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Stormwater Management Plan ST RMWATER MANAGEMENT REPORT and STORMWATER POLLUTION PREVENTION ALAN NARRATIVE for LUZERNE STORAGE - ADDITION LUUZE SNE ROAD QUEENS RY, N.Y. Town of Queensbury Warrren County, New York Prepared by: NACE ENGINEERING, P.C. 169 HAVILAND ROAD QUEENSBURY,NY 12804 Thomas R. Center Jr., P.E. February 16, 2016 October,2016 Revised January,2018 File: #47392 u Pro ect Owner - Operator LUZERNE HOLDINGS,INC 169 Haviland Road Queensbury,NY 12804 Phone: 518-792-9474 Contact: Matt Steves Signature: _ _ Date: Prepared By Nace Engineering, P.C. Civil Engineers 169 Haviland Road, Queensbury,NY 745-4400 fax 792-8511 Contact: Thomas R. Center, P.E. S.W.P.P.P. Requirements 1. The SWPPP includes information on all Drawings SP-1, SP-2 and RM-1 and the Stormwater Management Report. 2. Prior to commencement of construction, the contractor shall have the engineer conduct an assessment of the site and certify in an inspection report that the appropriate erosion and sediment controls have been adequately installed. Following commencement of construction, the engineer shall make weekly site inspections and shall prepare a report as required by the general permit. 3. The contractor shall maintain a record of all inspection reports in a site log book, maintained on-site and available to the permitting authority upon request. 4. At competition of construction, the contractor shall perform a final inspection to certify that the site has undergone final stabilization and that all temporary erosion and sediment controls have been removed. Site Location The project site is on the north side of Luzerne Road and just West of West Drive. The construction area is currently vacant and is also adjacent to the Luzerne Storage facility top the south. The total site is 6.46 acres. Existing Conditions The construction site is currently vacant but is adjacent to the Luzerne Storage facility. The entire parcel is owned by Luzeme Holdings Inc. The lot is bordered on the east by West Drive, the south by Luzerne Road, the west by a vacant light industrial lot and to the north by a future residential lot. The construction site slopes gently to the south. Soils on this site are classified by the Warren County SCS Soils Survey as Oakville loamy fine sand. Test pits for Luzeme Storage facility confirmed the soil classification with fine and medium sandy loam over coarse sands. No water or mottling was found. These are deep, well drained soils and are very suitable for stormwater infiltration. The existing percolation rate for the existing infiltration basin was 1 minute per inch. The site is relatively flat and with the well drained soils there is no evidence of any runoff leaving the site. Existing Conditions Summa Parcel Area: 6.46 acres Building Coverage: 27,050 sf = 9.6% Pavement Coverage 62,554 sf = 22.2% Pervious Surface: 191,794 sf = 68.2% 2 Proposed Development The proposed project consists of construction of a 60 ft x 80 ft storage building, associated parking area. The proposed project will result in the following lot coverage: P osc+d Conditions Summa Development Area: 6.46 acres Building Coverage: 31,850 sf = 11.3 % Access Drive Coverage: 95,100 sf = 33.8 % Pervious Surface: 154,448 sf = 54.9% Construction Phasing The project sitework and building foundations will be constructed in one phase. Proposed Stormwater Management Stormwater from new building and parking area impervious surfaces will be directed to an existing infiltration pond to the south of the proposed addition. All new runoff will be infiltrated into the well- drained soils on the site. The new impervious surfaces will be directed to an infiltration trench adjacent to the access road. In the event of a storm event larger than the design storm, excess runoff will be directed to existing stormwater ponds adjacent to the access road on the Luzeme Holdings parcel. This stormwater report will address only the stormwater management of the new project area, the existing area that is contributory to the existing infiltration pond and the new access road. Pretreatment of all new runoff will occur in the grassed swales and grassed strips prior to entering the existing infiltration pond. Runoff from the north section of building roof will be directed to a grassed swale which will channel the runoff from the north side of the building to the west then to the south towards the existing infiltration basin. Runoff from the south side of the roof and all new parking will be directed to the south where it will be pretreated by the grassed strip and existing woods/brush buffer prior to entering the existing infiltration basin. The Hydro-Cad model provided clearly depicts the existing infiltration basin is adequately sized to handle all stormwater runoff from the northsection of existing storage building roofs and existing access drives and all proposed new impervious surfaces. Green Infrastructure Practices and Requirements As stated in the New York State Stormwater Management Design Manual, Section 3.2— Green Infrastructure for Stormwater Management "The objective is to replicate pre- development hydrology by maintaining pre-construction infiltration,peak runoff flow, 3 discharge volume, as well as minimizing concentrated flow by using runoff control techniques to provide treatment in a distributed manner before runoff reaches the collection system". Due to the permeable nature of the existing site soils (hydrologic soil group A), infiltration practices will be used to handle runoff from the entire developed site. Specific Green Infrastructure Practice goals are being addressed as follows: Plannina Practices for;Preservation of Natural Features and Conservation Preservation of undisturbed areas—The large section of existing woods and brush will be left undisturbed between the proposed addition and the existing infiltration basin allowing an undisturbed buffer and extended pretreatment of runoff prior to entering the existing infiltration basin. Reduction of clearing and grading—see above. Locating development in less sensitive areas—The proposed development is in a previously approved Commercial Light Industrial Subdivision. Open space design—project is located in high density industrial/commercial area of Queensbury where services are readily available. Judicious development in this high density area will relieve development on other areas of the town where open space is more valuable. Soil restoration—Existing soil on the proposed infiltration areas will be protected from use by heavy, rubber tired equipment during construction. All disturbed areas will be restored by deep ripping to maintain infiltration capabilities. Plannine Practices for Reduction of Impervious Cover Roadway reduction—There is no roadway construction involved in this project. Sidewalk reduction—There is no sidewalk construction proposed. Driveway reduction—Driveway length has been reduced as much as possible. Building footprint reduction—multi-story buildings are not appropriate for this use. Parking reduction—the proposed use requires large pavement areas for access to multiple storage units. 4 Runoff Reduction Since the existing soils are suitable for infiltrative stormwater practices, we are infiltrating 100% of WQv to achieve 100% RRv. Runoff Calculations • All computations SCS TR-20, HydroCAD * 10 year, 24 hour storm - Type II rainfall =4.54" 50 year, 24 hour storm- Type II rainfall=6.38" 100 year, 24 hour storm- Type II rainfall=7.40" • Infiltration basin percolation results = 1 minutes, 0 seconds per inch =60 inches per hour • Exfiltration rate used in Hydro-Cad= 10 inches per hour which is quite conservative HydroCAD calculations have been performed to determine the amount of runoff from the developed site. The developed site has been modeled as a series of subcatchments (discrete drainage areas), reaches and ponds as shown on the attached HydroCAD drainage diagram. The attached HydroCAD calculations show the stormwater routing for the site and summaries for each of the subcatchments, reaches and ponds. Water Quality Control Since all stormwater runoff is being infiltrated WQv calculations for each subcatchment and associated treatment device are redundant and WQv requirements are obviously being met. Channel Protection Volume The Cpv requirement does not apply when reduction of the entire Cpv volume has been achieved through green infrastructure practices. Overbank Flood Control Overbank flood control is required by the DEC Stormwater Management Design Manual. The overbank flood control requires that the peak discharge rate from the 10 year 24 hour storm be reduced to pre-development rates. All runoff from the 10-year design storm is being infiltrated. Therefore the design meets DEC criteria for overbank flood control. Town of Queensbury 50-Year Design Storm The Town of Queensbury Code requires that the peak discharge from the 50 year storm be reduced to pre-development rates. 5 All runoff from the 50-year design storm is being infiltrated. Therefore the design meets Town of Queensbury peak discharge criteria. Extreme Storm Control Extreme storm control is required by the DEC Stormwater Management Design Manual. The extreme storm control requires that the peak discharge from the 100 year storm be reduced to pre-development rates. All runoff from the 100-year design storm is being infiltrated. Therefore, the design meets DEC criteria for extreme storm control. Threatened or Endangered Species The proposed project will not adversely affect a listed or proposed to be listed, endangered or threatened species or its critical habitat. Documentation in the form of a Threatened or Endangered Species sign-off was provided when the Luzeme Road Light Industrial Park Subdivision was approved. Historical Places or Archaeological Resources It is believed that the proposed project will not adversely affect any properties listed or eligible to be listed on the National Register of Historic Places; nor will it affect any properties mapped as archaeologically sensitive by OPRHP. SHPO sign-off was provided when the Luzerne Road Light Industrial Park Subdivision was approved. Temporary Erosion and Sediment Control Measures Erosion and sediment control measures will be incorporated into the construction of the project. These practices will comply with the New York State Department of Environmental Conservation publication entitled "New York Guidelines for Urban Erosion and Sediment Control" (the blue book). Separate erosion and sediment controls will be installed for each phase of construction. The following temporary erosion and sediment control devices will be utilized. Sediment Control Fence: Silt fence shall be used to control erosion from sheet flow on slopes not to exceed 3 on 1. Concentrated flows shall not be directed toward the silt fence. The silt fence must be installed parallel to the contour lines to eliminate drainage along the fence. Temporary Sediment Tra Basins will be excavated below each construction site and seeded with ryegrass to accept stormwater runoff from the construction site allowing sediment to settle out. Sediment Traps shall be constructed in the location and be of the size and type specified to collect sediment laden stormwater. 6 TeMpgrary Seeding: Land that is stripped of vegetation will be seeded and planted as soon as possible. Any area that will remain cleared but not under construction for 10 days or longer will be seeded with a ryegrass mixture and mulched to stabilize soil until construction resumes. Toinporary Diversion Swales: Temporary diversion swales shall be constructed either to divert clean stormwater runoff from newly graded areas or to direct sediment laden runoff to a sediment trapping device. Stabilized Construction Entrance: Existing roads will be protected by installation of a crushed stone blanket for cleaning construction vehicle wheels. Blankets shall be placed at any intersection of a construction road with a paved or publicly owned road. Stabilized construction entrances shall be installed as necessary. Dust Control: Measures for dust control during construction shall be implemented as needed (daily water sprays will be used during dry conditions. In addition to water sprays, temporary mulching, temporary seeding and covering stockpiles with tarps shall be implemented when necessary. Control of Litter, Construction Debris and Construction Chemicals During the course of infrastructure and building construction, the site shall be kept clear of debris and litter which could be transported by water or wind. This material shall be picked up daily and shall be stored in waste debris containers where it is securely held. All petroleum products or other waste contaminants which are water soluble or could be dispersed and transported by stormwater shall be stored in covered containers and be regularly removed from the site and properly and legally disposed of. All petroleum or other hazardous materials shall be stored and handled in conformance with NYSDEC spill prevention and containment requirements. Sequence of Construction Sediment control fence will be installed along the low side of each area to be disturbed to contain runoff from the construction site. The area of the sediment basins shall be graded, topsoiled, seeded and mulched. The outlet structure and pipe between the settling basins shall be installed. During all site disturbance operations all stormwater runoff shall be directed into one of the three temporary sediment basins. The temporary sediment traps shall be a minimum of 3,600 cf per acre of disturbed area. The total site disturbance is 0.7 acres =2,520 cf of storage required. 7 After the site is stabilized, the sediment basins shall be cleaned out and final grades established as shown on the Grading and Drainage Plan. After the site is stabilized all drainage shall be directed into the permanent stormwater basins. Maintenance of Temporary Erosion and Sediment Control Devices The sediment traps shall be inspected at least weekly and after every rain event by the Contractor. When 50% of the volume of the trap is full, The Contractor shall remove collected sediment and dispose of properly. The Contractor shall inspect the sediment control fence weekly and after every rain event and remove trapped sediment and maintain the devices in good working order. Permanent Erosion Control All pervious areas shall be graded, topsoil installed and seeded or planted as soon as practical. Seed beds shall be mulched with straw or hydro-mulch with tackifier and plant beds shall be mulched with pine bark mulch. Seeded areas on slopes over 3:1 shall be stabilized with erosion control netting as specified on the plans. Post-Construction Operation and Maintenance of Stormwater Control Devices All portions of the stormwater control system shall be inspected on a periodic basis and shall be cleaned and/or repaired as appropriate. • Infiltration basins -Inspect and clean basins fall and spring. Keep grass cut short and repair all bare spots as soon as possible. Infiltration trench -Inspect and clean trench area in the fall & spring. Repair all wash out areas as soon as possible. Keep maintenance records showing dates and descriptions of all inspections and maintenance. Appendix ydroCAD ■ Post Development-Drainage Area Map & HydroCAD Diagram • Post Development Conditions— 10 Year Design Storm ■ Post Development Conditions—50 Year Design Storm Post Development Conditions— 100 Year Design Storm 8 A a. G Io C)"N' S'T DEVELOPMENT C"O"NDITIONS, DRAINAGE AREA PLAN HydroCAD DRAINAGE DIAGRAM ts �. EXISTING EXISTING NEW SUBCATCHMENT TO INFILTRATION POND SUBCTACHMENT TO POND POND /2P\ NEW ACCESS ROAD ACCESS ROAD INFILTRATION TRENCH �bjcs t� h Drslogige MW&rn for 47M-CLU'rE S MO ACCESS ROAD RCAMON !.Ink Prepared by{enter your company name here}, Printed 1!18/2018 HydroCAD®9.10 sh 03732 0 2010 F"roCAD Software Sdutions LLC 47392-CLUTE STORAGE ACCESS ROAD MODIFICATION Prepared by{enter your company name here) Printed 1/16/2018 HydroCAD89.10 s/n 03732 02010 HygroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 1.006 39 >75%Grass cover, Good, HSG A (1 S, 2S) 1.098 98 Paved parking 8 roofs (1 S, 2S) 0.382 98 Paved parking, HSG A (3S) 2.486 TOTAL AREA 47392-CLUTE STORAGE ACCESS ROAD MODIFICATION Prepared d bY{{enter company S } Printed 1/16/2018 HA9,10s/n 037320 20 0 H droCAD Software Solutions LIC Ban I Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 1.388 HSG A 1 S, 2S, 3S 0.000 HSG B 0.000 HSG C 0.000 HSG D 1.098 Other 1 S, 2S 2.486 TOTAL AREA V POST DEVELOPMENT CONDITIONS -YEAR DESIGN STORM o- 47392-CLUTE STORAGE ACCESS ROAD IMAODIFI Type 11 24-hr 10 YR STORM Rainfall=4.54" Prepared by {enter your company name here} Printed 1/16/2018 HydroCAD89,10 s/n 03732 02010 H droCAD Software Solutions LLC Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: EXISTING Runoff Area=46,386 sf 69.01% Impervious Runoff Depth>2.31" Flow Length=100' Slope=0.0100'/' Tc=6.0 min CN=80 Runoff=4.55 cfs 0.205 of Subcatchment 2S: NEW SUBCTACHMENT Runoff Area=45,263 sf 34.99% Impervious Runoff Depth>0.92" Flow Length=261' Tc=11.3 min CN=60 Runoff=1.43 cfs 0.080 of Subcatchment 3S: NEW ACCESS ROAD Runoff Area=16,640 sf 100.00% Impervious Runoff Depth>4.08" Flow Length=50' Slope=0.0200'/' Tc=6.0 min CN=98 Runoff=2.40 cfs 0.130 of Pond 113: EXISTING INFILTRATION POND Peak EIev=389.02' Storage=89 cf Inflow=5.68 cfs 0.284 of Outflow--5.68 cfs 0.284 of Pond 213: ACCESS ROAD INFILTRATION Peak EIev=0.02' Storage=0.000 of Inflow--2.40 cfs 0.130 of Discarded=2.40 cfs 0.130 of Primary--0.00 cfs 0.000 of Outflow--2.40 cfs 0.130 of Total Runoff Area=2.486 ac Runoff Volume= 0.414 of Average Runoff Depth =2.00" 40.45%Pervious= 1.006 ac 59.55%Impervious= 1.480 ac 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type 11 24-hr 10 YR STORM Rainfall=4.54" Prepared by{enter your company name here} Printed 1/16/2018 HygroCADO 9.10 s/n 03732 .0,,2010 HydroCAD Software 8olufions LI-C Summary for Subcatchment 1S: EXISTING SUBCATCHMENT TO POND Runoff = 4.55 cfs @ 11.97 hrs, Volume= 0.205 af, Depth> 2.31" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR STORM Rainfall=4.54" Area CN Description 8,117 98 Paved parking & roofs 23,891 98 Paved parking & roofs 14,377 39 >75% Grass cover. Good. HSG A 46,385 80 Weighted Average 14,377 30.99% Pervious Area 32,008 69.01% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 1.8 100 0.0100 0.90 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 1.8 100 Total, Increased to minimum Tc = 6.0 min Summary for Subcatchment 2S: NEW SUBCTACHMENT TO POND Runoff = 1.43 cfs @ 12.05 hrs, Volume= 0.080 af, Depth> 0.92" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 10 YR STORM Rainfall=4.54" Area JED CN Description 15,837 98 Paved parking & roofs 29,426 39 >75% Grass cover, Good HSG A 45,263 60 Weighted Average 29,426 65.01% Pervious Area 15,837 34.99% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 0.7 40 0.0200 0.99 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 9.0 60 0.0127 0.11 Sheet Flow, SHEET FLOW Grass: Short n= 0.150 P2= 2.40" 1.6 161 0.0127 1.69 Shallow Concentrated Flow, SHALLOW CONC. FLOW Grassed Waterway Kv= 15.0!g§ 11.3 261 Total 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type 1124-hr 10 YR STORM Rainfall=4.54" Prepared by{enter your company name here} Printed 1/16/2018 t3gLqCAD09,10 s/n 03732 ®2010 H droCAD Software Solutions LLC Page 9 Summary for Subcatchment 3S: NEW ACCESS ROAD Runoff = 2.40 cfs @ 11.96 hrs, Volume= 0.130 af, Depth> 4.08" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10 YR STORM Rainfall=4.54" Area (sf) CN Description 16 640 98 Paved parkigg,HSG A 16,640 100.00% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ftft/sec cfs 0.8 50 0.0200 1.04 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 0.8 50 Total, Increased to minimum Tc = 6.0 min Summary for Pond 1 P: EXISTING INFILTRATION POND Inflow Area= 2.104 ac, 52.21% Impervious, Inflow Depth > 1.62" for 10 YR STORM event Inflow = 5.68 cfs @ 11.98 hrs, Volume= 0.284 of Outflow = 5.68 cfs @ 11.99 hrs, Volume= 0.284 ef, Atten= 0%, Lag= 0.3 min Discarded = 5.68 cfs @ 11.99 hrs, Volume= 0.284 of Routing by Stor-Ind method,Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 389.02' @ 11.99 hrs Surf.Area=4,982 sf Storage= 89 cf Plug-Flow detention time= 0.3 min calculated for 0.284 of(100% of inflow) Center-of-Mass det. time= 0.2 min ( 795.1 - 794.9 ) Volume Invert Avail.Stora a Stora a Description #1 389.00' 15,965 cf Custom Stage Data (Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store feet (s-ft cubic-feet cubic-feet 389.00 4,937 0 0 390.00 7,480 6,209 6,209 391.00 12,032 9,756 15,965 Device Routin Invert Outlet Devices #1 Discarded 389.00' 55.000 In/hr Exfiltration over Surface area Mlscarded OutFlow Max=6.34 cfs @ 11.99 hrs HW=389.02' (Free Discharge) Exfiltration (Exfiltration Controls 6.34 cfs) 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type //24-hr 10 YR STORM Rainfall=4.54" Prepared by(enter your company name here) Printed 1/16/2018 H roCAD®9.10 s/n 03732 ®2010 H droCAD Softre Solutions LLC Summary for Pond 2P: ACCESS ROAD INFILTRATION TRENCH Inflow Area = 0.382 ac,100.00% Impervious, Inflow Depth > 4.08" for 10 YR STORM event Inflow = 2.40 cfs @ 11.96 hrs, Volume= 0.130 of Outflow = 2.40 cfs @ 11.96 hrs, Volume= 0.130 af, Atten= 0%, Lag= 0.0 min Discarded = 2.40 cfs @ 11.96 hrs, Volume= 0.130 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 0.02' @ 11.96 hrs Surf.Area= 0.067 ac Storage= 0.000 of Plug-Flow detention time= 0.0 min calculated for 0.130 of(100% of inflow) Center-of-Mass det. time= 0.0 min ( 714.4- 714.4 ) Volume Invert Avaii.Stora a Storage Descri tion #1 0.00' 0.001 of 3.50'W x 835.00'L x 3.00'H Prismatoid 0.201 of Overall x 0.4% Voids Device Routing Invert Outlet Devices #1 Discarded 0.00' 55.000 In/hr Fxfiltration over Surface area #2 Primary 3.00' 835.0' long x 2.0'breadth Broad-Crested Rectangular Weir -- Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 iscarded OutFlow Max=3.72 cfs @ 11.96 hrs HW=0.02' (Free Discharge) Exfiltration (Exfiltration Controls 3.72 cfs) trnary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' (Free Discharge) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) I P r a s 1 " H v roCAD RESUFI�L11" 50;-YEAR DESIGN STORM 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type 1124-hr 50 YR STORM Rainfall=6.38" Prepared by{enter your company name here} Printed 1/16/2018 HydroCADS9.10 s/n 03732 02010 H droCAD Software Solutions LLC page Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: EXISTING Runoff Area=46,385 sf 69.01% Impervious Runoff Depth>3.84" Flow Length=100' Slope=0.0100 'P Tc=6.0 min CN=80 Runoff=7.39 cfs 0.341 of Subcatchment 2S: NEW SUBCTACHMENT Runoff Area=45,263 sf 34.99% Impervious Runoff Depth>1.96" Flow Length=261' Tc=11.3 min CN=60 Runoff=3.21 cfs 0.170 of Subcatchment 3S: NEW ACCESS ROAD Runoff Area=16,640 sf 100.00% Impervious Runoff Depth>5.83" Flow Length=50' Slope=0.0200'P Tc=6.0 min CN=98 Runoff=3.38 cfs 0.186 of Pond 1P: EXISTING INFILTRATION POND Peak Elev=389.25' Storage=1,315 cf Inflow=10.09 cfs 0.511 of Outflow=7.10 cfs 0.511 of Pond 2P: ACCESS ROAD INFILTRATION Peak Elev=0.03' Storage=0.000 of Inflow--3.38 cfs 0.186 of Discarded=3.38 cfs 0.186 of Primary=0.00 cfs 0.000 of Outflow=3.38 cfs 0.186 of Total Runoff Area=2.486 ac Runoff Volume=0.696 of Average Runoff Depth=3.36" 40.45%Pervious= 1.006 ac 59.55° Impervious= 1.480 ac 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type 1124-hr 50 YR STORM Rainfall=6.38" Prepared by{enter your company, name here} Printed 1/16/2018 H droCA 9.10 /n 03 "32 2010 H droCAO S re SoIuticns LLC Summary for Subcatchment 1S: EXISTING SUBCATCHI4i'IENT TO POND Runoff = 7.39 cfs @ 11.97 hrs, Volume= 0.341 af, Depth> 3.84" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 50 YR STORM Rainfall=6.38" Area CN Description 8,117 98 Paved parking & roofs 23,891 98 Paved parking & roofs 14,377 39 >75% Grass cover, Good HSG A 46,385 80 Weighted Average 14,377 30.99% Pervious Area 32,008 69.01% Impervious Area Tc Length Slope Velocity Capacity Description min feet ftfft ftiec cfs 1.8 100 0.0100 0.90 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 1.8 100 Total, Increased to minimum Tc= 6.0 min Summary for Subcatchment 2S: NEW SUBCTACHIIENT TO POND Runoff = 3.21 cfs @ 12.04 hrs, Volume= 0.170 af, Depth> 1.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 50 YR STORM Rainfall=6.38" Areas CN Description 15,837 98 Paved parking & roofs 29,426 39 >75% Grass cover, Good HSG A 45,263 60 Weighted Average 29,426 65.01% Pervious Area 15,837 34.99% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 0.7 40 0.0200 0.99 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 9.0 60 0.0127 0.11 Sheet Flow, SHEET FLOW Grass: Short n= 0.150 P2= 2.40" 1.6 161 0.0127 1.69 Shallow Concentrated Flow, SHALLOW CONC. FLOW Grassed WatepAM Kv= 15.0-fps 11.3 261 Total 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type H 24-hr 50 YR STORM Rainfall=6.38" Prepared by(enter your company name here) Printed 1/16/2018 hydroCAD09.110 s/n 03732 02010 IH droCAD Software Solutions LLC Pagg 10 Summary for Subcatchment 3S: NEW ACCESS ROAD Runoff = 3.38 cfs @ 11.96 hrs, Volume= 0.186 af, Depth> 5.83" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt=0.05 hrs Type II 24-hr 50 YR STORM Rainfall=6.38" Area (sn CN Description 16 640 98 Paved parking, HSG A 16,640 100.00% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 0.8 50 0.0200 1.04 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2=2.40" 0.8 50 Total, Increased to minimum Tc=6.0 min Summary for Pond 1 P: EXISTING INFILTRATION POND Inflow Area = 2.104 ac, 52:21% Impervious, Inflow Depth > 2.91" for 50 YR STORM event Inflow = 10.09 cfs @ 11.98 hrs, Volume= 0.511 of Outflow = 7.10 cfs @ 12.06 hrs, Volume= 0.511 af, Atten= 30%, Lag=4.5 min Discarded = 7.10 cfs @ 12.06 hrs, Volume= 0.511 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 389.25' @ 12.06 hrs Surf.Area= 5,573 sf Storage= 1,315 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 0.7 min ( 784.8 - 784.0 ) Volume Invert Avail.Stora a Storage Description #1 389.00' 15,965 cf Custom Stage Data(Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store feet s -ft cubic-feet cubic-feet 389.00 4,937 0 0 390.00 7,480 6,209 6,209 391.00 12,032 9,756 15,965 Device Routin Invert Outlet Devices #1 Discarded 389.00' 55.000 in/hr Exflltration over Surface area iscarded OutFlow Max=7.017 cfs @ 12.06 hrs HW=389.24' (Free Discharge) Eflltration (ExriItration Controls 7.07 cfs) 47392-CLUTE STORAGE ACCESS ROAD MODIFI Type ll 24-hr 50 YR STORM Rainfall=6.38" Prepared by{enter your company name here} Printed 1/16/2018 H roCADO 9.10 s/n 03732 C 2010 H droCAD Software Solutions LLC Pam Summary for Pond 2P: ACCESS ROAD INFILTRATION TRENCH Inflow Area = 0.382 ac,100.00% Impervious, Inflow Depth > 5.83" for 50 YR STORM event Inflow = 3.38 cfs @ 11.96 hrs, Volume= 0.186 of Outflow = 3.38 cfs @ 11.96 hrs, Volume= 0.186 af, Atten= 0%, Lag= 0.0 min Discarded = 3.38 cfs @ 11.96 hrs, Volume= 0.186 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Rooting by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0,.05 hrs Peak Elev= 0.03' @ 11.96 hrs Surf.Area= 0.067 ac Storage= 0.000 of Plug-Flaw detention time= 0.0 min calculated for 0.185 of(100% of inflow) Center-of-Mass det. time= 0.0 min ( 709.1 -709.1 ) Volume Invert Avail.Stora a Storage Description #1 0.00' 0.001 of 3.50'W x 835.Q0'L x 3.00'H Prismatold 0.201 of Overall x 0.4% Voids Device Routing Invert Outlet.Devices #1 Discarded 0.00' 55.000 In/hr Exfiltration over Surface area #2 Primary 3.00' 835.0' long x 2.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 Mlsca�rded OutFlow Max=3.72 cfs @ 11.96 hrs HW=0.03' (Free Discharge) Exfiltration (Exfiltration Controls 3.72 cfs) mary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' (Free Discharge) �ri 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) F nydroCAD RESULTS 100-YEAR DESIGN STORM o- I 47392-CLUTE STORAGE ACCESS ROAD MODI Type 1124-hr 100 YR STORM Rainfall=7.40" Prepared by{enter your company name here} Printed 1/16/2018 H droCAD 9410 s/n 03732 0 2010 H droCAD Software Solutions LLC Pjge 12 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 13: EXISTING Runoff Area=46,385 sf 69.01% Impervious Runoff Depth>4.73" Flow Length=100' Slope=0.0100 'P Tc=6.0 min CN=80 Runoff=8.99 cfs 0.420 of Subcatchment 2S: NEW SUBCTACHMENT Runoff Area=45,263 sf 34.99% Impervious Runoff Depth>2.62" Flow Length=261' Tc=11.3 min CN=60 Runoff=4.33 cfs 0.227 of Subcatchment 3S: NEW ACCESS ROAD Runoff Area=16,640 sf 100.00% Impervious Runoff Depth>6.80" Flow Length=50' Slope=0.0200 'P Tc=6.0 min CN=98 Runoff=3.92 cfs 0.216 of Pond 1P: EXISTING INFILTRATION POND Peak Elev=389.47' Storage=2,589 cf Inflow=12.68 cfs 0.647 of Outflow--7.80 cfs 0.647 of Pond 213: ACCESS ROAD INFILTRATION Peak Elev=2.05' Storage=0.001 of Inflow--3.92 cfs 0.216 of Discarded=3.79 cfs 0.217 of Primary--0.00 cfs 0.000 of Outflow--3.79 cfs 0.217 of Total Runoff Area= 2.486 ac Runoff Volume=0.863 of Average Runoff Depth=4.17" 40.48%Pervious= 1.006 ac 59.55%Impervious= 1.480 ac 47392-CLUTE STORAGE ACCESS ROAD MODI Type 11 24-hr 100 YR STORM Rainfall=7.40" Prepared by{enter your company name here} Printed 1/16/2018 HygroCAQ0,9.10 s/n 03732 02010 H droCAD Software Solutions LLC Ent 13 Summary for Subcatchment 1S: EXISTING SUBCATCHMENT TO POND Runoff = 8.99 cfs @ 11.97 hrs, Volume= 0.420 af, Depth> 4.73" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt=0.05 hrs Type 11 24-hr 100 YR STORM Rainfall=7.40" Areas CN Description 8,117 98 Paved parking & roofs 23,891 98 Paved parking & roofs 14,377 39 >75% Grass cover, Good HSG A 46,385 80 Weighted Average 14,377 30.99% Pervious Area 32,008 69.01% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ftft/sec cfs 1.8 100 0.0100 0.90 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 1.8 100 Total, Increased to minimum Tc = 6.0 min Summary for Subcatchment 2S: NEW SUBCTACHMENT TO POND Runoff = 4.33 cfs @ 12.04 hrs, Volume= 0.227 af, Depth> 2.62" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100 YR STORM Rainfall=7.40" Area J§n CN Description 15,837 98 Paved parking & roofs 29 426 39 >75%Grass cover, Good HSG A 45,263 60 Weighted Average 29,426 65.01% Pervious Area 15,837 34.99% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft f sec cfs 0.7 40 0.0200 0.99 Sheet Flow, SHEET FLOW Smooth surfaces n= 0.011 P2= 2.40" 9.0 60 0.0127 0.11 Sheet Flow, SHEET FLOW Grass: Short n= 0.150 P2= 2.40" 1.6 161 0.0127 1.69 Shallow Concentrated Flow, SHALLOW CONC. FLOW Grassed Waterway Kv= 15.0 fps 11.3 261 Total 47392-CLUTE STORAGE ACCESS ROAD NODI Type /124-hr 100 YR STORM Rainfall=7.40" Prepared by{enter your company name here} Printed 1/16/2018 jjydroCAD09.10 s/n 03732 02010 HydroCAD Software Solutions LLC Bage 14 Summary for Subcatchment 3S: NEW ACCESS ROAD Runoff = 3.92 cfs @ 11.96 hrs, Volume= 0.216 af, Depth> 6.80" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100 YR STORM Rainfall=7.40" Area (sn CN Description 16,640 98 Paved parking, HSG A 16,640 100.00% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 0.8 50 0.0200 1.04 Sheet Flow, SHEET FLOW Smooth surfaces n=0.011 P2= 2.40" 0.8 50 Total, Increased to minimum Tc = 6.0 min Summary for Pond 1 P: EXISTING INFILTRATION POND Inflow Area = 2.104 ac, 52.21% Impervious, Inflow Depth > 3.69" for 100 YR STORM event Inflow = 12.68 cfs @ 11.98 hrs, Volume= 0.647 of Outflow = 7.80 cfs @ 12.08 hrs, Volume= 0.647 af, Atten= 38%, Lag= 5.6 min Discarded = 7.80 cfs @ 12.08 hrs, Volume= 0.647 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 389.47' @ 12.08 hrs Surf.Area= 6,127 sf Storage= 2,589 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 1.5 min ( 781.0-779.5 ) Volume Invert Avail.Stora a Storage Description #1 389.00' 15,965 cf Custom Stage Data (Prismatic) Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store feet s -ft cubic-feet cubic-feet 389.00 4,937 0 0 390.00 7,480 6,209 6,209 391.00 12,032 9,756 15,965 Device Routin Invert Outlet Devices #1 Discarded 389.00' 55.000 in/hr Wiltration over Surface area MIscarded0utFlow Max=7.77 cfs @ 12.08 hrs HW=389.46' (Free Discharge) E filtration (ExfiItration Controls 7.77 cfs) 47392-CLUTE STORAGE ACCESS ROAD MODI Type // 24-hr 100 YR STORM Rainfall=7.40" Prepared by{enter your company name here} Printed 1/16/2018 H droCAD®9.10 s/n 03732 0 2010 H droCAD Software Solutions LLC Poge 1§ Summary for Pond 2P: ACCESS ROAD INFILTRATION TRENCH Inflow Area = 0.382 ac,100.00% Impervious, Inflow Depth > 6.80" for 100 YR STORM event Inflow = 3.92 cfs @ 11.96 hrs, Volume= 0.216 of Outflow = 3.79 cfs @ 11.98 hrs, Volume= 0.217 af, Atten= 3%, Lag= 0.8 min Discarded = 3.79 cfs @ 11.98 hrs, Volume= 0.217 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routing by Stor-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peals Elev= 2.05' @ 11.99 hrs Surf.Area= 0.067 ac Storage= 0.001 of Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-oaf-Mass det. time= 0.0 min ( 707.1 - 707.0 ) Volume Invert Avail.Stora a Storage Description #1 0.00' 0.001 of 3.50'W x 835.00'L x 3.00'H Prismatoid 0.201 of Overall x 0.4% Voids Device Routing Invert Outlet Devices #1 Discarded 0.00' 55.000 In/hr Exfiltration over Surface area #2 Primary 3.00' 8X0' long x 2.0' breadth Basad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85 3.07 3.20 3.32 iscarded OutFlow Max=3.72 cfs @ 11.98 hrs HW=1.67' (Free Discharge) Exfiltration (Exfiltration Controls 3.72 cfs) "rimary OutFlow Max=0.00 cfs @ 0.00 hrs HW=0.00' (Free Discharge) 2 Broad-Cres regular Weir ( Controls 0.00 cfs)