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HomeMy WebLinkAboutConsultant Review - 107 CAMPION ROAD 7/15/2014 Eggleston Environmental July 15,2014 North Andover Planning Board 1600 Osgood Street North Andover,MA 01 845 Attn: Curt Bellevance, Director of Community Development RE: Watershed Special Permit 107 Campion Road Dear Mr. Bellevance and Board Members: In follow-up to my June 17, 2014 comments on the above-referenced project, I have received the June 23, 2014 response letter and the July 9, 2014 revised plan and calculations submitted by James Fairweather,P.E. of Andover Consultants Inc. Based on the recent soil tests and runoff calculations, Mr. Fairweather has satisfactorily demonstrated that the three proposed rain gardens would adequately mitigate projected increases in the volume or rate of runoff from the site resulting from the proposed development. Per the analysis, roof runoff from the proposed building should be directed onto pervious surfaces or infiltrated via a drip trench or dry wells; it should not be piped directly to the rain garden. As outlined in my previous comments,the Board should consider requiring a covenant on the property to ensure that future property owners maintain the rain gardens and do not regrade or otherwise alter their fiinctionality as stormwater management structures. While Mr. Fairweather's response letter suggests that the rain gardens are solely for the benefit of the subject property, I would argue that they also perform an important function in preventing erosion on downgradient properties and protecting the water quality of Lake Cochichewick. I also recommend that the conditions outlined in my previous comments #6 and #7 be incorporated in any approvals issued for the project. Since the project will not be subject to the EPA Construction General Permit, the Conservation. Commission may want to address erosion & sediment control requirements in its Order of Conditions as well. Once again, 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. Sincerely, EGGLESTON ENVIRONMENTAL Lisa D. Eggleston,P.E. C: Jennifer Hughes, Conservation Coordinator 32 Old Framingham Rd Unit 29 Sudbury MA 01776 tel 508.259.1137 /t7 andover 1 East River Place consultants Methuen, Massachusetts 01844 inc. Tel. (978) 687-3828 Fax (978) 686-5100 www,andoverconsultants.com June 23,2014 North Andover Planning Board Town Offices 1600 Osgood Street North Andover,MA 01845 RE: Watershed Special Permit 107 Campion Road Ladies and Gentlemen: We are in receipt of review comments made by your consultant, Ms. Lisa Eggleston, P.E., for the project captioned above, contained in her letter to the North Andover Planning Board dated June 17, 2014. Five copies of the revised plan revision dated June 19, 2014 are attached. The plan was revised in response to some of the review comments as noted below: Comment 1. The entire project site is located within the Watershed Protection District (WPD). It is my understanding that the lot was created prior to Oct 24, 1994 and is therefore not subject to the "Conservation Zone" requirements of the Watershed Protection District regulations, however this should be confirmed. In addition, the Non Disturbance Zone should be shown on the plan as extending 100 feet from the edge of all wetland resource areas within the watershed district and the Non Discharge Zone should be shown to include all of the area within 325 feet of the edge of all wetland resource areas within the watershed district The proposed uses are allowed by Special Permit within these zones, however the construction of a new permanent structure within the Non- Disturbance Zone also requires a variance from the Zoning Board of Appeals. The Special Permit Requirements also call for proof that there is no reasonable alternative outside of the Non- Disturbance and/or Non Discharge Zones for any proposed discharge, structure or activity to occur. Response: The lot was created in 1985 by a subdivision approved by the North Andover Planning Board on March 26, 1985 and recorded at the Essex North registry of Deeds as Plan No. 9887. The 100 foot Non-Disturbance Zone coincides with the 100 foot buffer zone and the notation revised accordingly. The 325 Non-Discharge offset from the wetland extends beyond the property limits; the entire lot is within this zone. The applicant was granted a variance by the North Andover Zoning Board of Appeals on May 13, 2014 for the proposed dwelling in the non-disturb zone under Petition No. 2014-004. Comment 2. The Project Description states that the rain garden areas are proposed to compensate for the filling of the wetland, however no calculations have been submitted to demonstrate this. The rain gardens should not only provide sufficient storage to compensate for the filling of the wetland, but also for the increase in impervious surface associated with the development of the site. Based on the evidence of soil erosion I observed on the slope downgradient of the site gust upgradient of the cul-de-sac at the end of Bonny Lane), no increase in overland flow from this site should be allowed. Civil Engineers @ Land Surveyors 9 Land Planners it cops ltant inc. Response: The project is exempt from the MassDEP stormwater standards as it is for a single family dwelling. Also, the existing wetland area is on a slope of approximately 6.5% and provides no storage. The rain gardens are proposed to provide areas to intercept runoff from the proposed impervious areas and allow for infiltration of this runoff in compliance with the requirement, in the Watershed Protection District, to infiltrate to the extent possible, (4.136.4.g.). In addition, the interior of the rain gardens will be planted with various plants tolerant of frequent or alternate inundation and the outside slopes will be planted with other plants. The proposed plantings are intended to replace those lost in the isolated wetland because of construction. Comment 3. Several test pit locations are shown on the Site Plan however the logs were not included in the materials I reviewed. While the NRCS soil map indicates that the site soils should be suitable for the infiltration proposed, the presence of the isolated wetland suggests that there may be more restrictive soils on the site as well. Response: The isolated wetland area was used for a soil stockpiling and staging area during the construction of the sub-division and is the reason for the more compacted nature and reduced infiltrative capacity at this location. Comment 4. Proposed rain garden "A"should be moved as far upslope as feasible to minimize the potential for breakout of infiltrated,flow on the downgradient slope. Response: Rain garden A was placed to pick up tributary area from as much of the lot as possible while providing a reasonable back yard behind the house. The rain garden slopes are 3 to 1 and the interior, infiltrative surface of the rain garden is at least 25 feet from the nearest down slope property line and in an area that much of the existing lot drains to now. Comment 5. The Board may want to require a drainage easement or covenant on the property to ensure that future property owners do not regrade or otherwise alter the proposed stormwater management structures. Response: The rain gardens are on private property for the benefit of the impervious surfaces on the private lot. The rain gardens will require regular maintenance and possible replacement of the soil media from time to time by the owner. Easements are not needed. Comment 6. As with similar projects in the Watershed Protection District, the creation of new lawn area be limited to that which is absolutely necessary, and any new landscape area be constructed in such a manner as to minimize the maintenance that is required, e.g. the soil should be well aerated, it should have a minimum of 6-inches of topsoil and, where possible, native vegetation should be planted to minimize the need for fertilizer and watering. The use of fertilizers and other landscape chemicals on the site should be limited to organic, slow-release and low- phosphorus products. Also consistent with recently permitted projects within the District, both the limits of approved clearing and the restriction on lawn care products should be permanently recorded on the deed to the property. Response: The Applicant will comply if conditioned in the permit. Comment 7 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. Likewise, the use of copper on the building exterior should be prohibited within the Watershed Protection District to prevent the leaching of this toxic heavy metal into the water supply. Response: The Applicant will comply if conditioned in the permit. and over conSUIte°nts Mc Comment 8. It appears that the proposed project will entail the disturbance of more than one acre of land; hence it is subject to EPA's NPDES Construction General Permit (CGP) and will require filing for coverage under the CGP and the preparation and implementation of a Stormwater Pollution Prevention Plan (SWPPP) prior to construction. The SWPPP should be prepared in conjunction with the site contractor and should include a construction sequence aimed at minimizing the duration of exposure of unstabilized soils on the project site. The Planning Board and/or Conservation Commission may want to request documentation of coverage under the CGP and a copy of the SWPPP and/or monitoring reports. Response: The entire lot contains one acre. Portions of the lot will remain undisturbed such that less than an acre of the lot will be disturbed. Conservatively assuming that the entire lot uphill of the hay bales is disturbed, approximately 40,900± sf or 0.94± acres will be disturbed. As such, an NPDES CGP is not required for this project. Should you have any comments or require any additional information concerning the revisions above, or have any additional questions, feel free to contact us. Sincerely, ANDOVER CONSULTANTS,INC. James S. Fairweather II, P.E. Project Engineer Enclosures cc Eggleston Environmental Dimitrios Saragas