HomeMy WebLinkAbout1991-11-29 Environmental Impact & Drainage Study DEF SUB PRD g
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ENVIRONMENTAL. IMPACT SUMMARY
EROSION CONTROL PLAN
PROJECT SCHEDULE
DRAINAGE ANALYSIS
FOR,
PHILLIPS COMMON
PREPARED; FOR
PHILLIPS COMMON' REALTY TRUST
P.O BOX' 6700,
'NORTH. ANDOVER; MASSACHUSETTS 01845,
OCTOBER 1991
MERRIMACK ENGINEERIPJG SERVICES, Inc.
66 Park Street
Andover, Massachusetts 01810
planners 0 engineers 0 surveyors
PHILLIPS COMMON
NORTH ANDOVER MASSACHUSETTS
CONSTRUCTION SCHEDULE
Construction of this development will be driven by the response
of sales within the project. However, the following is antici-
pated , given the market analysis at this time :
Grubbing clearing , layout,
initial excavation December , 1991
Utility construction January , April , 1992
Roadway pavement ( binder) April , 1992
* Model construction 1 Unit February , 1992
* House construction 6 Units March , 1992
* House construction 7 Units June , 1992
* House construction 7 Units September , 1992
* House construction 5 Units March , 1993
Final roadway construction May , 1993
* Miscellaneous roadway construction to occur during this
period.
MERRIMACK ENGINEERING SERVICES. INC. - 66 PARK STREET 6 ANDOVER, MASSACHUSETTS 01810
EROSION CONTROL PLAN
Although there are no wetlands located on or adjacent to the
premises , erosion control techniques will still be applied to
this project.
The project construction methodology calls for limited tree
clearing on the site , clearing and grubbing of the existing
surface cover , and the installation of utilities during the time
that the roadway is brought to subgrade . Associated with the
utility construction , is the installation of two detention ponds
on the site .
As part of the erosion control program for the site , each deten-
tion pond will be constructed initially at the time the roadway
is being brought to subgrade . Excess soil material will be
stockpiled in the center of the site , in the vicinity of a
landscaping berm , proposed to be constructed in the center loop
of the development.
Outlets to the ponds will not be constructed until after the
drainage system is installed in the street and is operational on
site . In the meantime , each of these detention ponds , located in
relatively low points of the site , will act as sedimentation
collection traps , collecting runoff from the site , and allowing
sediment contained within the runoff, to be deposited within the
pond . It is anticipated that prior to installation of the drain-
age outlets , each of the ponds will be cleaned and reexcavated to
the subgrade of the pond , the drainage outlets then installed ,
and the entire pond area loamed and seeded . Landscaping will
then be installed in the proper season in and adjacent to the
pond , per the drawings of the architect.
In addition to the above , each of the catch basins within the
drainage system will be equiped with sumps , which will allow for
sediment collection , prior to the sediment being carried by storm
water runoff and discharged into the detention ponds . Haybales
will be placed around the top of the catch basins in order to
filter soil from the runoff water before it even enters the catch
basin . After the roadway is completed , and during intervals of
construction , on an as needed basis , the catch basin sumps will
be cleaned so as to function properly .
Where necessary , erosion control siltation fencing will be placed
in selected ares on the site . Especially located around soil
stockpile areas , the siltation fencing will prevent large amounts
of sediment flow into the existing wooded areas which are to
remain in place around the project perimeter.
It is not anticipated that berms , dikes , or other similar con-
struction techniques will need to be utilized on this site since
the site is relatively gently sloping , and does not have any
steep hillside areas that are on or adjacent to it.
1
MERRIMACK ENGINEERING SERVICES, INC. ® 66 PARK STREET ® ANDOVER, MASSACHUSETTS 01810
However, when necessary , areas will be sodded to prevent erosion ,
and in areas where trees are not provided to be planted , or mulch
landscaping beds are not proposed to be installed , disturbed
areas will be loamed and seeded as soon as possible after instal -
lation of foundations , so as to minimize soil runoff from the
site . When necessary , these loamed and seeded areas will be
mulched with hay, to provide additional protective matting , and
to promote the growth of grass on these finish graded areas .
2
MERRIMACK ENGINEERING SERVICES, INC. ® 66 PARK STREET ® ANDOVER, MASSACHUSETTS 01810
STATEMENT OF ENVIRONMENTAL IMPACT
PHILLIPS COMMON
NORTH ANDOVER , MASSACHUSETTS
In accordance with the requirements of the Town of North Andover
Subdivision Control Regulations , this Statement of Environmental
Impact has been prepared for the project:
A. TOPOGRAPHY AND EXISTING SITE FEATURES
The site consists of approximately 16 . 67 acres of land at
the intersection of Chickering Road and Massachusetts Avenue
adjacent to Osgood Street in the Town of North Andover
( Essex County ) Massachusetts .
Located on the site is a historic house , commonly refered to
as The Manse , and an outbuilding ( garage ) ®
The land slopes from the rear of the Manse , about 200 feet
from Osgood Street, down toward Chickering Road . The general
slope of the land is slight to moderate , with the slope of
the land ranging between two and four percent slopes .
The site is wooded and open field . Some stone walls exist
in areas along the perimeter property lines of the site ;
there are no internal stone walls on the property . The
woods consists primarily of hardwood trees , with some mixed
evergreens in various areas of the site . Except for the
remnants of an old garden located in the vicinity of the
Manse , there are no other substantial outstanding botanical
or other features on the site . There are no wetlands or
specialty wildlife habitat areas on site .
Testing undertaken on the site in 1987 and 1991 indicates
that the water table varies throughout the premises , from a
depth of ten feet up to a depth of three feet in some areas
of the site . The soils are relatively pervious and more
adeptly described in the Storm Drainage Analysis , which is
attached hereto ®
B . PROPOSED DEVELOPMENT-PHYSICAL ENVIRONMENT
The scope of work proposed for this development includes the
construction of approximately 1 , 600 lineal feet of roadway ,
entering the site from Massachusetts Avenue , and traversing
the site in a general cloverleaf loop fashion , closing upon
itself, in order to service 26 single family homes .
The 26 single family homes would be constructed each upon
their own lot, and each would be serviced with municipal
sanitary sewer and water which would be constructed within
the proposed roadway . A storm drainage line will be con-
structed within the roadway to collect surface drainage
runoff from the roadway and each of these homes ®
1
MERRIMACK ENGINEERING SERVICES, INC. - 66 PARK STREET - ANDOVER, MASSACHUSETTS 01810
Proposed under the PRD Requirements of the Town of North
Andover Zoning By-Law , this development was designed after a
conventional subdivision plan was initially prepared for the
site . Recognizing that the site is currently zoned R-3 ,
which permits the construction of single family homes on
lots 25 ,000 square feet in size , each with 125 feet of
frontage , the conventional plan depicted the possibility of
26 lots subdivided from this site . Under the PRD By-Law,
each lot within this proposed PRD will contain at least 100
of frontage and 12 , 500 square feet of land area . Each of
the homes within the development would be setback at least
20 feet from the roadway right-of-way , and 20 feet from the
rear property line , or side property line , of each lot. The
PRD By-Law also permits some homes to be constructed to zero
feet from the side lot line , as long as the adjacent home is
constructed at least 20 feet from the adjoining lot line .
In this development, all requirements of the Zoning By-Law
relative to PRD are met, as relating to frontage and area as
well as setback . The PRD By-Law also requires that at least
35 percent of the entire tract area be set aside as open
space . The total of 42 . 92 percent of this site is proposed
to be set aside as open space . This set aside also includes
the area adjacent to the existing Manse ( shown on the plan
as Lot Y ) . Substracting out the lot area associated with
the Manse ( Lot Y ) , 36 . 73 percent of the entire site will be
set aside as open space .
The Manse which is existing on Lot Y is proposed to remain
and will be sold along with the land area on Lot Y , so as to
permit the owner and occupant, to preserve the historic
value of this Manse . Covenants will be placed on the land
and building , which require the future owner to rehabilitate
structure , and to restore it to is natural historic condi-
tion . In addition , certain improvements to the grounds
adjacent to the Manse on Lot Y , will also be made by the
future owner. These covenants which significantly restrict
activity and modification to the building and land on Lot Y
will be prepared and submitted to the Town and the
Historical Society for review, and subsequently will be made
a part of the future deed of conveyance of Lot Y.
The 26 new homes to be constructed within the development
are depicted upon plans prepared by Woodman Associates ,
Architects , of Newburyport Massachusetts . Four different
styles of homes will be constructed on the site , each in
varied locations throughout the development. Each of these
home styles and the finish grades of the houses are depicted
upon the architectural and engineering site plans . Each of
the homes will have attached garages , and will have three or
four bedrooms ®
As part of the site design , attention was given to the
historical nature and value of the site ® As such , a sight
2
MERRIMACK ENGINEERING SERVICES, INC. 0 66 PARK STREET - ANDOVER, MASSACHUSETTS 01810
corridor behind the Manse was layed out , and respected with
this design , so that no homes are built directly behind the
existing Manse . In addition , careful consideration was
given to maintaining as much of the existing vegetated wood-
land buffer as possible , thereby utilizing the existing
perimeter landscaping as a natural landscaping amenity for
the project. Additional landscaping as depicted on the
architects plans will be constructed and installed as part
of this development.
Additional landscaping amenities include the creation of
privacy berms in the center lots of the project . Stone
walls and multiple tree plantings will also be installed in
this center loop area .
In order to provide extensive visual character within the
development, the outside perimeter of the roadway will be
heavily landscaped , and a fence constructed along the
property line of the roadway ® In addition to providing
significant visual identity , this fence will provide a
continuous connection from the development out to
Massachusetts Avenue ® Significant landscaping at the
gateway to the project on Massachusetts Avenue will occur.
The sanitary sewer which will service each house in the
development, will be connected to the existing Massachusetts
Avenue Sanitary Sewer System. This proposed interconnection
is shown on the Engineering Site Plans and Plan and Profiles
for the roadway improvements . Off site mitigation of
infiltration at the rate of 2 : 1 will be provided for this
project.
The water service within the development will be from a
connection to the existing municipal service on
Massachusetts Avenue , run through the development, and be
interconnected or looped to the existing municipal service
main on Osgood Street. Hydrants have been provided at
1 ,000+ foot intervals , so as to maximize fire protection on
the site . Sprinklers will be provided in each house , as an
additional means of fire protection .
As indicated previously , a storm drainage system has been
designed and layed out to adequately collect surface runoff
from the site prior to its ultimate discharge into the
existing storm drainage system on Massachusetts Avenue and
Chickering Road . These are both locations where surface
drainage runoff from the site currently flows .
Catch basins with sumps will collect the water , and sediment
contained within the surface water during and after
construction is complete , will be collected in these sumps .
The stormwater will then be piped to one of two detention
ponds ® The first detention pond , located at the entrance to
the site , adjacent to Massachusetts Avenue , will collect
much of the surface water runoff which currently runs to
3
MERRIMACK ENGINEERING SERVICES, INC. ® 66 PARK STREET • ANDOVER, MASSACHUSETTS 01810
Massachusetts Avenue as well as Chickering Road . At that
point, it will enter the detention basin , and ultimately
outlet through a pipe which would be interconnected to the
existing Massachusetts Avenue drainage system. The rate of
flow out of the detention area and into the Massachusetts
Avenue system will be controled by the size of the pipe and
outlet configuration .
Drainage flow into the Chickering Road area detention pond ,
will be through overland surface flow and direct piping .
Because of the reduced area of flow to this pond , no outlet
has been proposed . Much of the drainage entering this pond
will be recharged into the existing ground water table , or
be stored , in such a fashion that only a small amount of
drainage will be allowed to be discharged overland from the
pond , entering the woods adjacent to the pond and Chickering
Road , and ultimately flowing , after it reaches a small berm
which exists along Chickering Road , to the storm drainage
system which exists along this roadway .
The storm water collection system within the roadway has
been designed to accommodate a 24 hour 10 year storm, while
the detention pond themselves , have been designed to accom-
modate a 24 hour 100 year storm. Drainage system design and
detention ponds respectively , have been designed in accor-
dance with Town of North Andover Requirements for the
Subdivision Land, as well as the Requirements of the USDA
Soil Conservation Service . A zero percent increase in the
peak rate of runoff for the 100 year storm has been designed
for this site . References are made to the drainage computa-
tions attached hereto for a further discussion as to the
storm drainage design .
At this time , it is anticipated that each of the homes in
the development will be serviced with underground gas
service , to be provided within the site by the Bay State Gas
Company . Underground telephone , electric , and cable TV
service will be provided to each home .
Designed as a village concept , it is anticipated that this
development will have no negative visual or other impacts
upon the adjacent land uses . It will complement the exist-
ing residential uses located to the north and east as well
as south portion of this site . Further , it is not antici-
pated that any negative impact on the existing sanitary
sewer, drainage or water system in this area , will result
from implementation of this development.
C . SURFACE WATER, AND SOILS CONDITIONS
Since there are no wetlands , ponds or streams on or adjacent
to the premises , and a selfcontained storm drainage system
is proposed , it is anticipated that no negative impacts to
4
MERRIMACK ENGINEERING SERVICES, INC. - 66 PARK STREET - ANDOVER, MASSACHUSETTS 01810
any of the mentioned resources will occur from implementa-
tion of this development . Since the cut and fill conditions
of the site are extremely limited , no extensive erosion is
anticipated to occur . However , consideration has been given
to erosion during construction and after completion of the
development , and the reader is refered to the erosion
control plan attached hereto for further discussion relative
to this item.
Regarding the subsurface soil conditions on the site , no
special footings or foundations are required for the homes
to be constructed on the site . The drainage report attached
hereto , further discusses the USDA and other soil conditions
found on the site .
It should be noted that the North Andover Building Depart-
ment requires foundation drains around the perimeter of the
houses , and a layout has been prepared for this drainage
system , which will allow interconnection of footing drains
to the storm drainage system which will be constructed
within the roadway . Given the installation of subsurface
footing drains , no special subsurface drainage or collection
is anticipated to be required at this time . However, as
construction conditions dictate , specialized waterproofing
and backfill of foundations may be provided by the home
builder as part of this development.
D. SUBSURFACE CONDITIONS
No percolation tests have been undertake for this project,
as municipal sanitary sewer will be provided to all of the
homes within the development.
E. TOWN SERVICES
Previous discussions within the report have indicated the
methodology for interconnection of services from this
development into existing municipal services .
Given the construction of 26 homes , each with four bedrooms ,
a maximum of 11 ,440 gallons per day of water demand may
occur. In addition , an equal amount of sewerage flow may
result from this development. It appears that the existing
systems adjacent to the site , at the point of interconnec-
tion , have adequate capacity to service and handle the flows
projected from this development, with the implementation of
offsite infiltration mitigation .
It is estimated that approximately 208 vehicle trips per day
will be generated at the time of full construction of this
development . Approximately 30 trips per hour at the peak
hour may occur into or out of this site .
MERRIMACK ENGINEERING SERVICES. INC, ® 66 PARK STREET ® ANDOVER, MASSACHUSETTS 01810
Massachusetts Avenue has adequate capacity to accommodate
the traffic from this development. Further , studies for
previous developments of a similar nature , but higher den-
sity ( 40 units and 55 units respectively ) at this site
indicated that no negative impact to the traffic systems at
the intersection of Massachusetts Avenue or Chickering Road
would result from implementation of those developments .
Since significantly fewer units are proposed for the
Phillips Common Development it is further anticipated that
no negative impacts upon the traffic circulation system in
the project area will result®
It is anticipated that many of the home owners within this
development will be existing Town of North Andover residents
who rent or live with others within the community ® As such ,
the impact upon the educational facilities will be limited
by target marketing to this group . However , marketing will
occur outside of the project area , and residents outside of
this area may be attracted to reside in this development.
Based on averages for other projects of this type , it is
anticipated that between 15 and 39 children may reside
within this development.
F. GENERAL FISCAL IMPACT TO THE TOWN
As stated previously , no negative impacts are expected from
this development in terms of water quality , flood control ,
erosion , or significant demand upon public services such as
police or fire . Fiscal demands upon the system will be
limited to providing services of public safety and education
as are currently being provided within the community . The
development will generate significant revenue in terms of
property taxes to the Town , and because of the minimization
of the roadway and utilities within the development through
the PRD concept, the reduction in the cost of maintenance of
the roadway , as compared to that which would be experienced
under a conventional development, will occur.
6
MERRIMACK ENGINEERING SERVICES, INC. - 66 PARK STREET - ANDOVER, MASSACHUSETTS 01810
Drainage Analysis
Phillips
Chickering Road and
Massachusetts Avenue
on
North Andover, Massachusetts
Prepared for
Phillips on Realty Trust
P.O. x
North 6700
vMassachusetts
October 1991
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Project : Phillips Common - North Andover, Massachusetts October ED 9=91
Table of Contents
3 Site Locus
4 Street Drainage Design
11 Pre and Post Development Methodology
13 Summary
14 Pre Development Analysis
20 Post Development Analysis
OF I
ERT C.
z DALEY
CIVIL
No.31650
o Date b�ertC.
Page No. 2
Merrimack Engineering Services, Inc. * 66Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1"8
[—Project : Phillips Common - North Andover, Massachusetts October 14, 1991
United States Geological Survey
South Groveland quadrangle
Site locus at 1" = 2,083' (1 : 25,000)
0 1000 2000 4000
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Merrimack Engineering Services, Inc. °66 Park Street-Andover, Massachusetts 01810"Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 1, 1991
Street Draminage Desmign
Page No. 4
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
F—project : Phillips Common - North Andover, Massachusetts October 14, 19911
Plan of street drainage contributory areas
scale : 1 200'
0 100 200 400
7
Page No. 5
Merrimack Engineering Services, Inc. 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
I Project �Phillips Common - North Andover, Massachusetts October
Techniques and parameters:
o Peak flows were calculated using the Rational Method( Q=CiA
o All street drainage was designed for the 2 and 10 year storm events.
o The selected cover type coefficients are;
C=0.90 for any impervious area.
C=0.30 for any area to loaned and reseeded(disturbed).
C=0.20 for any area to remain in a natural state(undisturbed).
o All street drainage pipe to be reinforced concrete with a minimum
diameter of 12 inches.
o Manning's coefficient of friction for all pipe is assumed to be equal to
0.013.
o The minimum pipe slope is 0.5%
o The minimum pipe flow velocity is 2.5 feet per second.
o The maximum pipe flow velocity is 10.0 feet per second. The maximum
flow velocity exiting a headwall or flared end section is 6.0 feet per
second.
o The minimum cover over all pipe is to be 3 feet except for class V RCP
for which the minimum cover will be 2.5 feet.
o Catch basins are to be located on both sides of the roadway on continuous
grades at intervals of not more than 300 feet or 400 feet from a high point
in the roadway. Catch basins shall be located at all sags in the roadway
and near the upstream comers of intersecting roadways unless the
intersection is at the top of a vertical curve.
Page No. 6
Merrimack Engineering Services, Inc. ' 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
Project :. Phillips Common - North Andover, Massachusetts October 14, 1991
From structure CB103+94,RT CB203+94,LT DMH103+84 C83@16+75,LT DMH2@1+80
To structure DMH1 @3+84 DMFIi 03+84 DMH2@1+80 DMH2@1+80 DMH3@1+35
Area(acres) 1.545 0.465 1.363
%Impervious 23.5 41.9 23.3
%disturbed 56.2 58.1 76.7
%natural 20.3 - -
Weighted C 0.42 0.55 - 0.44 -
Sum of CAs 0.65 0.26 0.90 0.60 1.50
Hydraulic length(it) 480 390 380 -
Average slope(%) 1.0 1.0 - 1.4 -
Tc(minutes) 27 20 27 22 27
Pipe size(inches) 12 12 12 12 15
Pipe slope(ft/ft) 1.4 2.6 0.93 1.0 1.0
2 year Intensity(in/hr) 1.6 1.9 1.6 1.8 1.6
Q=CIA(cis) 1.0 0.5 1.4 1.1 2.4
Flow velocity(fps) 3.9 4.1 3.7 3.6 4.4
Flow depth(inches) 4.4 2.6 5.9 4.8 6.7
10 year Intensity(in/hr) 2.5 3.0 2.5 2.8 2.5
Q=CIA(cfs) 1.6 0.8 2.3 1.7 3.8
Flow velocity(fps) 4.5 4.7 4.1 4.0 4.9
Flow depth(inches) 5.7 3.3 8.1 6.1 9.2
From structure CB4@1+50,RT CB54f16+75,RT DMH3@1+35 DMN4,90+90 CB6@11+50,RT
To structure DMH3@1+35 DMF1361+35 DMH4@0+90 FES1@0+75,LT DMH5@11+60
Area(acres) 0.977 0.290 0.942
•impervious 34.3 51.7 32.6
•disturbed 65.7 48.3 - - 53.3
%natural - - 14.1
Weighted C 0.51 0.61 - - 0.48
Sum of CAs 0.50 0.18 2.18 2.18 0.45
Hydraulic length(it) 320 160 - - 480
Average slope(%) 1.3 1.0 - - 1.0
Tc(minutes) 18 10min 27 27 24
Pipe size(inches) 12 12 15 15 12
Pipe slope(ft/ft) 0.5 1.0 1.0 1.0 t,6
2 year Intensity(in/hr) 2.0 2.6 1.6 1.6 1.7
Q=CiA(c!s) 1.0 0.5
Flow velocity(fps) 2.7 2.9 4.8 4.8 4.6
Flow depth(inches) 5.8 3.4 8.6 8.6 3.4
10 year Intensity(in/hr) 3A 4.2 2.5 2.5 2.7
Q=CiA(cis) 1.6 0.8 5.5 6.5 1.2
Flow velocity(fps) 3.0 3.4 5.2 5.2 5.1
Flow depth(inches) 7.8 4.2 12,0 12,0 4.0
Merrimack Engineering Services, Inc. " 66 Park Street-Andover, Massachusetts 01810'Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 1TI-1-991-1
From structure CB7@11+50,LT DIVIH5611+60 DIVII-166112+00 DMH7012+50 CB8013+37,RT
To structure DMH5@11+60 DMH6012+00 DMH7012+50 DIVII-18@113+25 DIVII-18613+25
Area(acres) 0.399 0.494
•Impervious 35.3 56.9
•disturbed 64.7 43.1
•natural -
Weighted C 0.51 - - - 0.64
Sum of CAs 0.20 0.66 0.66 0.66 0.32
Hydraulic length(it) 350 - - 200
Average slope(%) 1.0 - - - 1.0
Tc(minutes) 20 24 24 24 11
Pipe size(inches) 12 is is is 12
Pipe slope(ft/ft) ') C7- 1.0 1.0 1.0 2.2
2 year Intensity(In/hr) 1.9 1.7 1.7 1.7 2.5
Q--CIA(cfe) 0.4 1.1 1.1 1.1 0.8
Flow velocity(fps) 2.7 3.5 3.5 3.5 4.4
Flow depth(inches) 3.0 4.5 4.5 4.5 3.4
10 year Intensity(In/hr) 3.0 2.7 2.7 2.7 4.0
Q=CIA(cis) 0.6 1.8 1.8 1.8 1.3
Flow velocity(fps) 3.0 4.1 4.1 41 5.0
Flow depth(inches) 3.6 6.0 6.0 6.0 4.3
From structure CB9@13+37,LT DMH8@13+25
To structure DMH8@13+25 FES2@13+00,RT
Area(acres) 1.568
•impervious 20.5
•disturbed 79.5
•natural -
Weighted C 0.42 -
Sum of CAs 0.66 1.63
Hydraulic length(it) 380 -
Average slope(%) 2.0 -
Te(minutes) 21 24
Pipe size(inches) 12 is
Pipe slope(ft/ft) 1.0 1.0
2 year Intensity(In/hr) 1.8 1.7
Q=CiA(cfs) 1.2 2.8
Flow velocity(fps) 3.7 4.7
Flow depth(inches) 5.3 7.6
10 year Intensity(in/hr) 2.9 2.7
Q=CiA(cfe) 1.9 4.4
Flow velocity(fps) 4.1 5.0
Flow depth(inches) 7.0 10.0 Page No. 8
Merrimack Engineering Services, Inc. 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Design charts for Rational Method:
10.
o
�.o
5.0
4.0 INN
3.0
a �
1.0 Q
t
C 0.e
es
C
0.3
®.2
D 1 0.1 W 03 CIA 0.3 07 1 2 3 4 5 6 T 0 9 0 is 20 30 40 so 6010
Durafion of Storm in'Hours
Fla. 4. Intensity of precipitation at Boston,Mass.,for various durations and frequencies.
(Sherman,Frequency and Intlimlil of Excessive Rainfalls at SOstan, Mass., Trans. Am. Sole.
Civic Engrs.,sod. 95, P• 956, 1931.)
Figure showing relation of
IiEQ
z z travel time to overland distance,
w average overland slope,and
coefficient(C)-for use in the
ael
EC Rational Method.
wwJ
W
� Source:
z44HP VA
cc 7o Wright-McLaughlin
Engineenngs"Airport Drainage",
Federal Aviation Administration
Washington,DC 1965
a Page No. 9
Merrimack Engineering Services,Inc."66 Park Street-Andover,Massachusetts 01810*Tel.(508)475-3555 Fax.(508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 11 1 991
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Page No. 10
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810°Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 1K, 19=91
Pre and Post Development
Methodology
Page No. 11
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 1 , 1991
Technique;
The analyses were performed using the methods outlined in the Soil Conser-
vation Service Technical Release 55 (TR55). The analyses were performed for the
10 and 100 year storm events with 24 hour rainfalls of 4.5 and 6.5 inches respec-
tively.
Soil data:
The site is composed of two soil Hydrologic Percent See the SCS soil plan on the
types, listed at right, as defined by the SO1I type Group coverage next sheet.
Soil Conservation Service in its report PaB-Paxton c 63.4
titled"Soil Survey of Essex County, WrA-Woodbridge c 36.6
Massachusetts Northern Part". g
Site watershed description: See the overall watershed
The site consists of an old hayfield or pasture surrounded by a predominately plans on sheets 15 and 21.
pine forest. The site is located at the top of a gently sloping hill in such a way that
no appreciable runoff enters the property from any outside watersheds.Thus to
simplify analysis it was decided to clip all the subarea boundaries at the site
property line.
Pre development analysis -The site was defined as four subareas. Subareas
PRE and PRE2 are small in area and runoff as sheet flow toward design points 1
and 2 respectively which are along Osgood Street. Subarea PRE3 is the largest
subarea containing 75% of the entire site. Runoff from subarea PRE3 travels as
sheet and shallow concentrated flows toward design point 3 at the intersection of
Massachusetts Avenue and Chickering Road. Runoff from subarea PRE4 collects
on the site in two small depressions behind the existing house on Osgood Street.
Since no runoff from Subarea PRE4 leaves the site it was not included in the
analyses.
Post Development analysis -The site was defined as seven subareas. What
was subarea PRE3 has been divided into subareas POND 1,POND2, POST and
POST2. Subareas POND and POND2 contain the most heavily developed areas
of the site and runoff to proposed detention ponds 1 and 2 respectively. Subareas
POST1 and POST2 consist mostly of the buffer areas along the site perimeter and
runoff to design points 3 and 4 respectively. Subarea POST3 is identical to subarea
PRE 1. Except for the additon of a walkway subarea POST4 is identical to subarea
PRE2. Except for the loss of some area due to the proposed site grading, subarea
POSTS is identical to subarea PRE4, and just as subarea PRE4 was not included in
the analysis subarea POSTS is not as well. Note that the total areas within the pre
and post development analyses do not match, since subarea POND2 collects part
of PRE4 (an area that was ignored in the pre development analysis). Two ponds
were added to the analysis to mitigate the increased runoff due to the addition of
impervious area. Proposed pond 1 is a retention pond, it is intended to store much
of the incoming runoff.When pond 1 overtops any incoming runoff will flow out
of the pond to design point 3. Proposed pond 2 is a detention pond, it was designed
with a 12"RCP outlet connected to the Massachusetts Avenue drainage system.
Page No. 12
Merrimack Engineering Services, Inc. ` 66 Park Street -Andover, Massachusetts 01810`Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Conclusions:
Listed at right are the results of the Pre Post
pre and post development analyses at Development Development
each of the design points. At each design Design point 1 _
point there is either no change or a 10 year storm 1.0 1.0
100 year storm 2.0 2.0
decrease in runoff rate after development.
Design point 2
The total rate of runoff from the entire 10 year storm 1.0 1.0
site shows a 3.1 cfs decrease for the 10 100 year storm 3.0 3.0
year storm event and a 4.5 cfs decrease Design point 3
for the 100 year storm event. 10 year storm 9.0 2.0
During the 10 year storm the peak 100 year storm 19.0 10.2
rate of overtopping runoff from and 1 is Design point 4
pp g runo p 10 year storm n.a. 0.0
1.0 cfs. The peak rate of flow through the too year storm 1.0
12"RCP outlet of pond 2 is 3.9 cfs. Total
During the 100 year storm the peak 10year
y astorm
s o m 11.0 19 b
rate of overtopping runoff from pond 1 is
6.2 cfs. The peak rate of flow through the
12"RCP outlet of pond 2 is 5.4 cfs.
Soil Conservation Service Soil Survey - Essex County
Northern Part sheet no. 30 of 42.
Soils map at 1" = 1 ,320' (1'° = 1/4 mile)
0 500 1000 2000
_ �y 'k•tia,M'� /qt pai ."\� �'(�, ti rt '1y 1� t''i� 3... m a ..w� a.;,{
�Pac
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LL 31 c': PbDUD
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W9" A c � St
\+1 1;:.� by t T�'�, c 1. \ t _ 9• r c.�
WsB
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er
P f, w WW`
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R18, WEB
r UD 9
i'W58` w a h; ,;' ' �C Wg u°� Page No. 13
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusefts October 14
Pre Development Analysis
Page No. 14
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
---------------
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Pre Development Subarea Plan.
scale : 1" = 200'
0 100 200 400
,.,- DESIGN POINT 1
\ IR4
3.
o —
a
�1
7.
zi
DI-SIGN POINt-
5'
Page No. 15
Merrimack Engineering Services, Inc. ' 66 Park Street -Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Subarea PRE1
PaB-Paxton C 100
Cover description Acreage Percentage of subarea Curve Number
Lawn-good condition 0.140 13.0 74
Woods-good condition 0.960 87.0 70
1.100 100 70.52 use 71
Sheet flow 280 0.018 light woods 70.8647
Time of concentration=0.864 hr to design point 1.
Subarea PRE2
PaB-Paxton C 100
Cover description Acreage Percentage of subarea Curve Number
Existing house 0.050 2.5 98
Lawn-good condition 0.170 1 9.5 74
Meadow-Continuous grass 0.600 33.0 71
Woods-good condition 1.010 55.0 70
1 1.830 100 71.41 use 71
Sheet flow 300 0.017 light woods 0.935
Time of concentration=0.935 hr to design point 2.
Page No. 16
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448 1
[Project Phillips Common - North Andover, Massachusetts October 14, 1991
Subarea PRE3
PaB-Paxton C 100
WrA-Woodbridge
Cover description Acreage Percentage of subarea Curve Number
Lawn-good condition 0280 2.2 74
Meadow-Continuous grass 5.900 46.8 71
Woods-good condition 6.430 1 51.0 1 70
12.610 100 70.56 use 71
Sheet flow 300 0.018 light woods 0.913
Shallow concentrated flow 360 0.025 unpaved 0.039
Shallow concentrated flow 320 0.006 unpaved 0.071
Time of concentration=1.023 hr to design point 3.
Subarea PRE4 - not included in analysis.
Page No. 17
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448 1
Project : Phillips Common - North Andover, Massachusetts October 1 , 1991
TR-SS TABULAR DISCHARGE METHOD VERSION 1.11
Project Phillips Common User: SAS Date: 10-10-91
County Essex State: MA Checked: Date:
Subtitle: Pre Development
Total watershed area: 0.005 sq mi Rainfall type: III Frequency: 10 years
Subareas
PRE1 PRE2 PRE3
Area(sq mi) 0.00 0.00 0.02
Rainfall(in) 4.S 4.S 4.5
curve number 71 71 71
Runoff(in) 1.75 1.7S 1.75
Tc (hrs) 0.86* 0.93* 1.02*
(Used) 0.75 1.00 1.00
TimeToOutlet 0.00 0.00 0.00
Ia/P 0.18 0.18 0.18
Time Total Subarea Contribution to Total Flow (cfs)
(hr) Flow PRE1 PRE2 PRE3
11.0 0 0 0 0
11.3 0 0 0 0
11.6 0 0 0 0
11.9 1 0 0 1
12.0 1 0 0 1
12.1 1 0 0 1
12.2 1 0 0 1
12.3 2 0 0 2
12.4 2 0 0 2
12.5 6 iP iP 4
12.6 7 1 1 5
12.7 9 1 1 7
12.8 10 1 1 8
13.0 11P 1 1 9P
13.2 11 1 1 9
13.4 9 1 1 7
13.6 7 0 1 6
13.8 6 0 1 5
14.0 5 0 1 4
14.3 3 0 0 3
14.6 2 0 0 2
15.0 2 0 0 2
15.5 2 0 0 2
16.0 1 0 0 1
16.S 1 0 0 1
17.0 1 0 0 1
17.5 1 0 0 1
18.0 1 0 0 1
19.0 1 0 0 1
20.0 1 0 0 1
22.0 0 0 0 0
26.0 0 0 0 0
P - Peak Flow * - value(s) provided from TR-SS system routines
Page No. 18
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
TR-SS TABULAR DISCHARGE METHOD VERSION 1.11
Project : Phillips Common User: JAS Date: 10-10-91
County Essex State: MA Checked: Date:
Subtitle: Pre Development
Total watershed area: 0.005 sq mi Rainfall type: III Frequency: 100 years
Subareas
PRE1 PRE2 PRE3
Area(sq mi) 0.00 0.00 0.02
Rainfall(in) 6.5 6.5 6.5
Curve number 71 71 71
Runoff(in) 3.31 3.31 3.31
Tc (hrs) 0.86* 0.93* 1.02*
(Used) 0.75 1.00 1.00
TimeToOutlet 0.00 0.00 0.00
Ia/P 0.13 0.13 0.13
Time Total Subarea Contribution to Total Flow (cfs)
(hr) Flow PRE1 PRE2 PRE3
11.0 1 0 0 1
11.3 1 0 0 1
11.6 1 0 0 1
11.9 2 0 0 2
12.0 2 0 0 2
12.1 2 0 0 2
12.2 3 0 0 3
12.3 6 1 1 4
12.4 8 1 1 6
12.5 10 1 1 8
12.6 15 2P 2 11
12.7 18 2 2 14
12.8 21 2 2 17
13.0 24P 2 3P 19P
13.2 21 1 3 17
13.4 17 1 2 14
13.6 14 1 2 11
13.8 10 1 1 8
14.0 8 0 1 7
14.3 6 0 1 5
14.6 5 0 1 4
15.0 S 0 1 4
15.5 3 0 0 3
16.0 2 0 0 2
16.5 2 0 0 2
17.0 2 0 0 2
17.5 2 0 0 2
18.0 1 0 0 1
19.0 1 0 0 1
20.0 1 0 0 1
22.0 1 0 0 1
26.0 0 0 0 0
P - Peak Flow * - value(s) provided from TR-SS system routines
Page No. 19
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Post Development Analysis
Page No. 20
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)4
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Post Development Subarea Plan.
scale : 1" = 200'
MEMO= DESIGN POINT 1
0 100 200 400 DESIGN POINT 2
—QOO9S0
\ �---�J �.—
°
\
i
\ \ ,
t
a i
1
TA
it zi�
o \ <Y a e
fO,
`p
DE SIGN POINT
ZIA
Page No. 21
Merrimack Engineering Services, Inc. °66 Park Street -Andover, Massachusetts 01810°Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 19=91
Subarea POND1
PaB-Paxton C 100
WrA-Woodbridge
Cover description Acreage Percentage of subarea Curve Number
Prop.roadway and sidewalk 0.437 11.4 98
Prop.houses and drives 0.660 17.2 98
Exist.lawn-good condition 0.055 1.4 74
Prop.lawn-good condition 2.359 61.5 74
Woods-good condition 1 0.328 8.5 1 70
3.839 100 80.52 use 81
Sheet flow 300 0.019 lawn 0,894
Shallow concentrated flow 85 0.019 unpaved - 0.011
Pipe flow 140 0.039 3.89 0.010
I
Time of concentration=0.915 hr to proposed detention pond 1.
Subarea POND2
PaB-Paxton C 100
WrA-Woodbridge
Cover description Acreage Percentage of subarea Curve Number
Prop.roadway and sidewalk 0.596 11.8 98
Prop.houses and drives 0.804 15.9 98
Exist.lawn-good condition 0.248 4.9 74
Prop.lawn-good condition 3.094 61.2 74
Woods-good condition 1 0.314 6.2 70
5.056 100 80.40 use 80
Sheet flow 300 0.015 lawn - 0.982
Gutter and pipe flow 240 0.010 2.02 0.033
Time of concentration=1.015 hr to proposed detention pond 2.
Page No. 22
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1 481
Project : Phillips Common - North Andover, Massachusetts October 14, -1-9-9-11
Subarea POST1
PaB-Paxton C 100
WrA-Woodbridge
Cover description Acreage Percentage of subarea Curve Number
Prop.houses and drives 0.132 4.0 98
Prop.lawn-good condition 0.395 11.9 74
Woods-good condition 2.783 1 84.1 70
3.310 100 71.60 use 72
Sheet flow 300 0.013 light woods 1.040
Shallow concentrated flow 685 0.015 unpaved 0.096
Time of concentration=1.136 hr to design point 3.
Subarea POST2
PaB-Paxton C 100
WrA-Woodbridge
Cover description Acreage Percentage of subarea Curve Number
Meadow-Continuous 0.147 30.0 71
Woods-good condition 1 0.343 70,0 70
0.490 100 70.30 use 70
300 0.008 light woods 1.263
Sheet
w7con7centrated 7flw 80 0.008 unpaved 0.015
'171me of concentration=1.278 hr to design point 4.
Page No. 23
Merrimack Engineering Services, Inc. *66 Park Street -Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusefts October 1±1-1-99--1i
Subarea POSTS identical to PRE1
PaB-Paxton C 100
Cover description Acreage Percentage of subarea Curve Number
Lawn-good condition 0,140 13.0 74
Woods-good condition 0.960 87.0 70
Y- 1.100 100 70.52 use 71
Sheet flow 280 0.018 light!woods 0.864
Time of concentration=0.864 hr to design point 1.
Subarea POST4
PaB-Paxton C 100
Cover description Acreage Percentage of subarea 7. Curve 7Number
Exist.house and prop.walk 0.06 3.5 98
Exist.lawn-good condition 0.17 10.2 74
Meadow-Continuous grass 0.60 35.3 71
Woods-good condition 0.88 1 51.0 1 70
1.71 100 71.7 use 72
Sheet flow 300 0.017 light woods 0.935
Time of concentration=0.935 hr to design point 2.
Subarea POST5 - not included in the analysis.
Page No. 24
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
TR-55 TABULAR DISCHARGE METHOD VERSION 1.11
Project Phillips Common User: JAS Date: 10-23-91
County : Essex State: MA Checked: Date:
Subtitle: Post Development
Total watershed area: 0.024 sq mi Rainfall type: III Frequency: 10 years
Subareas
POND1 POND2 POST1 POST2 POST3 POST4
Area(sq mi) 0.01 0.01 0.01 0.00 0.00 0.00
Rainfall(in) 4.5 4.5 4.5 4.5 4.S 4.S
Curve number 81 80 72 70 71 71
Runoff(in) 2.S5 2.46 1.82 1.67 1.75 1.75
Tc (hrs) 0.91* 1.02* 1.14* 1.28* 0.86* 0.93*
(Used) 1.00 1.00 1.25 1.25 0.75 1.00
TimeTooutlet 0.00 0.00 0.00 0.00 0.00 0.00
Ia/P 0.10 0.11 0.17 0.19 0.18 0.18
Time Total Subarea Contribution to Total Flow (cfs)
(hr) Flow POND1 POND2 POST1 POST2 POST3 POST4
11.0 0 0 0 0 OP 0 0
11.3 0 0 0 0 0 0 0
11.6 0 0 0 0 0 0 0
11.9 1 0 1 0 0 0 0
12.0 2 1 1 0 0 0 0
12.1 2 1 1 0 0 0 0
12.2 2 1 1 0 0 0 0
12.3 2 1 1 0 0 0 0
12.4 4 1 2 1 0 0 0
12.5 8 2 3 1 0 1P 1P
12.6 9 3 3 1 0 1 1
12.7 10 3 4 1 0 1 1
12.8 13 4 5 2P 0 1 1
13.0 15P 5P 6P 2 0 1 1
13.2 13 4 5 2 0 1 1
13.4 11 3 4 2 0 1 1
13.6 9 3 3 2 0 0 1
13.8 7 2 3 1 0 0 1
14.0 6 2 2 1 0 0 1
14.3 4 1 2 1 0 0 0
14.6 3 1 1 1 0 0 0
15.0 3 1 1 1 0 0 0
15.5 3 1 1 1 0 0 0
16.0 2 1 1 0 0 0 0
16.5 1 0 1 0 0 0 0
17.0 1 0 1 0 0 0 0
17.5 0 0 0 0 0 0 0
18.0 0 0 0 0 0 0 0
19.0 0 0 0 0 0 0 0
20.0 0 0 0 0 0 0 0
22.0 0 0 0 0 0 0 0
26.0 0 0 0 0 0 0 0
P - Peak Flow * - value(s) provided from TR-S5 system routines
Page No. 25
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810`Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
TR-55 TABULAR DISCHARGE METHOD VERSION 1.11
Project Phillpis Common User: JAS Date: 10-21-91
County Essex State: MA Checked: Date:
Subtitle: Post Development
Total watershed area: 0.024 sq mi Rainfall type: III Frequency: 100 years
Subareas
POND1 POND2 POST1 POST2 POST3 POST4
Area(sq mi) 0.01 0.01 0.01 0.00 0.00 0.00
Rainfall(in) 6.5 6.5 6.5 6.5 6.5 6.5
Curve number 81 80 72 70 71 71
Runoff(in) 4.34 4.24 3.41 3.21 3.31 3.31
TC (hrs) 0.91* 1.02* 1.14* 1.28* 0.86* 0.93*
(Used) 1.00 1.00 1.25 1.25 0.75 1.00
TimeToOutlet 0.00 0.00 0.00 0.00 0.00 0.00
Ia/P 0.07 0.08 0.12 0.13 0.13 0.13
(Used) 0.10 0.10 0.12 0.13 0.13 0.13
Time Total Subarea Contribution to Total Flow (cfs)
(hr) Flow POND1 POND2 POST1 POST2 POST3 POST4
11.0 1 0 1 0 0 0 0
11.3 1 0 1 0 0 0 0
11.6 2 1 1 0 0 0 0
11.9 2 1 1 0 0 0 0
12.0 3 1 1 1 0 0 0
12.1 3 1 1 1 0 0 0
12.2 4 1 2 1 0 0 0
12.3 7 2 2 1 0 1 1
12.4 9 3 3 1 0 1 1
12.5 13 4 5 2 0 1 1
12.6 17 5 6 2 0 2P 2
12.7 21 6 8 3 0 2 2
12'.8 24 7 9 4 0 2 2
13.0 28P 8P lop 4 iP 2 3P
13.2 25 7 9 5P 1 1 2
13.4 21 6 7 4 1 1 2
13.6 15 4 5 3 0 1 2
13.8 12 3 4 3 0 1 1
14.0 9 3 3 2 0 0 1
14.3 8 2 3 2 0 0 1
14.6 6 2 2 1 0 0 1
15.0 4 1 2 1 0 0 0
15.5 3 1 1 1 0 0 0
16.0 3 1 1 1 0 0 0
16.5 3 1 1 1 0 0 0
17.0 3 1 1 1 0 0 0
L7.5 2 1 1 0 0 0 0
L8.0 2 1 1 0 0 0 0
L9.0 1 0 1 0 0 0 0
?0.0 0 0 0 0 0 0 0
?2.0 0 0 0 0 0 0 0
?6.0 0 0 0 0 0 0 0
? - Peak Flow * - values) provided from TR-55 system routines
Page No. 26
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810`Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Proposed detention pond 1 description:
Level Elevation Area Level storage Cumulative storage
(sq.ft) (ac.ft) (ac.ft)
5 192.0 7,493 0.079 0.564
4 191.5 6,252 0.194 0.485
3 190.0 5,013 0.186 0.291
2 188.0 3,093 0.105 0.105
1 186.0 1,493 0 0
Pond controls;
o 10 If, I inch diameter outlet pipe(to model infiltration).
n=0.015, s=0.010 ft/ft, inv.out= 186.0
o 178 degree"V" notched weir, inv.out= 191.5
Proposed detention pond 2 description:
Level Elevation Area Level storage Cumulative storage
(sq.ft) (ac.ft) (ac.ft)
4 196.5 7,963 0.082 0.435
3 196.0 6,240 0.231 0.353
2 194.0 3,840 0.122 0.122
1 192.0 1,467 0 0
Pond controls;
o 10 If, I inch diameter outlet pipe(to model infiltration).
n=0.015, s=0.010 ft/ft, inv.out= 192.0
o 115 If, 12 inch diameter RCP, n=0.015, s=0.0074 ft/ft, inv.out= 192.0
well rounded entrance(FES).
o 178 degree"V" notched weir, inv.out= 197.0
Page No. 27
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (508)475-1448 1
Project : Phillips Common - North Andover, Massachusetts OctoberiLl -199--1j
Proposed retention pond 1 - 10 year storm flow data:
Time Inflow Outflow Elevation Storage
(hr) (cfs) (cfs) (ac.ft)
11.0 0.0 0.0 186.1 0.00
11.2 0.0 0.0 186.1 0.00
11.4 0.0 0.0 186.1 0.00
11.6 0.0 0.0 186.1 0.00
11.8 0.0 0.0 186.1 0.00
12.0 1.0 0.0 186.1 0.01
12.2 1.0 0.0 186.4 0.03
12.4 1.0 0.0 186.8 0.05
12.6 3.0 0.0 187.4 0.09
12.8 4.0 0.0 188.2 0.14
13.0 5.0 P 0.0 189.0 0.22
13.2 4.0 0.0 189.8 0.29
13.4 3.0 0.0 190.3 0.35
13.6 3.0 0.0 190.7 0.40
13.8 2.0 0.0 191.0 0.43
14.0 2.0 0.0 191.2 0.46
14.2 1.3 0.0 191.4 0.49
14.4 1.0 0.0 191.6 P 0.50 P
14.6 1.0 1.0 P 191.6 0.50
14.8 1.0 1.0 191.6 0.50
15.0 1.0 1.0 191.6 0.50
15.2 1.0 1.0 191.6 0.50
15.4 1.0 1.0 191.6 0.50
15.6 1.0 1.0 191.6 0.50
15.8 1.0 1.0 191.6 0.50
16.0 1.0 1.0 191.6 0.50
P -indicates peak value.
Page No. 28
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Proposed detention pond 2 - 10 year storm flow data:
Time Inflow Outflow Elevation Storage
(hr) (cfs) (cfs) (ac.ft)
11.0 0.0 0.0 192.1 0.00
11.2 0.0 0.0 192.1 0.00
11.4 0.0 0.0 192.1 0.00
11.6 0.0 0.0 192.1 0.00
11.8 0.7 0.1 192.1 0.01
12.0 1.0 0.4 192.3 0.02
12.2 1.0 0.7 192.4 0.03
12.4 2.0 0.9 192.6 0.04
12.6 3.0 1.6 193.0 0.07
12.8 5.0 2.6 193.5 0.10
13.0 6.0 P 3.6 194.1 0.14
13.2 5.0 3.8 194.4 P 0.17 P
13.4 4.0 3.9 P 194.4 0.17
13.6 3.0 3.8 194.4 0.16
13.8 3.0 3.8 194.3 0.15
14.0 2.0 3.6 194.1 0.13
14.2 2.0 3.1 193.8 0.11
14.4 1.7 2.7 193.5 0.09
14.6 1.0 2.1 193.2 0.07
14.8 1.0 1.7 193.0 0.06
15.0 1.0 1.4 192.9 0.05
15.2 1.0 1.3 192.8 0.05
15.4 1.0 1.2 192.7 0.04
15.6 1.0 1.1 192.7 0.04
15.8 1.0 1.1 192.6 0.04
16.0 1.0 1.0 192.6 0.04
P -indicates peak value.
Page No. 29
Merrimack Engineering Services, Inc.* 66 Park Street-Andover, Massachusetts 01810*Tel. (508)475-3555 Fax. (50 E)4:75=-1�8
Project : Phillips Common - North Andover, Massachusetts October 1K,19=91
Proposed retention pond 1 - 100 year storm flow data:
Time Inflow Outflow Elevation Storage
(hr) (cfs) (Cfs) (ac.ft)
11.0 0.0 0.0 186.1 0.00
11.2 0.0 0.0 186.1 0.00
11.4 0.3 0.0 186.1 0.01
11.6 1.0 0.0 186.3 0.02
11.8 1.0 0.0 186.7 0.04
12.0 1.0 0.0 187.1 0.05
12.2 1.0 0.0 187.5 0.07
12.4 3.0 0.0 188.1 0.11
12.6 5.0 0.0 188.9 0.19
12.8 7.0 0.0 190.0 0.29
13.0 8.0 P 0.0 190.9 0.42
13.2 7.0 3.9 191.6 0.50
13.4 6.0 6.2 P 191.7 P 0.51 P
13.6 4.0 4.4 191.6 0.50
13.8 3.0 3.2 191.6 0.49
14.0 3.0 3.0 191.6 0.49
14.2 2.3 2.5 191.6 0.49
14.4 2.0 2.0 191.6 0.49
14.6 2.0 2.0 191.6 0.49
14.8 1.5 1.6 191.6 0.49
15.0 1.0 1.1 191.6 0.49
15.2 1.0 1.0 191.6 0.49
15.4 1.0 1.0 191.6 0.49
15.6 1.0 1.0 191.6 0.49
15.8 1.0 1.0 191.6 0.49
16.0 1.0 1.0 191.6 0.49
P -indicates peak value.
Page No. 30
Merrimack Engineering Services, Inc. *66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-148
[-Project-: Phillips Common - North Andover, Massachusetts October 14, 9=91
Proposed detention pond 2 - 100 year storm flow data:
Time Inflow Outflow Elevation Storage
(hr) (cfs) (cfs) (ac.ft)
11.0 1.0 0.7 192.4 0.02
11.2 1.0 0.8 192.5 0.03
11.4 1.0 0.9 192.6 0.03
11.6 1.0 1.0 192.6 0.03
11.8 1.0 1.0 192.6 0.03
12.0 1.0 1.0 192.6 0.03
12.2 2.0 1.1 192.7 0.04
12.4 3.0 1.7 193.0 0.05
12.6 6.0 3.2 193.9 0.10
12.8 9.0 4.0 194.6 0.18
13.0 10.0 P 4.6 195.4 0.26
13.2 9.0 5.1 196.1 0.33
13.4 7.0 5.3 196.3 0.37
13.6 5.0 5.4 P 196.4 P 0.37 P
13.8 4.0 5.3 196.3 0.36
14.0 3.0 5.2 196.2 0.32
14.2 3.0 5.0 195.9 0.29
14.4 2.7 4.8 195.6 0.26
14.6 2.0 4.5 195.3 0.22
14.8 2.0 4.2 194.9 0.18
15.0 2.0 4.0 194.6 0.15
15.2 1.6 3.7 194.3 0.11
15.4 1.2 3.2 193.8 0.08
15.6 1.0 2.2 193.3 0.06
15.8 1.0 1.6 193.0 0.04
16.0 1.0 1.3 192.8 0.04
P -indicates peak value.
Page No. 31
Merrimack Engineering Services, Inc. * 66 Park Street -Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Post development - 10 year storm runoff summary:
Time Pond 2 Design Design Design Design Total
(hr) outflow point 1 point 2 point 3 point 4 flow(cfs)
11.0 0.0 0.0 0.0 0.0 0.0 P 0.0
11.2 0.0 0.0 0.0 0.0 0.0 0.0
11.4 0.0 0.0 0.0 0.0 0.0 0.0
11.6 0.0 0.0 0.0 0.0 0.0 0.0
11.8 0.1 0.0 0.0 0.0 0.0 0.1
12.0 0.4 0.0 0.0 0.0 0.0 0.4
12.2 0.7 0.0 0.0 0.0 0.0 0.7
12.4 0.9 0.0 0.0 1.0 0.0 1.9
12.6 1.6 1.0 P 1.0 P 1.0 0.0 4.6
12.8 2.6 1.0 1.0 2.0 P 0.0 6.6
13.0 3.6 1.0 1.0 2.0 0.0 7.6
13.2 3.8 1.0 1.0 2.0 0.0 7.8
13.4 3.9 P 1.0 1.0 2.0 0.0 7.9 P
13.6 3.8 0.0 1.0 2.0 0.0 6.8
13.8 3.8 0.0 1.0 1.0 0.0 5.8
14.0 3.6 0.0 1.0 1.0 0.0 5.6
14.2 3.1 0.0 0.3 1.0 0.0 4.4
14.4 2.7 0.0 0.0 1.0 0.0 3.7
14.6 2.1 0.0 0.0 2.0 0.0 4.1
14.8 1.7 0.0 0.0 2.0 0.0 3.7
15.0 1.4 0.0 0.0 2.0 0.0 3.4
15.2 1.3 0.0 0.0 2.0 0.0 3.3
15.4 1.2 0.0 0.0 2.0 0.0 3.2
15.6 1.1 0.0 0.0 1.8 0.0 2.9
15.8 1.1 0.0 0.0 1.4 0.0 2.5
16.0 1.0 0.0 0.0 1.0 0.0 2.0
P -indicates peak value.
Page No. 32
Merrimack Engineering Services, Inc. 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (508)475-1448
['Project : Phillips Common - North Andover, Massachusetts October 14, 1991
Post development - 100 year storm runoff summary:
Time Pond 2 Design Design Design Design Total
(hr) outflow point 1 point 2 point 3 point 4 flow(cfs)
11.0 0.7 0.0 0.0 0.0 0.0 0.7
11.2 0.8 0.0 0.0 0.0 0.0 0.8
11.4 0.9 0.0 0.0 0.0 0.0 0.9
11.6 1.0 0.0 0.0 0.0 0.0 1.0
11.8 1.0 0.0 0.0 0.0 0.0 1.0
12.0 1.0 0.0 0.0 1.0 0.0 2.0
12.2 1.1 0.0 0.0 1.0 0.0 2.1
12.4 1.7 1.0 1.0 1.0 0.0 4.7
12.6 3.2 2.0 P 2.0 2.0 0.0 9.2
12.8 4.0 2.0 2.0 4.0 0.0 12.0
13.0 4.6 2.0 3.0 P 4.0 1.0 P 14.6
13.2 5.1 1.0 2.0 8.9 1.0 18.0
13.4 5.3 1.0 2.0 10.2 P 1.0 19.5 P
13.6 5.4 P 1.0 2.0 7.4 0.0 15.8
13.8 5.3 1.0 1.0 6.2 0.0 13.5
14.0 5.2 0.0 1.0 5.0 0.0 11.2
14.2 5.0 0.0 1.0 4.5 0.0 10.5
14.4 4.8 0.0 1.0 3.7 0.0 9.5
14.6 4.5 0.0 1.0 3.0 0.0 8.5
14.8 4.2 0.0 0.5 2.6 0.0 7.3
15.0 4.0 0.0 0.0 2.1 0.0 6.1
15.2 3.7 0.0 0.0 2.0 0.0 5.7
15.4 3.2 0.0 0.0 2.0 0.0 5.2
15.6 2.2 0.0 0.0 2.0 0.0 4.2
15.8 1.6 0.0 0.0 2.0 0.0 3.6
16.0 1.3 0.0 0.0 2.0 0.0 3.3
P -indicates peak flow.
Page No. 33
f
Merrimack Engineering Services, Inc. * 66 Park Street-Andover, Massachusetts 01810 Tel. (508)475-3555 Fax. (50