HomeMy WebLinkAbout2025/08/07 - 3rd Stormwater Peer Review - - 364 JOHNSON STREET %�.
Horsley Wiften Group
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SUStainable, Ehvirownental Solutions
112 W'at r `tr t-61 Floor-Boston,MBA 02109 ..........
August 7, 2025
Ms. Jean Enright, Planning Director
Planning Department
Town of North Andover
120 Main Street
North Andover, Massachusetts 01845
Re: Third Stormwater Peer Review
Proposed Improvements— 364 Johnson Street
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 third review of the Watershed Special Permit Application for the
proposed improvements at 364 Johnson Street in North Andover, MA. The plans were prepared
by John J. McDonnell, MSCE, PE, PLS on behalf of Gergory and Melissa Buitkus (Applicant).
The project proposes a 376 square foot (sf) expansion of the existing two-story dwelling within
the 325-foot "Non-Discharge Buffer Zone" to Bordering Vegetated Wetlands (BVW). The
stormwater management for the proposed improvements includes a 160-gallon mini drywell and
a subsurface system for infiltration on the east side of the existing building. The existing footprint
of the house is 890 sf. The proposed footprint of the expanded house is 1,266 sf. A total
increase of approximately 376± sf of impervious surface area is proposed within the 26,571-sf
parcel. It appears that the total land disturbance will be less than 43,560 sf.
The residential lot is located within the Watershed Protection District and was created in 1964,
before October 24, 1994. The lot is located within the urbanized area and the area of
disturbance is less than 1 acre. The project is proposed within the 325-foot Non-Discharge
Buffer Zone from the edge of a BVW. The BVW is located along the western side of the
roadway at 365 Johnson Street. The closest point of the proposed expansion to the BVW is
approximately 260 feet. The proposed limit of disturbance is greater than 100 feet from the
wetland resource area. In accordance with §195-4-19 B.(2)(a) 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 following additional documents and plans were received by HW in response to our second
review letter dated August 1, 2025:
• Email to Jean Enright, regarding 1st Horsley Witten Stormwater Peer Review Letter, sent
by Greg Buitkus, dated August 6, 2025 (2 pages);
• Stormwater Management Report, 364 Johnson Street, North Andover, MA, prepared by
John J. McDonnell, MSCE, PE, PLS, dated August 3, 2025 (15 pages); and
r � [f n. t- I, " ii tte n G ro u p �IM Horsley Wtten Group, [iris.
Town of North Andover
August 7, 2025
Page 2of5
• Plan of Land, 364 Johnson Street, North Andover, MASS, prepared by John J.
McDonnell, MSCE, PE, PLS, revised August 5, 2025 (Sheets 1 and 2 of 2).
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 second review letter dated July 7, 2025. Follow up
comments are provided in bold underlined font.
1. The Applicant has provided a Plot Plan of Land. HW recommends adding a north arrow
to the plan and providing a legible signed and stamped copy of the plan to the Planning
Board.
August 1, 2025: The Applicant has added a north arrow to Sheet 1 of 2 of the Plan
of Land provided. HW appreciates that a second sheet at a scale of 1" = 10` has
been included. However, we recommend that a north arrow also be added to Sheet
2 of 2.
August 7, 2025: A north arrow has been provided on Sheet 2 of 2. No further
action is requested.
2. The Applicant has called out erosion controls and notes on the Plan. A callout for a silt
sock is noted but it is unclear where it is located. It is also unclear where stockpiling
onsite will occur and the limits of the disturbance for work. HW recommends showing the
limits of disturbance and locations of silt sock in addition to where the stockpiles will be
located during construction. HW recommends that the erosion controls be added along
the tree line parallel to the eastern property line to protect the wetland from sediment
transported by construction equipment onto the existing driveway. HW further
recommends that erosion controls be extended along the tree line to the north of the
house to protect the area from sediment transported by construction equipment using
the proposed construction access.
August 1, 2025: The Applicant has clarified the location of the silt sock, onsite
stockpiling and the limit of disturbance. No further action is requested.
3. HW recommends that the Applicant callout a defined construction access point to the
work onsite. HW recommends that the Applicant consider construction matting or other
measures to minimize the tracking of sediment offsite per§250-25.E.(13) of the North
Andover Code.
Town of North Andover
August 7, 2025
Page 3of5
August 1, 2025: The Applicant has provided the location of the construction
access point on the Plan of Land. The Applicant states that construction matting
will be provided. No further action is requested.
4. HW recommends that the Applicant provides a path and mechanism to divert
uncontaminated water around the disturbed areas per§250.25.E.(l 0) and §250-
26.A.(27) of the North Andover Code.
August 1, 2025: The Applicant has added an earthen berm to divert
uncontaminated water around the disturbed area. No further action is requested.
5. HW recommends that the Applicant includes measures to maintain the infiltration
capacity of the existing soils where infiltration is proposed per §250-25.E.(12) of the
North Andover Code. The USDA soil maps list the soil type for this site as hydrologic soil
groups `C' and `D' which are poor for infiltration. HW also recommends that the Applicant
provide the field permeability tests to confirm the 24 inches/hour infiltration rate
documented.
August 1, 2025: The Applicant conducted a soil infiltration test on June 8, 2025
and determined that the rate of infiltration is 24.3 inches per hour (iph). The
Applicant provided a Field Infiltration Test Report within its response package and
has labeled the test hole on the Plan of Land. The exfiltration rated used in the
HydroCAD model is appropriate. No further action is requested.
6. The Applicant has provided some results of the HydroCAD report and analysis for the
proposed system. HW recommends that the Applicant provides the entire HydroCAD
output for the 100-year event and includes the stage storage tables for the infiltration
system that will be used in the drawdown calculations.
August 1, 2025: The Applicant has provided the HydroCAD output for the 100-year
event and included the stage storage tables for the infiltration system as
suggested. The proposed infiltration system should manage the impervious area
directed to it as designed. No further action is requested.
7. The Applicant has provided a drywell to provide pretreatment prior to the infiltration
system. A drywell also infiltrates water. It is not clear how the drywell serves as a `pre-
treatment' to the infiltration rather than additional storage. Furthermore, it appears that
any Total Suspended Solids (TSS) being treated in the drywell system would clog the
system over time. HW recommends that the Applicant provide a sump for solids to settle
within the drywell or providing a deep sump catch basin instead of a drywell as part of
the proposed project.
August 1, 2025: The Applicant has provided a detail of the drywell illustrating a 24-
inch sump. No further action is requested.
Town of North Andover
August 7, 2025
Page 4 of 5
8. HW notes that the Applicant has described the proposed 376 sf addition in the
Watershed Permit Application. HW notes that roof runoff that is being directed to the
subsurface chamber system is considered clean and does not need pretreatment.
August 1, 2025: No further action is requested.
9. HW further notes that the Applicant has included 900 sf of future paved area in the
Stormwater Management Report. However, this area is not shown on the plans or in the
Permit Application. The driveway runoff should include pretreatment prior to infiltrating.
August 1: The Applicant no longer plans to include the future 900 sf of paved area
within the jurisdictional area of the lot. No further action is requested.
10. HW recommends that the Applicant includes the bottom of stone, bottom of chamber,
top of chamber, top of stone and proposed surface elevation on the Cultec Recharger
Detail provided.
August 1, 2025: The Applicant has provided the bottom of stone, bottom of
chamber, top of chamber, top of stone and proposed surface elevation of the
Cultec Recharger Detail on the provided Plan of Land. No further action is
requested.
11. HW recommends that the Applicant illustrate the drainage connection from the roof
downspouts and from the proposed driveway surface. As shown, it is not obvious how
stormwater will get into the drywell or into the Cultec chambers.
August 1, 2025: The Applicant has illustrated the drainage pipe connection from
the roof downspouts. HW understands that the paved driveway is no longer
included in this submission. HW recommends that a detail of the downspout is
provided.
August 7, 2025: The Applicant has included a detail of the downspout as
suggested. No further action is requested.
12. HW recommends that the Applicant include any proposed grading on the site plan. It
appears that the Cultec recharge system proposed will require a change in surface
grades.
August 1, 2025: The Applicant has provided the proposed grading for the project
including the area over the Cultec recharge system. It appears that the Limit of
Disturbance outline should be expanded to include the proposed contours.
August 7, 2025: The Applicant has expanded the limit of disturbance on the plan
set. No further action is requested.
13. The Applicant has provided an Operation and Maintenance (O&M) Plan as part of the
drainage report. HW recommends that the Applicant includes an inspection and
Town of North Andover
August 7, 2025
Page 5 of 5
maintenance log and a simple sketch that clearly labels the stormwater practices as part
of the O&M Plan for use by the homeowner.
August 1, 2025: The Applicant has provided an inspection and maintenance log
and a system diagram of the proposed stormwater system. The purpose of the
proposed sketch is for the homeowner to be able to locate the stormwater
practices in future years. The drawing with a scale of 1" = 10' will be useful to the
homeowner and should be attached to the O&M Plan.
August 7, 2025: The Applicant has included a sketch in Appendix A of the O&M
Plan. No further action is requested.
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, P.E.
Principal