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HomeMy WebLinkAboutApplication - 858 GREAT POND ROAD 1/28/2011 Sullivan Engineering Group, LLC 1'ivil Engineers&Land Development Consultants January 28, 2011 e � 4 Town of North Andover Planning Board c/o Judith Tymon- Town Planner " 1600 Osgood Street North Andover,MA 01845', Re: Watershed Special Permit Application 858 Great Pond Road, North Andover Ms. Tymon; On behalf of the owner/applicant, David& Gay Tracy,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(a copy of the check is provided as well) 3) A certified abutter's list 4) Engineering calculations for sizing the proposed drywell 5) A Proposed Site Development Plan for 858 Great Pond Road prepared by Sullivan Engineering Group, LLC scale F"--20% dated January 25, 2011. 6) Architectural Plans by Sidney Graves (8 sheets) 7) A check for$2,000.00 payable to the Town of North Andover for the review consultant fee. j should have an questions or require additional information please feel free to contact me. ruly Yo ullivan,P.E. Attachments (as noted) 22 Mount Vernon Road — Boxford,Massachusetts 01921 — (978)352-7871-Phone — 978352-7871 -Fax Print Form e ow r, 5 tf f'13 S7 aa n PLANNUG DEPARTNIEN I Community Development Division edaR Permit- Watershed Permit AfppflIlcAon _71 Please type or print clearly. 1.Petitioner:David&Gay Tracy Petitioner's Address:858 Great Pond Road, North Andover, MA 01845 Telephone number:978-685-2365 2.Owners of the Land:(Same as Petitioner) Address: Number of years of ownership: 1 year 3.Year lot was created: 1968 (lot subdivided per Landcourt Plan 20252C) 4. Is the lot currently on septic or sewer? If on sewer,please provide date the sewer connection was completed:7-27-1995 5.Description of Proposed Project: The petitioner is proposing a vertical expansion of the existing structure from 1 story to 2 story. A small addition is proposed off the rear of the house. The existing two car garage will be expanded to a 3 car garage&the garage will be connected to the dwelling structure by means of a proposed roofed walkway... 6.Description of Premises:A 4.21 acre parcel directly abutting Lake Cochichewick 7.Address of Property Being Affected:858 Great Pond Road Zoning District: R1 Assessors Map: 103 Lot#:36 Registry of Deeds:Book#: 108 Page#: 389 8.Existing Lot: Lot Area(Sq.Ft): 183,388 s.f. Building Height: 16.37 Street Frontage: 162.90 Side Setbacks:49.4 Front Setback:294.8 Rear Setback: 140'+/- Floor Area Ratio:n/a Lot Coverage:n/a 9.Proposed Lot(if applicable): Lot Area(Sq.Ft): Building Height: Street Frontage: Side Setbacks: Ire 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 Building Height:35. Street Frontage: 175 Side Setbacks:30 Front Setback:30 Rear Setback:30 Floor Area Ratio:n/a Lot Coverage:n/a 11.Existing Building(if applicable): Ground Floor(Sq.Ft.): 1,980 #of Floors: 1 Total Sq.Ft.:1,980 Height: 16.37' Use:Residential Type of Construction:Wood Frame 12.Proposed : Additions: Ground Floor(Sq.Ft.): #of Floors:2 Total Sq.Ft.546 Height:2 Story Use:Residential Type of Construction:Wood Frame 13.Has there been a previous application for a Special Permit from the Planning Board on these premises?No If so,when and for what type of construction? 14.Section of Zoning Bylaw that Special Permit Is Being Requested Section 4.136 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 fumish 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: id G y Owner's Signature: Print or type name here* vi Gay Tracy 16.Please list title of plans and documents you will be attaching to this application. Prop. Site Development Plan by Sullivan Engineering Group,LLC dated 1/25/11 (2 shts) Architectural Plans by Sidney Graves (8 sheets) Drainage Calculations 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.townofnorthandover.com Edited 8/6/07 Sullivan Engineering Group, LLC Civil Engineers&Land Development Consultants WATERSHED SPECIAL PERMIT 858 GREAT POND ROAD, NORTH ANDOVER To: North Andover Planning Board From: Jack Sullivan,P.E. Date: January 24,2011 Subject: 858 Great Pond Road,North Andover—Written Support for Project Planning Board Members; The following written summary is prepared on behalf of the owner/applicant,David& Gay Tracy,in support of adding minor additions to an existing single family dwelling in the Watershed District. A proposed 500 gallon drywell will be installed to mitigate the increased stormwater runoff associated with the increase in impervious area The following items as outlined in the Watershed Special Permit requirements are listed below(responses to required items are in italic); -- I. Encouraging the most appropriate use of laud---- This site.is zoned residential and t`he proposed site development items listed above are appropriate far this parcel The proposed site workwim demgmed to provide,mm mum-dwhwbmwe to the exWmgmte. 2. Ftevemtmg overcrowding of land The proposed additions and exiensiori of the patio are small in nature-and will overcrowd the,land 3_ Conserving the value of land and-buildings_ The proposed site development will enhance surrounding b.wl&ng and land values, while being aesthetically pleasing_ 'The building additions will be mutually hen�al to the applicant as well -as the abutters 4_ Lessening congestion ofiraffic This projectwdl not increase Traffic congestion, since there will be no increase in the number of vehicles or vehicle trips 5. Preventing undue concentrafion of population There will be no population change aslkeresult ofthisproject_ Itwill re main a single family residence and there will be no addition to the current number of residents in the premises_ 6. Providing adequate light and air There will.be no adverse impact to current background or and light levels 7. Reducing the hazards from fire and other danger, There will be no increase in hazard levels from fire or other dangers: The proposed additions will be accessible to fire fighting equipment acid the additions will meet Building Code requirements in providing smoke;detectors 22 Mount Vernon Road — Boxford,Massachusetts 01921 — (978)352-7871-Phone — 978352-7871 -Fax -^!8.�Agisting in the economical provision of transportation,water,sewerage,schools,parks,and ofhex public s. This project will not impact the above noted public fadlitres and/or utc7ities. There will be not be a negative impact to the economics of arty public utility_ 9. Controlling the use of bodies of water,including watercourses; This project will;not have awegative impact on present uses of the.Lake or tributaries thereto_ 10. Reducing the probability of losses resulting from floods; The applicant isproposing to install drainage infrastructure, includingpiping and a 500 Gallon Drywell, to collect all runoffassociated with the roofareas oftheproposed additions: The drainage infrastructure is designed to handle the 100 year storm event nd will serve io mitigate anypgrendal stormwater runojfprobtems,from ---- t—pop–os–ed- addion 11. Reserving and increasing the amemitires of the Town This projectwill xcrease the amenities gf the Town through an improvement to the property and additional tax revenue due to new construction assessment_ The Planning Board,in reviewing this application,will note that all the 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 CoduchevvieL The proposed site work described in this letter will not have a negative impact to the surrounding watershed There will not be any sign frcant degradation ofthe quality or quantity ofwater in or enteringLake Cochichewick The proposed drywell will serve to collect stop nwater runoff and provide a means of recharging the groundwater table. The diywel4 in addition to'the minimal site grading changes,will serve to promote mitigation measures to protect rung fj from entering surrounding wetland areas which.ultimately discharge to the Lake.. 2. Proofthat there is no reasonable altemafave location.oufside the Non-Disturbance and/or Non-Discharge Buffer Zones,whichever is applicable,forany discharge,structure,or ac;t vify,associated with the-proposed use to occur_ Based on the site topography, resWgive wetland buffer fjer zones, existing building layout; and zoning setback requirements.there is'no akenzOtive location that wouldworkfor thisproperty. 3_ Evidence of approval by the Mass.DEP of any industrial washer 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,waste water disposal, fertilizer applications,and.septic systems will not.%wk concentrations-of Nitrogen in groundwater,greater than the Federal limit at the downgradient property boundary. Thrssite:is connected to the Town ofNorth_k dover municipal srewikiige system. Construction activity will not increase background Nitrogen levels in the groundwater. 5. Projections ofdowngradient conc6iftatians ofnitrogen,-phosphorus and otherrelevant-chemicals at property boundaries and other locations deemedpeztaneat bvthe SPCA. There will be no downgradient concentration of the above referenced chemicals due to the proposed Site development conditions The property is currently connected to the municipal sewer system which eliminates arty potential nitrogen transport Futhermore, a deed restriction will be placed restricting fertilizers to be organic or slow-release nitrogen. 22 Mount Vernon Road -r -Boxford;/Massachusetts 01921 – (973)352-7871-Phone – 978352-7871-Fax Abutter to Abutter( ) Building Dept. ( ) Conservation ( X ) Zoning ( ) REQUIREMENT MGL 40A,Section 11 states in part'Partles in Interest as used In this chapter shall mean the petitioner, abutters,owners of land directly oppositeon any public or private way,and abutters to abutters within three hundred(300)feet of the property line of the petitioner as they appear on the most recent applicable tax list,notwithstanding that the land of any such owner Is located in another city or town,the planning board of the city or town,and the planning board of every abutting city or town' Subject Proveriy: MAP PARCEL Name Address 103 36 David Tracy 858 Great Pond Road,North Andover,MA 01845 Abutters Properties Map Parcet Name Address 103 19 Jose Baez V 865 Great Pond Road,North Andover,MA 01845 103 21 ,/Stephen Scully✓ 808 Great Pond Road,North Andover,MA 01845 103 111 ,l Robert Ercolini t,/ 195 Bridle Path,North Andover,MA 01845 103 112 tlRonald McCluskey✓ 870 Great Pond Road,North Andover,MA 01845 103 113ulichael Batal V 834 Great Pond Road,North Andover,MA 01845 103 116 l� Ian Camera / 795 Great Pond Road,North Andover,MA 01845 103 117 ✓Oleksandr Stupnskyi ✓ 855 Great Pond Road,North Andover,MA 01845 103 131 Charles Papalia / 61 Coachmans Lane,North Andover,MA 01845 Lake Cochichewick Commonwealth of MA 0.� 100 Cambridge Street,Boston MA 02202 This certifies that the names appearing on the records Of the Assessors Office as of Certified by: Date/ C s .Roof Area to Drywell 1R 4" PVC oof Drain 1P 500 Gallon Drywell w/ 30" Stone Surrounding Subcat Reach on Link Drainage Diagram for 858 Great Pond Road,North Andover Prepared by Sullivan Engineering Group, LLC 1/26/2011 HydroCAD®7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 858 Great Pond Road, North Andover Type 111 24-hr 2 yr Rainfall=3.90" Prepared by Sullivan Engineering Group, LLC Page 2 HydroCADO 7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 1/26/2011 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: Roof Area to Drywell Runoff Area=1,136 sf Runoff Depth=2.68" Tc=6.0 min CN=98 Runoff=0.08 cfs 254 cf Reach 1R: 4" PVC Roof Drain Peak Depth=0.13' Max Vet=2.3 fps Inflow=0.08 cfs 254 cf D=4.0" n=0.011 L=60.0' S=0.0100'/' Capacity=0.22 cfs Outflow=0.08 cfs 254 cf Pond 1 P: 500 Gallon Drywell w/30"Stone Surro Peak Elev=144.15' Storage=49 cf Inflow=0.08 cfs 254 cf Outflow=0.02 cfs 254 cf Total Runoff Area= 1,136 sf Runoff Volume= 254 cf Average Runoff Depth = 2.68" 858 Great Pond Road, North Andover Type ///24-hr 2 yr Rainfall=3.90" Prepared by Sullivan Engineering Group, LLC Page 3 HydroCAD®7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Subcatchment 1S: Roof Area to Drywell Runoff = 0.08 cfs @ 12.09 hrs, Volume= 254 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" Area (sf) CN Description 1,136 98 Roof Area to Drywell Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, From Roof Subcatchment IS: Roof Area to Drywell Hydrograph 0.085-1 0.08-': 10.0 8 cfs 0.075_ Type 11124-hr 2 yr 0.07 0.065 Rainfall=3.10" Runoff Area=1,1 36- f 0.055 0.05-: - Runoff Volume=254 cf 0.045- 0 0.04- Runoff Depth-2.68" u 0.035. _ Tc-6.0 min 0.03- 0.025 CN-98 0.02- 0.015 0.01 0.005 ra,. 0� . 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type ///24-hr 2 yr Rainfall=3.10" Prepared by Sullivan Engineering Group, LLC Page 4 HydroCAD®7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 1/26/2011 Reach 1 R: 4" PVC Roof Drain Inflow Area = 1,136 sf, Inflow Depth = 2.68" for 2 yr event Inflow = 0.08 cfs @ 12.09 hrs, Volume= 254 cf Outflow = 0.08 cfs @ 12.10 hrs, Volume= 254 cf, Atten= 2%, Lag= 0.7 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 2.3 fps, Min. Travel Time= 0.4 min Avg. Velocity= 0.9 fps, Avg. Travel Time= 1.1 min Peak Depth=0.13' @ 12.09 hrs Capacity at bank full= 0.22 cfs Inlet Invert= 146.60', Outlet Invert= 146.00' 4.0" Diameter Pipe n= 0.011 Length= 60.0' Slope= 0.0100 '/' Reach 1 R: 4" PVC Roof Drain Hydrograph 0.085 [I Inflow 0.08 cfs _ 0 Outflow - 0.08- Area=1 7 136 sf 0.08 cfs f 0.075 r{ 0.07 Peak Depth=0.13, = 0.065 t - 0.06 Max-Vet=23 fps = 0.055. D.=4.0". 0.05. 0.045 n=0.01 7 c 0 0.04= L-60.0' u 0.035= 0.03: _ 5=0.0100 T _ x 0.025 0.02- � , �, - Capacity=0.22-cfs 0.015 0.01 0.005 �r w 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type 111 24-hr 2 yr Rainfall=3.10" Prepared by Sullivan Engineering Group, LLC Page 5 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Pond 1P: 500 Gallon Drywell w/30" Stone Surrounding Field Percolation Rate of Soil = 8 MPI Inflow Area = 1,136 sf, Inflow Depth = 2.68" for 2 yr event Inflow = 0.08 cfs @ 12.10 hrs, Volume= 254 cf Outflow = 0.02 cfs @ 11.80 hrs, Volume= 254 cf, Atten= 72%, Lag= 0.0 min Discarded = 0.02 cfs @ 11.80 hrs, Volume= 254 cf Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 144.15' @ 12.45 hrs Surf.Area= 121 sf Storage=49 cf Plug-Flow detention time= 11.9 min calculated for 253 cf(100% of inflow) Center-of-Mass det. time= 11.6 min (751.7-740.0) # Invert Avail Storage Storage Description 1 143.25' 167 cf 11.00'W x 11.00%x 4.00'H Prismatoid 484 cf Overall-67 cf Embedded =417 cf x 40.0% Voids 2 143.75' 67 cf 6.33'D x 3.00'H Vertical Cone/Cylinder Inside#1 234 cf Total Available Storage # Routing Invert Outlet Devices 1 Discarded 0.00' 0.010400 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.02 cfs @ 11.80 hrs HW=143.29' (Free Discharge) t-1=Exfiltration (Exfiltration Controls 0.02 cfs) Pond 1 P: 500 Gallon Drywell w/ 30" Stone Surrounding Hydrograph - - p Inflow 0.08 ds _ Q Discarded 0.08 136 sf Inflow Area=1-, - 0.075 ' 0.07 Peak Elev=144.15' 0.065 Storage=49 cf 0.055 - r w 0.05 r 0.045--_ 3 � 0 0.04 u 0.035 gib, 0.03 0.025--. 0.82 ds 0.02- 0.015_ 0.01- 0.005- 5 6 7 8 9 10 11 1 1 12 13 1 1 14 1 1 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type ///24-hr 10 yr Rainfall=4.80" Prepared by Sullivan Engineering Group, LLC Page 6 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 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: Roof Area to Drywell Runoff Area=1,136 sf Runoff Depth=4.24" Tc=6.0 min CN=98 Runoff--0.12 cfs 401 cf Reach 1R: 4" PVC Roof Drain Peak Depth=0.17' Max Vet=2.6 fps Inflow=0.12 cfs 401 cf D=4.0" n=0.011 L=60.0' S=0.0100'/' Capacity=0.22 cfs Outflow=0.12 cfs 401 cf Pond 1 P: 500 Gallon Drywell w/30"Stone Surro Peak Elev=145.12' Storage=109 cf Inflow=0.12 cfs 401 cf Outflow=0.02 cfs 401 cf Total Runoff Area= 1,136 sf Runoff Volume=401 cf Average Runoff Depth =4.24" 858 Great Pond Road, North Andover Type 11124-hr 10 yr Rainfall=4.80" Prepared by Sullivan Engineering Group, LLC Page 7 HydroCAD®7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Subcatchment 1S: Roof Area to Drywell Runoff = 0.12 cfs @ 12.09 hrs, Volume= 401 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" _ Area (so CN Description 1,136 98 Roof Area to Drywell Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, From Roof Subcatchment 1S: Roof Area to Drywell Hydrograph 0.13 Runoff ... - _ 5712crs 0.12 - - Type-III-24-hr 10 yr 0.1- Rainfall=4.80° 0.09 Runoff Area=1,136 sf 0.08 ' Runoff Volume=401 cf 3 Runoff Depth 4.24" i° 0.06 _Tc=6.0 min 0.05 CN=98 0.04- P 0.03, 0.02 0.01 mfr 0 . , 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type 111 24-hr 10 yr Rainfall=4.80" Prepared by Sullivan Engineering Group, LLC Page 8 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Reach 1 R: 4" PVC Roof Drain Inflow Area = 1,136 sf, Inflow Depth = 4.24" for 10 yr event Inflow = 0.12 cfs @ 12.09 hrs, Volume= 401 cf Outflow = 0.12 cfs @ 12.10 hrs, Volume= 401 cf, Atten= 1%, Lag=0.6 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity= 2.6 fps, Min. Travel Time= 0.4 min Avg. Velocity= 1.0 fps, Avg. Travel Time= 1.0 min Peak Depth= 0.17' @ 12.09 hrs Capacity at bank full= 0.22 cfs Inlet Invert= 146.60', Outlet Invert= 146.00' 4.0" Diameter Pipe n= 0.011 Length= 60.0' Slope= 0.0100 '/' Reach 1 R: 4" PVC Roof Drain Hydrograph El Inflow 0.13- 0.12 cfs B Outflow 0.12= 0.,2 crs Inflow Area=1,136 sf - 0.11 - - f Peak Depth=0.17' 0.1 Max Vet=2.6 fps 0.09- - - Wq 0.08_ ;^rr D=4.0" 0.07= n=0.011 FO ° L=60.0' s 0.05- $=0.0100 0.04- _ _ - Capacity=0.22 cfs 0.03- r s 0.02- 0.01- r s 5 6 7 8 9 10 11 12 13 14 15 16 11'711 1 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type 111 24-hr 10 yr Rainfall=4.80" Prepared by Sullivan Engineering Group, LLC Page 9 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Pond 1P: 500 Gallon Drywell w/30" Stone Surrounding Field Percolation Rate of Soil = 8 MPI Inflow Area = 1,136 sf, Inflow Depth = 4.23" for 10 yr event Inflow = 0.12 cfs @ 12.10 hrs, Volume= 401 cf Outflow = 0.02 cfs @ 11.70 hrs, Volume= 401 cf, Atten= 82%, Lag= 0.0 min Discarded = 0.02 cfs @ 11.70 hrs, Volume= 401 cf Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 145.12' @ 12.56 hrs Surf.Area= 121 sf Storage= 109 cf Plug-Flow detention time= 29.7 min calculated for 401 cf(100% of inflow) Center-of-Mass det. time= 29.5 min (765.9-736.4) _# Invert Avail Storage Storage Description 1 143.25' 167 cf 11.00'W x 11.00'L x 4.00'H Prismatoid 484 cf Overall -67 cf Embedded =417 cf x 40.0% Voids 2 143.75' 67 cf 5.33'D x 3.00'H Vertical Cone/Cylinder Inside#1 234 cf Total Available Storage # Routing Invert Outlet Devices 1 Discarded 0.00' 0.010400 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.02 cfs @ 11.70 hrs HW=143.30' (Free Discharge) 't--1=Exfiltration (Exfiltration Controls 0.02 cfs) Pond 1 P: 500 Gallon Drywell w/ 30" Stone Surrounding Hydrograph 0 Inflow 0.13 o.iz ors El Discarded 0.12 - - - -Inflow Area=1,136 sf 0.11 Peak Elev=145.12' 0.1 _. - r _St0rage=109. d 0.09- 0.08 r 0.07 LL 0.067 _ - r 0.05- t 0.04- 0.03-- o.oz r5 0.02 - - 0.01 a 5 6 7 8 9 10 11 12 1 1 13 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type 11124-hr 100 yr Rainfall=6.40" Prepared by Sullivan Engineering Group, LLC Page 10 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 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: Roof Area to Drywell Runoff Area=1,136 sf Runoff Depth=5.69" Tc=6.0 min CN=98 Runoff=0.16 cfs 539 cf Reach 1R: 4" PVC Roof Drain Peak Depth=0.21' Max Vet=2.8 fps Inflow=0.16 cfs 539 cf D=4.0" n=0.011 L=60.0' S=0.0100 '1' Capacity=0.22 cfs Outflow=0.16 cfs 539 cf Pond 1 P: 500 Gallon Drywell w/30"Stone Surro Peak Elev=146.10' Storage=169 cf Inflow--O.16 cfs 539 cf Outflow=0.02 cfs 538 cf Total Runoff Area= 1,136 sf Runoff Volume= 539 cf Average Runoff Depth =5.69" 858 Great Pond Road, North Andover Type ///24-hr 100 yr Rainfall=6.40" Prepared by Sullivan Engineering Group, LLC Page 11 HydroCAD®7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Subcatchment 1S: Roof Area to Drywell Runoff = 0.16 cfs @ 12.09 hrs, Volume= 539 cf, Depth= 5.69" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100 yr Rainfall=6.40" Area (sf) CN Description 1,136 98 Roof Area to Drywell Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, From Roof Subcatchment 1S: Roof Area to Drywell Hydrograph p Runoff 0.17- 0.16= = 0.15- Type-11124-hr 100 yr - _ _ 0.14 _ Rainfall-6.40" 0.13 0.12 Runoff Area-1,136 sf 0.1. - Runoff Volume=539 :cf - 3 0.09 _ Runoff Depth=5.69" ti 0.08-:. 0.07 Tc=6.0 min 0.06 t - CN=98 0.05' _0.04-: - 0.03- 0.02. - - - 0.01 r r 0-, , . . . , 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type Ill 24-hr 100 yr Rainfall=6.40" Prepared by Sullivan Engineering Group, LLC Page 12 HydroCAD®7.00 s/n 001433 ©1986-2003 Applied Microcomputer Systems 1/26/2011 Reach 1 R: 4" PVC Roof Drain Inflow Area = 1,136 sf, Inflow Depth = 5.69" for 100 yr event Inflow = 0.16 cfs @ 12.09 hrs, Volume= 539 cf Outflow = 0.16 cfs @ 12.10 hrs, Volume= 539 cf, Atten= 1%, Lag= 0.6 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Max. Velocity=2.8 fps, Min. Travel Time= 0.4 min Avg. Velocity= 1.1 fps, Avg. Travel Time= 0.9 min Peak Depth=0.21' @ 12.09 hrs Capacity at bank full= 0.22 cfs Inlet Invert= 146.60', Outlet Invert= 146.00' 4.0" Diameter Pipe n= 0.011 Length= 60.0' Slope= 0.01007' Reach 1 R: 4" PVC Roof Drain Hydrograph D Inflow 0.16 cfs ._ - - - - _ ..-.... 0 oufflow 0.16 ds Inflow Area=1 136 sf 0.16- 0.15- Peak Depth=0.21' 0.14- 0.13 Max Vet=2 8 fps 0.12- - D=4.0" __ 0.11. r F 0.1- n=0.011 0.09,:, ° 0.08- L=60.0' 0.07- y - S=0.0100 '/' 0.06 0.05= Capacity-0.22 cfs - 0.04- 0.03= 0.02- 0.01 r f 0 5 6 7 8 9 10 11 12 1 13 1 14 15 16 17 18 19 20 Time (hours) 858 Great Pond Road, North Andover Type Ill 24-hr 100 yr Rainfall=6.40" Prepared by Sullivan Engineering Group, LLC Page 13 HydroCADO 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 1/26/2011 Pond 1 P: 500 Gallon Drywell w/30" Stone Surrounding Field Percolation Rate of Soil = 8 MPI Inflow Area = 1,136 sf, Inflow Depth = 5.69" for 100 yr event Inflow = 0.16 cfs @ 12.10 hrs, Volume= 539 cf Outflow = 0.02 cfs @ 11.65 hrs, Volume= 538 cf, Atten= 87%, Lag= 0.0 min Discarded = 0.02 cfs @ 11.65 hrs, Volume= 538 cf Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 146.10' @ 12.64 hrs Surf.Area= 121 sf Storage= 169 cf Plug-Flow detention time= 51.8 min calculated for 537 cf(100% of inflow) Center-of-Mass det. time= 51.4 min (786.3- 734.9) # Invert Avail Storage Storage Description 1 143.25' 167 cf 11.00'W x 11.00'L x 4.00'H Prismatoid 484 cf Overall-67 cf Embedded =417 cf x 40.0% Voids 2 143.75' 67 cf 5.33'D x 3.00'H Vertical Cone/Cylinder Inside#1 234 cf Total Available Storage # Routing Invert Outlet Devices 1 Discarded 0.00' 0.010400 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.02 cfs @ 11.65 hrs HW=143.30' (Free Discharge) t-1=Exfiltration (Exfiltration Controls 0.02 cfs) Pond 1 P: 500 Gallon Drywell wi 30" Stone Surrounding Hydrograph D Inflow 0.iscfs -- D Discarded 0.17. Inflow Area=1,136 Sf 0.16 0.15 0.14 - Peak Elev=146.10' 0.13,:: Storage=169 d 0.12 0.11 F 0.1 0.09- - 0.08 lL 0.07 0.06- 0.05 0.04 0.03= 0.02 cfs ,. . 0.02- - 0.01 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours)