HomeMy WebLinkAbout2019-06-04 Stormwater Review Horsley Wiften Groin
Sustainalble Environmental Solutions
204 Washinoton Street•Suite 801•Boston.MA02108
867-263-8193•horsleyveitten.com
March 28, 2019
Ms. Monica Gregoire, Staff Planner
Planning Department
Town of North Andover
120 Main Street
North Andover, Massachusetts 01845
Ref: A.L. Prime Energy Consultant, Inc.
1725 Turnpike Road, North Andover, Massachusetts
Map 107.13, Block 0056, Lot 0,0 (Parcel 2101107.B-0056-0000.0), Zoned GB
Dear Ms. Gregoire and Board Members:
The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board
with this letter report summarizing our initial review of the Stormwater Report and permitting
plans for the proposed renovated gas station with 'fuel pumps and convenience store at 1725
Turnpike Road, North Andover, MA. The stormwater design was prepared by Landplex, LLC for
A.L. Prime Energy Consultant, Inc. (Applicant). HW understands that the Applicant is proposing
to raze the existing gas station and construct a new gas station with fuel pumps and parking and
stormwater best management practices (BMPs) for the proposed roof and canopy areas. No
part of the project is within a wetland resource area or associated buffers.
The following documents and plans were received by HW:
• Memorandum submitted in support of the Site Plan Review Application, A.L. Prime Energy
Consultant, Inc., 1725 Turnpike Road, North Andover, Massachusetts, Map 107.B, Block
0056, Lot 0.0 (Parcel 2101107.B-0056-0000,0), Zoned GB, not dated;
• Wetland Survey, 1725 TPKE Street, Andover, MA, prepared by Gove Environmental
Services, Inc., dated June 31, 2018;
• Technical Memorandum, 1725 Turnpike Road, North Andover, MA, prepared by Gillon
Associates, dated August 27, 2018;
• Special Permit— Site Plan Review Application for property at 1725 Turnpike Street;
• Stormwater Report, 1725 Turnpike Street, North Andover, MA, prepared by Landplex, LLC,
dated February 22, 2019; and
• Site Plans, Replace C-Store, A.L. Prime #108, 1725 Turnpike Rd (Rte 114), N. Andover, MA
01845, which include:
a Cover Sheet C-0 (2019-03-15)
o Existing Conditions (Landmark) --- (Nov. 30, 2016)
o Site Layout C-1 A (2019-02-25)
o Grading and Utilities C-2 (2019-02-25)
HorsleyWitten.com (i)HorsleyWOtenGroup Horsley Witten Grate, Inc.,
Town of North Andover
March 28, 2019
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o Site Plan --- (2019-02-22)
o Erosion Control ER-1 (2019-02-25)
o Landscape Plan (KDTurner Design) L-1 (2019-02-5)
o Lighting UR-4286-S1 (rla) --- (2019-02-07)
o Tank and Piping TK-1 (2019-02-25)
o Tank and Piping Details TK-2 (2019-02-25)
o Self Service Fire Suppression FSP-1 (2019-02-25)
o Tanker Path TR-1 (2019-02-25)
o EMGCY Vehicle Path TR-2 (2019-03-14)
o Signage SG-1 (2019-02-26)
o Site Details 1 SD-1 (2019-02-25)
o Site Details 2 SD�2 (2019-02-25)
o Floor Plan A-1 (2018-02-25)
o BLDG Elevations A-2 (2019-02-25)
o Canopy Elevations A-3 (2019-02-25)
Stormwater Management Design Peer Review
HW offers the following overall comments concerning the stormwater management design as
per the Zoning Bylaw for the Town of North Andover, last amended May 16, 2017 and the
Massachusetts Stormwater Handbook (MSH) dated February 2008 as well as standard
engineering practice. The North Andover Stormwater Management and Erosion Control
Regulations adopted February 5, 2011 and the North Andover Stormwater Management and
Erosion Control Bylaw are not applicable as the land disturbance is less than 43,560 sf.
In accordance with Article 8.3, section 5.e)viii) of the Zoning Bylaw, all applications for Site Plan
Review shall demonstrate full compliance with the Massachusetts Stormwater Standards,
therefore the comments below correlate with the MSH standards. In accordance with
Massachusetts Department of Environmental Protection (MassDEP) the project is considered a
mix of new and redevelopment which allows for some standards to be met to the maximum
extent practicable.
1. Standard 1 states that no new stormwater conveyances (e.g. outfalls) may discharge
untreated stormwater directly to or cause erosion in wetlands or waters of the
Commonwealth.
a. The Applicant has provided stormwater management to infiltrate the roof runoff which
accounts for the additional impervious area. The northern half of the pavement area will
continue to discharge to the closed drainage system on Turnpike Street via an existing
catch basin located within the driveway entrance. The southern portion of the property
appears to discharge under existing and proposed conditions towards a vegetated swale
within the state right-of-way adjacent to the Donald Johnston property. It appears that
the Applicant has reduced the runoff to both of these locations. However HW
recommends that the Applicant confirm that the two final discharge points do not cause
erosion in waters of the Commonwealth.
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b. Route 114 is a State Highway. HW recommends that the Applicant confirm that
MassDOT will allow the property to continue to discharge into the state stormwater
system.
2. Standard 2 states that storm wafer management systems shall be designed so that post-
development peak discharge rates do not exceed pre-development peak discharge rates.
a. The Applicant has indicated that the stormwater runoff from the proposed building roof
and fuel canopies will be collected via an 8-inch PVC pipe and directed to the
subsurface infiltration system and have provided the pipe connections on the Landplex
Site Plan. A note on the plan states "12" Manifold (see Detail)" however, HW was not
able to locate the manifold detail in the plan set. HW recommends that the Applicant
provide additional details for the subsurface infiltration system including observation
ports and clean outs, if roof leaders are proposed these should be detailed as well.
Furthermore, the detail for the Stormtech SC-740 or approved equal Includes a
reference to the SC-310 Chamber, HW recommends that the Applicant correct this
discrepancy,
b. The Applicant has consistently used curve number (CN) values for grass cover
indicating a "poor" condition. Standard engineering practice is to use "good" condition
unless there is a clear explanation. HW recommends changing the grass/landscape
cover values to "good" or provide an explanation to the Planning Board for the use of
"poor".
c. The Applicant has provided data for two test pits, one of which is at the location of the
proposed infiltration chambers. According to MSH Vol. 2, Ch. 2, p. 104 each subsurface
Infiltration system requires at least 2 test pits within the approximate location of the
Infiltration structure. HW recommends performing an additional test pit at the north end
of the subsurface chamber. The Site Plan indicates exposed ledge north of the
subsurface system, the Applicant must verify that there is sufficient separation from the
bottom of the system to groundwater as well as to bedrock. Furthermore, HW requests
that the Applicant include the full soil test report in the stormwater report for
documentation purposes.
d. The Applicant has indicated different hydrologic soil groups (HSG) throughout the
narrative and HydroCAD calculations. Both the NRCS soil survey and the existing test
pits indicate the soil to be HSG A. HW recommends updating the narrative and the
stormwater calculations or clarify why the various HSG values have been utilized.
e. The Applicant has evaluated the subcatchments flowing towards Turnpike Street at one
analysis point. It appears that the site evaluation should consider two analysis points,
one being the catch basin in the north entrance and one being the swale to the south of
the site. The MSH requires Applicants to verify that the post-development discharge
does not increase over the pre-development discharge at each downgradient property
boundary which may require evaluation at more than one design point. HW recommends
that the Applicant analyze the subcatchments under existing and proposed conditions at
the two separate analysis points or clarify why the one analysis point is appropriate.
f. The Applicant has interchanged subcatchment "5S" and "6S"for the same subcatchment
(small canopy). HW recommends rectifying these titles for clarity.
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3. Standard 3 states that the annual recharge from post-development shall approximate the
annual recharge from pre-development conditions based on soil type.
a. The Applicant provided calculations to demonstrate that the subsurface infiltration basin
was sized to capture and recharge the groundwater recharge volume. However, the
recharge volume for HSG B (0.35) has been used, while the existing test pit data and the
NRCS soil survey indicate HSG A. HW recommends adjusting the recharge volume
calculation to reflect HSG A.
b. HW recommends that the Applicant provide documentation clearly noting how the
provided recharge volume has been calculated.
c. The Applicant has listed two ponds (4P and 5P) in the drawdown calculations, which are
not consistent with the plans or the HydroCAD calculations. HW recommends
resubmitting the drawdown calculations for the proposed subsurface infiltration system.
d. Test pit TH-3 indicates that groundwater was not observed however the bottom of the
test hole was 110 inches below the surface. Therefore, the estimated seasonal high
groundwater (ESHGW) elevation is assumed to be at 135.8. The bottom of the
subsurface infiltration system is set at 136.0. In accordance with MSH Vol. 2, Ch. 2, p.
97 a minimum of 2 feet is required between the bottom of the system and the ESHGW.
HW recommends that the Applicant adjust accordingly. Furthermore, in accordance with
MSH Vol. 3, Ch. 1, p. 28 a mounding analysis may be required. HW recommends that
the Applicant verify if a mounding analysis is required and provide if applicable.
4. Standard 4 states that the stormwater management system shall be designed to remove
80% of the average annual postconstruction load of Total Suspended Solids (TSS) and is
sized to treat 1.0-inches of volume from the impervious area for water quality.
a. The calculations provided for Standard 4 do not appear to be applicable to this project.
HW recommends that the Applicant revisit these calculations and adjust accordingly.
b. The StormTech Specifications and Drawings, which are attached to the stormwater
report, include details of an inspection port. The location of this inspection port is not
included on the plan. HW recommends adding the location to the plan set and the
inspection port detail to the detail sheet.
c. The Applicant has only submitted TSS removal calculations for the roof area, which is
treated through the infiltration basin. However, the roof runoff is considered clean and
therefore this treatment train is not necessary. The Applicant must include the treatment
train for the pavement area of the project site and provide some level of TSS removal
prior to discharging offsite. As this project is considered a mix of new development and
redevelopment the Applicant is required to improve existing conditions which includes
providing additional measures to improve water quality.
5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads
(LUHPPL).
a. The existing and proposed use of the site is considered a LUHPPL therefore the
Applicant is required to comply with Standard 5 to the maximum extent practicable and
utilize BMPs listed in the MSH Vol. 1, Ch. 1, p. 14. The gas station itself is considered a
LUHPPL as well as the high intensity vehicle use of the site. Stormwater discharges
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from LUHPPLs require the use of a treatment train that provides 80% TSS removal prior
to discharge, this treatment train shall provide at least 44%TSS removal prior to
discharge to an infiltration BMP and shall also be designed to treat 1.0 inch of runoff
times the total impervious area at the post-development site. As noted previously the
project site is a mix of new and redevelopment therefore the Applicant is required to j
meet Standard 5 to the maximum extent practicable while improving existing conditions.
b. The Applicant has stated that the roof or canopy should, at a minimum, cover the split
containment pad and preferably extend several additional feet to reduce the introduction
of windblown rain. The plans indicate, however, that the canopy is not covering the
entire containment pad. HW recommends adjusting the design to prevent direct entry of
precipitation onto the spill containment pad.
c. The Applicant has listed several operational practices in the stormwater report. These
are, however, not included in the operations and maintenance plan. HW recommends
adding those to the operations and maintenance plan.
6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone 11 or
an Interim Wellhead Protection Area of a public water supply.
a. The proposed project is not located within a critical area therefore Standard 6 is not
applicable.
7. Standard 7 states that a redevelopment project is required to meet the following Stormwater
Management Standards only to the maximum extent practicable: Standard 2, Standard 3,
and the pretreatment and structural best management practice requirements of Standards 4,
5, and 6. Existing stormwater discharges shall comply with Standard 9 only to the maximum
extent practicable. A redevelopment project shall also comply with all other requirements of
the Stormwater Management Standards and improve existing conditions.
a, The proposed development is considered a mix of new and redevelopment. The
Applicant is increasing the impervious cover by approximately 2,500 sf. Please refer to
the applicable comments for Standards 2-6 noted above.
b. The Applicant should be aware that incorporating low impact development (LID)
techniques and practices is particularly relevant for the Town of North Andover. As a
redevelopment project the Applicant is required to improve existing conditions and to
demonstrate that it has made a complete evaluation of possible stormwater
management measures, including environmentally sensitive site design and LID
techniques that minimize land disturbance and impervious surfaces. HW recommends
that the Applicant demonstrate to the Town that it has conducted a complete evaluation
of LID techniques that were consider in the design phase of this project.
8. Standard 8 requires a plan to control construction related impacts including erosion,
sedimentation or other pollutant sources.
a. The Applicant has proposed the installation of straw wattles to control erosion.
Considering that the proposed development includes the construction of new fuel
pumps, HW recommends adding additional erosion control measures at all
downgradient boundaries.
b. HW recommends that a construction entrance detail be added to the plan set.
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c. HW recommends that the following items are added to the Erosion Control Plan:
• Path and mechanism to divert uncontaminated water around disturbed areas, to the
maximum extent practicable;
• Location of temporary and permanent seeding, vegetative controls, and other
temporary and final stabilization measures; and
• Locations for storage of materials, waste, vehicles, equipment, soil, snow and other
potential pollutants.
d. HW recommends that the following conditions are added to the Sediment and Erosion
Control Plan:
• Sediment shall be removed once the volume reaches 114 to 1/2 the height of a hay
bale. Sediment shall be removed from silt fence prior to reaching the load-bearing
capacity of the silt fence which may be lower than 114 to 112 the height;
• Sediment from sediment traps or sedimentation ponds to be removed when it reaches
a depth of six inches;
• Topsoil shall be stripped from disturbed areas, stockpiled in approved areas and
stabilized with temporary vegetative cover if it is to be left for more than 30 calendar
days; and
• Soil stockpiles must be stabilized or covered at the end of each workday. Stockpile
side slopes shall not be greater than 2:1.
9. Standard 9 states that a long-term operation and maintenance (O&M) plan shall be
developed and implemented to ensure that stormwater management systems function as
designed.
a. MSH Vol. 2, Ch. 2, p. 106 requires mosquito controls to be included in the O&M Plan.
HW recommends adding these to the O&M Plan,
b. HW recommends that the Applicant add inspection report templates to the O&M Plan.
c. To comply with this standard, HW recommends adding the following information to the
O&M Plan:
• Instructions on how future property owners will be notified of the presence of the
stormwater system and the requirements for proper operation and maintenance;
• A simple plan that is drawn to scale and shows the location of all stormwater BMP's;
and
• An estimated operations and maintenance budget.
d. HW recommends that the following items are added to the O&M Plan:
• The name(s) of the owner(s)for all components of the system.
• The signature(s) of the property owner(s).
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• The names and addresses of the person(s) responsible for operation and
maintenance. If responsibility is to be contracted to a third party, a copy of the
maintenance agreement(s) must be provided.
• A plan or map showing the location of the systems and facilities, including easements,
catch basins, manholes/access lids, main, and stormwater devices.
• A list of easements with the purpose and location of each. Easements shall be
recorded with the Essex North Registry of Deeds prior to issuance of a certificate of
completion by the Planning Board.
• Provisions for the Planning Board or its designee to enter the property at reasonable
times and in a reasonable manner for the purpose of inspection.
10. Standard 10 requires an Illicit Discharge Compliance Statement to be provided.
a. The Applicant has not provided a signed Illicit Discharge Compliance Statement. HW
recommends providing an Illicit Discharge Compliance Statement signed by the property
owner.
11. Miscellaneous Comments:
a. The Applicant has included "Taxes x media" and "Viburnum x burkwoodii" in the
landscaping plan, which are not native to Essex County. HW recommends that the
proposed plant species be native to inland Essex County or to be cultivars of these
native species. HW recommends that the Applicant choose native species for the
proposed landscaping.
Conclusions
HW recommends that the Planning Board require that the Applicant address these comments
as part of the Board's review process. The Applicant is advised that provision of these
comments does not relieve him/her of the responsibility to comply with all Town of North
Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations
as applicable to this project. Please contact Janet Bernardo at 774-413-2999 ext 202 or at
lernardo@horsleywitten.com if you have any questions regarding these comments.
Sincerely,
HORSLEY WITTEN GROUP, INC.
Janet Carter Bernardo, P.E. Maria Pozimski
Senior Project Manager Staff Planner
CC: Jennifer A. Hughes, Conservation Administrator
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Sustainable Environrnenfal Solutions
294 Washington Street•Suite 801 Boston,MA 02108
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May 17, 2019
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Ms. Monica Gregoire, Staff Planner
Planning Department
Town of North Andover
120 Main Street
North Andover, Massachusetts 01845
Ref: 2nd Peer Review
A.L. Prime Energy Consultant, Inc.
1725 Turnpike Road, North Andover, Massachusetts
Dear Ms. Gregoire and Board Members:
The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board
with this letter report summarizing our second review of the Stormwater Report and permitting
plans for the proposed renovated gas station with fuel pumps and convenience store at 1725
Turnpike Road, North Andover, MA. The stormwater design was prepared by Landplex, LLC for
A.L. Prime Energy Consultant, Inc. (Applicant). HW understands that the Applicant is proposing
to raze the existing gas station and construct a new gas station with fuel pumps and parking and
stormwater best management practices (BMPs)for the proposed roof and canopy areas. No
part of the project is within a wetland resource area or associated buffers.
The following additional documents and plans were received by HW in response to our March
28, 2019 initial peer review:
• Letter to North Andover Planning Board, regarding Response to Review Comments,
prepared by A.L. Prime Energy Consultant, Inc., dated May 13, 2019;
Stormwater Report, 1725 Turnpike Street, North Andover, MA, prepared by Landplex, LLC,
dated February 22, 2019, revised May 7, 2019; and
• Site Plans, Replace C-Store, A.L. Prime ##108, 1725 Turnpike Rd (Rte 114), N. Andover, MA
01845, which include:
o Cover Sheet C-0 (2019-05-10)
o Existing Conditions (Landmark) --- (2016-11-30)
o Site Layout C-1,0 (2019-04-25)
o Grading and Utilities C-2 (2019-04-25)
o Site Plan --- (2019-05-07)
o Erosion Control ER-1 (2019-05-10)
o Landscape Plan (KDTurner Design) L-1 (2019-04-22)
o Lighting UR-4286-S1 (rla) --- (2019-02-02)
o Tank and Piping TK-1 (2019-02-25)
HorsleyWitten.com 91((Z�HorsleyWittenGroup IM Horsley Witten Group, Inc.
Town of North Andover
May 17, 2019
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o Tank and Piping Details TK-2 (2019-02-25)
o Self Service Fire Suppression FSP-1 (2019-02-25)
o Tanker Path TR-1 (2019-02-25)
o EMGCY Vehicle Path TR-2 (2019-03-14)
o Signage SG-1 (2019-02-26)
o Site Details 1 SD-1 (2019-02-25)
Q Site Details 2 SD-2 (2019-02-25)
o Floor Plan A-1 (2018-02-25)
o BLDG Elevations A-2 (2019-02-25)
o Canopy Elevations A-3 (2019-02-25)
Stormwater Management Design Peer Review
The comments below correlate to our initial review dated March 28, 2019. Follow up comments
are provided in hold font:
1. Standard 1 states that no new stormwater conveyances(e.g. outfalls) may discharge
untreated stormwater directly to or cause erosion in wetlands or waters of the
Commonwealth.
a. The Applicant has provided stormwater management to infiltrate the roof runoff which
accounts for the additional impervious area. The northern half of the pavement area will
continue to discharge to the closed drainage system on Turnpike Street via an existing
catch basin located within the driveway entrance. The southern portion of the property
appears to discharge under existing and proposed conditions towards a vegetated swale
within the state right-of-way adjacent to the Donald Johnston property. It appears that
the Applicant has reduced the runoff to both of these locations. However, HW
recommends that the Applicant confirm that the two final discharge points do not cause
erosion in waters of the Commonwealth.
The Applicant has conducted a field survey of the area and has stated that there is
no evidence of existing erosion. HW is satisfied.
b. Route 114 is a State Highway. HW recommends that the Applicant confirm that
MassDOT will allow the property to continue to discharge into the state stormwater
system.
The Applicant has stated that it has met with MassDOT. If there is any written
documentation from MassDot regarding the suggestion to leave the current ROW
conditions adjacent to the site as-is HW recommends providing the documents to
the Town.
The Applicant complies with Standard 1.
2. Standard 2 states that stormwater management systems shall be designed so that post-
development peak discharge rates do not exceed pre-development peak discharge rates.
a. The Applicant has indicated that the stormwater runoff from the proposed building roof
and fuel canopies will be collected via an 8-inch PVC pipe and directed to the
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subsurface infiltration system and have provided the pipe connections on the Landplex
Site Plan. A note on the plan states "12" Manifold (see Detail)" however, HW was not
able to locate the manifold detail in the plan set. HW recommends that the Applicant
provide additional details for the subsurface infiltration system including observation
ports and clean outs, if roof leaders are proposed these should be detailed as well.
Furthermore, the detail for the Stormtech SC-740 or approved equal includes a
reference to the SC-310 Chamber. HW recommends that the Applicant correct this
discrepancy.
The Applicant has added the requested details to the Landplex Site Plan.
However, the elevations listed on the Site Plan differ from the HydroCAD model by
one foot. The elevations on the Site Plan provide the required four feet of
separation, the HydroCAD model indicates that the infiltration chambers are sized
adequately. For documentation purposes, HW recommends that the Applicant
adjust the plans or the HydroCAD model for consistency.
b. The Applicant has consistently used curve number (CN)values for grass cover
indicating a "poor" condition. Standard engineering practice is to use "good" condition
unless there is a clear explanation. HW recommends changing the grass/landscape
cover values to "good" or provide an explanation to the Planning Board for the use of
.`poor".
The Applicant has adjusted the surface conditions as requested. HW is satisfied.
c. The Applicant has provided data for two test pits, one of which is at the location of the
proposed infiltration chambers. According to MSH Vol. 2, Ch. 2, p. 104 each subsurface
infiltration system requires at least 2 test pits within the approximate location of the
infiltration structure. HW recommends performing an additional test pit at the north end
of the subsurface chamber. The Site Plan indicates exposed ledge north of the
subsurface system, the Applicant must verify that there is sufficient separation from the
bottom of the system to groundwater as well as to bedrock. Furthermore, HW requests
that the Applicant include the full soil test report in the stormwater report for
documentation purposes.
The Applicant has conducted additional soil test pits. HW is satisfied.
d. The Applicant has indicated different hydrologic soil groups (HSG)throughout the
narrative and HydroCAD calculations. Both the NRCS soil survey and the existing test
pits indicate the soil to be HSG A. HW recommends updating the narrative and the
stormwater calculations or clarify why the various HSG values have been utilized.
The Applicant has utilized HSG A in the HydroCAD model and calculations. HW is
satisfied.
e. The Applicant has evaluated the subcatchments flowing towards Turnpike Street at one
analysis point. It appears that the site evaluation should consider two analysis points,
one being the catch basin in the north entrance and one being the swale to the south of
the site. The MSH requires Applicants to verify that the post-development discharge
does not increase over the pre-development discharge at each downgradient property
boundary which may require evaluation at more than one design point. HW recommends
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that the Applicant analyze the subcatchments under existing and proposed conditions at
the two separate analysis, points or clarify why the one analysis point is appropriate.
The Applicant has divided the subcatchment areas into two analysis points and
has documented that the post development discharge will not increase over the
pre-development discharge at either location. HW is satisfied.
f. The Applicant has interchanged subcatchment'W" and "6S"for the same subcatchment
(small canopy). HW recommends rectifying these titles for clarity.
The Applicant has adjusted the labels as recommended.
The Applicant complies with Standard 2.
3. Standard 3 states that the annual recharge from post-development shall approximate the
annual recharge from pre-development conditions based on soil type.
a. The Applicant provided calculations to demonstrate that the subsurface infiltration basin
was sized to capture and recharge the groundwater recharge volume. However, the
recharge volume for HSG B (0.35) has been used, while the existing test pit data and the
NRCS soil survey indicate HSG A. HW recommends adjusting the recharge volume
calculation to reflect HSG A.
The Applicant has revised the required recharge volume calculation as requested,
HW is satisfied.
b. HW recommends that the Applicant provide documentation clearly noting how the
provided recharge volume has been calculated.
HW agrees with the provided recharge volume listed by the Applicant.
c. The Applicant has listed two ponds (4P and 5P) in the drawdown calculations, which are
not consistent with the plans or the HydroCAD calculations. HW recommends
resubmitting the drawdown calculations for the proposed subsurface infiltration system.
The Applicant has adjusted the drawdown calculations and verified that the
proposed infiltration system will empty in less than 72 hours.
d. Test pit TH-3 indicates that groundwater was not observed however the bottom of the
test hole was 110 inches below the surface. Therefore, the estimated seasonal high
groundwater(ESHGW) elevation is assumed to be at 135.8. The bottom of the
subsurface infiltration system is set at 136.0. In accordance with MSH Vol. 2, Ch. 2, p.
97 a minimum of 2 feet is required between the bottom of the system and the ESHGW.
HW recommends that the Applicant adjust accordingly. Furthermore, in accordance with
MSH Vol. 3, Ch. 1, p. 28 a mounding analysis may be required. HW recommends that
the Applicant verify if a mounding analysis is required and provide if applicable.
The Applicant has provided additional test pit data and has confirmed that the
proposed infiltration system has greater than 4 feet of separation to ground water.
HW is satisfied and agrees that a mounding analysis is not needed.
The Applicant complies with Standard 2.
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4. Standard 4 states that the stormwater management system shall be designed to remove
80% of the average annual postconstruction load of Total Suspended Solids (TSS) and is
sized to treat 9.0-inches of volume from the impervious area for water quality.
a. The calculations provided for Standard 4 do not appear to be applicable to this project.
HW recommends that the Applicant revisit these calculations and adjust accordingly.
The roof runoff from the proposed building and fuel station canopies is directed
into the subsurface infiltration system. The runoff is considered clean and
therefore does not require additional water quality measures. Under existing
conditions, the roof runoff flows onto the paved area and combines with the
driveway runoff discharging into the municipal system in Turnpike Street. The
proposed pavement runoff continues to flow untreated into the municipal system.
The Applicant is improving existing conditions by reducing the paved impervious
area that discharges offsite by approximately 2,500 sf and by reducing the flow
and volume of stormwater entering the municipal drainage system.
b. The StormTech Specifications and Drawings, which are attached to the stormwater
report, include details of an inspection port. The location of this inspection port is not
included on the plan, HW recommends adding the location to the plan set and the
inspection port detail to the detail sheet.
The Applicant has clarified the location of the inspection port on the Landplex Site
Plan. HW is satisfied.
c. The Applicant has only submitted TSS removal calculations for the roof area, which is
treated through the infiltration basin. However, the roof runoff is considered clean and
therefore this treatment train is not necessary. The Applicant must include the treatment
train for the pavement area of the project site and provide some level of TSS removal
prior to discharging offsite, As this project is considered a mix of new development and
redevelopment the Applicant is required to improve existing conditions which includes
providing additional measures to improve water quality.
As noted above, the Applicant is improving existing conditions by reducing the
impervious area that discharges offsite by approximately 2,500 sf and by reducing
the flow and volume of stormwater entering the municipal drainage system. The
Applicant strongly opposes infiltrating the runoff from the paved surface even
with appropriate pretreatment measures. HW recommends that the Applicant
present its reasoning to the Planning Board for discussion.
5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant loads
(LUHPPL).
a. The existing and proposed use of the site is considered a LUHPPL therefore the
Applicant is required to comply with Standard 5 to the maximum extent practicable and
utilize BMPs listed in the MSH Vol. 1, Ch. 1, p. 14. The gas station itself is considered a
LUHPPL as well as the high intensity vehicle use of the site. Stormwater discharges
from LUHPPLs require the use of a treatment train that provides 80% TSS removal prior
to discharge, this treatment train shall provide at least 44% TSS removal prior to
discharge to an infiltration BMP and shall also be designed to treat 1.0 inch of runoff
times the total impervious area at the post-development site. As noted previously the
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May 17, 2019
Page 6 of 9
project site is a mix of new and redevelopment therefore the Applicant is required to
meet Standard 5 to the maximum extent practicable while improving existing conditions.
As noted above the Applicant believes it has met the stormwater standards to the
maximum extent practical and strongly opposes infiltrating stormwater runoff
from the paved surfaces. HW recommends that the Applicant present its
reasoning to the Planning Board for discussion.
b. The Applicant has stated that the roof or canopy should, at a minimum, cover the spill
containment pad and preferably extend several additional feet to reduce the introduction
of windblown rain. The plans indicate, however, that the canopy is not covering the
entire containment pad. HW recommends adjusting the design to prevent direct entry of
precipitation onto the spill containment pad.
The Applicant has clarified the limits of the fueling operation. HW is satisfied.
c. The Applicant has listed several operational practices in the stormwater report. These
are, however, not included in the operations and maintenance plan. HW recommends
adding those to the operations and maintenance plan.
The Applicant has added additional operational practices to the O&M Plan as
suggested. HW is satisfied.
6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone li or
an Interim Wellhead Protection Area of a public water supply.
a. The proposed project is not located within a critical area therefore Standard 6 is not
applicable.
No further comment needed.
7. Standard 7 states that a redevelopment project is required to meet the following Stormwater
Management Standards only to the maximum extent practicable: Standard 2, Standard 3,
and the pretreatment and structural best management practice requirements of Standards 4,
5, and 6. Existing stormwater discharges shall comply with Standard 1 only to the maximum
extent practicable. A redevelopment project shall also comply with all other requirements of
the Stormwater Management Standards and improve existing conditions.
a. The proposed development is considered a mix of new and redevelopment. The
Applicant is increasing the impervious cover by approximately 2,500 sf. Please refer to
the applicable comments for Standards 2-6 noted above.
The proposed roof runoff from the proposed building and fuel station canopies is
directed into the subsurface infiltration system. Under existing conditions, the
roof runoff flows onto the paved area and combines with the driveway runoff
discharging into the municipal system in Turnpike Street. The Applicant is
improving existing conditions by reducing the impervious area that discharges
offsite by approximately 2,500 sf and by reducing the flow and volume of
stormwater entering the municipal drainage system.
b. The Applicant should be aware that incorporating low impact development (LID)
techniques and practices is particularly relevant for the Town of North Andover. As a
redevelopment project the Applicant is required to improve existing conditions and to
11:11 rojec:is�201a11rj0Fi N Andover Qn-Ca11118065-- Prime EE necgy%Repoits1190516 2nd Peer Reviow AI_Prime Energy.docx
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May 17, 2019
Page 7 of 9
demonstrate that it has made a complete evaluation of possible stormwater
management measures, including environmentally sensitive site design and LID
techniques that minimize land disturbance and impervious surfaces. HW recommends
that the Applicant demonstrate to the Town that it has conducted a complete evaluation
of LID techniques that were consider in the design phase of this project.
The Applicant has provided a list of LID practices that it has incorporated into the
design and others that it has considered.
8. Standard 8 requires a plan to control construction related impacts including erosion,
sedimentation or other pollutant sources.
a. The Applicant has proposed the installation of straw wattles to control erosion.
Considering that the proposed development includes the construction of new fuel
pumps, HW recommends adding additional erosion control measures at all
downgradient boundaries.
The Applicant has noted that the work at the fueling area is below the existing and
proposed base course and therefore there is no potential for runoff from these
construction areas. However, under comment c below the Applicant describes the
storage of materials to be kept on site during construction. HW recommends
adding additional erosion control measures at a[I downgradient boundaries or
eliminating the stockpiling of materia[s on site.
b.. HW recommends that a construction entrance detail be added to the plan set.
The construction detail has been added as requested.
c. HW recommends that the following items are added to the Erosion Control Plan:
• Path and mechanism to divert uncontaminated water around disturbed areas, to the
maximum extent practicable;
HW's concern is that runoff from the woods west of the site or from the
Johnston property south of the site will flow onto the site during construction
and cause construction sediment to flow into the municipal system. HW
recommends that the Applicant verify that runoff from adjacent properties does
not flow onto the site during construction.
• Location of temporary and permanent seeding, vegetative controls, and other
temporary and final stabilization measures; and
The Applicant has stated that the construction disturbance will be only a short
period therefore temporary seeding is not needed and that the surface above the
infiltration system will be seeded as soon as it is backfilled. Additionally,
temporary stabilization notes have been added to Sheet ER-1. HW is satisfied.
• Locations for storage of materials, waste, vehicles, equipment, soil, snow and other
potential pollutants.
The Applicant has described the storage of potential pollutants and how they
will be managed during construction. The Planning Board may choose to
include the Applicant's response as a condition of approval.
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May 17, 2019
Page 8 of 9
d. HW recommends that the following conditions are added to the Sediment and Erosion
Control Plan:
• Sediment shall be removed once the volume reaches 1/4 to 112 the height of a hay
bale. Sediment shall be removed from silt fence prior to reaching the load-bearing
capacity of the silt fence which may be lower than 114 to 112 the height;
A note has been added to Sheet ER-1. HW is satisfied.
• Sediment from sediment traps or sedimentation ponds to be removed when it reaches
a depth of six inches;
A note has been added to Sheet ER-1 stating that the construction entrance will
be monitored and cleaned of sediment as needed on a daily basis. The Planning
Board may choose to include this note as a condition of approval.
• Topsoil shall be stripped from disturbed areas, stockpiled in approved areas and
stabilized with temporary vegetative cover if it is to be left for more than 30 calendar
days; and
The Applicant has added the requested note.
• Soil stockpiles must be stabilized or covered at the end of each workday. Stockpile
side slopes shall not be greater than 2:1,
The Applicant has added the requested note.
9. Standard 9 states that a long-term operation and maintenance (O&M) plan shall be
developed and implemented to ensure that stormwater management systems function as
designed.
a. MSH Vol. 2, Ch. 2, p. 106 requires mosquito controls to be included in the O&M Plan.
HW recommends adding these to the O&M Plan.
The Applicant has added a mosquito control section as requested.
b. HW recommends that the Applicant add inspection report templates to the O&M Plan.
The Applicant has added the inspection report templates as requested.
c. To comply with this standard, HW recommends adding the following information to the
O&M Plan:
• Instructions on how future property owners will be notified of the presence of the
stormwater system and the requirements for proper operation and maintenance;
• A simple plan that is drawn to scale and shows the location of all stormwater BMP's;
and
• An estimated operations and maintenance budget.
The Applicant has included the requested information in the O&M Plan.
d. HW recommends that the following items are added to the O&M Plan:
• The name(s) of the owner(s)for all components of the system.
• The signature(s) of the property owner(s).
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Town of North Andover
May 17, 2019
Page 9 of 9
• The names and addresses of the person(s) responsible for operation and
maintenance. If responsibility is to be contracted to a third party, a copy of the
maintenance agreement(s) must be provided.
• A plan or map showing the location of the systems and facilities, including easements,
catch basins, manholeslaccess lids, main, and stormwater devices.
• A list of easements with the purpose and location of each. Easements small be
recorded with the Essex North Registry of Deeds prior to issuance of a certificate of
completion by the Planning Board.
• Provisions for the Planning Board or its designee to enter the property at reasonable
times and in a reasonable manner for the purpose of inspection.
The Applicant has included the applicable items in the O&M Plan,
The Applicant complies with Standard 9.
10. Standard 94 requires an Illicit Discharge Compliance Statement to be provided.
a. The Applicant has not provided a signed Illicit Discharge Compliance Statement. HW
recommends providing an Illicit Discharge Compliance Statement signed by the property
owner.
The Applicant has provided the signed Illicit Discharge Compliance Statement and
therefore complies with Standard 10.
11. Miscellaneous Comments:
a. The Applicant has included "Taxus x media" and "Viburnum x burkwoodii" in the
landscaping plan, which are not native to Essex County. HW recommends that the
proposed plant species be native to inland Essex County or to be cultivars of these
native species. HW recommends that the Applicant choose native species for the
proposed landscaping.
The Applicant has revised the proposed landscaping as requested.
Conclusions
HW recommends that the Planning Board require that the Applicant address the remaining
comments as part of the Board's review process. The Applicant is advised that provision of
these comments does not relieve him/her of the responsibility to comply with all Town of North
Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations
as applicable to this project. Please contact Janet Bernardo at 774-413-2999 ext 202 or at
Thernardo@horsleywitten.com if you have any questions regarding these comments.
Sincerely,
HORSLEY WITTEN GROUP, INC.
Janet Carter Bernardo, P.E. Maria Pozimski
Senior Project Manager Staff Planner
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Horsley Witten Group OF
>
Sustainable Environmental Solutions I
294 Washington Street•Suite 801•Boston,MA 02108 !
857-263-8193•horsleywilten.com
May 21, 2019
Ms. Monica Gregoire, Staff Planner
Planning Department
Town of North Andover
120 Main Street
North Andover, Massachusetts 01845
Ref; V Peer Review
A.L. Prime Energy Consultant, Inc.
1725 Turnpike Road, North Andover, Massachusetts
Dear Ms. Gregoire and Board Members:
The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board
with this letter report summarizing our third review of the Stormwater Report and permitting
plans for the proposed renovated gas station with fuel pumps and convenience store at 1725
Turnpike Road, North Andover, MA. The stormwater design was prepared by Landplex, LLC for
A.L. Prime Energy Consultant, Inc. (Applicant). HW understands that the Applicant is proposing
to raze the existing gas station and construct a new gas station with fuel pumps and parking and
stormwater best management practices (BMPs)for the proposed roof and canopy areas. No
part of the project is within a wetland resource area or associated buffers,
The following additional documents and plans were received by HW in response to our May 21,
2019 second peer review:
• Letter to North Andover Planning Board, regarding Response to Review Comments,
prepared by A.L. Prime Energy Consultant, Inc., dated May 20, 2019;
Stormwater Report, 1725 Turnpike Street, North Andover, MA, prepared by Landplex, LLC,
dated February 22, 2019, revised May 20, 2019; and
• Site Plans, Replace C-Store, A.L. Prime #108, 1725 Turnpike Rd (Rte 114), N. Andover, MA
01845, which include:
o Erosion Control ER-1 (211" Rev 2019-05-10)
Stormwater Management Design Peer Review
The comments below correlate to our March 28, 2019 and May 17, 2019 peer review letters.
Follow up comments are provided in underlined bold font:
1. Standard 7 states that no new stormwater conveyances (e.g. outfalls) may discharge
untreated stormwater directly to or cause erosion in wetlands or wafers of the
Commonwealth.
a. The Applicant has provided stormwater management to Infiltrate the roof runoff which
accounts for the additional impervious area. The northern half of the pavement area will
HorsleyWiftenxom 91`)HorsleyWittenGroup Horsley Witien Group, Inc.
Town of North Andover
May 21, 2019
Page 2 of 9
continue to discharge to the closed drainage system on Turnpike Street via an existing
catch basin located within the driveway entrance. The southern portion of the property
appears to discharge under existing and proposed conditions towards a vegetated swale
within the state right-of-way adjacent to the Donald Johnston property. It appears that
the Applicant has reduced the runoff to both of these locations. However, HW
recommends that the Applicant confirm that the two final discharge points do not cause
erosion in waters of the Commonwealth.
The Applicant has conducted a field survey of the area and has stated that there is
no evidence of existing erosion. HW is satisfied.
b. Route 114 is a State Highway. HW recommends that the Applicant confirm that
MassDOT will allow the property to continue to discharge into the state stormwater
system.
The Applicant has stated that it has met with MassDOT. If there is any written
documentation from MassDot regarding the suggestion to leave the current ROW
conditions adjacent to the site as-is HW recommends providing the documents to
the Town.
The Applicant complies with Standard 1.
2. Standard 2 states that storm water management systems shall be designed so that post-
development peak discharge rates do not exceed pre-development peak discharge rates.
a. The Applicant has indicated that the stormwater runoff from the proposed building roof
and fuel canopies will be collected via an 8-inch PVC pipe and directed to the
subsurface infiltration system and have provided the pipe connections on the Landplex
Site Plan. A note on the plan states "l2" Manifold (see Detail)" however, HW was not
able to locate the manifold detail in the plan set. HW recommends that the Applicant
provide additional details for the subsurface infiltration system including observation
ports and clean outs, if roof leaders are proposed these should be detailed as well.
Furthermore, the detail for the Stormtech SC-740 or approved equal includes a
reference to the SC-310 Chamber. HW recommends that the Applicant correct this
discrepancy.
The Applicant has added the requested details to the Landplex Site Plan.
However, the elevations listed on the Site Plan differ from the HydroCAD model by
one foot. The elevations on the Site Plan provide the required four feet of
separation, the HydroCAD model indicates that the infiltration chambers are sized
adequately. For documentation purposes, HW recommends that the Applicant
adjust the plans or the HydroCAD model for consistency.
The HydroCAD calculations have been revised as requested. HW is satisfied.
b. The Applicant has consistently used curve number (CN) values for grass cover
indicating a "poor" condition. Standard engineering practice is to use "good" condition
unless there is a clear explanation. HW recommends changing the grass/landscape
cover values to "good" or provide an explanation to the Planning Board for the use of
"poor".
The Applicant has adjusted the surface conditions as requested. HW is satisfied.
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May 21, 2019
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c. The Applicant has provided data for two test pits, one of which is at the location of the
proposed infiltration chambers. According to MSH Vol. 2, Ch. 2, p. 104 each subsurface
infiltration system requires at least 2 test pits within the approximate location of the
infiltration structure, HW recommends performing an additional test pit at the north end
of the subsurface chamber. The Site Plan indicates exposed ledge north of the
subsurface system, the Applicant must verify that there is sufficient separation from the
bottom of the system to groundwater as well as to bedrock. Furthermore, HW requests
that the Applicant include the full soil test report in the stormwater report for
documentation purposes.
The Applicant has conducted additional soil test pits. HW is satisfied.
d. The Applicant has indicated different hydrologic soil groups (HSG) throughout the
narrative and HydroCAD calculations. Both the NRCS soil survey and the existing test
pits indicate the soil to be HSG A. HW recommends updating the narrative and the
stormwater calculations or clarify why the various HSG values have been utilized.
The Applicant has utilized HSG A in the HydroCAD model and calculations. HW is
satisfied.
e. The Applicant has evaluated the subcatchments flowing towards Turnpike Street at one
analysis point. It appears that the site evaluation should consider two analysis points,
one being the catch basin in the north entrance and one being the swale to the south of
the site. The MSH requires Applicants to verify that the post-development discharge
does not increase over the pre-development discharge at each downgradient property
boundary which may require evaluation at more than one design point. HW recommends
that the Applicant analyze the subcatchments under existing and proposed conditions at
the two separate analysis points or clarify why the one analysis point is appropriate.
The Applicant has divided the subcatchment areas into two analysis points and
has documented that the post development discharge will not increase over the
pre-development discharge at either location. HW is satisfied.
f. The Applicant has interchanged subcatchment "5S" and "6S"for the same subcatchment
(small canopy). HW recommends rectifying these titles for clarity.
The Applicant has adjusted the labels as recommended.
The Applicant complies with Standard 2.
3. Standard 3 states that the annual recharge from post-development shall approximate the
annual recharge from pre-development conditions based on soil type.
a. The Applicant provided calculations to demonstrate that the subsurface infiltration basin
was sized to capture and recharge the groundwater recharge volume. However, the
recharge volume for HSG B (0.35) has been used, while the existing test pit data and the
NRCS soil survey indicate HSG A. HW recommends adjusting the recharge volume
calculation to reflect HSG A.
The Applicant has revised the required recharge volume calculation as requested.
HW is satisfied.
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May 21, 2019
Page 4 of 9
b. HW recommends that the Applicant provide documentation clearly noting how the
provided recharge volume has been calculated.
HW agrees with the provided recharge volume listed by the Applicant.
c. The Applicant has listed two ponds (4P and 5P) in the drawdown calculations, which are
not consistent with the plans or the HydroCAD calculations. HW recommends
resubmitting the drawdown calculations for the proposed subsurface infiltration system.
The Applicant has adjusted the drawdown calculations and verified that the
proposed infiltration system will empty in less than 72 hours.
d. Test pit TH-3 indicates that groundwater was not observed however the bottom of the
test hole was 110 inches below the surface. Therefore, the estimated seasonal high
groundwater (ESHGW) elevation is assumed to be at 135,8. The bottom of the
subsurface infiltration system is set at 136.0. In accordance with MSH Vol. 2, Ch. 2, p.
97 a minimum of 2 feet is required between the bottom of the system and the FSHGW.
HW recommends that the Applicant adjust accordingly. Furthermore, in accordance with
MSH Vol. 3, Ch. 1, p. 28 a mounding analysis may be required. HW recommends that
the Applicant verify if a mounding analysis is required and provide if applicable.
The Applicant has provided additional test pit data and has confirmed that the
proposed infiltration system has greater than 4 feet of separation to ground water.
HW is satisfied and agrees that a mounding analysis is not needed.
The Applicant complies with Standard 2.
4. Standard 4 states that the stormwater management system shall be designed to remove
80% of the average annual postconsfruction load of Total Suspended Solids (TSS) and is
sized to treat 1.0-inches of volume from the impervious area for water quality.
a. The calculations provided for Standard 4 do not appear to be applicable to this project.
HW recommends that the Applicant revisit these calculations and adjust accordingly.
The roof runoff from the proposed building and fuel station canopies is directed
into the subsurface infiltration system. The runoff is considered clean and
therefore does not require additional water quality measures. Under existing
conditions, the roof runoff flows onto the paved area and combines with the
driveway runoff discharging into the municipal system in Turnpike Street. The
proposed pavement runoff continues to flow untreated into the municipal system.
The Applicant is improving existing conditions by reducing the paved impervious
area that discharges offsite by approximately 2,500 sf and by reducing the flow
and volume of stormwater entering the municipal drainage system.
b. The StormTech Specifications and Drawings, which are attached to the stormwater
report, include details of an inspection port. The location of this inspection port is not
included on the plan. HW recommends adding the location to the plan set and the
inspection port detail to the detail sheet.
The Applicant has clarified the location of the inspection port on the Landplex Site
Plan. HW is satisfied.
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c. The Applicant has only submitted TSS removal calculations for the roof area which is
pp Y
treated through the infiltration basin, However, the roof runoff is considered clean and
therefore this treatment train is not necessary, The Applicant must include the treatment
train for the pavement area of the project site and provide some level of TSS removal
prior to discharging offsite. As this project is considered a mix of new development and
redevelopment the Applicant is required to improve existing conditions which includes
providing additional measures to improve water quality.
As noted above, the Applicant is improving existing conditions by reducing the
impervious area that discharges offsite by approximately 2,500 sf and by reducing
the flow and volume of stormwater entering the municipal drainage system. The
Applicant strongly opposes infiltrating the runoff from the paved surface even
with appropriate pretreatment measures. HW recommends that the Applicant
present its reasoning to the Planning Board for discussion.
HW defers to the Planning Board for the acceptance of the Applicant's argument.
HW agrees that the Applicant's concerns have some merit.
5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads
(LUHPPL).
a. The existing and proposed use of the site is considered a LUHPPL therefore the
Applicant is required to comply with Standard 5 to the maximum extent practicable and
utilize BMPs listed in the MSH Vol. 1, Ch. 1, p. 14. The gas station itself is considered a
LUHPPL as well as the high intensity vehicle use of the site. Stormwater discharges
from LUHPPLs require the use of a treatment train that provides 80% TSS removal prior
to discharge, this treatment train shall provide at least 44% TSS removal prior to
discharge to an infiltration BMP and shall also be designed to treat 1,0 inch of runoff
times the total impervious area at the post-development site. As noted previously the
project site is a mix of new and redevelopment therefore the Applicant is required to
meet Standard 5 to the maximum extent practicable while improving existing conditions.
As noted above the Applicant believes it has met the stormwater standards to the
maximum extent practical and strongly opposes infiltrating stormwater runoff
from the paved surfaces. HW recommends that the Applicant present its
reasoning to the Planning Board for discussion.
HW defers to the Planning Board for the acceptance of the Applicant's argument.
b. The Applicant has stated that the roof or canopy should, at a minimum, cover the spill
containment pad and preferably extend several additional feet to reduce the introduction
of windblown rain. The plans indicate, however, that the canopy is not covering the
entire containment pad, HW recommends adjusting the design to prevent direct entry of
precipitation onto the spill containment pad.
The Applicant has clarified the limits of the fueling operation. HW is satisfied.
c. The Applicant has listed several operational practices in the stormwater report. These
are, however, not included in the operations and maintenance plan. HW recommends
adding those to the operations and maintenance plan.
The Applicant has added additional operational practices to the OW Plan as
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suggested. HW is satisfied.
6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone II or
an Interim Wellhead Protection Area of a public water supply.
a. The proposed project is not located within a critical area therefore Standard 6 is not
applicable.
No further comment needed.
7. Standard 7 states that a redevelopment project is required to meet the following Stormwater
Management Standards only to the maximum extent practicable: Standard 2, Standard 3,
and the pretreatment and structural best management practice requirements of Standards 4,
5, and 6. Existing stormwater discharges shall comply with Standard 1 only to the maximum
extent practicable. A redevelopment project shall also comply with all other requirements of
the Stormwater Management Standards and improve existing conditions.
a. The proposed development is considered a mix of new and redevelopment. The
Applicant is increasing the impervious cover by approximately 2,500 sf. Please refer to
the applicable comments for Standards 2-6 noted above.
The proposed roof runoff from the proposed building and fuel station canopies is
directed into the subsurface infiltration system. Under existing conditions, the
roof runoff flows onto the paved area and combines with the driveway runoff
discharging into the municipal system in Turnpike Street. The Applicant is
improving existing conditions by reducing the impervious area that discharges
offsite by approximately 2,500 sf and by reducing the flow and volume of
stormwater entering the municipal drainage system.
b. The Applicant should be aware that incorporating low impact development (LID)
techniques and practices is particularly relevant for the Town of North Andover. As a
redevelopment project the Applicant is required to improve existing conditions and to
demonstrate that it has made a complete evaluation of possible stormwater
management measures, including environmentally sensitive site design and LID
techniques that minimize land disturbance and impervious surfaces. HW recommends
that the Applicant demonstrate to the Town that it has conducted a complete evaluation
of LID techniques that were consider in the design phase of this project.
The Applicant has provided a list of LID practices that it has incorporated into the
design and others that it has considered.
8. Standard 8 requires a plan to control construction related impacts including erosion,
sedimentation or other pollutant sources.
a. The Applicant has proposed the installation of straw wattles to control erosion.
Considering that the proposed development includes the construction of new fuel
pumps, HW recommends adding additional erosion control measures at all
downgradient boundaries.
The Applicant has noted that the work at the fueling area is below the existing and
proposed base course and therefore there is no potential for runoff from these
construction areas. However, under comment c below the Applicant describes the
storage of materials to be kept on site during construction. HW recommends
IOProjects12011.MO65 N Andovor OnrC;aIM8065E Prime Eriergy\Repor1sN190521_3rd Peer Reviow At_Prime Energy.docx
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adding additional erosion control measures at all downgradient boundaries or
eliminating the stockpiling of materials on site.
The Applicant clarified the extent of excavation. HW had previously thought that
new fuel tanks were proposed, and that the excavation of the small lot would be
extensive. HW is satisfied with the erosion controls proposed for the amount of
excavation described by the Applicant.
b. HW recommends that a construction entrance detail be added to the plan set.
The construction detail has been added as requested.
c. HW recommends that the following items are added to the Erosion Control Plan:
• Path and mechanism to divert uncontaminated water around disturbed areas, to the
maximum extent practicable;
HW's concern is that runoff from the woods west of the site or from the
Johnston property south of the site will flow onto the site during construction
and cause construction sediment to flow into the municipal system. HW
recommends that the Applicant verify that runoff from adjacent properties does
not flow onto the site during construction.
The Applicant has added a mechanism to divert the offsite stormwater from
entering the site. HW is satisfied.
• Location of temporary and permanent seeding, vegetative controls, and other
temporary and final stabilization measures; and
The Applicant has stated that the construction disturbance will be only a short
period therefore temporary seeding is not needed and that the surface above the
infiltration system will be seeded as soon as it is backfilled. Additionally,
temporary stabilization notes have been added to Sheet ER-1. HW is satisfied.
• Locations for storage of materials, waste, vehicles, equipment, soil, snow and other
potential pollutants.
The Applicant has described the storage of potential pollutants and how they
will be managed during construction. The Planning Board may choose to
include the Applicant's response as a condition of approval
d. HW recommends that the following conditions are added to the Sediment and Erosion
Control Plan:
• Sediment shall be removed once the volume reaches 1/4 to 1/2 the height of a hay
bale. Sediment shall be removed from silt fence prior to reaching the load-bearing
capacity of the silt fence which may be lower than 1/4 to 112 the height;
A note has been added to Sheet ER-1. HW is satisfied.
• Sediment from sediment traps or sedimentation ponds to be removed when it reaches
a depth of six inches;
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Town of North Andover
May 21, 2019
Page 8of9
A note has been added to Sheet ER-'I stating that the construction entrance will
be monitored and cleaned of sediment as needed on a daily basis. The Planning
Board may choose to include this note as a condition of approval.
• Topsoil shall be stripped from disturbed areas, stockpiled in approved areas and
stabilized with temporary vegetative cover if it is to be left for more than 30 calendar
days; and
The Applicant has added the requested note.
• Soil stockpiles must be stabilized or covered at the end of each workday. Stockpile
side slopes shall not be greater than 2:1.
The Applicant has added the requested note.
9. Standard 9 states that a long-term operation and maintenance (O&M)plan shall be
developed and implemented to ensure that stormwater management systems function as
designed.
a. MSH Vol. 2, Ch. 2, p. 106 requires mosquito controls to be included in the O&M Plan.
HW recommends adding these to the O&M Plan.
The Applicant has added a mosquito control section as requested.
b. HW recommends that the Applicant add inspection report templates to the O&M Plan.
The Applicant has added the inspection report templates as requested.
c. To comply with this standard, HW recommends adding the following information to the
O&M Plan:
• Instructions on how future property owners will be notified of the presence of the
stormwater system and the requirements for proper operation and maintenance;
• A simple plan that is drawn to scale and shows the location of all stormwater BMP's;
and
• An estimated operations and maintenance budget.
The Applicant has included the requested information in the O&M Plan.
d. HW recommends that the following items are added to the O&M Plan:
• The name(s) of the owner(s) for all components of the system.
• The signature(s) of the property owner(s).
• The names and addresses of the person(s) responsible for operation and
maintenance. If responsibility is to be contracted to a third party, a copy of the
maintenance agreement(s) must be provided.
• A plan or map showing the location of the systems and facilities, including easements,
catch basins, manholes/access lids, main, and stormwater devices.
• A list of easements with the purpose and location of each. Easements shall be
recorded with the Essex North Registry of Deeds prior to issuance of a certificate of
completion by the Planning Board.
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Town of North Andover
May 21, 2019
Page 9 of 9
• Provisions for the Planning Board or its designee to enter the property at reasonable
times and in a reasonable manner for the purpose of inspection.
The Applicant has included the applicable items in the O&M Plan.
The Applicant complies with Standard 9.
10. Standard 10 requires an Illicit Discharge Compliance Statement to be provided.
a. The Applicant has not provided a signed Illicit Discharge Compliance Statement. HW
recommends providing an Illicit Discharge Compliance Statement signed by the property
owner.
The Applicant has provided the signed Illicit Discharge Compliance Statement and
therefore complies with Standard 10.
11. Miscellaneous Comments:
a. The Applicant has included "Taxus x media" and "Viburnum x burkwoodii" in the
landscaping plan, which are not native to Essex County. HW recommends that the
proposed plant species be native to inland Essex County or to be cultivars of these
native species. HW recommends that the Applicant choose native species for the
proposed landscaping.
The Applicant has revised the proposed landscaping as requested.
Conclusions
HW is satisfied that the Applicant has adequately addressed our comments. The Applicant is
advised that provision of these comments does not relieve him/her of the responsibility to
comply with all Town of North Andover Codes and By-Laws, Commonwealth of Massachusetts
laws, and federal regulations as applicable to this project. Please contact Janet Bernardo at
774-413-2999 ext 202 or at jbernardo@horsleywitten.com if you have any questions regarding
these comments.
Sincerely,
HORSLEY WITTEN GROUP, INC.
Janet Carter Bernardo, P.E.
Senior Project Manager
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