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HomeMy WebLinkAboutApplication - 316 GREAT POND ROAD 3/10/2014 Sullivan Engineering Group, LLC Civil Engineers&Land Development Consultants March 10, 2014 Town of North Andover Planning Board c/o Judith Tymon- Town Planner 1600 Osgood Street North Andover, MA 01 845 Re: Watershed Special Permit Application 316 Great Pond Road, North Andover Ms. Tymon; On behalf of the owner/applicant,Bill Karras, I am submitting an application to the Planning Board for a Watershed Special Permit for the above referenced site. Enclosed for your review are the following items: 1) A completed Application for Watershed Special Permit. 2) A check for$300.00 payable to the Town of North Andover 3) A certified abutter's list 4) Engineering calculations for sizing the proposed crushed stone drip trench surrounding the pool/patio. 5) A Proposed Site Development Plan for 316 Great Pond Road prepared by Sullivan Engineering Group, LLC scale 1"=20', dated March 5, 2014 6) A check for$2,000.00 payable to the Town of North Andover for the review consultant fee. If you should have any questions or require additional information please feel free to contact me. Very T y Yours, Xc k ivan,P.E. Attachments (as noted) 22 Mount Vernon Road — Boxford,Massachusetts 01921 — (978)352-7871-Phone — 978352-7871 -Fax Print Form peRTa o m- � n � SgCHtlg�t PLANNING DEPARTMENT Community Development Division ecial Permit— VSlater�hed Permit A licati®n Please type or print clearly. 1.Petitioner:Bill Karras Petitioner's Address:316 Great Pond Road,North Andover Telephone number:781-883-9588(E-mail:316bilika @gmail.com) 2.Owners of the Land: Bill Karras Address: 1316 Great Pond Road, North Andover Number of years of ownership:2 years(Purchased on 313/12) 3.Year lot was created: 1986 4. Is the lot currently on septic or sewer? SNE9 If on sewer,please provide date the sewer connection was completed:1992 5.Description of Proposed Project: The applicant is proposing to construct an inground pool,patio,shed,fence,and landscaping within the 100 foot Non-Disturbance Zone. 6. Description of Premises:54,962 s.f. developed lot with residential dwelling and deck 7.Address of Property Being Affected:316 Great Pond Road Zoning District: R1 (within Watershed Protection District) Assessors Map:37A Lot#:53 Registry of Deeds:Book* 12880 Page#:91 8.Existing Lot: g a 35 feet Lot Area(Sq.Ft): 54,962 Buildin g Height: 151.83 feet Side Setbacks:30.3 feet Street Frontage: Front Setback:122 feet Rear Setback: 103 feet Floor Area Ratio:n/a Lot Coverage.n/a 9.Proposed Lot(if applicable): Building Height: Lot Area(Sq.Ft): Side Setbacks: Street Frontage: Page 1 of 2 1600 Osgood Street,North Andover,Bldg.20,Suite 2-36 Planning Dept.,Massachusetts 01845 Phone 978.688.9535 Fax 978.688.9542 Web www.townofnorthandover.com Edited 8/6/07 Front Setback: Rear Setback: Floor Area Ratio: Lot Coverage: 10.Required Lot(as required by Zoning Bylaw): Lot Area(Sq.Ft):87,120 s.f. Building Height:35 feet max. Street Frontage: 175 ft Side Setbacks:30 feet Front Setback:30 feet Rear Setback:30 feet Floor Area Ratio:n/a Lot Coverage:n/a 11.Existing Building(if applicable): Ground Floor(Sq.Ft.): 1220 #of Floors:2 Total Sq.Ft.:3112 Height:<35 feet Use:Single Family Residential Type of Construction:Wood Frame 12.Proposed Building: Ground Floor(Sq.Ft.): #of Floors: Total Sq.Ft. Height: Use:Accessory Inground Pool Type of Construction:Gunite 13.Has there been a previous application for a Special Permit from the Planning Board on these premises? If so,when and for what type of construction? 14.Section of Zoning Bylaw that Special Permit Is Being Requested 4.136 (3)C6 15.Petitioner and Landowner signature(s): Every application for a Special Permit shall be made on this form, which is the official form of the Planning Board. Every application shall be filed with the Town Clerk's office. It shall be the responsibility of the petitioner to furnish all supporting documentation with this application. The dated copy of this application received by the Town Clerk or Planning Office does not absolve the applicant from this responsibility. The petitioner shall be responsible for all expenses for filing and legal notification. Failure to comply with application requirements, as cited herein and in the Planning Board Rules and Regulations may result in a dismissal by the Planning Board of this application as incomplete. Petitioner's Signature: ; Print or type name here: B arras Owner's Signature: Print or type name here: arras 16.Please list title of plans and documents you will be attaching to this application. 1) Site Development Plan of Land prepared by Sullivan Engineering dated 3/5/14,scale V=20' Page 2 of 2 1600 Osgood Street,North Andover,Bldg.20,Suite 2-36 Planning Dept.,Massachusetts 01845 Phone 978.688.9535 Fax 978.688.9542 Web www.townoftnorthnndover.com Edited 816/07 Sullivan Engineering Group, LLC Civil Engineers&Land Development Consultants Watershed Special Permit Application 316 Great Pond Road, North Andover To: North Andover Planning Board From: Jack Sullivan, P.E. Date: March 10, 2014 Subject: 316 Great Pond Road—Written Support for Project Planning Board Members: The following written summary is prepared on behalf of the owner/applicant, Bill Karras,in support of constructing an inground pool,patio, shed, and associated landscaping. This lot was created prior to 1994 (created in 1986). The applicant is filing with the North Andover Conservation Commission concurrently since a portion of the above referenced work falls within 100 feet of a bordering vegetated wetland. All the work is outside of 400 feet to Lake Cochichewick. Since a portion of the work falls within the 100 foot"Non- Disturbance"watershed boundary a special permit is being sought from the North Andover Planning Board. The following items as outlined in the Watershed Special Permit requirements are listed below(responses required items are in italic); q sted below to 1. Encouraging the most appropriate use of land This site is zoned residential and the proposed site development items listed above are appropriate and allowed uses for this parcel. The proposed construction is located over a previously disturbed area 2. Preventing overcrowding of land The proposed accessory structures (pool and shed) conforms to zoning requirements and is greater than 440 feet from the Lake. 3. Conserving the value of land and buildings. The proposed site development will enhance surrounding building and land values, while being aesthetically pleasing. 4. Lessening congestion of traffic This project will not increase traffic congestion since this is a single family dwelling with limited trips per day. The number of residents within the household has not changed, therefore the number of vehicle trips. 5. Preventing undue concentration of population This project is consistent with surrounding property uses and as such will not have a measurable impact on population. 6. Providing adequate light and air There will be no adverse impact to current background air and light levels. 22 Mount Vernon Road — Bo x ,Masachuetts s 01921 — (978)352-7871-Phone 978 352-7871 -Fax 7. Reducing the hazards from fire and other danger. There will be no increase in hazard levels from fire or other dangers. 8. Assisting in the economical provisions of transportation, water, sewerage, schools, parks, and other public facilities. This project will not impact the above noted public facilities and/or utilities. There will not be a negative impact to the economics of any public utility. 9. Controlling the use of bodies of water, including watercourses: This project does not directly abut the Lake and will not have a negative impact on present uses of the Lake or tributaries thereto. 10. Reducing the probability of losses resulting from floods: This property is not located within a designated Flood Plain as shown as the latest FIRM maps. The proposed construction will utilize drainage mitigation to collect &recharge stormwater runoff back to the groundwater table. There will be no increase of stormwater runoff from this site. There will be no increase in flooding probability due to the development of the property. 11. Reserving and increasing the amenities of the Town This project will increase the amenities of the Town through an improvement to the property and additional tax revenue due to the new construction assessment. The Planning Board, in reviewing this application, will note that all threshold requirements for granting the Special Permit are met and/or exceeded. Further written documentation is provided below(responses to required items are in italics) 1. Written certification by a Registered Professional Engineer, or other scientist educated in and possessing extensive experience in the science of hydrology and hydrogeology, stating that there will not be any significant degradation of the quality or quantity or water in or entering Lake Cochichewick. 1) No pesticides,fungicides, chemicals, or non-organic fertilizers will be used in lawn care or maintenance. Presently, there are no limitations on the type or quantity offertilizers. 2) Siltation controls are proposed at the limit of work during construction and until the site is final stabilized by landscaped means to protect the lake and surrounding properties from any potential runoff impacts. 3) Stormwater mitigation has been provided to account for the pool and patio area Runoff associated with these surfaces will be conveyed to a crushed stone drip trench. 4) The existing dwelling is connected to the municipal sewer system; therefore there will be no potential increase in nitrogen levels over the existing background levels at the property. 5) This site does not directly abut the lake. Additionally, natural wooded buffers will be retained within 25 feet of all wetland resource areas. A portion of the 25 foot buffer zone which is presently grass in the rear yard will be planted with 20 shrubs and a wildflower seed mixture to establish a `natural' buffer to the wetland resource area. 6) Carefully planning went into the pool layout to limit site grading changes and to match the existing topography. By limiting the grading changes onsite, existing drainage watercourses will continue to function as in the undeveloped state. 2. Proof that there is no reasonable alternative location outside the Non-Disturbance and/or Non-Discharge Buffer Zones, whichever is applicable, for any discharge, structure, or activity, associated with the proposed use to occur. 22 Mount Vernon Road — Boxford,Massachusetts 01921 — (978)352-7871-Phone — 978352-7871 -Fax Over 95%of the subject property falls within the Non-Disturbance zone. The majority of the area outside the Non-Disturbance zone is presently a paved driveway. The area outside the Non- Disturbance zone is insufficient in area to accommodate the pool/patio project. 3. Evidence of approval by Mass DEP of any industrial waste water treatment or disposal system or any waste water treatment of system 15,000 GPD capacity. This item does not apply to this site. 4. Evidence that all on-site operations including,but not limited to, construction,water water disposal, fertilizer applications,and septic systems will not create concentrations of Nitrogen in groundwater, greater than the federal limit at the downgradient property boundary. The existing dwelling is connected to the municipal sewer system and the deed restriction only allowing organic or slow-release nitrogen,phosphorus free produce for fertilizer use will insure that background nitrogen levels in the groundwater table will not be increased. 5. Projections of downgradient concentrations of nitrogen,phosphorus, and other relevant chemicals at property boundaries and other locations deemed pertinent by the SPGA. There will be no downgradient concentration of the above referenced chemicals as outlined in the response to Item 4 above. If you should have any questions or require additional information please feel free to contact me. Very Tru Yours, Jack ul , E. Attachments (as noted) Cc: Bill Karras, Owner 22 Mount Vernon Road — Boxford, Massachusetts 01921 — (978)352-7871-Phone — 978352-7871 -Fax AbwBer to Abutter( )BuUMV Dept ( )Canservafb ( ) Zonog ( 1 REOUIREMENr: VGt 40A Sr;:w 11 eta:es'n pan'Partes m'.nn:est a9 sea n mss toad r mar mean me Ccatmcr. .N,r,__of lard W.t,,opMtlron any(RrAK«pma:e way.and abu7ers to aW:teS wN.ts rrco rvrp'od(300)loot Q,'?o acpem r e of the pets—as trot appex on 9.e most rttent apVs Vo w h5,not vtt wW dnq mat mo'and of ary such—1 11:ocatpd'tn anamet cry«town.me ptwM'1 roattl at merry«tam+,and ma o'enn.g ooaro of_Y aown9 sublect ProurN: MAP PARCEL Name Address 37.A 53 Bill Karras 316 Great Pond Road North Andover,MA 01645 Abutters Properties Mao Parcel Name Address 37.A 3 William O'Brien 326 Great Pond Road North Andover,MA 01845 37.A 5 Ismail Erhan 350 Great Pond Road North Andover,MA 01845 37.A 6 Anthony Dinapoli 254 Great Pond Road North Andover,MA 01845 37.A 6-0000.A Town of North Andover 120 Main Street North Andover,MA 01845 37.A 8 Christopher Brown 25 Castlemere Place North Andover,MA 01845 37.A 10 JMB Realty Trust 325 Great Pond Road North Andover,MA 01845 37.A 11 Luis Lopez-Algarra 2 Marbleridge Road North Andover,MA 01845 37.A 12 Roger La Fauci 16 Marbleridge Road North Andover,MA 01845 37.A 35 C.George 10 Castlemere Place North Andover,MA 01845 37.A 41 Robert Cuomo 45 Castlemere Place North Andover,MA 01845 37.A 52 James Cavallaro 20 Castlemere Place North Andover,MA 01845 37.A 56 Nancy Leland 254 Great Pond Road North Andover,MA 01845 37.A 57 Nancy Leland 254 Great Pond Road North Andover,MA 01845 37.A 58 Nancy Leland 254 Great Pond Road North Andover,MA 01845 37.A 59 Nancy Leland 254 Great Pond Road North Andover,MA 01845 37.0 11 Kingfish Trust 11 Marbleridge Road North Andover,MA 01845 Date 3''372014 page 1 of 1 s?hat the names appearing on the n Assessors Office as of Gerd fiett b ' Date 3 Sullivan Engineering Group, LLC Civil Engineers&Land Development Consultants March 10, 2014 Town of North Andover Planning Department Re: 316 Great Pond Road, North Andover Drainage Mitigation for Pool/Patio project in Watershed Planning Department; The owner, Bill Karras, of 316 Great Pond Road is proposing to construct an inground, gunite pool with a pool patio consisting of pervious pavers within the watershed of Lake Cochichewick. A conservation approach has been taken in planning/designing the drainage mitigation for this project. The inground pool, although "impervious"would not create surface water runoff to down gradient areas since the pool typically is not at full volume. It would be an extreme case that the pool would ever overtop. The pool patio will be constructed with pervious pavers with some degree of infiltration being provided between the spacing between the patio blocks to an underlying stone bedding system. The drainage design assumes the worst case scenario...that the pool is overtopping and the patio surface is impervious. A 2' x 2' crushed stone infiltration trench is proposed surrounding the pool patio edging. This crushed stone trench has been sized to store and infiltrate the entire 100 Year Storm event. HydroCAD calculations have been provided demonstrating the crushed stone trench is capable of storingdnfiltrating the 2, 10, and 100 year storm event. Sincerely, Jo iv , .E. Cc: Bill Karras, Owner 22 Mount Vernon Road — Boxford,Massachusetts 01921 — (978)352-7871-Phone — 978 352-7871 -Fax { i� Y'fC Pool/Patio Area 2'x2' Crushed Stone Infiltation Trench Reach On Link Drainage Diagram for 316 Great Pond Road Y},;'S ❑ Prepared by Sullivan Engineering Group,.-- 9 9 , LLC 3/10/2014 p HydroCADO 7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 316 Great Pond Road Type /// 24-hr 2 yr Rainfall=3.10" Prepared by Sullivan Engineering Group, LLC Page 2 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 3/10/2014 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1 S: Pool/Patio Area Runoff Area=2,035 sf Runoff Depth=2.68" Tc=6.0 min CN=98 Runoff--0.14 cfs 455 cf Pond 1P: 2'x2' Crushed Stone Infiltation Trench Peak Elev=102.54' Storage=77 cf Inflow=0.14 cfs 455 cf Outflow=0.04 cfs 455 cf Total Runoff Area= 2,035 sf Runoff Volume=455 cf Average Runoff Depth=2.68" 316 Great Pond Road Type 11124-hr 2 yr Rainfall=3.10" 3 Prepared by Sullivan Engineering Group, LLC 3/1 Page age 3 H droCADO 7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems Subcatchment 1S: Pool/Patio Area Runoff = 0.14 cfs @ 12.09 hrs, Volume= 455 cf, Depth= 2.68" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2 yr Rainfall=3.10" Areas CN Description 2,035 98 Roof Area to Drywell Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 6.0 Direct Entry, From Pool/Patio Subcatchment 1 S: Pool/Patio Area Hydrograph Runoff 0.15 AI cfs 0.14 Type III 24-hr 2 yr 0.13 0.12 _ Rainfall=31.0" 0.1, Runoff-Area=25035 sf 0.1 0.09 Runoff Vol u me=45 5 cf 0.08 Runoff Depth=2.68" 0.07 U. Tc=6.0 min 0.06 - - 0.05 CN=98 0.04 0.03 0.02 0.01 0 5 6 7 8 9 10 11 J'3. 14 15 16 17 18 19 Time (hours) 316 Great Pond Road Type 11124-hr 2 yr Rainfall=3.10" Prepared by Sullivan Engineering Group, LLC Page 4 H droCAD®7.00 s/n 001433 © 1986-2003 Applied Microcom uter Systems 3/10/2014 Pond 1P: 2'x2' Crushed Stone Infiltation Trench Field Percolation Rate of Soil = 12 MPI Inflow Area = 2,035 sf, Inflow Depth = 2.68" for 2 yr event Inflow = 0.14 cfs @ 12.09 hrs, Volume= 455 cf Outflow - 0.04 cfs @ 11.85 hrs, Volume= 455 cf, Atten= 69%, Lag= 0.0 min Discarded = 0.04 cfs @ 11.85 hrs, Volume= 455 cf Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 102.54' @ 12.40 hrs Surf.Area= 362 sf Storage= 77 cf Plug-Flow detention time= 9.0 min calculated for 455 cf(100% of inflow) Center-of-Mass det. time= 8.8 min (747.7 -738.9) # Invert Avail.Stora a Storage Description 1 102.00' 290 cf 2.00'W x 181.00%x 2.00'H Prismatoid 724 cf Overall x 40.0% Voids # Routing Invert Outlet Devices 1 Discarded 0.00' 0.006944 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.04 cfs @ 11.85 hrs HW=102.03' (Free Discharge) t-1=Exfiltration (Exfiltration Controls 0.04 cfs) Pond 1 P: 2'x2' Crushed Stone Infiltation Trench Hydrograph ®Inflow 0.15 0.1a ers Discarded 0.14 Inflow Area=21035 Sf 0.13 Peak Elev=102.54' Storage--77 Cf 0.1 0.09 -°- 0.08 c 0.07 LL - - 0.06 0.05 0.04 as 0.04 0.03 0.02 0.01 0 5 6 7 8 9 10 11 Time (hours) 14 15 16 17 18 19 20 316 Great Pond Road Type 111 24-hr 10 yr Rainfall=4.80" Prepared by Sullivan Engineering Group, LLC Page 5 HydroCADO 7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 3/10/2014 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pool/Patio Area Runoff Area=2,035 sf Runoff Depth=4.24" Tc=6.0 min CN=98 Runoff--0.21 cfs 718 cf Pond 1P: 2'x2' Crushed Stone Infiltation Trench Peak Elev=103.25' Storage=181 cf Inflow=0.21 cfs 718 cf Outflow=0.04 cfs 718 cf Total Runoff Area= 2,035 sf Runoff Volume=718 cf Average Runoff Depth=4.24" Type ///24-hr 10 yr Rainfall=4.80" 316 Great Pond Road Page 6 Prepared by Sullivan Engineering Group, LLC 3/10/2014 H droCADC�7.00 s/n 001433 ©1986-2003 Applied Microcom uter S stems Subcatchment IS: Pool/Patio Area Runoff = 0.21 cfs @ 12.09 hrs, Volume= 718 cf, Depth= 4.24" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 yr Rainfall=4.80" Areas CN Descri tion 2,035 98 Roof Area to Drywell Tc Length Slope Velocity Capacity cfs Description min feet ft/ft ft/sec Direct Entry, From PoollPatio 6.0 Subcatchment 1S: Pool/Patio Area Hydrograph Runoff 0.23 02 cts - 0.22 Type 11124-hr 10 yr 0.21 Rainfall=4.80 " 0.19 0.17 Runoff Area=21,035 Sf 0.16 0.15 Runoff Volume=718 Cf .. 0.14 0.13 Runoff-Depth=4.24" 0.12 0.11 TC=6.0 min u 0.1 0.09 CN=98 0.08 0.07 0.06 - 0.05 - 0.04 0. 0.003 2 0.01 0 9 10 11 12 13 14 15 16 17 18 19 20 5 6 7 8 Time (hours) Type 11124-hr 10 yr Rainfall=4.80" 316 Great Pond Road Page 7 Prepared by Sullivan Engineering Group, LLC 3/10/2014 Hydro r'A r-i 7.00 s/n 001433 ©1986-2003 plied Microcomputer S stems Pond 1 P: 2'x2' Crushed Stone Infiltation Trench Field Percolation Rate of Soil = 12 MPI Inflow Area = 2,035 sf, Inflow Depth = 4.24" for 10 yr event Inflow 0.21 cfs @ 12.09 hrs, Volume= 718 cf = Outflow = 0.04 cfs @ 11.70 hrs, Volume= 718 cf, Atten= 80%, Lag= 0.0 min 718 cf Discarded = 0.04 cfs @ 11.70 hrs, Volume= Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 103.25' @ 12.52 hrs Surf.Area= 362 sf Storage= 181 cf Plug-Flow detention time= 23.7 min calculated for 716 cf(100% of inflow) Center-of-Mass det. time= 23.3 min (758.7-735.4) # Invert Avail.Stora a Stora a Descri tion 1 102.00' 290 cf 2.00'W x 181.00'L x 2.00'H Prismatoid 724 cf Overall x 40.0%Voids # Routin Invert Outlet Devices 1 Discarded 0.00' 0.006944 fpm Exfiltration over entire Surface area Discarded OutFlow Max--0.04 cfs @ 11.70 hrs HW=102.02' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0.04 cfs) Pond 1P: 2'x2' Crushed Stone Infiltation Trench Hydrograph ■Inflow p Discarded 021 ds 0.23 - Inflow-Area=2,035 sf 0.22 0021 0.2 - Peak Elev=103.25' 0.19 0.13 Storage-181 cf 0.17 0.16 0.15 a 0.14 - 0.13 0.12 0 0.11 - a 0.1 - 0.09 0.08 0.07 0.06 0.04 ds 0.05 0.04 0.03 0.02 0.01 0 8 9 10 11 12 13 14 15 16 17 18 19 20 5 6 7 Time (hours) Type Ill 24-hr 100 yr Rainfall=6.408' M6 Great Pond Road 3/1 age 8 Prepared by Sullivan Engineering Group, LLC H droCAD®7.00 s/n 001433 ©1986-2003 A lied Microcomputer S stems Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=2,035 sf Runoff Depth=5.69" Subcatchment 1S: Pool/Patio Area Tc=6.0 min CN=98 Runoff--0.29 cfs 965 cf k Elev=103.98' Storage=287 cf lnflow=0.29 cfs 965 cf Pond 1P• 2 x2 ' Crushed Stone Infiltation Trench Pea outflow=0.04 cfs 965 cf . Total Runoff Area= 2,035 sf Runoff Volume=965 cf Average Runoff Depth = 5.69" Type III 24-hr 100 yr Rainfall=640" Page 9 316 Great Pond Road Group, LLC 311012014 Prepared by Sullivan Engineering oCAp®7.00 sln 001433 ©1986-2003 A lied Microcom uter System H dr Subcatchment 1S: PoollPatio Area 12.09 hrs, Volume= 965 cf, Depth= 5.69" Runoff = 0.29 cfs @ UH=SCS,Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Runoff by SCS TR-20 Rainfall=Type III 24-hr 100 y Ra Areas CN Descri tion 2,035 98 Roof Area to Drywell Slope Velocity Capacity Description Tc Length ft/ft ft/sec cfs From Pool/Patio min Direct Entry, 6.0 Subcatchment 1 S: Pool/Patio Area Hydro graph ®Runoff 0.32 FO-29 de Type 11124-hr 100 yr 0.3 0.28 Rainfall=6.40" 0.26 0.24 Runoff Area=2,035 Sf 0.22 Runoff Volume=965 cf 0.2 th=5.69'. 0.18 Runoff Dep 016 - Tc=6.0 min M 0.14 - CN=98 0.12 - 0.1 0.08 0.06 0.04 0.02 13 14 15 16 17 18 19 20 11 12 0 5 6 7 8 g 10 Time (hours) Type III 24-hr 100 yr Rainfall=6.40" 316 Great Pond Road Page 10 Prepared by Sullivan Engineering Group, LLC 3/10/2014 H droCADO 7.00 s/n 001433 ©1986-2003 A lied Microcomputer S stems Pond 1 P: 2'x2' Crushed Stone Infiltation Trench Field Percolation Rate of Soil = 12 MPI Inflow Area = 2,035 sf, Inflow Depth = 5.69" for 100 yr event 0.29 cfs @ 12.09 hrs, Volume= 965 cf Inflow = 965 cf, Atten= 85%, Lag= 0.0 min Outflow = 0.04 cfs @ 11.65 hrs, Volume= g65 cf Discarded = 0.04 cfs @ 11.65 hrs, Volume= Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 103.98' @ 12.59 hrs Surf.Area= 362 sf Storage= 287 cf Plug-Flow detention et time=41.5 min (775.4 calculated 733.9)5 cf( 100% of inflow) Center-of-Mass # Invert Avail.Stora a Stora a Descri tion 1 102.00' 290 cf 2.00'W x 181.00'L x 2.00'H Prismatoid 724 cf Overall x 40.0%Voids # Routing Invert Outlet Devices 1 Discarded 0.00' 0.006944 fpm Exfiltration over entire Surface area �iscarded OutFlow�Iltraf.04 cfsr @s 11.65 hrs 0.04 cf) HW 102.03' (Free Discharge) 1=Exfiltration (E Pond 1 P: 2'x2' Crushed Stone Infiltation Trench Hydrograph ■Inflow p Discarded 0.32 o2s cfs 0.3 Inflow-Area=2,035 sf 0.28 - Peak Elev=103.9.8' 0.26 0.24 Storage=--287 0.2 0.18 0.16 LL 0.14 0.12 0.1 0.08 0.06 0.°4 ds 0.04 0.02 0 8 9 10 11 12 13 14 15 16 17 18 19 20 5 6 7 Time (hours) e^ N J VhJ o-) Q ` D >- J < rr � m LLI> c m O < a' cn Q o— Z (3) < p-- > 0 ca � � `� v z _ Cr Lli � - -tz v v v a„ .eo. "'".. .. S 337 VF V/H C 3 r N i 1 C3 fl! — 7,11 "IN i BYO so 'y \ �` sir