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HomeMy WebLinkAboutConsultant Review - 120 CAMPION ROAD 11/13/2013 Eggleston Environmental November 13, 2013 North Andover Planning Board 1600 Osgood Street North Andover,MA 01845 Attn: Judy Tymon,Town Planner RE: Watershed Special Permit Review 120 Campion Road Dear Ms. Tymon and Board Members: Per your request, I have conducted an initial technical review of the October 7, 2013 Watershed Special Permit Application packet for the above-referenced project, prepared by Sullivan Engineering Group, LLC on behalf of Scott Sigman. The proposed project entails modifications to an existing single family home, including replacement and expansion of an existing garage, additional driveway area to access the expanded garage and other exterior renovations to the existing home. Most of the proposed work is located within the Non-Disturbance Zone of the Watershed Protection District, as well as within the 100-ft buffer zone of a bordering vegetated wetland. The remainder of the work is within the Non-Discharge Zone of the Watershed Protection District since it is located within 325 ft of the wetland. My comments on the application are outlined below: 1. The plan should reference the limits of the Non-Discharge Zone on the property; 325 ft from Lake Cochichewick and 325 ft from wetland resource areas within the Watershed District. The Plan should also show the Zone A for the Lake Cochichewick public water supply, defined by the Massachusetts Drinking Water Regulations (3 10 CMR 22.02) as including the land area within a the land area within a 400 foot lateral distance from the upper boundary of the bank of a Class A surface water source and 200 foot lateral distance from the upper boundary of the bank of a tributary or associated surface water body. 2. The boundaries of the buffer zones are based on the horizontal setback from the edge of wetland resource areas, as defined by the Wetlands Protection Act and the North Andover Wetland Bylaw. It is not clear whether the wetland boundary shown on the plan has been confirmed by the Conservation Commission, e.g. through an ANRAD or NOI. 3. The proposed project calls for expansion of an existing permanent structure by less than 25 percent, allowable in the Non-Disturbance Zone by Special Permit. If a Special Permit is approved for this project, it should limit any further expansion of the structure. Noting that the architectural plans also call for the addition of 32 Old Framingham Rd Unit 29 Sudbury MA 01776 tel 508.259.1137 fax 866.820.7840 120 Campion Rd, Technical Review 2 November 13, 2013 dormers to the 3rd floor of the existing house, it should also be verified that additional living space is not being added there as well. 4. Based on historic aerial photography, it appears that the swimming pool and patio surround were added to the property sometime after 1995. It should be determined whether a Watershed Special Permit was issued for that work and, if so, whether the current proposal is consistent with the terms of the permit. 5. The proposed plan calls for a net increase in impervious area on the site of just over 480 square feet (sf), 140 sf of which is pavement. As proposed, runoff from 685 ft of roof area on the new addition will be directed to a subsurface drywell to provide compensatory recharge. It is unclear whether this will in fact provide a net increase in recharge on the property as claimed, since I suspect that much of the roof runoff from the existing garage drains to pervious areas and is recharged on site. Artificial recharge also does not compensate for losses due to increased evaporation from impervious surfaces. While the Watershed Protection District regulations do not specifically address impervious area, the Planning Board should be aware that for new and expanded Class A Surface Water Sources the Massachusetts Drinking Water Regulations (3 10 CMR 22.20C) restrict land uses that result in rendering impervious more than 15% (or more than 20% with artificial recharge) or 2500 square feet of any lot, whichever is greater. The plan should enumerate the total impervious area on the property and, if the Board permits the proposed project, I recommend that any further increase in impervious cover be restricted. 6. Sheet A001 of the architectural plans call for an 8-in copper drip edge on the new roof. Recent studies have shown that when exposed to acid rain, the runoff from copper roofs can carry levels of ionic copper that are potentially toxic to aquatic life and the Massachusetts DEP has taken the position that infiltration of runoff from metal roofs or roofing elements, specifically galvanized metal and copper, should be prohibited in Critical Areas, including the recharge zones for public water supplies. 7. The plan does not indicate how the existing driveway is graded, or what will happen to the runoff from the additional pavement area. It should not be drained toward the wetland without some form of treatment. 8. Per the Special Permit requirements, the Plan should show the proposed edge of vegetation clearing/limit of work. 9. The application calls for a restriction on lawn care products consistent with the requirements of the Watershed Protection District and similar Special Permits issued by the Board. I also recommend that the use of coal tar-based pavement sealants be prohibited on the property, as they have been determined to contribute high levels of polycyclic aromatic hydrocarbons (PAHs)to stormwater runoff. 120 Campion Rd, Technical Review 3 November 13, 2013 10. It appears that the proposed erosion control barriers should be extended past the existing slate patio. I appreciate the opportunity to assist the North Andover Planning Board with the review of this project, and hope that this information is suitable for your needs. Please feel free to contact me if you or the applicants have any questions regarding the issues addressed herein. Sincerely, EGGLESTON ENVIRONMENTAL Lisa D. Eggleston,P.E.