HomeMy WebLinkAbout2019-04-02 Stormwater Review I
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March 18, 2019
s. Monica Gregoire, Staff Planner,
,Jennifer A. Hughes, Conservation Adminlistrator
Town of'North, Andover
120 Main Street
North Andover,; Massachusetts, 01845
fil 1010 Willow Street
Town of North r
Dear Ms., Gregoire,, Ms. Hughes are Board embers
The Horsley itt n Group, Inc. H is pleased to provide the North,Andover Planning Board
and Conservation Commission ith this letter report,summarizing our second' review It tl
Stiormwateir Management Plan and Permitting Plans prepared by he Morin-Cameron Group,
Inc. for Gourmet Specialty Foods (Applicant) 100,WillowStreet, North Andlover,
The following additional documents and plans were received y HW in response to,our initial
pacer review dated March 5, 201
Site Improvement Plans, 100 Willow Street, North Andover, Massachusetts 9 pages),,
prepare y'The Morin-Cameron n Group, Inc., dated March 15, 2019, which include:
• Car Sheet C-
• Existing Conditions C-2
• Site Layout C-3,
• Grading, Utility & Drainage inage C-
• Landscape Plan L-
• tmetric Flan L-2,
• Construction Details, I D
• Construction Details, II D-2
Building Elevation -
Letter to North, Andover Planning Department, prepared y The Morin-Cameron Group, Inc.,,
date' March 15, 2 9-, with attachments
o Land Disturbance Sketch—SK- , dated' March 15, 2 19
o Long Term Sty r water Best Management Practices, Operation and Maintenance
Plan, ate March 15, 20195
o Drainage System Key Plan, dated March 15, 2 , 9-
St armwat r Managernerit Calculations, revised March 15, 20191
HydroCAD model,, printed March 15, 2019and
of Existing and "r ose Subcatchment. Plans, revised r h 151, 2019
sl,e
Town of North Andover
March 18, 2019
Page 2 of
stormwater Man.agement Desicin Peer Review
The following comments correlate with our initial review letter dated march 5, 2019, additional
comments are provided in bold fort.
The application states that the North Andover Stormwater Management and Erosion Control
Bylaw and associated Regulations do not apply to the project because the project site and
tributary drainage area are less than one acre (43,560 sf in size. however, the Applicant
presents a total drainage area for both the existing and proposed conditions of 1.02 acres
(44,395f . Therefore, HW recommends that the Applicant demonstrate compliance with the
additional requirements under the Bylaw and associated Regulations and file for a Land
Disturbance Permit. The comments below correlate with the MSH standards and where the
more stringent Town requirements are applicable additional comments are noted.
The Applicant has provided additional evidence that the proposed project and watershed
area is less than 43,560 sf. It is IOW's opinion that the Applicant is required to meet the
Massachusetts St rmwater Standards as part of'the site Plan Review permitting process.
However, it does not appear that the Applicant is required to comply with the more
stringent requirements of a Land Disturbance Permit.
1. standard I states that no new stormwater conveyances may cause erasion in wetlands of
the Commonwealth.
A. The Applicant proposed to use existing discharge points to the rear of the property
(Design Points I and 2 # which ultimately discharge to wetlands. Design Point I
discharges stormwater runoff via overland flew from the existing parking and loading
area to the wetland. The Applicant is not proposing any treatment of existing
stormwater from this design point. While tine Applicant is not proposing any work,
HW recommends that the Applicant consider providing stormwater treatment from
the existing impervious corer to improve the ecisting condition and improve water
quality.
The Applicant complies with standard 1. The Planning Board may choose t
include a condition stating that the existing paring area located outside of the
limit of work will not be repaved as part of this project,
2. standard 2 requires that post-development runoff does not exceed pre-development runoff
off site, for a redevelopment project per Mass MassDEP this standard must he met to the
maximum extent practicable.
In conducting this review, HW had the following comments relative to the HydroCAD model
and design of the stormwater management system.
A. In both the existing condition subcatchment S-1 and proposed condition
subcatchnent Ps1, potential run-on to the project area from Willow street
(specifically contour 2 is not captured in the calculations. HW recommends that
the Applicant extend the watershed boundaries beyond the limit of work and property
fines to quantify potential run-on to the project area from Willow Street.
The Applicant has provided evidence indicating that the stormwater runoff
from Willow street does not flog onto the site. HW is satisfied that the
Applicant has adequately addressed this comment.
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March 18, 2019
Page 3 of
It is unclear from the information provided how roof top runoff from the exist i ng
building is being managed. HW recommends that the Applicant provide details on
how existing and proposed rooftop drainage will be provided and recommends that
the Applicant consider providing a drywell for infiltration of rooftop runoff.
The Applicant has provided an explanation of hew the existing and proposed
roof runoff is managed.. The runoff flows over a landscaped area and is not
causing erosion behind the building.
C. In accordance with Town Regulations} the Applicant has not provided calculations for
the 1-inch and 25-year storm events. HW recommends that the Applicant include
calculations for the 1-inch and 2 -year storm event .o inches).
HW agrees that the Applicant is net required to comply with the North Andover
st rmwater Management and Erosion control Bylaw. No further comment is
needed.
D. The precipitation depths used by the Applicant are not consistent with Town
Regulations. HW recommends that the Applicant use the precipitation depths
provided in the storrnwater Regulations for the HrdroCAD analyses.
11 agrees that the Applicant is net required to comply with the North Andover
ver
st rmw ter Management and Erosion control Bylaw. No further comment is
needed.
E. The Applicant uses a direct entry time of concentration value of 6 minutes for all
subcatchments in both the existing and proposed conditions. The Applicant provides
time of concentration pathways on the existing drainage map over the vegetated
portions of the project area. HW recommends that the Applicant confirm that the time
of concentration pathways shown on the drainage map are not greater than
minutes, especially since water is flowing over vegetated cover as opposed to
impervious cover. If they are greater than 6 minutes, HW recommends that the
Applicant use these values and update the HydroCAD model accordingly.
HW is satisfied that a direct entry of 6 minutes is a reasonable time of
concentration for the delineated watershed.
F. In the existing conditions HydroCAD model, the Applicant models "lawn depressions
as providing storage of st rmwater runoff and mitigation of peek discharges. It is
unclear from the information prodded where these lawn depressions are located and
how the stage storage relationship was developed. HW recommends that the
Applicant provide additional details on how this was calculated.
Farther, the curve number and time of concentration consider potential surface
interception and depression storage over the land surface and therefore, it is not
typical for these micro changes in topography to be modeled to this level of detail
and could result in r`double counting'the impacts of the vegetation. HW recommends
that the lawn depressions be removed from the model as they should be captured in
the time of concentration as stated in comment E above).
The Applicant has provided addi tonal detail and explanatlen regarding the
depressions. HW is satisfied that the depressions have been reasonably
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Town of North Andover
March 18, 2019
Page 4 of
modeled in the reprised HydroCAD calculations.
G. Infiltration Practices:
1. The Applicant uses an a cfiltration rate of 2.41 inches per hoar(iph) for the
infiltration-basin; however, this e filtration rate Is not consistent with the
underlying soil characterized for the project area (HSG C . According to the
soil logs, provided as Attachment H, the published soil data has a saturated
hydraulic conductivity of 0.06-o. o iph. HW recommends that the Applicant
revise the infiltration rate to reflect the limiting layer for infiltration from the
basin based on the soil test logs, which appears to be sandy loam.
HW discussed the chosen a cfiltrati n rate with the Applicant during a
telephone conversation March 12, 2019. HW is satisfied that the rate
f 2.41 ih is reasonable,
2. Device#3— -inch round culvert is modeled which an invert of 241. ;
however, the design plans show an invert of 241.2. Also, the infiltration basin
plan view detail shows that this pipe has a slope of o; o ftlft and the
subsurface detention system plan view detail shows that this pipe has a slope
of 0.0 ft/ft. HW recommends that the Applicant reconcile the model with the
design plans.
The Applicant has reconciled the differences as requested.
. The MSH requires a minimum of o -feet upslope setback from any building
foundation including slab foundations without basements. Using the scale on
the drawing it appears that the infiltration basin is approximately 0-feet from
the building foundation and does not meet the minimum setback
requirements.
The Applicant has chosen to maintain 70 feet between the infiltration
system and the existing building which is on a slab, less than the
recommended separation listed on volume 2, Chapter 2, page 88 of the
MSH. The proposed infiltration basin is 2 feet lower than the building
slab, therefore HW agrees that the 7 foot separation is sufficient,
4. The KNISH recommends that for each test pit, where an infiltration practice is
proposed, evaluate the saturated hydraulic conductivity of the soil, depth to
seasonal high groundwater, NRCS soil textural class, NRCS HSG and the
presence of fill materials. Based on review of the soil longs it does not appear
that the Applicant has evaluated the saturated hydraulic conductivity of the
soils. HW recommends that the Applicant verify the infiltration rates of the soil
underlying the proposed infiltration basin.
The Applicant has provided the necessary soil test pit information.
H. Subsurface Detention Brat
1. The plan view detail shows a proposed inspection port within the system on
the right; however, it is difficult to verify if inspection ports are also proposed
within the system on the left. Further, the location of clean-outs are not
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March 18, 2019
Wage 5 of
identified. HW recommends that the Applicant confirm that inspection ports
will be in both systems and provide clean-out locations.
The Applicant has clarified the location of the inspection ports as
requested.
. The system as design will not prohibit infiltration into groundwater and is
located approximately ately Feet from the building foundation. consistent with
comment 2.G.3 above, this type of practice should be located approximately
1 oo-feet upslope of a building foundation. HW recorn mends that the Applicant
reconsider the design of the subsurface system to meet the requirements in
the MSH.
As stated previously the proposed detention system will not prohibit
infiltration of stormwater and is located less than 10 feet from the
,wilding. The Applicant is satisfied that the system has been designed
o that it will not be determinantal to the building slab. HW would prefer
a barrier be provided to prohibit infiltration so close to the building. For
comparison purposes section 15.211 of the MassDEP Title 5 regulations
for septic systems requires a minimum of 10 feet from a slab foundation
to a soil absorption system located 4 feat above seasonal high
groundwater.
. Standard 3 requires that the annual recharge from post-development F ant fall approximate
annual recharge from pre-development en on ition .
A. The Applicant provided calculations to demonstrate that the infiltration basin was
sized to capture and recharge the groundwater recharge volume for HSG c
generated from the new impervious area. The Applicant also provides draw-down
calculations for the basin using a Rawls Fate of 2.41 inches per hour. consistent :.
with comment 2.G.1 above, an efiltration rate consistent with the most restrictive
lager in the soil test logs should be used for these calculations. HW recommends that
the Applicant provide revised calculations.
The Applicant has provided the required recharge volume in the infiltration
system. 1-1W is satisfied that the Applicant complies with Standard 3.
. Standard requires that the stormwater system be designed to remove % Total
Suspended Solids (TSS) and to treat 1.0-inch of volume from the impervious area for water
quality.
A. Tss calculations are provided in the stormwater report and indicate that the
infiltration basin provides 0% Tss based on adequate pretreatment. The Applicant
states that a one-foot stone diaphragm and three-foot-wide sod strip are provided for
pretreatment. The IVISH recommends that a vegetated filter strip have a one-foot
stone diaphragm and a grass filter strip with a minimum length of 25 feet. Therefore,
the current pretreatment design does not provide adequate pretreatment for the
infiltration basins. HW recommends that the Applicant provide sufficient pretreatment
for the infiltration basin to meet the standard.
The Applicant has provided a reasonable reference for the length of sod. HW is
satisfied.
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Town of North Andover
March 18, 201
Page 6 of
B. The Stormwater Deport states that the infiltration basin was sized to provide storage
and infiltration of the I-inch water quality volume; however, calculations have not
been provided. HW recommends that the Applicant provide calculations for the water
quality volume.
The Applicant has provided the requested calculations. HW is satisfied that the
Applicant complies with Standard 4.
. standard 5 is related to projects with a Land use of Higher Potential Pollutant Loads
(LUHPPL).
Standard 5 is not applicable to this project.
No further comment needed.
6. standard 6 is related to projects with stormwater discharging into a critical area, a Zone or
are Interim Wellhead Protection,area of a public water supply.
Standard 6 is not applicable to this project.
No further comment needed.
. standard 7 is related to projects considered Redevelopment
Standard 7 is not applicable to this project.
No further comment needed.
. standard 8 requires a plan to control construction related impacts including erosion,
sedimentation or other pollutant sources.
A. Appropriate erosion and sediment control during construction will ensure that
infiltration practices function as designed. HW recommends that these areas be
visibly demarcated throughout construction to protect from sedimentation and
compaction.
A note has been added to sheet c- . HW is satisfied.
B. HW recommends that the Applicant include a note on the plans stating that soil stock
piles must be kept outside of the 1 00-foot buffer zone.
A note has been added to sheet c: . HW is satisfied.
c. HW recommends that a construction entrance detail be added to the plan set.
A detai l has been added to sheet -1. HW is satisfied that the Applicant
complies with standard 8.
9. Standard 9 requires a Long-Term Operatlon and Maintenance M Plan to be prodded.
A. For the infiltration basin, the Applicant states "the infiltration basin shall be inspected
after every major rain event for the first three months after construction; a major
storm event is 3.9 inches of rainfall in a 2 -hour period -year storm .,7 In
accordance with the MSH, a major storm event is defined as a stem equal to or
greater than the 2-years 2 -hour storm event (generally 2.9 inches to 3.6 inches).
HW recommends that the Applicant revise the inspection criteria to be consistent
with the MSH.
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Town of North Andover
March 18, 21019
Page 7 of 7'
The Long Term Stormwater Best Management Practl*ces Operation and
Maintenance Plan has been revised as recommended.
B. The maintenance guldelines,for the subsurface detention system appear to, be more
in line with maintenance for a surface detention system. HW recommends,that the
Applicant include specific maintenance requirements for the proposed system.
The Lon Term Stormwater Best Management Practices Operatio n and
9
Maintenance Plan has been revised as recommended.
C. For the level spreader, HW recommends that the major storm event criteria be
updated in accordance with comment 9.A above.
The Long Term Stormwater Best Management, Practices Operation and
Maintenance Plan has been revised as recommended.
D. The Long-Term O&M Plan should become a standalone document and include a
simple sketch to clearly indicate the location of'all stormwater practices to be
inspected as well as locations for snow storage. HW recommends that the Applilcant
include a simple sketch thiat will be provided to the property owner.
A sketch has been included wit the Long 'Term St warn,water Best Management
Practices Operation and Maintenance Plan as recommended. is satisfied
that the Applicant compfles with Standard 9.
10. Standard 10 requires an Illicit Dis' charge Compliance Statement to be provided.
A. The Applicant provided a signed Illicit Discharge Compliance Statement. No further
comment needed.
No, further comment is needed.
11. Miscellaneous Comments:
A. The Applicant is proposing light poles within the proposed vegetated infiltration
basin. Future repairs of the lights or maintenance of thie basin may be difficult.
The AppHicant is satisfled 'that'the light poles and infiltration system will
function appropriatety as, designed. HW has no further comment.
Conclusions
HW is satisfied that the Applicant has adequately responded to our comments. Please contact
Janet Bernardo at 774-4,13-2999 ext 202 or,at J rr~n r ' h rsl itten.co if you have any
questions.
Sincerely,
HORSLEY WITTEN G,ROU�P, INC.
qN
Janet Carter Bernardo, P.E.
Senfor Project Manager
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March 15, 2019
North,Andover Planning Department
Attu. Novice Gregoire, Staff Planner
120 Main, Street
North, Andover, MA 01845
RE: Site Pta n Review Ap plicatio n— 100 Willl w Street
Resoonse to HoailteyWitten Group,, earl
Clear Ms. Gregoire,and Board Members:
We are In receipt of a peer review letter for the above-referenced project, dated march 5, 2019,
prepared the Horsley Witten Group, Inc. " G"). e,also had' i subsequent phone conversation
with Janet Bernardo, PE from,H G on March 12,tl to discuss the,peer review comments. This response
letter, along with the,enclosed revised site plans and documentation, has, been prepared to address
the comments raised 'lr the HWG review letter.
This response lever, is organLzeci, in the same format as the H review letter to address each item
independently and help simplify the review.
Sorer Manaciement Design Peer Retew
Due to the limited size proposed disturbance area and tributary watershed, Lan, 'Disturbance
' rmit r not requiredl for t e pr ect, and therefore true North Andover St r w ter Management
Erosion Control Bylaw does not apply. See the attached Land Disturbance Sketch prepared y The
Morin-Carneron Group,Inc.dated March 13, 2019 for ireference. In Chapter - A there are seven
(7) regulated a til ities that mire compliance with the North Andover St rmwater Management
Erosion Control Bylaw. Below is a list of the seven regulated activities, in the same,order as the Bylaw,
expl irring why each regulated activity is not applicable to this project.
1. This proilect does not disturb 431,,5 s or more of tand associated with construcfion
or reconstruction of stru t res. The proposed project disturbs approximately 37,6 ,,
I�
s (see Land Disturbance Sketch attached).
2. This project does n include multiple separate activities in discontinuous locations
r different schedules that will disturb, 3,5,6 r more of land.,
I This project dies not include paving or charge, in surface material for an are;
43,560 sf or more.
4. This project does not include construction of a new drainage system or alteration, o
an existing drainage system or clonveyance draining an area,of'43,560 sf or more. The
proposed p,ro ect site is located wt the top of the watershed, so the tributary area
flowing to the new drainage system is g e niera Ity the s a m a as the proposed disturbance
area (less than 143,560 so.
5. This pr Oil
Ject does not have, a direct connection or discharge to the VIS4
6. The project does not include, any activity on a land area of 43,560, sf or more that
changes the water,quality,or the force,quantity,direction,firning or l c wtiorr of runoff
flowing from the area;
7. This project is not ai Town of North Andover r roje .
CIVIL ENGINEERS o LAND SURVEYORS lo ENVIRONMENTAL CONSULTANTS LAND USE PLANNERS
6 Elm Street, n III, MA 4 923 978.777.8586 FAX 9 .7 � 'w:348 -
Providing Professional Services Since 1978
www.mo,ri merion.com
North Andover Planning Board March 15, 2019
The HWG letter references a disturbance area of 44,395 sf(1.02 acres), which was obtained from the
Hydro CAD model. This number only represents the particular area that was selected for the
hydrologic analysis, and therefore it is not related to determining appii abitity of the North Andover
Stor water M a n a 9 ennent and Erosion Control Bylaw. As shown o n the LandD&tu nc Sketch,the
total area of disturbance is approximately 37,600 sf (0.86 acres). Since the project site is located at
the top of the watershed,this number also represents the tributary watershed area for the proposed
drainage system. Based on this information, the Borth Andover Stormwater Management&Erosion
ontroi Bylaw does not amply to this proj-e t,
Stormwater Standards
1. Standard 1
A. The project scope is limited only to the work associated with constructing the
proposed parking facility. The proposed site design intentionally avoids working
within the 100 foot buffer zone to the Bordering Vegetated Wetland to minimize
construction related impacts. The existing paved parking area drains overland where
a measure of treatment is provided by the vegetative ground corer. No
improvements or modifications to the existing paved areas or existing drainage
patterns are required for this project, and none are proposed. This project has been
designed to keep all proposed work outside of the 100' buffer zone while ensuring
that the existing hydrologic conditions are generally preserved,
Standard ...;.:.:...:
A. Runoff from Willow Street is
captured in the municipal
stormwater system along billow k
Street, which will not be altered as
a result of the proposed project. :. kr.:
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callow Street pavement r
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drain wards the shoulder of the �;� .�:� �}� :..::.
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roadway and r conveyed to the M .:.:
cater basins located along Willow
Street aria roadside gutters. Since
the roadway runoff is not r
of tributary R....::: k...
to the project site,these areas were
not included in the drainage ::.``: :,.w:
The photo at right shows
anal s i Th h
the roadway gutter at the existing
driveway, r Hoff to the
+ Ir agle,�.Ex stingR driveway entrance Hooking Brea t)...
willow Street catch basins.
B. During a site visit, roof downspouts were observed at the rear of the building. No
roof runoff is conveyed to the front of the building toward the proposed parking lot.
The existing roof drainage characteristics will remain the same in post construction
conditions. Since the roof drainage system will not be changed, no new stormwater
management system is proposed for the existing roof runoff.
C. The forth Andover Stormw ter Management&Erosion Control Bylaw does not a ppt
(See response under Stormwater Management Design Peer Review).
D. The North Andover Stormwater Management&Erosion Control Bylaw does not apply
(See response under Stormwater Management Design Peer Review),
Forth Andover Planning Board March 15, 2019
E. The time of concentrations were confirmed to be reported correctly in the HydroCAD
model. They were not adjusted because it was determined during the phone call with
HWG that the lawn depressions should rem a in in the existing conditions model,whi h
is a more conservative approach to analyzing the existing conditions watershed.
F. The [awry depressions were observed during a site visit and were determined to be
significant to the existing conditions analysis. The stage storage was interpolated
from existing spot grades in order to model a ponding area (see lawn depression
elevations, surface areas and storage alu[ation in the HydroCAD analysis). The
xistin ubc- men Plan(Figure has been revised to delineate the location rid
size of the approximate ponding areas.
G.
1. Soil testing was performed on the project site by a certified soil evaluator
from the Morin-Cameron Group, Inc. on February 1, 2019 to determine the
actual soil conditions. This testing determined the underlying parent soil
material horizon)to be a loamy sand. Per table 2.3.3 "l 982 Rawls Rates",
volurne 3, Chapter 1 of the Massachusetts Stormwater Handbook, an
infiltration rate of 2.41 in hr was used for the design of the infiltration basin.
In our experience, using the actual observed sail textures for determining
infiltration rates is appropriate for storrnwater management design, and is
commonly used in practice.
. The design plans and H do AD model have been reconciled to ensure that
pipe inverts and slopes match.
3. The Massachusetts Storrnwater Handbook lists contradicting setback
distances to building s[abs for different types of infiltration practices. Some
are recommended to be 100 feet away, while others are recommended to
be only 20 feet away. Our profe ionalju m t and standard engineering
practice in Massachusetts suggest that the location of the proposed
infiltration basin from the existing structure is sufficient and will not be
detrimental to the surrounding building.
. The in-situ soil testing determined the underlying soil to be a loamy sand
texture. The Rawls rates as provided in table 2.3.3 "1982 Rawls Rates',
volume 3, Chapter 1 of the Massachusetts Stour water Handbook were used
for the do of the infiltration basin. These rates represent conservative
saturated hydraulic conductivity values based on soil texture.
H.
1. Inspection ports are proposed for both sides of the systems per side). The
detail has been revised to better illustrate the location of all inspection ports.
Also added to the plan are clean--outs located its the center of the system,
although the system is not anticipated to require cleaning.
. The detention system has not been designed to infiltrate because two feet
of separation from the seasonal high water table could not be provided.
While infiltration may still occur from this detention system,there will be no
detrimental impacts to the existing building. The top of the detention
system is located below the concrete slab of the existing building. The
detention system also includes a three inch diameter low outlet, which gill
allow all stormwater to drain out of the detention system at a slow rate.
Additionally, the lour outlet pipe will provide protection against the
accumulation of groundwater ire the vicinity of the existing building.
North Andover Planning Board March 15, 2019
. Standard
A. The required groundwater recharge volume was calculated based on a Hydrologic
Sail Group C because the soil testing discovered a th ick sandy Joann tpsii lager. This
sandy Joann topsoil is consistent with the mapped Hydrologic Soil Group C,which is
appropriate to use for required recharge volume calculations.
As stated previously, the Rawls rate for a toamy sand was used for the design of the
infiltration basin. The design calls for the sandy loan (more restrictive layer) to b
completely removed from the infiltration basin's bottom area. As shown on the
infiltration basin detail, the infiltration system is also located within a cut condition,
which necessitates removal of the sandy loan layer.
. Standard
A. I of me 2, Chapter 2, Page 25 states that for sheet flaw a pretreatment option is "A
grass and gravel combination. Th& should consist of at least 6 inches of gravel
folio wed by 3 to 5 feet of sod." 1 h ite this pretreatment pra dice is listed under the
bi -retention section in the Handbook,- it is our understanding that it can be applied
as a pre-treatment method for any infiitratirng B M P.Therefore,the proposed filter strip
with stone diaphragm provides adequate pre-treatment as required by the
Handbook.
B. Calculations for the 1"' water quality volume have been added to the st rmwat r
management calculations, The size of the infiltration basin was slightly increased t
provide the required storage for the 1"' water quality v lume. The infiltration basin
outlet elevation was raised by 0.10 feet. Refer to the revised St rrr mat r Management
Calculations and revised HydroCAD model.
. Standard
No response warranted.
. Standard
No response warranted.
. Standard
No response warranted.
8. Standard
A. A note has been added to the Grading, Utility and Drainage Plan.
B. A note has been added to the Grading, Utility and Drainage Plan.
C. A construction entrance and settling basin detail has been added to the details
(Construction Details 1 —Sheet -1 .
9. Standard
A. The major storm event rainfall amount has been revised in the Long-Terra Operation
and Maintenance Plan for the infiltration basin section.
B. Maintenance requirements for the subsurface detention basin have been reprised in
the Long-Term Operation and Maintenance Plan,
C. The major storm event rainfall amount has been reprised in the Long-Terra Operation
and Maintenance plan for the level spreader.
North Andover Nanning Board March 15, 2019 5
D. A sketch indicating the location of all stormwater practices and snow storage areas
has been included. A copy of the sketch along with the Long-Term Operation and
0
Maintenance Plan will be provided to the property owner.
10. Standard 10
No response warranted.
11. Miscellaneous Comments
I .
A. Llignt polle, bases are located approximately 7' off the edge of the parking area. As
proposed, the light pole base locations will, not inhiblit r' n er ai el the basin or the
poles, and therefore the tocations have not been revised.
We trust, that the revised plans and calculations, allong with this response letter, address the,
comments raised in Hlorsley Witten Group, Inc.'s peer review Letter.
We,took forward to meeting with the Planning Board at your reigullarly scheduted meeting on March
1,9, 2019 to formally present the proposed project. If you should have a ray quest[ons phor to the
meeting , roles m
ase do not,hesitate to contact e.,
,
Sincerely,
THE, MORIN-CAMERON GROUP, INC.,
00l
Michael C. Laharn, PE,
re Manager
01
MCL/kmm
Enclosures
cc** Gourmet Specialty Foods (via email)
,
Jeff Pratt tv is email)
X\Gangem�Br*tan\,3819\Docs,\PB Response Comments\3,819 Review comments Response Letter.idocx
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LAND DISTURBANCE SKETCH tcv"Um LATE Mwr4 of'03 orin-t-Ameron
I
NORTH AND OVER, b�►� ' p S T It&V GROUPt INC.
. a no uAri.t ram �O$
MRMET ���
Long Term Storm at r Best Management Practices
_Operation and Maintenance Ptah
for
100 Wiw Street
North Andover Massachusetts
March 15,, 2019
The following operation and maintenance plan has been provided to satisfy the requirements of
Standard 9 of the Mass D P Stor water Management handbook associated with development of the
site and associated infrastructure, The success of the Storm water ter Management Plan depends on the
proper implementation, operation and maintenance of several management components. The
following procedures shall be implemented to ensure success of the Storm wr ter Management Plan:
1. The contractor shall. comply with the details of construction of the site as shown on the
approved plans.
2. The stormwater management system shall be inspected and maintained as indicated
below.
3. Effective erosion control measurers during and after construction shall be maintained until
a stable turf is established on all altered areas.
. A Storrnwater Management Maintenance Log is included at the end of this Appendix.
Batc Information
Stormwater Management System owner: Gourmet Specialty Foods
123 Tewksbury Street
Andover, MA 01810
P: (978)470-1 07
North Andover Engineering Department: 384 Osgood Street
North Andover, MA 01845
P: 978 85-0950
North Andover Planning Board: Town Hall
120 Main Street
. North Andover, MA 01845 -
P: 978 88-9 3
Long Term Stormwater Best Management Practices Operation&Maintenance Ptan
0 0 Wittow Street, North Ando er, Massachusetts
March 1 a,,2019—Page I of 4
Erosion and Sedimentation Controts during Construction:
The site and drainage construction contractor shall be responsible for managing stornnwater during
construction. Routine monitoring of disturbed soils shall be performed to ensure adequate runoff and
pollution control during construction,
sediment and erosion control barrier will be placed as shown on the Grading, Utility & Drainage
Plan prlorto the cam n ence ment of a ny c lea ri g,grubbing,and earth re m ovaI o r con struction activity.
The integrity of the erosion control barrier will be maintained by periodic inspection and replace rn e nt
as necessary. The erosion control farrier wilt remain in place until the first course of pavement has
been placed and all side slopes have been loamed and seeded and vegetation has been established.
operations and maintenance plans for the Stormwater Management construction phase and long tern
operation of the system have been attached to this report.
General Conditions
1. The site contractor shall be responsible for scheduling regular inspections and maintenance of
the stormwater BMPfs until the project has been completed. The BMP maintenance shall be
conducted as detailed in the following tong-terra pollution prevention plan and illustrated on the
attached Drainqge t r K y lan nd on the approved d s'1
gn plans:
"'Site improvement Pian in North Andover, Massachusetts, 100 Wiliow Street" prepared for
Gourmet Specitatty Foods by The Morin-Cameron Group, Inc. dated February 13, 2019 and
reprised through March 15, 2019.
2. All Stormwater MP's shall be operated and maintained in accordance with the design plans and
the following Long-Terra Pollution Prevention Plea.
. The owner shall:
a. Maintain an operation and Maintenance Log (see Attachment for the last three gears. The
Log shalt include all BMP inspections, repairs, replacement activities and disposal activities
(disposal"material and disposal location shalt be included in the Log);
b. Make the log available to the North Andover Planning Board and Engineering Department
upon request;
c. Allow members and agents of the forth Andover Planning Board and Engineering
Department to enter the premises and ensure that the owner has complied with the
Operation and Maintenance Plan requirements for each BMP.
4. A recommended inspection and maintenance schedule is outlined below based on statewide
averages. This inspection and maintenance schedurle shall be adhered to at a minimum for the
first year of service of all BMP's referenced in this document. At the commencement of the first
year of service, a more accurate inspection/maintenance schedule shall be determined based o
the level of Searle for this site.
Long Tern Stor wat r Best Management practices Operation &Maintenance Plan
100 widow Street, North Andover, Massachusetts
March 15,2019—Page 2 of
Long-Term Pott tion Prevention P LTPPP
Vegetated Areas:
Immediately after construction, monitoring of the erosion control systems shall occur until
establishment of natural vegetation. Afterwards, vegetated areas shall be maintained as such.
Vegetation shall be replaced as necessary to ensure proper stabilization of the site.
Cost: Included with annual landscaping budget. Consult with local landscape contractors.
Paved Areas:
Sweepers shall sweep paved areas periodically during dry weather to remove excess sediments and
to reduce the amount of sediments that the drainage system shall have to remove from the runoff.
The sweeping shalt be conducted primarily between March 1 Sty and November 1 th. Special
attention should be made to sweeping paved surfaces in March and April before spring rains wash
residual sand into the drainage system.
Cost: Consult with local landscaping companies for associated cosh if necessary.
Salt used for de-icing on the roadway during winter months stall be Rmited as much as possible as
this will reduce the need for removal and treatment. Sand containing the minimum amount of
calcium chloride or approved equivalent) needed for handling may be applied as part of the routine
winter maintenance activities.
Infitrio Basin:
The infiltration basin shall be inspected after every major storm evert for the first 3 months after
construction;a major storm event is 3.1 inches of rainfall in a 24 h our period year storm). Thereafter,
the basin shall be inspected twice per year, typically in the spring and fall. If erosion or loss of
vegetation is observed in the basin, it shaii be repaired immediately and new vegetation shall be
established. Trash, leaves, branches, etc,shall be removed from facility.
The area drains and catch basin outlet shall be inspected annually for obstructions and structural
integrity. The inspections shall be conducted by qualified personnel.
Cost:Consult with local landscaping companies for associated costs if necessary,
Subsurface Detention stem:
The subsurface pipe detention system shall be monitored annualty to ensure that it is draining
properly. The outlet structure shall be checked for debris accumulation twice per year, in the spring
and fall. In the case that water remains in the detention system for greater than three days after
storm event, an inspection is warranted and necessary maintenance or repairs should be addressed
as necessary. Confirm that the low flow outlet in the outlet structure Is not obstructed by debris.The
inspections shall be conducted by qualified personnel.
Cost: Consult with local landscaping companies for associated casts if necessary.
Public Safety Concerns: Manhole covers or inspection port corers shall not be left open and
unattended at any time during inspection, cleaning or otherM e. Broken covers or frames shall be
replaced immediately. At no time shall any person enter the subsurface structure unless measures
have been taken to ensure safe access in accordance with OSHA enclosed space regulations.
Long Term Stormwater Best Management men Practices operation Matntenance Plan
100 widow Street, North Andover, Massachusetts
March 15,2019—Page 3 of
Level Spreader:
The inlet pipe, rip-rap basin and overflow berm shall be inspected after every major storm evert for
the first 3 months after construction; a major storm event is 3.1 inches of rainfall in a 24 hour period
year storm). Thereafter, the system shall be inspected on are annual basis, typically in the spring
months. Any signs of erosion shall b e repaired imrn ediate ly,and any trash or debris shall be removed,
Cost:Consult with local landscaping companies for associated costs if necessary.
Debrts& litter:
All debris and titter shall be removed from the roadway and parking lots as necessary to prevent
migration into the drainage system.
Pest 'ides, HerjoMdes, and Fertilizers:
Pesticides and herbicides shall be used sparingly. Fertilizers shall be restricted to the use of organic
fertilizers only. All fertil€ ers, herbicides, pesticides, sand and salt for deicing and the like shall b
stored in dry area that is protected from Breather.
Cost; Included in the routine landscaping maintenance schedule. The -owner shall consult local
landscaping contractors for details.
NNW Safety Concerns;Chernicals shall be stored in a secure area to prevent children from obtaining
access to them. Any major spills shall be reported to municipal ipal officials.
Prevention of Its€ it r e :
Illicit discharges to the stormwater management system are not allowed, Illicit discharges are
discharges that are not comp6sed entirely of stormwater. Pursuant to Mass DFP Stour water Standards
the following activities or facilities are not considered illicit discharges:firefighting,grater line flushing,
landscape irrigation, uncontaminated groundwater, potable water sources, foundation drains, air
conditioning condensation,footing drains,individual resident car washing,flows from riparian h a b itats
and wetlands, de hl rinated water from swimming poots, grater used for street washing and water
used to clean residential building without detergents.
To prevent illicit discharges to the stormwater management system the following policies should be
implemented:
1. Provisions For Storing Materials And Waste Products Inside or Under Corer
. Vehicle Maintenance And Dashing Controls
3. Requirements uirements for Routine Inspections of the Stormwater Management System i.e.; catch
basins,area drains, infiltration basins &subsurface infiltration system.)
. Spill Prevention and Response Plans.
Long Term Stor water Best Management Practices Operation&Maintenance Plan
100 1 itto r Street, North Andover, Massachusetts
March 15,201 —Page 4 of
DRAINAGE SYSTEM KEY LOT D
PLAN
AREA=217,119�
SF±
eMM FOR ASSESSOR'S
GOURMET SPECIALTY FOODS MAP 98D, LOT 54
100 WILLOW STREET
NORTH ANDOVEk MA
DAM l CH I St 2019
PLAN
SCALE: 1'} "" "
50 100
r
EXISTING
BUILDING
T A (#100WILLOW STREET) LEASPREADER
SNOW AREA Tom,) SUBSURFACE DETENTION Y T !
} INSPECTION PT OUTLET CONTROL
TP. F
STRUCTURE
IT
STONE DIAPHRAGM AND LEANOUT
VEGETATED INFILTRA11ON FILTER TRIP TYP. TYP. OF
AREA DRAIN WTH BONE BASIN
GRATE (TYP. F ' rt .* } is r}}ri. r•..■}.in s .+'�...
}.•..*r#yam.�►a�r�.n,r,. •yww�ww�+•�wrM.,yq++ rr rr*fr
. ..� _ CATCH BASH Y TH
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CATCH BASIL
(P R I AT .
......................................................................................................................................................................................................................................................................................................................................... .............
February 13, 2019
Revved March 15f 2019
Stormwater Management CaLcuL
100 w i low Street— North An d r, M
STANDARD ; Recharge To Groundwater& Static Method
• Catcutate New Impervious Area
(From HydroC Model)
Existing Impervious Area Soil) = 6,052 SF
Proposed Impervious Area SG C Soil) . 25,153 SF
New Impervious Area (HSG C Soil) = 19,101 SF
• Determine Rainfalt Depth to be Recharged
(MassDEP Stormwater Management Handbook Table 2.3.2
Hydrologic Soil Group Recharcie Rain alt Depth
0.259.1
• Calculate Recharge Volume
Rv [0.25" x 19,101 F] 12 -Ire
Rv 398 CF
• Capture Area Adjustment
Schedule of Areas Tributary to Recharge Systems
HCAD Tributary
System ID Impervious Area
PS2 19jr591f
Total: 19,591s
Totat Impervious Area 25,153 SF
Capture Area Adjustment = 2 , f 19,591 s f = 1.29
I equired Recharge Vo ume "Rvf= 1.29 x Rv = 1.29 x 398 CF 5 14 CF
• Provided Recharge Volumes
HCAD Lowest System
Voture
System ID System Outlet Description
Eift-4242,60
Pi 242.60 1,678 CF Infi tration Basin
Total Volume: 1,678 CF
Recharge volume provided measured to lowest outlet or 10-year storm
elevation, whichever is lower:
February 1 ,2019
Msed March 15,2019
Required Recharge VoLume Summary of Rsuft
Tot L VoLume Provided 1,678 CF
otaL VoLume Required
Verif
y Drawdown,Maximum 7 -Hours: Static Method
H AD Recharge Bottom Drawdown Time
System Volume Surface Ir date A - Descry do
Inches Hour
I Area (SF) our
P1 1,678 1,985 2.41 4,2 Infittr tion Basin
"Design Comp ie with h Recharge Volume Standard"
STANDARD : Water aLL Volut e
Stage-Area-Storage for PoM P is In if mtkm i
f`evakn Surfam Storage
• Tributary Impervious Area - 19,591 SF ffeg ( g- Icybir fee
41.90 724 0
241.92 96 17
0 calculate required w t r quality volur 1` depth) 1.9241.96 1, 1 6
WQV [1 x 19,591 SF] 12 SF-1 n 1,63 3 CF
42,00 1,985 135
242.02 2,022 176
242.04 2,059 216
a Lowest outlet elevation 242.6 242-06 2,096 25
42.08 2,133 30
24Z10 2,171 343
QV providedbelow lowest outlet � 1,678 F (OK) � . 2F �s 387
42.14 2,245 432
242,16 2,282 477
242.18 Z319 623
242.20 2,356 670
242.22 2,393 617
24224 Z 430 665
242.26 2,468 714
242.23 2,505 764
242.30 21642 814
242.32 2,679 58
242.34 2,616 913
42.36 2,663 970
242.38 2, 90 1,024
242AU 2,727 1,073
242.4t,� 2,765 1,133
242.44 2,802 1,189
242.46 2.839 1,24
242A8 2,676 1,302
242.50 2,913 1,360
242.52 3,019 1,419
242.64 3,126 1,481
242.56 3,22 1,544
242.58 3,338 1,6i Q
I AM
242.62 3,550 1,743
242.64 3,657 1,520
2y4+2�. 6 3,763 1,584
2 42. 3,86 1,970
242.70 3,975 2,049
24232 4,052 21129
242.74 4,188 24212
ProposedPark Area
f'.
Infil SurDetention
D -7
'P
F.
NORTH WEST OF Existing Side Yard
BUILDING
Su
b _ , 'l Routing Diagram for 3819 Proposed o ditl n
= FHyd
pared y The Morin-Cameron Group,Inc., Printed /1 l '�9
DO 10.00-13 sla00401 0 2014 H dro AD 8 o ware S of bons LL
3819 Proposed Conditions Type 2 - r 2-Year in1l=3.1011
Prepared by The Morin-Cameron Group, Inc. Printed 31 9
hLdroCADO10.0 -13 s/n oo o1 0 2014 Hyd oCAD Software Solutions LLC f
Summary for Subcatchment Ps2# Proposed Parking Area
Runoff 1.63 efs 12.0 rs, Volume= 5,1`i o of, Depth= 2.08"
Runoff by SCS Try-20 method, =SCS, Weig ted-Dl , Time Span 0. o- 6.00 hrs, dt= 0.01 hrs
Type III 2 - r 2-Fear inf il=3.10
Area .....CN Des ri tion
192591 98 Paved parking, HSG C
91942 74 >75% Grass corer, Good, HSG
29,533 Weighted Average
, 33. 6% Pervious Area
19,591 6 .3 ° Impervious Area
To Length Slope Velocity Capacity Description
(minL..-
feet fft fts (cfs)
.o Direct Entry, Direct Entry
Summary for Subcatchment Psi: Existing side Yard
Runoff = 0.11 ofs 12.10 h rs, Volume= 372 of, Depth= 0.97"
Runoff by SCS T -20 method, =SCS, Weighted-CN, Time Spar►= . -3 .t hrs, dt=0.01 hrs
Type III -hr -Meer Rainfalf= .10
Area Description
3 74 >75% Grass cover, Good HSG C
,8 3 100.00% Pervious Area
To Length Slope Velocity Capacity Description
n 'r feet ftltt fuse o ofs
6.0 Direct Entry, Direct Entry
Summary for Reach P2: NORTH WEST of BUILDING
Inflow Area 34 2126 sf, 57.41% i rn pervious, l nfio v Depth 0.22" for 2-Year event
Inflow 0.11 ofs @ 12.10 hrs, Volume= 620 d
Outflow 0.11 ofs 1 .10 hrs, Volume= 620 cf, Atten %, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span=0. 0-3 .0hrs, dt= 0.01 hrs
Summary for Pond PI: Infiltration Basin
Inflow Area 2 , 38 sf, 66.34% impervious, Inflow Depth = . 8" for 2-Year evert
Inflow 1.63 ofs @ 12.09 hrs, Volume= 5.110 o
oufflow 0.73 o s @ 12.28 hrs, V lame= 5,110 of, Men= o, Lag= 11.5 min
Discarded = 0.18 cfs @ 12.28 hrs, Volume e of
Primary 0.55 ofs @ 12.28 hrs, Volume= 644 of
Secondary 0.00 ofs 0.00 hrs, Vol me= 0 of
3819 Proposed Conditions Type / 2 - 2-Year Rainfall=3. "
Prepared by The Morin-Cameron Group, Inc. Printed 3 2019
HLdroCADO 1 . 0-1 s n 00401 0 2014 HLdroCAD Software Solutions LLC l
Routing by Stor-Ind method, Time Spare 0.00-36.00 hrs, dt= 0,01 hrs
Peak Elev=242.54' @ 12.28 hrs Surf.Area� 3,142 sf Storage= 1�490 cf
PIu -Flow detention tine=65.4 min calculated for 5,10 of 00% of inflow)
Center-of-Mass a det, time= 65.4 min . - 808.1
Volume Invert Avall.Stora a Storage Description
#1 2 1.90' 2,254 of Custom Stage Data rrs ft Listed below (Recale)
Elevation S r"f.Area Inc.Store Curn.S ore
(feet)....,
241.90 724
242.00 11985 135 13
42.50 2191 ,225 1 t360
242.75 41241 894 2,264
Device Routi.nS., I avert Cutlet Devices
1 Discarded 241.90' 2.410 ln# r EVIltration over surface area
#2 Primary 241. ' io#' Round Culvert x 2.00 L=49.0' Ke= 0.50
Inlet#Outlet l n e& 241.2 ' 241.20' S= 0.0000' ' C =0.900
n= 0.012, Flow Area 0.35 sf
#3 Primary 24 .50' .0"" Round Culvert L= 1 7.0' Ke= 0.500
Inlet/Outlet l avert= 241.5 ' 24 .20' S= 0.0026T C =0.900
n= 0.012, Flow Area- 0.35 sf
#4 Device 2 242.5 }' 12.0" Horl * Orifice/Grate X 2.00 C=0.600
Limited to weir flow at low heads
#5 Device 2 242. 0' 4.0"Hors , Orifice/Grate C= 0.600 Limited to weir flow at low head
Device 8 242.50' 12.0"H ri . Orifice/Grate x 2.00 � 0.600
Limited to weir flog at low heads
#7 Secondary 242.7 ' 10.0' long x 6,0" breadth Broad-Crested Rectangular Weir
Toad (feet) 0.20 0.40 0. 0 0. 0 1.00 1.20 1. 0 1.60
Coef. (English) 2.68 2.70 2.70 2.64 2.03 2.64 2.64 2.63
,9rsoarded ou tFlo Max=0.1 f @ '12. hrs1�W=242. ' (Free'1 (Exfiltrati
Discharge)
=Exf!ltratloon Controls 0.'18 f
Primary OutFlow Max-0.55 cfs @ 12.28 hrs 1"IW�2 2.54' (Free Discharge)
n
lvert (Passes 0.37 cfs of 2.38 ef potential flow)
= rlfice/Grate (Weir Controls 0.18 cfs @ 0.05 fps)
=orifice/Grate (Weir Controls 0.18 cfs @ 0.68 fps)
=Culvert (Passes 0.18 ofs of 0.88 cfs potential flaw)
=orifloe/Grate (Weir Controls 0.1 fs @ 0.68 fps)
§econdary OutFlow lax= . 0 cfs @ 0.00 hrs HW=241,90' (Free Discharge)
7=Broad-Crested Rectangular Weir Controls 0.0 fs
3819 Proposed Conditions Type ///2 -hr 2-Year I airy ll_3.10.{
Prepared by The Morin-Cameron Group, Inc. Printed 3/ 2 10
iroCAD 1 . - 3 s1n 00401 0 2014 H D Software Solutions LLG Ira
Summary for Pond 2: subsurface Detention
Inflow Area = 2 , 33 sf, 66.34% Impervious, Inflow Depth _ .2 " for 2-Year evert
Inflow 0.55 ofs @ 12.28 hrs, Volume= cf
Outflow = 0.09 cfs @ 12.67 hrs, Volume= 248 cf, Aden= 4%, Lag= 23.5 min
Primary _ .0 cfs @ 12.67 hrs, Volume= 248 cf
Routing by Stor-Ind method, Time Span . 0-3 .0hrs, d = 0.01 hrs
Peak Bev= 2 .23'@ 12.67 hrs Surf.Area=2,498 sf Storage= 532 cf
Plug-Flow detention tire=39.0 min calculated for 243 cf 38% of inflow)
Center-of-Mass de . time 30.3 miry 774.7- 744.4
Volume Invert Avail.St ra a Storage Des ri tion
#1A 2 0.70' 947 cf 16.801W 8 "".66%x 1.82'H Field
2, 27 cf Overall- 160 cf Embedded = 2,367 cf x 40.0%Voids
##2A 241.2 ' 160 of C P 8 x 16 Inside#
Inside= 8. "W x 8. "H => 0.47 sf x 20.00'L= 9.4 cf
Outside= . "W x 9.9"H = .47 sf x 20.001= g.4 cf
Rows of 4 Chambers
1 . ' leader x 0.47 sf x 2= 10.1 cf Inside
#3 21.2 ' 37 cf *0"' Round tripe storage x 2
L= 3.7'
##4C 2 .7 ' 731 cf I 6,80W .66%x 1.82'H Field c
1,951 cf Overall- 123 of Embedded = 1 828 cf x 40.0%Voids
# C 2 .2 ' 123 cf CPP 8 x 12 inside#4
Inside= . "W x 8.0"H = 0.47 sf x 20.001# 9.4 cf
Outside= . "W x g. " 0.47 sf x 20.001 9.4 cf
4 Rows of 3 Chambers
1 .8 ' Header x 0.47 sf x 2= 10.1 cf inside
#6 2 . ' 34 of . 'D x 2.7 'H Vertical Cone/Cylinder
2,033 cf Total Available Storage
Storage Group A created with Chamber Wizard
Storage Group C created with Chamber Wizard
Device Routing Invert Outlet Devices
._ #1 Primary 2 1.1 ` 1 . ' long x 2. ' breadth Broad-Crested Rectangular weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.2 1.60 1.80 2.00
2.60 3.00 3.50
Goef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.83 2.3
3. 7 3.20 3.32
##2 Device 1 24 .7 ' 't 2. " Round culvert
L_ 7. ' CPP, projecting, no headwall, fie= 0.900
Inlet#Outlet Invert=2 0.7 '#2 0. ' S= .00 43' ' Co=0.900
-0.012 Corrugated PE, smooth interior, Flow Area-0.79 sf
#3 Device 2 240.7 ' 3. "'Vert. Orifice/Crate C= 0.600
#4 Device 2 2 .3 ' 2. "W x 3. " H Vert. Orifice/Grate C= 0.600
#5 Device 2 2 1. 5' 1 . "' 3. " H Vert. Orifice/Grate C= 0.600
6 Device 2 2 2. ' . ' long x ON breadth Broad-crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00
3819 Proposed Conditions Type H/24-hr 2-Year F i ll=3.10"
Prepared by The Morin-Cameron Group, Inc. Printed I1 I2o19
jjjd.roCAD0 1 . o-13 s n 00401 0 2014roCAD Software Solutions LLG Page 5
Co f. (English) 2.80 2.92 3.08 3.30 3.32
Primary ry OutFlow M =9,09 ofs @ 12.67 hrs W=241.2 ' (Free Discharge)
1�--4L=— road-Crested Rectangular Weir (Basses 0.09 ifs of 1.25 cfs potential flow)
=Culy rf (Passes 0.09 cfs of 9.47 cfs potential flow)
T�3=0riflce/Grate (Orifice Controls 0.99 efs @ 1.76 fps)
0ri i eIG rate Controls 9.90 s
=Ori l eIG rate Controls 9.0 fs
-=Broad-CrestedRectangular Weir Controls 0.00 s
3819 Proposed conditions Type 1112 -hr 10-Year it l-- .5 "
Prepared by The Morin-Cameron Group, Inc. Printed 3/16/20 9
droCA 10. -13 Ire 00401 @ 2014 CAD Software Solutions LLC Page 0
Summary for Subcatchment PS2: Proposed Parking Area
Runoff 2. l cfs @ 12. 9 hrs, of ems- 81357 cf, Depths 3. 0"
Runoff by SCS R-20 method, Ulf=SCS, weighted-CN, Time Span= 0.00-3 .00 hrs, d =0.01 hrs
Type 111 2 -hr 10-Year Rainfall 4.50"
Area CN Descript(on
1%591 98 Paved parking, HSG C
9 2 7 7 % Grass cover Good HSG C
293533 90 Weighted Average
91942 33. 6% Pervious Area
1%591 6 .3 % Impervious Area
To Length Slope Velocity Capacity Description
girt feed fft (Wseq).. . .
6.0 Direct Entry, Direct Entry
Summary for sctn Psi: Existing side Yard
Runoff 0.24 cfs .12.09 hrs, Volume= 755 of, Depth= 1.97"
Runoff by SCS TR-20 method, =SCS, Wei d-CN, Time Spar= 0. -36.00 hrs, eft=0.01 hrs
Type III 2 -hr 10-Year Rainfall=4.50"
Area CN Description
r593 74 >76% Gress cover, Good, FISG C
4,593 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(rain) f ftlft f lsec cfs
6.0 Direct Entry, Direct Entry
Summary for Reach # NORTH WEST OF BUILDING
Inflow Area ` 3 ,'120 sf, 57. 1° Impervious, InfiowDepth = .0 " for 0- ear evert
Inflow 1.0 of @ 12.32 hrs, Volume= 2,849 cf
fflow '1.0 1 cfs @ 12.32 hrs, olu e= 2,849 cf, A#er 0 L 0.0 min
Routing by Stor Ind+Trans method, Time Span 0.00-36.00 hrs} d = 0.01 hrs
Summary for Pond I: Infiltration Basin
Inflow Area - 29,533 sf, 00.34% impervious, inflow Depth 3.40" for 1 0-Year evert
Inflow 2.62 cfs @ 12.09 hrs, Volume= 8,357 cf
for 2.35 cfs @ 12.13 hrs, Volume 8,357 cf, Men= 10%, Lag=2.4 miry
Discarded 0.19 cfs @ 12.13 hrs, Volume= 5,867 cf
Primary = 2.16 cfs @ 12.13 hrs, Volume= 2,490 cf
Secondary 0.00 cfs @ 0.00 hrs, Volume= 0 cf
3819 Proposed conditions Type U/24- r -Year in fI=4.50"
Prepared by The Morin-Cameron Group, Inc. Printed 3/15/2019
-HydroCADO 1 . o-1 Ire 00401 0 2014H drocAD Software Solutions L c P
Routing y Stor-Ind method, Time Spar= o.o -3 , hrs, dt= 0.01 hrs
Peak Elev= 42. '1' @ 12.13 hrs S rf.Area= 3,481 sf Storage ,702 cf
Plug-Flow detention time= 56.1 miry calculated for 8,355 cf 0% of inflow)
Center-of-Mass det. tire= 56.1 miry . -794.4
Volume Invert Avall.Storage Storage Description
#1 241.90' 2,254 cf custom stage Data (Prismatic)Listed below 1 ec 1c
Elevation Surf.Area Inc.Store C rn.Store
Leet). ,f {cubic-feet ubic-feet
W MrWiY1111YWWYWWIW4IYY I.
241.90 724 0
242.00 1, 135 135
242-75 41241 4 2,264
Device Routing Invert Outlet Devices
#1 Discarded 241. ' 2.41 in# r E41tration over surface area
#2 Primary 241.2 r . " Round Culvert X 2,00 L=4 . ' fie=0.500
Inlet/Outlet Invert= 241. 0'#241.2 ' S=o.00 ' ' Cc=0.900
n� 0.012, Flew Area=0.35 sf
#3 Primary 241 f { .oar Round Culvert L= 7. ' I e� 0.600
1Met Outlet invert= 4 . 0' 241.2 r S= 0.0026 T C c= 0.900
= 0.012, Flow Area=0.35 sf
##4 Device 2 242-50' 11 0" on . orifice#Grate x #oo C= 0.600
Limited to weir flow at low heads
#5 Device 2 4 . ' 4.0" Hori . 0rif11cel rate C= 0.600 Limited to weir flew at low heads
Device 3 242.50' 112. " Hori . Odf ice#Grate X .00 C= 0.600
Limited to weir flow at low heads
#7 Secondary 42.70' 1 o.0' non g x 26.0' breadth Broad-crested F ectan [ar weir
Head (feet) 0.20 0.40 0.60 0.80 1. 1.20 1.40 1.60
coef. (English) 2.68 2.70 .70 2.64 2.63 2.64 2.64 2.63
Placarded Outflow Max=0.19 cfs @ 12.13 hrs HIV= 4 . 1' (Free Discharge)
=ftfiltrati n xflltrafion controls 0.19 cfs)
Primary o tFlow Max=2.16 cfs @ 12.13 hrs W= 4 . " (Free Discharge)
q=C lvert (masses 1.43 cfs of .4 cfs potential flow)
= rifice/Gr to (Weir Controls .72 cfs @ .0 fps)
=06f[ce/G rate (Weir Controls 0.72 cfs @ 1.07 fps)
=culvert (Passes 0.72 cfs of 0.92 cfs potential flow)
=orifice#Grate (Weir Controls 0.72 cfs @ 1.07 fps)
§econdary outFlow Max=0.00 cfs @ 0.00 hrs HW44 . ' (Free Discharge)
7=B road-crested Rectangular Weir Controls 0.00 cfs)
3819 Proposed Conditions Type U/2 -hr -Year ain all= .5
Prepared by The Morin-Cameron Group, Inc. Printed 3/15/2019
droCA 1 .o -13 s/n 00401 0 2014 HydroCAD Software Solutions LLC Pa
Summary for Pond P : subsurface Detention
Inflow Area= 29,533 sf, 66.34% Impervious, Inflow Depth = 1.01 for 1 0-Year event
Inflow 2.16 cfs @ 12.13 hr , Volume= 2,490 of
Outflow = 0.93 Cfs @ 12.33 hrs, volume= 2,994 of, Atte = 57° , Lag= 12.2 min
Primary 0.93 cfs @ 12.33 hr , Volume= 2,094 cf
Routing by Stor-Ind method, Time Span=0.00-3 .0 rs, dt= 0.01 hr
Peak Bev= 4 . 9' @ 12.33 firs Sur1'.Area=2,539 of Storage= 1,11 of
Plug-Flow detention time=26.8 min calculated for 2,094 cf 34% of inflow)
Center-of-lass det. tire= 2 .7 min 760.7-740.0
Volume Invert Avail.Storae Storage Description
##1A 240.70' 947 f ' . `w . 5"L c 1.82'H Field
2,527 of Overall- 160 cf Embedded =2,367 of x 40.0% voids
##2A 241.20' 160 of CPP 8 x 16 Inside# 1
Inside= , " v x 8.0"H => 0.47 sf x 20.001= 9.4 cf
Outside= 9.9"W x 9.9"H _ 0.47 sf x 20.001 9.4 cf
Rows of 4 Chambers
10.3 ' Header x 0.47 sf x 2 = 10.1 cf Inside
##3 241.20' 37 of . " Round Pipe Storage x 2
L= 3./**'
4C 240.70' 731 of 16.80'W x 67.651 x 1.82"H Field C
1,9 f Overall - 12 of Embedded = 1,828 of x 40.0%Voids
##5C 241.20' 123 of CPP 8 x 12 Inside#4
Inside= .0"W x .0" k 0.47 f x 20.001 9.4 V
Outside= 9.9`#W x 9.9"H => 0.47 sf x 20.001_9.4 of
4 bows of 3 Chambers
10.8 ' Header x 0.47 sf x 2 10.1 of Inside
240.89 34 cf 4. 'D x 2.70'H vertical Cone/Cylinder
2,033 cf Total Available Storage
Storage Group A created with Chamber Wizard
Storage Group C created with Clamber Wizard
Device Routing Invert Outlet Devices
1 Primary 41. 0' 1 .0' long x 2.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.30 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.09 3. 0
Coef. (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85
3.07 3.20 3.3
#2 Device 1 240.70' 12. " Round Culvert
L=47.0' CPP, projecting, no headwall} Ike= 0.900
Inlet I Outlet Invert= 240.70'/ 40.50' S=0.0943 ' ' C = 0.900
=0.012 Corrugated PE, smooth Interior, Flow Area=019 sf
#3 Device 2 240.70' 3. "Vert. orifice/Grate C= 0.600
#4 Device 2 241.39 12,011 w x 3.0" H Vert. orifice/Grate C 0.600
##5 Device 2 24 .55' 0.0"w x 3. " H Vert. Orifice/Grate C=0. 00
#6 Device 2 42.45' 4f ' long x 0.6' breadth Broad-Crested Rectangular Weir
Dead (feet) 0.20 0.40 0.60 0.80 1.00
3819 Proposed Conditions Type ///2 -fir -Year jnfaP . "
Prepared by The Morin-Cameron Group, Inc. Printed 3 /2019
droCADO 1 . -13 s n 00401 0 2014 droCA Software Solutions LLC Page 9
Coef. (English) 2.80 2.92 3.08 3.30 3.32
Primary Oufflow lax=0.93 cfs @ 12.33 hrs HW=2 1. 9# Free Discharge)
t— :E1ro d-Crested ec a u la�r We!r (Passes 9.93 cfs of 1. 2 fs potential fl ow)
!=Culvert (Passes 0.93 efs of 1.93 cfs potential lever
w"orifi /Grate riff e Controls 0.18 cfs @ 3.70 fps)
=orifice/Grate orifl e Controls 0.61 cfs @ 2.45 fps)
=orifice/Grate (Orifice Controls 0.14 cfs @ 1.29 fps)
N�Broad-Crested
Rectangular Weir Controls 0.00 cfs)
3819 Proposed Conditions Type 1112 -err -Year inf ll=6.50"
Prepared by The Morin-Cameron Group, Inc. Printed 3/15120 9
hLdroCAD(9)1 . - 3 s/n 00401 0 2014 HydroCADSoftware Solutions LL.0 Pacie 10
Summary for Subcatchment Ps2: Proposed Parking Area
Runoff = 4.02 efs @ 12.06 hrs, Volume= 13,127 cf, Depth= .3 "
Runoff by SCS R-20 method, H=SCS! Weight -Cl , `rime Spar= 0.00-36.00 hrs, dt= 0.01 hrs
Type 111 24- r 1 00-Year Rainfall=6.60"
Area CN Description
9969 96 raved parking, HSG C
91942 74 >75% Grass corer Good, 1 SG C
29,533 90 Weighted Average
919 33.6 % Pervious Area
192591 6.3 % Impervious Area
Tc Length Slope Velocity Capacity Description
(min) f#ft) (ftec) (c Ls)
{ 6.6 Direct Entry, Direct Entry
Summary for Subcatchment Psi: Existing Sias Yard
Runoff - 0.45 efs .09 hrs, Volume- 1,3 82 cf, Dept = 3.61_
Runoff by SCS TR-20 method, H=SCS, Weigh a -CN, Time Sparc= 0.00-36.00 hrs, dt 0.01 hrs
Type 111 -hr 1 -Year Rainfall=6. #
Area (so CN Description
=693 74 >75% Grass cover, Good HSG C
�693 100. 0% Pervious Area
Te Length Slope Velocity Capacity Description
'1fn (feet) ifs
6.0 Direct Entry, Direct Entry
Summary for Reach P2: NORTH WEST of BUILDING
Inflow Area 34,126 sf, 57.41% I pervio s, Inflow Depth= 2.34" for 1 o -Year event
Inflow 2.52 cfs @ 12.21 hrs, Volume 6,654 of
outflow = 2.52 ofs 12.21 hrs, Volume= 6,654 cf, Men= 0%, Lague 0.0 rain
Routing y Stor-ind+Trans method, Time Spar= 0. 0-3 .00 hrs, dt= 0.01 hrs
Summary for Pond P : Infiltration Basin
Inflow Area = 29,533 sf, 66,3 % Impervious, inflow kept = .33" for 166-bear event
Inflow 4.02 ofs @ 12.08 hrs, Volume= 13,127 of
ufow 3.7 ofs @ 2.12 hrs, olu�me= 13,127 of, Men= %, Lag= 1.9 ruin
Discarded = 0.21 ofs @12.12 hrs, of me= 7,458 of
Primary = 3. 0 ofs @ 12.12 hrs, Volume= ,69 of
Secondary 0.00 ofs 0.06 hrs, Volume= 0 Cf
3819 Proposed Conditions Type /11 2 - r -Ye r ' in ff= .5 "
Prepared by The Merin-Cameron Group, Inc. Printed 3 1 1201
-HydroCA 1 . 0-13 s1n 00401 0 2014 FlLdroCAD Software Solutions LLC P 11
Routing by Stor-1 nd method, Time Span . 0-3 .0 hrs, dt=0.01 hrs
Peak Flev= 242. ' @ 12.12 hrs S rf.Area= 3,748 sf Storage= 1,884 cf
Plug-Flow detention tine=49.3 min calculated for 13,127 1 % of inflow)
Center-of-Mass det. time=49.3 rain 1.4- 782.2
Volume 1 nvert Avail.Storage St ra I e ri tlon
##1 24 . ' 2,254 cf Custom stage Data(Prismatic)Listed below(Recale)
Elevation Suff.Area 1no.Store Cum.Store
Len 1 --ft cubic-e
241. 724 0
242.00 11 135 13
242.50 21913 1022 10360
242.75 4,241 894 21254
Device Routing Invert Outlet Devices
#1 Discarded 241. ' 2.410 ire/hr EViltration over surface area
##2 Primary 241.20' .0" Round Culvert X 2. L=4 .0' Ke= 0.500
IMet#Outlet Invert=241.20'#241.2 ' S� 0.0000 V Cc= 0.900
n= 0.012, Flow Area=0.35 sf
#3 Primary 241. 0' . " Round Culvert L= 117. ' Ke=0.600
Inlet/Outlet I nvert- 24 1. 0' /241.2 ' S= 0.0026 '1' Cc= 0.900
= 0.012, Flaw Area 0.35 sf
#4 Device 2 242. 0' 1 . " H ri . orifice/Grate X 2,00 C= 0.600
Limited to weir flow at low heads
#5 Device 2 242. 0' 4. " H oriz. Orifice/Grate C= 0.600 Limited to weir flow at lover heads
Device 3 242.50' 2. " H ri . Orifice/Grate X 2.00 C� 0.600
Limited to weir flow at low heads
#7 Secondary 242.7 ' . ' tong x 2 * ' breadth Broad-Crested Rectan g u la We1r
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
ef. (English) 2,68 2.70 2.70 2.64 2.63 2.64 2.64 2.63
,9is arded OutFlow Ma 4.2'1 cfs o@ 12.12 hrs lW=242. ' (Free Discharge)
=Exflltrati Altration Controls 0.21 cfs)
Primary OutFlow Max=3.51 cfs@ 12.12 hrs HW=242. ' (Free Discharge)
=Curlve (Passes 2.56 cfs of 2.57 cfs potential flog)
_! orifice#Grate Weir Controls 1.2 fs @ 1.30 fps)
LL"
=orifice#Grate Weir Controls 1.28 cfs @ 1.30 fps)
=^uIv rt Farrel Controls 0.95 efs @ 2.72 fps)
*��=Orfflce/Grate (Passes 0.95 cfs f 1.28 cfs potential flow
§econdaryOuMo v l a = .0cfs @ 0.00 hrs W=24 . o' (Free Discharge)
= re ad-Crested Rectangular Weir Controls 0.0 cfs
3819 Proposed Conditions Type /if -hr -Year F ire 1= . "'
Prepared by The Morin-Cameron Group, Inc. Printed 3/15/2019
droCA� 10. 0-1 s/n 00401 2014 dr D Software Solutions LLC 2
Summary for Pond P2: Subsurface Detention
Inflow Area 2 }533 sf, 66.34% Impervious, Inflow Depth 2.3 " for 1 R ear evert
Inflow 3.50 cfs @ 12.12 hrs, Volume 5,669 cf
Outflow 2,27 cfs @ 12.22 hrs, Volume= 5,272 cf, Aden= 35%, Lag=6.4 min
Primary 2.27 cfs 12.22 hrs, Volume= 5,272 cf
Routing by S or-lnd method, Time Span- .00-3 .00 hrs,, dt=0.01 hrs
Peak Elev 242.37' @ 12.22 hrs Sur.Area-21466 sf Storage- 1,864 of
Plug-Flog detention time=23.3 rain calculated for 5,271 cf ° of inflow)
Center-of-Mass det. tire= 1 .7 min 75 . -741.4
Volume Invert Avail.S ora Storage Description
.............
#1A 240.70' 947 cf 1 . 0'W x 87.661 x 1.82'H Field
2,527 cf Overall- 160 cf Embedded 2,367 of x 4 .0%Voids
#2A 24 .2 ' 160 ef C P 8 x 16 Inside#1
Inside .o"W x . "1 0.47 sf x 2 .0 1= .4 cf
Outside- 0. "HIV x . t'1--1 - >0.47 sf x 20.001 - .4 of
Rows of 4 Chambers
1 .0 ' Header x 0.47 sf x 2 10.1 of Inside
##3 241.20' 37 cf . " round Pipe storage x 2
L 53.7'
#4C 24 .7 ' 731 cf 16.80'W x 67,651 x 1,82'H Field
,951 cf Overall- 123 cf Embedded 1,828 cf x 4 . %Voids
#5C 24 .2 ' 123 cf CPP 8 x 12 Inside#4
Inside= . "W x .0" = 0.47 f 20.001 . f
Outside= ; 'iW x 0. '{H => 0.47 sf x 20.001 9.4 cf
4 roves of 3 Chamber
1 . ' leader x 0.47 sf x 2 10.1 cf Inside
#6 2 0. ' 34 cf 4,0 "D x 2,70'H Vertical al Cone/Cylinder
2,033 cf Total Available Storage
Storage Group A created with Chamber Wizard
Storage Group C created with Chamber Wizard
Device Routing Invert Outlet Devices
##1 Primary 241.1 ' 1 . ' long x 2.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
2.50 3.00 3.50
Coe . (English) 2.54 2.61 2.61 2.60 2.66 2.70 2.77 2.89 2.88 2.85
3.07 3.20 3.32
#2 Device 1 24 .7 ' 12. " round Culvert
47.0' CPP# projecting, no headwall, 1 e= 0.900
Inlet Outlet Invert=240.7 ' 240.50' S= .0 43 ' ' Cc 0.900
n= 0.012 Corrugated PE, smooth interior, Flow Area 0.79 sf
#3 Device 2 2 .7 ' . "Vert. Orifice/Grate C 0.600
##4 Device 2 241.30' 12. "W x . " H Vert,Orifice/Grate C 0.600
#5 Device 2 241.55' 1 .0"W x . " H Vert,Orifice/Grate C=0.600
#6 Device 2 242.45' 4. ' long x 0.5' breadth Broad-Crested rectangular e!r
Head (feet) 0.20 0.40 0.60 0.80M
19 Proposed conditions T ///2 - -Fear ar'r aP . "
Prepared by The Merin-Cameron Group, Inc. Printed 311512019
HydroCADO 1 . -1 s 00401 0 2014 H Soffivare Solutions LLC Page 1
Co f. (English) 2.80 2.92 3.08 3.30 .3
Primary Oufflow Ma =2.27 cfs @ 12.22 errs HW=24 . 7' (Free Discharge)
Broad-Crested Rectangular bear (Passes 2.27 cfs of 38.84 cfs potential flow)
n
lvert (Passes 2.27 cfs of 3.23 cfs potential low
=orifice/Grate (Orifice Controls 0. 7 cfs @ 5.42 fps)
= rifice/Grate (Orifice Controls 1.17 cfs @ 4.67 fps)
= rifice/Grate (Orifice Controls 0.83 cfs @ 4.00 fps)
13road-Crested Recta ngul ar We!r Controls 0.00 a
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PROPOSED SUBCATCHMENT PLAN FIGURE The,
100 MELON STREET Morm-Cameron
NORTH A l VER, A SA HUSETTS a�a : FEBRUARY 13, 019 k� Y
TAt PREPARED FOR: REV:3/15/19 CIVIL ENGINEERS I EWROHMENFAL CONSULTAW
GOURMET SPECIALTY FOODS SCALE: i" = 0* "W EW °�� M PLANNERS
P.4rs7?SK P mm-m W,www
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Horsley W*iffen Group
Sustainable Envirolliltylet7tal soltitions
,d, ion u iiiuli iiiiuu`r
294 Washington Banat "unite 8101 Boston 1
March 5, 2019
Ms. Monlicia Gregol re, Staff Planner
Planning + curt ent
Town of North Andover
120 Main Street
North Andover, Massachusetts 0 1845
t: 100 WillowStreet
Town of N' rt h, Andover
Dear Ms. Gregoire and Board embers.
The Horsley itt n Group, Inc. is, pleased to provide the NorthAndover Planning Boat '
ithu this letter �� rt ur r arizing our it�itil l review the St rm terManagement Plan, r
Permitting Plans for the proposed Gourmet Specialty Foods at 100 WillowStreet,,, North
Andover, CIA (Applicant). The plans,were prepared for the Town, of North Andover by,The
Morin-Cam r ri Group, Inc. HW understands that the Applicant is proposing''to construct a new
parking facility and assoiclated st rm ter management best management practices (BIVIP,$)
and redevelop an existing25,424 square foot industrial building. Part of the existing building is
within the - ot buffer zone,to, an ad'alcent r er"i g eget, to wetlands , - however
no new work is proposed within this, buffer zone!. Incorporating LID practices, is particularly
relevant in rneeting the requirements North Andover's municipal separate storm, sewer
systems, Spermit.
The following documents and plans were received by H
Site Improvement Plans, Willow Street,, North Andover, Massachusetts pages),
prepared by The Morin-Cameron Group, Inc., dated February 13, 2019, which inclu +
o Cover Sheet C-1
o Existing Conditions C-2
o Site Layout, l 'l n, C-3
o Grading, Utility& Drainage Ilan C-
o Landscape Plan L-1
lo Photometric Plan,, L-
o Construction Details I
o Construction Details 11 _2
o Building Elevation A- '
0 Special P l r lit Corer Letter, prepared by The Morin-Cameron Group, Inc., dated February
3 2' 9
0 Planning BoardApplication,for Special Permit;
i
0 Special Permit—Site Plan B ie r Application'- anid
Town of North Andover
March 5, 2019
Pageof
Stormwater Management Report (104 pages) Site Improvement Plan, prepared by The
Morin-Cameron Group} Inc,, dated February 13, 2019, which includes:
o Drainage report narrative which includes an executive summary, existing site
description, existing watershed characteristics, proposed site description, hydrologic
analysis, review of stormwater management standards and conclusions;
o Figures including a USGS locus reap, i=EI1 A flood map, SCS soils raps and
descriptions, existing and proposed watershed plans,
o stormwater Management Report Checklist;
o Hydr'oCAD model results for existing and proposed conditions for the -j o- and 100-
yealr storms;
o Supplemental stormwater management t calculations including Tss removal and
groundwater recharge;
o Construction Phase Pollution Prevention Plan;
o Long-Terra Best Management Practices O&M Plan;
o Illicit Discharge statement;
o soils logs; and
o Letter of map amendment for the FEMA flood plain.
Stormwater Management design Peer Review
ww � i rim wrr irinr
I'-IW offers the following overall comments concerning the stormwater management design a
per the Massachusetts Stormwater Handbook (MSH) dated February 2008, the Borth Andover
Stormwater Management and Erosion Control Regulations s (StormwaterRegulations) adopted
February 5, 20 , and the Forth Andover Stormwater Management and Erosion Control Bylaw
(Bylaw).
The application stapes that the Forth Andover Stormwater Management and Erosion Control
Bylaw and associated Regulations do not apply to the project because the project site and
tributary drainage area are less than one acre (43,560 square feet) in size. However, the
Applicant presents a total drainage area for both the existing and proposed conditions of 1.02
acres 44,395 square feet). Therefore, HW recommends that the Applicant demonstrate
compliance with the additional requirements under the Bylaw and associated regulations and
file for a Lend Disturbance Permit. The comments below correlate with the MSH standards and
where the more stringent Town requirements are applicable additional comments are noted.
1. Standard 1 states that no new stormwater conveyances may cause erosion in wetlands of
the Commonwealth.
A. The Applicant proposed to use existing discharge points to the rear of the property
(Design Points I and 2), which ultimately discharge to wetlands. Design Point 1
discharges stormwater runoff via overland flow from the existing parking and loading
area to the wetland. The Applicant is not proposing any treatment of existing
stormwater from this design point. While the Applicant is not proposing any work,
HW recommends that the Applicant consider providing stormwater treatment from
the existing impervious cover to improve the existing condition and improve grater
quality.
1-1:Troje€:t�..01 18!180 65 N Alidover On-Cal 1\I 8065C 100 Wi Ilow Streoq epfmf.19030—Pur Review Will low St.cfocx
K
k
Town of North Andover
March 5, 2019
Page 3 of 6
2. standard 2 requires that post-development runoff does not exceed pre-de to r en runoff
off-site, for o redevelopment project per MassDEP this standard must e met to the
maximum extent practicable.
In conducting this review, HW had the following comments relative to the HydrocAD model
and design of the stormwater management system.
A. In both the existing condition subcatchnent s-1 and proposed condition
subcatchment PSI, potential run-on to the project area from willow street
(specifically contour 26) is not captured in the calculations. HW recommends that
the Applicant extend the watershed boundaries beyond the limit of work and property
lines to quantify potential run-on to the project area from Willow Street.
B. It is unclear from the information provided how roof top runoff from the existing
building is being managed. HW recommends that the Applicant provide details on
how existing and proposed rooftop drainage will be provided and recommends that
the Applicant consider providing a drywell for infiltration of rooftop runoff.
C. In accordance with Town Regulations, the Applicant has not provided calculations for
the I-inch and 26-year storm events. HW recommends that the Appiicant include
calculations for the 1-inch and 6-gear storm event 6.0 inches).
D. The precipitation depths used by the Applicant are not consistent with Town
Regulations. HW recommends that the Applicant use the precipitation depths
provided in the storrnwater Regulations for the HydrocAD analyses.
E. The Applicant uses a direct entry time of concentration value of 6 minutes for all
subcatchments in both the existing and proposed conditions. The Applicant provides
time of concentration pathways on the existing drainage map over the vegetated
portions of the project area. HW recommends that the Applicant confirm that the time
of concentration pathways shown on the drainage reap are not greater than 6
minutes, especially since water is flowing over vegetated cover as opposed to
impervious cover. If they are greater than 6 minutes, HW recommends that the
Applicant use these values and update the Hyd roCAD model accordingly.
F. In the existing conditions HydroCAD model, the Applicant models "lawn depressions'
as providing storage of storrnwater runoff and mitigation of peak discharges. It is
unclear from the information provided where these lawn depressions are located and
how the stage storage relationship was developed. HW recommends that the
Applicant provide additional details on how this was calculated.
Further, the curve number and time of concentration consider potential surface
interception and depression storage over the land surface and therefore, it is not
typical for these micro changes in topography to be modeled to this level of detail
and could result in "double counting„ the impacts of the vegetation. HW recommends
that the lawn depressions be removed from the model as they should be captured in
the time of concentration as stated in comment E above).
G. Infiltration Practices:
1. The Applicant uses an exfiltratlon rate of 2.41 inches per hour(iph)for the
infiltration basin; however, this e filtration rate is not consistent with the
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underlying soil characterized for the project area HSG c . According to the
soil lots, provided as Attachment H} the published soil data has a saturated
hydraulic conductivity of 0.06-o. o iph. HW recommends that the Applicant
revise the infiltration rate to reflect the limiting layer for infiltration from the
basin based on the soil test logs, which appears to be sandy loam.
2. Device #3— -inch round culvert is modeled which an invert of .5;
however, the design plans show an invert of 241.2. Also, the infiltration basin
plan vier detail shows that this pipe has a slope of 0.00 ft ft and the
subsurface detention system plan view detail shovers that this pipe has a slope
of 0.03 Rift. Hull recommends that the Applicant reconcile the model with the
design plans.
3. The MSH requires a minimum of I oo-feet upslope setback from any building
foundation including slab foundations without basements. Using the scale on
the drawing it appears that the infiltration basin is approximately 0-feet from
the building foundation and does not meet the minimum setback
requirements.
. The MSH recommends that for each test pit, where an infiltration practice is
proposed, evaluate the saturated hydraulic conductivity of the soil, depth to
seasonal high groundwater, MRCS soil textural class, NRCS HSG and the
presence of fill materials. Based on review of the soil logs it does not appear
that the Applicant has evaluated the saturated hydraulic conductivity of the
self. HW recommends ends that the Applicant verify the infiltration rates of the soil
underlying the proposed infiltration basin.
H. subsurface Detention System:
1. The plan vier detail shoves a proposed inspection port within the system on
the right; however, it is difficult to verify if inspection ports are also proposed
within the system on the left. Further, the location of clean-outs are not
identified. HW recommends that the Applicant confirm that inspection ports
will be in both systems and provide clean-out locations,
2. The system as design will not prohibit infiltration into groundwater and is
located approximately 8 feet from the building foundation. consistent with
comment 2.G.3 above, this type of practice should be located approximately
1 o-feet upslope of a building foundation; HW recommends that the Applicant
reconsider the design of the subsurface system to meet the requirements in
the NISH.
. standard 3 requires that the annual recharge from post-development shall approximate
annual recharge from pre-development conditions.
A. The Applicant provided calculations to demonstrate that the infiltration basin was
sized to capture and recharge the groundwater recharge volume for HSG c
generated from the new impervious area. The Applicant also provides drag-down
calculations for the basin using a Rawls rate of 2.41 inches per hoar. consistent
with comment 2.G.1 above, an eAltration rate consistent with the most restrictive
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layer in the soil test logs should be used for these calculations. HW recommends that
the Applicant provide revised calculations.
. standard 4 requires that the
storm water system be designed�i t remove % Total
Suspended solids (TSS) and to treat .0-inch volume from the impervious area ! water
quality.
A. TSS calculations are provided in the stormwater report and indicate that the
infiltration basin provides 0% TSS based on adequate pretreatment. The Applicant
states that a one--foot stone diaphragm and three-foot-wide sod strip are provided for
pretreatment. The MSH recommends that a vegetated filter strip have a one-foot
stone diaphragm and a grass filter strip with a minimum length of 25 feet. Therefore,
the current pretreatment design does not provide adequate pretreatment for the
infiltration basins. HW recommends that the Applicant provide sufficient pretreatment
for the infiltration basin to meet the standard.
B. The Storm water Deport states that the infiltration basin was sized to provide storage
and infiltration of the I-inch water quality volume; however, calculations have not
been provided. HW recommends that the Applicant provide calculations for the water
quality volume.
. standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads
(LUHPPL).
Standard 5 is not applicable to this project.
O. standard 6 is related to projects with s orr water discharging into a critical area, a Zane ll or
are Interim Wellhead Protection free of a public water supply.
Standard 6 is not applicable to this project.
. standard 7 is related to projects considered Redevelopment.
.
Standard 7 is not applicable to this project.
. standard 8 requires a plan to control construction related impacts including erosion
sedimentation or other pollutant sources.
A. Appropriate erosion and sediment control during construction will ensure that
infiltration practices function as designed. HW recommends that these areas be
visibly demarcated throughout construction to protect from sedimentation and
compaction.
B. H1I'!J recommends that the Applicant include a note on the plans stating that soil stock
plies must be kept outside of the 100-foot buffer zone.
C. HW recommends that construction entrance detail b added to the plan set.
9. Standard 9 requires Long-Term OperationandMaintenance 0 & M Plan to be provided.
A. For the infiltration basin, the Applicant states `the infiltration basin shall be inspected
after every major rain event for the fiat three months after construction; a major
storm event is 3.9 inches of rainfall in a 24-hour period -year storm). In
accordance with the MSH, a major storm event is defined as a storm equal to or
greater than the 2-gear, 24-hour storm event (generally 2.9 inches to 3.6 inches).
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March 5�, 20119
Page 6 of 6
HW recommends that the Applicant revise the inspection criteria to be consistent
with the MSH.
B. The: maintenance guidelines for the subsurface detention system appear to be more
in line with, maintenan�cle for a surface detention system,. HW recommends that the
Applicant include specific mainteriance, requirements for the proposed system,.
C. For the level spreader, HW recommends that the major storm, event criteria be
updated in accordance with comment 91.A.above.
D. The Long-Term, O&M Plan should become a standa.lone document and include a
simple sketch to clearly indicate the location of al"I stormwater practices to be
inspected as well as locat'lons for,snow storage. IOW recommends that the Appli,cant
include: a simple sketch that will be provided to the property owner.
10. Standard 10,requires an Illicit Discharge Compliance Statement,tobe p,rovideld.,
A. The Applicant, provided' a signed Illicit Discharge Compliance Statement. No further
comment.needed.
11. Miscellaneous Comments:
X 'The Applicant is proposing III
,ght poles within the proposed vegetated infiltration
basin. Future repair's of the lights or maintenance of the basin may,be difficult.
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 provisi'on of these
comments does, not relieve himi/her of the responsibility to comply with all Town of North,
Andover Codes and By-La rs, Commonwealth of Mass ach u setts, laws, and federal regulations
as applicable,to this project,. Please, contact Janet Bernardo at 774-413-2999 ext 202 or at
jber'nardo@,hors,leywitten.com if you have any questions, regarding, these comments.
Sincerely,
HORSLEY WITT EN GROUP, INC.,
.................
1V
I J
Renee L. Bourdeau, P.E. Janet Carter Bernardo, P.E.
Senior''Wtiter Resources Engineer Senior Project Manager
CC: Jennifer A. Hughes, Conservation Administrator
1-1:\Projecu�k2018\1806 «'Andovej-On-Cal I\1 8,065C 1010 Wil low,Street\keporl\1:90305.-Put-Revie\N?Willow St.docx
The,
...
......
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Planning Board
120 Main, Street
North Andover, 5
Re: 100 WillowStreet
Special Permit Applications
Dear,Board Members:
ers
On behalf of the applicant, Gourmet Specialty Foods, please find attached two speciat permit
applications for the above referenced property.
The two special rmits being requested are as follows:
Special, Permit *in accordance with 95- w " the North Andover Zoning Bylaw, t
allow for modifications to the required screen ing/tiandsica pingoff-street ark,n
Special, Permit *in accordance with 195-8.11(A)(3) of the North Andover Zoning Bylaw for
Site Peen Review,for are existing 'facility requiring five or more additional parking spaces
Gourmet Specialty Foods is a USDA Meat and Poultry manufacturing faitity. They have facilities
located in Tewksbury and rr ' l er, MA., Their products, include rnarlir ate ' meats, stuffed
proteins, valued added ground e and many more 'Items for the Retail Food Industry. They
'w w w� �h i4 �w w w �w 6
are reaching capacity at t e" current a riItre and are in a iirt� I were they can
consolidate into one location with room for future expansion. The building, at 100 Wittlow Street
r " es,the with the space they are looking, fir with potential for futureexpans1on.
Gourmet Specialty, Foods was created in 2 16w Over the years they have f6undl increased
demand for fresh, handmade, high quality, and safe quality foods within the retail food
segment. Gol r..met continues, texpand:: its product offeringsthat t satisfy the specific needs of
their current and ut r customers. heir is on consistency,, quality,, innovation, r
customization has resulted in significant sates, growth. i w t mers include Market
Basket, Stop and Shop, Big Y Food Stores, and Whole Foods just to name a few. Their overall
w
focus� In the, future is to continue to grow and diversify not only their customer base but their
overall manufacturing capabilities.
Its extrer ley*im rtant to Gourmet Specialty s to be abbe to provide growth opportunities
for their de6cated employees as well as create new Jobs, in the community. i new facility in
North Andover,will attow them to expand n the food service e industry.
CIVIL 'GI NEERS, e LAND, SURVEYORS ENVIRONMENTAL CONSULTANTS LAND USE PLANNERS
6 Elm Street, Danvers, MA 01923 9 ''8.777.8586 FAX 978.774.3488
Providing Professional Services Sig
www.mor,incam,ero�n.com
North Andover Planning Board February 13, 20,19 2
Minor modifications, to the building located at 100 Willow Street are proposed as part of the
project. Arch itectur t, plans are included inctuded in the submittal owing proposed minor changes
the front ofthe building to, accommodate the two new entrances,. 'the major portion of the
r c is the expansion of the parking facilities on the site to conform to the parking criteria for
the proposed use. The current facility has approximately 9 parking spaces with loading bays,.
The proposed industrial use wit witt require, 51 parkingspaces. Additional parking facilities are
proposed with s rr er management fined t mitigate the ire r in irn r l � to
accommodate the required increase ire! p wr tng. A total of 5 aces are ,proposed. Two (2)
loading bays are required for the proposed use, therefore, the 4 existing loading bays meet this
With regards to the Special Permitt fir modifications to 'the required screening/landscaping ofI
off street ,parking relief is reques,te�d to reduce the screening requirements along the proposed
parking in tot. There will be no, permanent, screening 'hedge or fence between Willow street and
the parking tot. Instead, new shade trees will be planted at a spacing 3 ' to, 40', dep nding
on site constraints,such as light poles, utilities rid drainage, infrastructure,. A critical component
of the Low-Impact Devel men stormwater management system is, the vegetated infiltration
basin along the edge of the parking lot. This stem will function best with a specialized seed'
r ig for permanent soil coverage, rather than m ul u, and shrubs which are more r n
m tnte ante probterns. We believe that, the landscaping proposed meets the 'intent the
landscaping requirement ire this,area.
As required', a, landscape plea is, being submitted with the applications. In accordance with
section 1 95- .1 . of the North Andover Zoning Bylaw all landscape plans shall prepared y
1
a certified landscape architect registered in the Commonwealth of Massachusetts. waiver is
being sought to allow the Landscape Plan to beprepareld by a Registered' Professional Civil
Engineer with, a background in ecological tandsc�ape design and management.
e look forward to meeting with the, Planning Board to discuss the Special Permit apptications,
Please notify our off ice of the date and time that this 'ism mill be, arBoard.,
If you have any questions prior to the meeting please do not hesitate,to contactrye,
Siruerel ,
THE I ERON GROUP,, I
vv� P/Llpol�v
John M. Moan, PE
Principal
MMAr r
Attachments
1
c: Gourmet Specialty Foods
X- Gangerni,Br*tan\38'19\Docs\PBSpedial Permit_site Plan w\ dat Permit Ltr.doc