HomeMy WebLinkAbout2026/03/06 - 2nd Stormwater Peer Review - 200 Bridle Path %�.
Horsley Wiften Group
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SLIStainable, Ehvirownental Solutions
112 W'at r `tr t-61 Floor-Boston,MBA 02109 ..........
March 6, 2026
Ms. Jean Enright, Planning Director
Planning Department
Town of North Andover
120 Main Street
North Andover, Massachusetts 01845
Re: Second Stormwater Peer Review
200 Bridal Path
North Andover, Massachusetts
Dear Ms. Enright and Board Members:
The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board
with this report summarizing our second review of the Watershed Special Permit Application for
the proposed improvements at 200 Bridal Path in North Andover, MA. The plans were prepared
by Andover Consultants, Inc. on behalf of Ryan and Alyssa Heffernan (Applicant). The Applicant
has noted on the site plan a parcel size of 46,361 square feet (sf). The project proposes two
additions to an existing family dwelling to accommodate an Accessory Dwelling Unit (ADU) as
well as a minor expansion of approximately 130 sf of the existing driveway. The proposed
additions will increase the house footprint from 2,069 sf to 2,644 sf, a total of 575 sf. The
stormwater management for the proposed improvements includes a 2-foot-wide by 2-foot-deep
crushed stone recharge trench that is approximately 50 feet long along the north edge of the
driveway to capture and infiltrate the stormwater runoff from the expanded driveway. It appears
that the total land disturbance is approximately 14,000 sf including erosion controls around the
site.
The residential lot is located within the Watershed Protection Overlay District and was created in
1976, before October 24,1994. The lot is located within an urbanized area, and the area of
disturbance is less than 1 acre. A portion of the proposed work is within the 50-foot No Build
Zone from the edge of a bordering vegetated wetland (BVW) located to the north and east of the
dwelling. Most of the project area is within the 100-foot Wetland Buffer Zone and the 100-foot
Non-Disturbance Buffer Zone. The proposed addition on the back of the dwelling is set 18.6 feet
from the BVW. The closest point of any construction activity to the BVW is the erosion control
barrier placed approximately 3 feet from wetland flag 5A. The proposed limit of disturbance is
less than 25 feet from the wetland resource area. In accordance with §195-4.19 B.(2)(c and f) of
the North Andover Zoning Bylaws, any surface or subsurface discharge of stormwater within the
Non-Discharge Buffer Zone is only allowed after a special permit has been granted by the North
Andover Planning Board.
The proposed project is within the jurisdiction of the North Andover Conservation Commission.
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Town of North Andover
March 6, 2026
Page 2 of 4
The following documents and plans were received by HW in response to our initial peer review
letter, dated February 27, 2026:
• Letter to Planning Board regarding Response to Peer Review, 200 Bridal Path, North
Andover, MA, prepared by Andover Consultants Inc., dated March 3, 2026 (3 pages); and
• Proposed Site Plan, 200 Bridal Path, North Andover, MA, prepared by Andover Consultants
Inc., dated February 11, 2026, revised March 3, 2026.
Stormwater Management Design Peer Review
In accordance with §195-4.19.B.(4)All construction in the Watershed Protection District shall
comply with best management practices for erosion, siltation, and stormwater control in order to
preserve the purity of the groundwater and the lake; to maintain the groundwater table; and to
maintain the filtration and purification functions of the land.
HW has the following comments and recommendations regarding the proposed stormwater
management design.
The following comments correlate to our initial review letter dated February 27, 2026. Follow up
comments are provided in bold font.
1. The Applicant has included erosion controls on the site plan including a 9-inch straw
wattle on the north and east side of the project area and a stockpile location on the west
side of the house. HW recommends that the Applicant provides a limit of work line on the
site plan confirming the total area of disturbance. and includes erosion controls around
the stockpile.
March 6, 2026: The Applicant has included the Limit of Work line on the Site Plan
as suggested. The limit of work area is approximately 15,880 sf. No further action
is requested.
2. The Applicant has proposed a temporary construction access around the north side of
the house. HW recommends that the Applicant provide a detail of the construction
access. If feasible, HW recommends that the Applicant evaluate whether the
construction access can be around the south side of the house further from the BVW.
Note 4 on the Site Plan indicates that the existing driveway will be used as the
construction entrance. The plan view and the note are not consistent. HW suggests that
the Applicant considers 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.
March 6, 2026: The Applicant has provided a detail for the construction entrance
and clarified the proposed location as suggested. No further action is requested.
3. The Applicant has noted that the project includes proposed work consisting of two small
additions to an existing single-family residence and is therefore exempt from the
Massachusetts Stormwater Management Standards pursuant to 310 CMR 10.05(6)(1).
Town of North Andover
March 6, 2026
Page 3 of 4
The Applicant has not provided stormwater calculations for the proposed work. However,
the Applicant has provided a stormwater trench adjacent to the proposed expanded
driveway. HW recommends that the Applicant provides runoff calculations for the
existing and proposed conditions to ensure that the stone trench is properly sized for the
increased impervious area and that the proposed improvements do not create adverse
conditions to downstream neighbors.
March 6, 2026: The Applicant has clarified the total additional impervious area and
the proposed storage of the crushed stone trench. The trench appears to be
adequately sized. No further action is requested.
4. HW recommends that the Applicant clarify the total increased impervious area. HW
could not confirm the impervious area to be removed and the total proposed impervious
area to be constructed. HW recommends that the Applicant provides a stormwater
calculation comparing the existing and proposed impervious areas and the runoff for
each. HW further notes that a roof drain is indicated on the Site Plan discharging
towards wetland flag 5A. HW recommends that the Applicant clarify if this roof drain will
remain after construction and if it is causing any erosion to the adjacent BVW.
March 6, 2026: The Applicant has clarified the total additional impervious area and
the proposed storage of the crushed stone trench. The existing roof drain will
remain as currently shown on the Site Plan. The Applicant has stated that the
current discharge is not causing erosion to the adjacent wetlands. No further
action is requested.
5. The Applicant has noted the existing soil conditions as Hydrologic Soil Group (HSG) B/D
per the Natural Resources Conservation Service (NRCS). HW recommends that the
Applicant provides the sizing calculations for the stormwater trench for this soil type. A
soil test pit within the footprint of the trench would be appropriate to confirm the
infiltration rate. The Board may consider requiring a test pit conducted prior to
construction with documentation provided to the Board as a special condition.
March 6, 2026: The Applicant has noted that the proposed storage within the
crushed stone trench excludes infiltration. HW supports the use of the trench to
manage the runoff from the driveway. However, confirming the elevation of
groundwater within the footprint of the trench would be beneficial to confirm it
can store the volume of water calculated by the Applicant and function as
intended. The Board may consider requiring a test pit conducted prior to
construction with documentation provided to the Board as a special condition.
Town of North Andover
March 6, 2026
Page 4 of 4
6. The Applicant has provided Erosion and Sedimentation Control elements on the Site
Plan. It does not appear there are any notes for stabilization on the plans or in the
supplementary information. HW recommends that the Applicant revise the plans as
needed to clarify how the site will be stabilized. HW further recommends that the
Applicant indicates how the landscaping will be restored at the end of construction.
March 6, 2026: The Applicant has added Erosion Control General Notes to the Site
Plan as suggested. No further action is requested.
7. HW notes the Applicant has proposed a stone trench along the driveway. The Applicant
does not mention how this will be maintained or how this affects the proposed runoff.
HW recommends that the Applicant provides information in the supplementary package
explaining how the trench should be maintained after construction and at what frequency
for the benefit of the homeowner.
March 6, 2026: The Applicant has added long-term inspection and maintenance
notes to the Crushed Stone Recharge Trench detail for the benefit of the
homeowner. The Board may consider confirming with the homeowner that it
understands the purpose of the crushed stone trench and that routine inspections
and maintenance will extend the long-term functionality.
Conclusions
HW is satisfied that the Applicant has adequately addressed our comments. We appreciate the
opportunity to assist the Town of North Andover with this project review. Please contact Janet
Bernardo at 508-833-6600 or at ibernardo(cD-horsleywitten.com if you have any questions
regarding these comments.
Sincerely,
HORSLEY WITTEN GROUP, INC.
Janet Carter Bernardo, PE
Principal