Calculated Data Total Project Area, Acres 0.51 —WQ Total Project Area, Square Feet 22,429 Recurrence Interval WQ 2 -Yr 5 -Yr 10 -Yr 25 -Yr 50 -Yr 10D -Yr Peak Flow Rate, Qpeak, cis 0.0 OA4 OSI O.SS 0.65 0.00 0.71 Total Ru noff Vol ume, V, cu bic feet 1,1] S,732 6, 7,595 8,528 0 9,274 Time to Peak Ru noff, hou rs ]$ 7.83 7331 7.931 7231 O.ODI 7$3 Runoff Hydrogroph 0.80 —WQ —2 -Year 0.70 —S -Year —10 -Year 0.60 —25 -Year 0.50 —50 -Year —100 -Year C" V 0.40 L J K 0.30 0.20 0.10 0.00 0 500 1000 ism 2000 2500 rrEe, n:nulea 80]Willa eru,Sr,tSuite4 Eurn,OP9]01 XL W09@ kpff. m Stormwater Facility Calculator Instructions: 1. Choose Facility Type 2. Choose shape 3. Complete information in highlighted cells Facility Planter Shape Amoeba Bottom Area: 293 sf Bottom Perimeter: 68 ft Vertical Sides 956 Storage Depth: 12 in Growing Media: 18 in Surface Storage Capacity 293 cf Infiltration Area 293 sf GM Infiltration Rate 2.5 in/hr Infiltration Capacity (avg) 0.017 cfs Results Below -Grade WATER QUALITY EVENT PASS ROCK CAPACITY N/A SURFACE CAPACITY 74% Recurrance Interval Peak Flow (cfs) Volume (cf) Rock Capacity Meets Infiltration? WQ 0.0170 956 N/A Filtration Only 2 -Yr 0.4425 5,461 N/A MYrinrltration volume (co: 5 -Yr 0.5120 6,396 N/A 10 -Yr 0.5814 7,313 N/A N/A 25 -Yr 0.6506 8,245 N/A 50 -Yr 0.0000 0 N/A 100-Yrl 0.70591 9,020 N/A 1201 Oak Street, Suite 100 Eu,ene,01197401 541.664.4902 kpa.cum lqj f Proje Name: Marwla 6asin:4 Date: 1/26/2023 Impermeable Liner kpff Project Name: Marcola Basin -4 Water quality Event Surface Facility Modeling Bate: 1/16/2023 0.1000 Iss Surface Inflow 0.0900 0% 0.0800 — —— Infiltration Capacity 0.0)00 IOX Percolation to Subsurface 0.0600 0% N 0.0500 10% --- Overflow 0 0.0400 iovc z 0.0300 —Surface Capacity '095 0.0 00 80% 0.0100 90% 0.0000 100% 0 500 1000 1500 2000 2500 Time, minutes Wa1nr nu.114 . Fmn1 A.1—fodn M.vinlinv 800 Willamette Street, Suite 400 EWene,OR97401 541.684.4902 kpa.wm