Loading...
HomeMy WebLinkAbout251121 Resp to 1st HW Peer Review - - 243 GREAT POND ROAD ` ^ PATRIOT " ° UUU ��� G�����Q�� K~WN��Q����K�B K���� � � PO BOX 362 Lexington,MA02420 Date: November 21, 2O25 Ms.Jean Enright, Planning Director Planning Department Town of North Andover 12O Main Street North Andover, Massachusetts O1845 Patriot Engineering offer the following response to the Initial Ctormvvater Peer Review 243 Great Pond Road North Andover, Massachusetts prepared byHORSLEYVV|TTEN GROUP, INC 1. The Applicant has included erosion controls including proposed construction fencing and a 12' inchfi|iermittontheConst/uctionk4anagementP|anandhasshownvvherethestockpi|eswi|| be located during construction. ° Noted 2. The Applicant has proposed a temporary construction entrance around the south side of the house. HW recommends that the Applicant consider construction matting or other measures to minimize the tracking of sediment onto the driveway and offsite per§250-25.E.(13) of the North Andover Code. ° A tracking pad detail ahs been added to the plans 3. It appears that the earthwork proposed will be contained to the area of the existing basketball court and the construction of the proposed greenhouse. HW recommends that the Applicant confirm that the area surrounded by the proposed post& rail fence will not be altered. ° A note has been added to the plan to define the area of earthwork for the project 4. The Stormwater Analysis and Calculations report does not include an existing drainage area figure.The Applicant has provided an existing conditions catchment area 2S with a total area of 24,908 sf.The paved area includes 4,340 sf. HW could not confirm the limits of the catchment area and could not determine if any of the existing house was included as part of the paved parking area. HW recommends that the Applicant provides an existing catchment area figure to confirm the values listed in the HydroCAD model for catchment area 2S. ° A catchment map has been provided and the HydroCAO model has been updated 10 match 5. The Applicant has not included a proposed catchment area figure. it has listed proposed catchment area 5S as having 24,908 sf.The paved parking area includes 3,691 sf.The Applicant has also included proposed catchment area 3S with a proposed DRIVE area of 890 sf. HW assumes that catchment area 3S is associated with the proposed greenhouse and agrees that the area modeled is reasonable. However, HW believes that the catchment area modeled as 3S should be subtracted from the catchment area modeled as 5S. HW recommends that the Applicant provides a proposed catchment area figure to confirm the values listed in the HydroCAD model for catchment area 3S and 5S. • A catchment map has been provided and the HydroCAD model has been updated to match 6. HW recommends that the Applicant clarify the total impervious area to be removed and the total proposed impervious area to be constructed. We could not confirm the values provided on Sheet C-3. • The chart on the plans has been updated to clarify the areas used 7. The Applicant has modeled the existing and proposed soil conditions as hydrologic soil group (HSG)A. In accordance with the Natural Resources Conservation Service (NRCS) the soils are HSG B or B/D. HW recommends that the Applicant revise the HydroCAD model accordingly. • The HydroCAD model has been updated to use HSG B 8. The Applicant has included an exfiltration rate of 1.02 inches per hour (iph) in the HydroCAD model for the Stone Trench. HW recommends that the Applicant provide soil testing or other documentation to confirm the exfiltration rate used. • Soil testing was performed to determine a parent soil material of Loamy Sand and the exfiltration rate within the HydroCAD model was adjusted accordingly 9. The HydroCAD model for the Stone Trench includes a 20 foot long by 1.0-foot-wide broad crested weir at elevation 155.95. HW recommends that the Applicant clarify where this is proposed on the site plans. HW notes that the plans include a proposed 156 contour grade line around the Greenhouse, HW further notes that during a 100-year storm event the stone trench will overtop the proposed weir. • The grading has been revised to accommodate for the overflow 10. HW recommends that the Applicant clarify if any existing trees will be removed as part of the proposed project. • No existing trees will be removed 11. HW notes that the Erosion and Sedimentation Control Measures narrative lists the Town of Lexington. HW recommends that the Applicant revise this to read North Andover. • The reference to Lexington has been removed 12. HW notes that the Applicant mentions a subsurface infiltration system in the narrative numerous times. It is HW's understanding that the proposed stormwater practice is a drip edge stone trench to manage the roof runoff from the proposed greenhouse. HW recommends that the Applicant modify the narrative to avoid confusion or provide the design information for the subsurface system. • The reference to a subsurface infiltration system has been removed Thank you, PATRIOT ENGINEERING LLC Michael J Novak, P.E.