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HomeMy WebLinkAbout2012-09-18 Planning Board Supplemental Materials (38)________________________________________________________________________________________ 22 Mount Vernon Road ~ Boxford, Massachusetts 01921 ~ (978) 352-7871-Phone ~ 978 352-7871 - Fax Sullivan Engineering Group, LLC Civil Engineers & Land Development Consultants September 5, 2012 Town of North Andover Planning Board c/o Judith Tymon - Town Planner 1600 Osgood Street North Andover, MA 01845 Re: Watershed Special Permit Application 0 Great Pond Road, North Andover Tax Map 103 Parcel 128 Ms. Tymon; Based on the Planning Board comments, Conservation Commission comments, and Eggleston Environmental (review consultant) comments the following plan changes have been made; 1) The proposed drywell to handle the rear roof runoff has been resized to a 1,000 gallon concrete drywell with 54 inches of stone surrounding. The need to resize the system was based on the drywell being modeled with a 1.02 in/hr hydraulic conductivity instead of the field percolation rate. The drywell sizing has capacity to store and infiltrate the 100 year storm event (HydroCAD calculations attached). 2) A note has been added to Sheet 1 of the design plan requiring the design engineer to conduct a deep observation soil test in the proposed driveway location prior to installation of the crushed stone subbase. Additionally, a note has been added for clean sand to be placed in the area of the old foundation following demolition/removal. 3) The stone surround for the drywell has been modeled as a cylinder. 4) On Sheet 2 a note has been added to the drywell construction detail that septic sand shall be provided as fill in the drywell area and 5 feet surrounding. Additionally, a 40 mil HPDE barrier is proposed between the drywell and proposed retaining wall to prevent breakout. 5) The proposed filter fabric for the drywell construction has been revised to be placed on the sidewalls and top of the system only. 6) A roof drain connection detail has been provided on Sheet 2. 7) The limit of work and limit of vegetation clearing have been labeled on the plan. Both limits are consistent with the proposed erosion control barrier for the site. 8) A note has been added to the cross-section of the Porous Pavement construction on Sheet 2 calling out that the porous asphalt shall be Polymer Modified Performance Grade Asphalt Binder. 9) The Operation and Maintenance requirements for the Porous Pavement on Sheet 2 now reflect annual vacuuming and prohibiting sealcoating. 10) A note has been added on Sheet 1 (see Note 8) for 6 inches of loam to be spread in all grassed areas. 11) The majority of the limit of work line has been moved away from the wetlands to leave a natural wooded buffer to the wetland resource areas. The Conservation Commission expressed concerns with invasive species growth in some of the wooded area to remain. The applicant is willing to work with the Commission to remove invasives beyond the limit of work as needed. ________________________________________________________________________________________ 22 Mount Vernon Road ~ Boxford, Massachusetts 01921 ~ (978) 352-7871-Phone ~ 978 352-7871 - Fax 12) The Planning Board asked for a composite plan of the 4 parcels of land under the Paolino’s ownership. This detail has been added on Sheet 2. 13) Setbacks have been added from the proposed house to the wetland line. Please note that that the hardscape features on the plan (walkways, driveway, retaining wall) represent the full extent of hardscape landscaping for the site. The majority of the site will be loamed/seeded (proposed grassed areas have been labeled) and there may be some mulch beds in the front of the house with typical landscape plantings. If you should have any questions or require additional information please feel free to contact me. Very Truly Yours, Jack Sullivan, P.E. Cc: Conservation Commission David + Corliss Paolino, Owners Drainage Diagram for 940 Great Pond Road, NA Prepared by Sullivan Engineering Group, LLC 9/5/2012 HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Subcat Reach Pond Link 3S Rear Roof Areas 2P 1,000 Gallon Drywell w/ 54" stone surrrounding Type III 24-hr 2 Year Storm Rainfall=3.10"940 Great Pond Road, NA Page 2Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 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=1,442 sf Runoff Depth=2.68"Subcatchment 3S: Rear Roof Areas Tc=6.0 min CN=98 Runoff=0.10 cfs 0.007 af Peak Elev=90.68' Storage=200 cf Inflow=0.10 cfs 0.007 afPond 2P: 1,000 Gallon Drywell w/ 54" stone sur Outflow=0.00 cfs 0.003 af Total Runoff Area = 0.033 ac Runoff Volume = 0.007 af Average Runoff Depth = 2.68" Type III 24-hr 2 Year Storm Rainfall=3.10"940 Great Pond Road, NA Page 3Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Rear Roof Areas Runoff=0.10 cfs @ 12.09 hrs, Volume=0.007 af, 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 Year Storm Rainfall=3.10" Area (sf)CNDescription 1,44298Portion of Bldg Roof + Rear Porch Roof TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Rear Roof Areas Runoff Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 2 Year Storm Rainfall=3.10" Runoff Area=1,442 sf Runoff Volume=0.007 af Runoff Depth=2.68" Tc=6.0 min CN=98 0.10 cfs Type III 24-hr 2 Year Storm Rainfall=3.10"940 Great Pond Road, NA Page 4Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Area =0.033 ac, Inflow Depth = 2.68" for 2 Year Storm event Inflow=0.10 cfs @ 12.09 hrs, Volume=0.007 af Outflow=0.00 cfs @ 9.15 hrs, Volume=0.003 af, Atten= 97%, Lag= 0.0 min Discarded=0.00 cfs @ 9.15 hrs, Volume=0.003 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 90.68' @ 15.87 hrs Surf.Area= 177 sf Storage= 200 cf Plug-Flow detention time= 174.8 min calculated for 0.003 af (43% of inflow) Center-of-Mass det. time= 67.9 min ( 806.8 - 738.9 ) #InvertAvail.StorageStorage Description 188.20'427 cf 15.00'D x 7.00'H Vertical Cone/Cylinder 1,237 cf Overall - 170 cf Embedded = 1,067 cf x 40.0% Voids 289.20'170 cf 6.00'D x 6.00'H Vertical Cone/Cylinder Inside #1 597 cfTotal Available Storage #RoutingInvertOutlet Devices 1Discarded0.00'0.001000 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.00 cfs @ 9.15 hrs HW=88.27' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.00 cfs) Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Discarded Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.033 ac Peak Elev=90.68' Storage=200 cf 0.10 cfs 0.00 cfs Type III 24-hr 10 Year Storm Rainfall=4.50"940 Great Pond Road, NA Page 5Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 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=1,442 sf Runoff Depth=3.96"Subcatchment 3S: Rear Roof Areas Tc=6.0 min CN=98 Runoff=0.14 cfs 0.011 af Peak Elev=92.20' Storage=334 cf Inflow=0.14 cfs 0.011 afPond 2P: 1,000 Gallon Drywell w/ 54" stone sur Outflow=0.00 cfs 0.003 af Total Runoff Area = 0.033 ac Runoff Volume = 0.011 af Average Runoff Depth = 3.96" Type III 24-hr 10 Year Storm Rainfall=4.50"940 Great Pond Road, NA Page 6Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Rear Roof Areas Runoff=0.14 cfs @ 12.09 hrs, Volume=0.011 af, Depth=3.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10 Year Storm Rainfall=4.50" Area (sf)CNDescription 1,44298Portion of Bldg Roof + Rear Porch Roof TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Rear Roof Areas Runoff Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 10 Year Storm Rainfall=4.50" Runoff Area=1,442 sf Runoff Volume=0.011 af Runoff Depth=3.96" Tc=6.0 min CN=98 0.14 cfs Type III 24-hr 10 Year Storm Rainfall=4.50"940 Great Pond Road, NA Page 7Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Area =0.033 ac, Inflow Depth = 3.96" for 10 Year Storm event Inflow=0.14 cfs @ 12.09 hrs, Volume=0.011 af Outflow=0.00 cfs @ 7.80 hrs, Volume=0.003 af, Atten= 98%, Lag= 0.0 min Discarded=0.00 cfs @ 7.80 hrs, Volume=0.003 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 92.20' @ 17.36 hrs Surf.Area= 177 sf Storage= 334 cf Plug-Flow detention time= 188.2 min calculated for 0.003 af (31% of inflow) Center-of-Mass det. time= 44.9 min ( 780.6 - 735.8 ) #InvertAvail.StorageStorage Description 188.20'427 cf 15.00'D x 7.00'H Vertical Cone/Cylinder 1,237 cf Overall - 170 cf Embedded = 1,067 cf x 40.0% Voids 289.20'170 cf 6.00'D x 6.00'H Vertical Cone/Cylinder Inside #1 597 cfTotal Available Storage #RoutingInvertOutlet Devices 1Discarded0.00'0.001000 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.00 cfs @ 7.80 hrs HW=88.27' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.00 cfs) Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Discarded Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.033 ac Peak Elev=92.20' Storage=334 cf 0.14 cfs 0.00 cfs Type III 24-hr 25 Year Storm Rainfall=5.50"940 Great Pond Road, NA Page 8Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 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=1,442 sf Runoff Depth=4.87"Subcatchment 3S: Rear Roof Areas Tc=6.0 min CN=98 Runoff=0.17 cfs 0.013 af Peak Elev=93.36' Storage=435 cf Inflow=0.17 cfs 0.013 afPond 2P: 1,000 Gallon Drywell w/ 54" stone sur Outflow=0.00 cfs 0.003 af Total Runoff Area = 0.033 ac Runoff Volume = 0.013 af Average Runoff Depth = 4.87" Type III 24-hr 25 Year Storm Rainfall=5.50"940 Great Pond Road, NA Page 9Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Rear Roof Areas Runoff=0.17 cfs @ 12.09 hrs, Volume=0.013 af, Depth=4.87" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25 Year Storm Rainfall=5.50" Area (sf)CNDescription 1,44298Portion of Bldg Roof + Rear Porch Roof TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Rear Roof Areas Runoff Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 25 Year Storm Rainfall=5.50" Runoff Area=1,442 sf Runoff Volume=0.013 af Runoff Depth=4.87" Tc=6.0 min CN=98 0.17 cfs Type III 24-hr 25 Year Storm Rainfall=5.50"940 Great Pond Road, NA Page 10Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Area =0.033 ac, Inflow Depth = 4.87" for 25 Year Storm event Inflow=0.17 cfs @ 12.09 hrs, Volume=0.013 af Outflow=0.00 cfs @ 7.00 hrs, Volume=0.003 af, Atten= 98%, Lag= 0.0 min Discarded=0.00 cfs @ 7.00 hrs, Volume=0.003 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 93.36' @ 18.10 hrs Surf.Area= 177 sf Storage= 435 cf Plug-Flow detention time= 202.9 min calculated for 0.003 af (26% of inflow) Center-of-Mass det. time= 35.5 min ( 770.1 - 734.6 ) #InvertAvail.StorageStorage Description 188.20'427 cf 15.00'D x 7.00'H Vertical Cone/Cylinder 1,237 cf Overall - 170 cf Embedded = 1,067 cf x 40.0% Voids 289.20'170 cf 6.00'D x 6.00'H Vertical Cone/Cylinder Inside #1 597 cfTotal Available Storage #RoutingInvertOutlet Devices 1Discarded0.00'0.001000 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.00 cfs @ 7.00 hrs HW=88.27' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.00 cfs) Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Discarded Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.033 ac Peak Elev=93.36' Storage=435 cf 0.17 cfs 0.00 cfs Type III 24-hr 100 Year Storm Rainfall=6.40"940 Great Pond Road, NA Page 11Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems 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=1,442 sf Runoff Depth=5.69"Subcatchment 3S: Rear Roof Areas Tc=6.0 min CN=98 Runoff=0.20 cfs 0.016 af Peak Elev=94.44' Storage=530 cf Inflow=0.20 cfs 0.016 afPond 2P: 1,000 Gallon Drywell w/ 54" stone sur Outflow=0.00 cfs 0.004 af Total Runoff Area = 0.033 ac Runoff Volume = 0.016 af Average Runoff Depth = 5.69" Type III 24-hr 100 Year Storm Rainfall=6.40"940 Great Pond Road, NA Page 12Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Subcatchment 3S: Rear Roof Areas Runoff=0.20 cfs @ 12.09 hrs, Volume=0.016 af, 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 Year Storm Rainfall=6.40" Area (sf)CNDescription 1,44298Portion of Bldg Roof + Rear Porch Roof TcLengthSlopeVelocityCapacityDescription (min)(feet)(ft/ft)(ft/sec)(cfs) 6.0 Direct Entry, Subcatchment 3S: Rear Roof Areas Runoff Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 100 Year Storm Rainfall=6.40" Runoff Area=1,442 sf Runoff Volume=0.016 af Runoff Depth=5.69" Tc=6.0 min CN=98 0.20 cfs Type III 24-hr 100 Year Storm Rainfall=6.40"940 Great Pond Road, NA Page 13Prepared by Sullivan Engineering Group, LLC 9/5/2012HydroCAD® 7.00 s/n 001433 © 1986-2003 Applied Microcomputer Systems Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Area =0.033 ac, Inflow Depth = 5.69" for 100 Year Storm event Inflow=0.20 cfs @ 12.09 hrs, Volume=0.016 af Outflow=0.00 cfs @ 6.45 hrs, Volume=0.004 af, Atten= 99%, Lag= 0.0 min Discarded=0.00 cfs @ 6.45 hrs, Volume=0.004 af Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 94.44' @ 19.56 hrs Surf.Area= 177 sf Storage= 530 cf Plug-Flow detention time= 217.2 min calculated for 0.004 af (22% of inflow) Center-of-Mass det. time= 30.3 min ( 764.2 - 733.9 ) #InvertAvail.StorageStorage Description 188.20'427 cf 15.00'D x 7.00'H Vertical Cone/Cylinder 1,237 cf Overall - 170 cf Embedded = 1,067 cf x 40.0% Voids 289.20'170 cf 6.00'D x 6.00'H Vertical Cone/Cylinder Inside #1 597 cfTotal Available Storage #RoutingInvertOutlet Devices 1Discarded0.00'0.001000 fpm Exfiltration over entire Surface area Discarded OutFlow Max=0.00 cfs @ 6.45 hrs HW=88.27' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.00 cfs) Pond 2P: 1,000 Gallon Drywell w/ 54" stone surrrounding Inflow Discarded Hydrograph Time (hours) 201918171615141312111098765 Fl o w ( c f s ) 0.22 0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.033 ac Peak Elev=94.44' Storage=530 cf 0.20 cfs 0.00 cfs