HomeMy WebLinkAbout2003 Response Comments SPR WITHDRAWN (F�3oSCHOFIELH BROTHERS
ENGINEERING - SURVEYING PLANNING
Schofield Brolhsrs of Now England,Inc.
1071 Worcester Road
Framingham,MA 01701-5298
508.679.0030
July 30, 2003 1-800-69s-2874
FAX 508-879-1797
21652
Mr. Scott Masse,Chairman
North Andover Conservation Commission
27 Charles Street
North Andover, MA 01845
RE: Foster Farm Elementary School Project
DEP File No. 242-1208
Dear Mr. Masse and Commission Members:
Schofield Brothers of New England, Inc., and the project architects, DiNisco Design
Partnership have reviewed the Technical Review Report received from Lisa Eggleston of
Eggleston Environmental. The report contains a thorough evaluation of the stormwater
rnana-ernent design and materials submitted to you with the Notice of Intent, and we
generally concur with the comments and recommendations contained in the report. We
plan to address all the concerns raised and have summarized the issues below and described
how we plan to address each item.
We have also received the Notification of Wetland Protection Act File Number from the
Northeast Regional Office of the DEP. That notification contains a few comments for
cotisideration, and we have provided responses to those comments that are contained at the
end of this letter.
Overall, there does not appear to be any major issues that will require substantial
modifications to the project layout and site plans. The additional information and
modifications to the plan can be satisfactorily addressed,
RESPONSES TO COMMENTS AND ISSUES CONTAINED EN THE EGGLESTON
ENVIRONMENTAL REPORT:
Item d - Groundwater Recharge
This itern addresses several related comments concerning the distribution of
volumes of groundwater recharge to the various sub-drainage areas on the site. The
cormnents to be addressed here include the following:
Page. 3 (2"d bullet); Page4 (3r1 and 4`i' bullets); Page 6 (Standard#3 Recharge to
Groundwater).
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--:�;',F?SCHOFIELD BROTHERS
ENL NFERING SURVEYINU • PLANNtNc
21652
North Andover Conservation Commission
July 30 2003
RE., Foster Farm Elementary School Page 2
As pointed out in Ms. Eggleston's review, the project design makes extensive use of
stoMwater infiltration BMPs. This is necessary because there is very little runoff
from the site under existing conditions. This requires recharging significant
quantities of storrnwater back into the -round to prevent an increase in the peak
rates of surface runoff to the adjacent wetland resource areas, particularly in the
smaller- storm events,
From any development where impervious surfaces will replace natural vegetated
areas, there will be an increase in runoff volume. The hydrologic budget changes
because the "transpiration"component of the budget is eliminated, and the
"interception" and "evaporation" is typically reduced because of the area reduction
in wetted surfaces in those areas that are rendered impervious. This results in either
an increase in surface water runoff volume to wetland resource areas, or as in this
case; an increase in groundwater recharge, or both.
It is clear from Ms, Eggleston's comments that she feels that some increase in
groundwater flow to the vernal pool wetland would be acceptable, but the
hydrologic budget to that system should not be significantly increased as indicated
on the calculations provided. Fortunately this can easily be adjusted by changing
the portion of the roof area that will drain to the system in the vernal pool sub-
drainage area.
She also points out that the budget calculations under-estimate the amount of
evaporation in the model equation. The model can easily be adjusted to correct for
that and we will also provide computations with a tabulation of the groundwater
recharge to each of the three down gradient wetland systems to provide a complete
picture of the groundwater input for the overall site as she has recommended.
Item 2—Roof Drain Inlet Protection (Page 3, P Bullet).
We concur With the recommendation. Inlet screens are a recommended practice for
these types of facilities. We will provide a detail of the unit(s) that would be used
for this building.
Item 3 — Planted Rock Filters (Page 3,41h Bullet; Page4, is` 2"', and 6"' Bullets)
The planted rock filters have been added to two of the stormwater drainage systems
as part of the Green Schools Initiative to provide additional treatment of stormwater
above that necessary to meet the rninimum standards of the Stormwater
Management Policies, Ms. Eggleston has raised some questions to be addressed
RB- SCOOFIELD BROTHERS
E\'GINFKHING • SERVE,YIN4 P1,ANNINC '.
21652
North Andover Conservation Commission
July 30, 2003
RE: Foster Farm Elementary School Page 3
and has made some good recommendations that we will incorporate into the plans.
These are summarized as follows:
a. She recomi-rends including a sub drainage system to help assure that the filters
will drain following a storm event. This will protect the installations against
freezing and frost action that may damage or block the distribution system,
b. There is some confusion on the piped distribution system and how the system
operates in relation to the basins and storm flours. Additional detail will be
provided on the drawings and further written explanation in the narrative to clarify
this.
c. Additional detail will be provided in the operation and maintenance plan for the
management of the systems. The plant species recommended for these systems are
upland, evergreen shrub species that can tolerate short term flooding of the root
systems but will thrive in normal soil moisture. For that reason, the system
tributary to the vernal pool, which will rarely be flooded from the stormwawr
system, will not need supplemental ii-rig,ation. Normal rainfall should be sufficient
to supply the shrubs.
Item 4_Southem Stormwater Basin (Pace 3, 5`1'Bullet),
This was discussed somewhat in Item 1 above. Additional detail will be provided
that will clarify how the distribution system functions in relation to the various
components, In the computer model of the hydraulic operation of the basin we have
intentionally neglected the initial volume captured by the planted cock filler, and
made the infiltration pits effective with the first inflow. This is done to simplify the
model and is a conservative assumption, recognizing that the volume of the rock
filter is relatively small in relation to the storm flow and that the Planted Rock Filter
is another infiltrating structure that is not included in the model. We agree that
additional information is necessary to make the model more clear as well as the
additional detail information to be provided on the plan that is discussed in Item i
above. Adjustment of the model to account for the initial flow to the Planted Rock
Filter is also possible and can also be provided if desired.
Item 5 — Parking Lot Grading-(Page 4, 5(11 Bullet),
We concur with the comment regarding the grading in the area of the handicapped
parking in front of the building. Some additional spot grade information is required
an the plan to make it clear that there is not to be a trapped low area at the comer of
the handicapped spot.
i
B�SCHOI=IELD BROTHELS
FNGJ 'EF,R[VG •,5L!RVJiY1NG PLANNING
21652
North Andover Conservation Commission
July 30, 2003
RE-. Foster Farm Elementary School Page 4
Itu-m 6 — Catch Basin 12 (Page S, IS`Bullet).
We concur with the comment. Additional information will be provided to clarify
this installation and function.
Itern 7 — Stormceptor (Page 5, 2nd Bullet).
Ms. Eggleston points out that if a substitute is to be made as an "equal" to the
specified Stormceptor, there may need to be a different design configuration to
accommodate the change. This is important and is the same thing that was recently
done in the High School project. In order for a proposed substitute to be approved
as an "equivalent", our process for that project was that the substitution must first
be approved by the project engineer to make sure that the unit will properly fit into
the system, and that it meets the requirements for the required TSS removal.
Following that, it must also be approved by the Conservation Commission and the
Town Engineer. We would recommend that this be. included in the Order of
Conditions for the project.
Item 8 —Dr well Infiltration S stems (Page 5, P Bullet).
It is recommended that the inlet and outlet pipes for the multiple drywell systems be
at the opposite ends of the system, rather than the same drywell. We concur with
that recommendation and will make the revisions to the plan.
Item 9— Additional Soil Testing (Page 5, 41h Bullet).
It is recommended that additional testing be conducted in the actual proposed
location of the infiltration structures to confirm the soil conditions. There is
extensive soil testing on the site and in relatively close proximity to the design
locations but we concur that the additional testing would be prudent and will be
performed. We will begin making arrangements for the testing immediately.
Item 10 —Replacement of Culvert at the Cart Path (Page 5, 5th Bullet),
Ms. Eggleston points out that the existing culvert (actually a stone crossing) needs
to replicate existing low flow capacity because it plays a role in the outflow from
the vernal pool. The elevation of the culvert is several feet below the upstream
vernal pool and the actual outflow is controlled at a point about 200 feet upstream
from the culvert, so it does not directly control the outflow of the vernal pool.
However the concern is valid and we do concur that a change in the location and
configuration of the stone culvert could have an impact on the hydrology of the
area, which could certainly impact the vernal pool. This is why we have chosen to
replace the stone crossing with one that, as best as we can determine, will replicate
the existing stone structure. The improvement will be a filter fabric to separate the
SCHOFIELD BROMERS
EV[:IN}:E:R1rC Sl:'RV4:YINt; PI,AN''NING
21652
North Andover Conservation Commission
July 30, 2003
RE: Foster Farm Elementary School Page 5
top of the stone from the walking path surface gravel to protect the stone and
provide a dryer mealking surface.
Item .11 —Drywell_Inlets (Page 5, 6"' Bullet).
We concur with the recommendation. We will add the information on the plan to
make it clear which units have Beehive Inlets and which unit have solid covers.
Item 12—Double Inlet Catch Basin (Page 5, 7`1' Bullet).
We concur that the symbol on the plan that designates a double inlet is small and
could use some additional clarification. We will add the words "Double Inlet" to
each catch basin label where a double inlet is required.
Item 13 --Inspection Ports for the Cultec Systems (Page 5, 81h bullet).
We concur with the recommendation that inspection ports be provided and will add
that to the detail on the drawing.
Item 14—Erosion and Sediment Control (Page 7, Standard 8),
We concur with the comment that temporary use of the vicinity of the northeast
retention/detention basin for the stockpiling of materials and also construction
activity in general on the site will cause soil compaction in that area. To mitigate
that impact, we propose to keep any stockpiling activity off the area of the proposed
infiltration systerns, and call for the upper soil in the other basin area to be
uncompacted by deep plowing and regrading of the subgrade material prior to
installation of the topsoil and finish grading of the basin bottom.
In addition to this, Ralph Perkins of the DEP -NERO has recommended providing
isolation protection of all the infiltration structures during construction and this
should be included on the Erosion and Sediment Control Plan. We concur and will
add that to the plan.
With respect to the Conservation Commission being provided the opportunity to
review and approve the Stormwater Pollution Prevention Plan (SWPPP) when it is
developed, we concur- and recommend that be included in the Order of Conditions.
The Order of Conditions is always included as part of the bidding and contract
documents, so this will snake all contractors bidding on the project aware of the
requirement of the Order-.
As for construction monitoring of the erosion controls, the current arrangement for
the High School project appears to be working well for that purpose, and is being
�E-D::>SCH0F1E1D BROTHERS
SURVEYING - PLANNING
21652
North Andover Conservation Commission
July 30, 2003
RE: Foster Farm Elementary School Page 6
used as a model in other Towns. We would recommend similar conditions be
placed in the Order for this project.
Item 15 —Operation and Maintenance Plan (Page 8, Standard 9).
We agree that the Commission should be provided the opportunity for input on the
preparation of the O&M Manual for the Stormwater Management System along
with the Town Engineer.
Also as recommended, a snow storage plan for the future management of the site
and disposal guidelines will be prepared and submitted to you as part of our
additional information that will be. provided for your review during this hearing
process. The guidelines will follow the DEP's current published snow disposal
guidelines,
COMMENTS INCLUDED BY DEP ON THE NOTIFICATION OF FILE NUMBER
FORM:
The first comment is that a written alternatives analysis must be required. This is in
reference to the proposed regrading within the Riverfront Area.
Our response to this is that the proposed alteration is very mi-nor and is located along the
outer fringe of the Riverfront Area. As stated in the narrative materials submitted with the
Notice of Intent, we feel that a naturally vegetated slope for the side of the driveway is the
preferable alternative to a retaining wall to avoid this minor change in grade. The area is
-now an open sloping field and the plan is to re-vegetate the area with native grasses to
blend in with the adjacent Riverfront Area. The replacement of the foot path is a
permittable minor project in accordance with the Regulations. We can provide additional
written discussion of this, but a "full-scope" alternatives analysis does not seem warranted
for such a minor intrusion where the Riverfront Area will remain intact in both form and
function. It meets the requirements of"No Significant Adverse Impact" under 10.58(4) and
the naturally vegetated slope is better in terms of wildlife habitat function. We feel the
commission has discretion to determine whether alternatives have been satisfactorily
addressed. A wall would not be cost prohibitive for the project, however we feel the
character and value of the Riverfront would best be served with a natural slope in that area.
A wall would also require some re-routing of the existing foot path. The foot path is an
important trail link to the adjacent conservation land.
r . �
�SCHUTIE�,D �3R07'HERS
�:\f>€NEtikF[:G, • ti[,'R��LlS'[Nl: PLANNING
21 652
North Andover Conservation Cornmissior,
July 30, 2003
RE: roster Farm Elementary School Pagy ;
The DEP comments relative to the stormwater peak flows, TSS remov~ t and the
StoYinceptor calculations have been. addressed In the Stormwater Report and rcviewed by
Eggleston Environmental.
The DE'P corp-ment regarding provisioll for i.-3-construction lsolatic) ()'f 3!11:I,1'i;;FQI] .YIPS in
[lie "Standard 8 Plan- (Erosion and ,Sedin el?4 Contro' Plan) is a good suggescion and w 11
be addressed as discussed in Mr-P. 14 above.,
Very truly yours,
-Schof:'lelel Brothers of New li ngland, Inc.
;r redric W. King, P.f✓.
Scnior: ngiiecr.' Wetland Specialist
^t : DiNi--o Drsiy; Part.nel'ship �foa'fullh;,r distribution}
Egylestol:r r:virontn:r:�.s.��l
F 11
Cam " BOTH
f ' ' Schofield Brothers of New England t,,ic��
1071 Worcester Road V
Framinghar^,IMA 01701-5298
808-879-0030• 1-800-B98-2874
Fax - - 1 5
September #, �003
? F 5088791797 LRJebsite 4r;rr1.5cnofietclbros.ccm
21652 1Jt k-111 ANDOVCI
1\41'. SCott Masse. Chairman
North Andover Conservation Commission
27 Charles Street
Norte, Andover. NIA 01845
RE: Foster Farm Elementary School Project
DEP File No. 2 42-1205
Dear Mr, Masse and Commission Members:
Enclosed please find S sets of the following revised plans and documents that have been prepared
to address the comments received from Lisa Eggleston of Eggleston Environmental as well as
comments received from the North Andover Planning Board and their consult;€nt, VHB, Inc. from
their review of the project. A complete copy of this letter with all the aMiChments has been sent
directly to Eggleston Environmental and the Mass. DEC',
Plans entitled "Foster Farm Elementary School, North Andover, MA" revised 19 September,
2003" including the following sheets:
Sheets 1.1A to 1.1.12 Prepared by Morice & Gary, Inc,
Sheets 1.2.0 to 1.2.1 Site Utilities Prepared by RW Sullivan, Inc.
Sheets 1,3.1 to 1.3.3 Erosion Control — By Schofield Brothers of New England,
Sheets 1.3.4 to 1.3.7 Stormwater—By Schofield Brothers of New England,
Plan Entitled " Exhibit — Possible Snow Storalge Sites"dated September 19, 2003.
- Report Entitled "Attachment 5 —Stormwater hlana4ement Report Revisions 9/23/03" prepared
by Schofield Brothers of New England. Inc.
Letter Report to DiNisco Design Partnership chted September 22, 2003 %\ith 5 Attachments.
This is (lie response to the comments from the Plannin` Boards consultant (VHB, Inc) relative
to Sto1'11mater Management.
Report Entitled "Attachnictlt 2 —Soil Test Report , Additional Testing on 9/12/03" prepared by
Schofield Brothers of New England, I11c.
The followin- information describes how each of the comments front the Eggleston Environmental
Report have been addressed in the plans and additional i11f01"11)ati011 submitted. It follows the
outline of our July 30, 2003 letter to you.
,- 21652
North Andover Conservation Commission
September 24, 2003
RE: Foster Farm Elementary School —DEP bile No. 242-1208 Paj-e. 2
RESPONSES TO CONIMENTS AND ISSUES CONTAINED IN THE EGGLESTO\
ENVIRONMENTAL REPORT:
Item I --_Groundwater Recharge
This item addresses several related continents concerning the distribution of volumes of
groundwater recharge to the various sub-drainage areas on the site. The comments to be
Addressed here include the follo\ving:
Page 3 (2"'bullet); Page4 ()"',in(] 4"' bullets); Page 6 (Standard 4 3 Recharge to
Gt-oUndwatel').
The majority of the changes to the Stormwuter Management Plans and Report involve
addressing this particular issue. The assessment of the Hydrologic Budget to determine
zoroundwater flows to the various resource areas was redone and is contained in the
"Stormlvater Management Report Revisions". Part 2 of that report contains a detailed
narrative that describes the changes made and how this issue is addressed. Also, summary
tables are included in that narrative as recommended to describe the groundwater flows to
the vur'ious downgradient receptors.
Item 2-Roof Drain Inlet Protection (Page 3, 3r`'Bullet),
Inlet screens are a standard practice for these types of facilities and will be included on this
building. Various standard screen fixtures are used for different roof inlet situations. The
final detailed construction drawings for the roof and drain inlets have not been prepared it
this point in (lie building design. A detail of the units) that would be used for this bu'sldintg
and specifications will be provided in the final Construction Documents, That information
will be provided to the Commission as soon as it is available and we would recommend a
Condition be included in the Order of Conditions.
Item 3 — Planted Rock Filters (Page 3, 4"i Bullet; Page4. 1" 2"`r and 6"' Bullets)
Since the last meeting with the Commission, it has been deteritnined that the Green Design
Grant will not be available for this purpose. As a result, the Planted Rock Filters have
been removed from the plan. As stated in the June 26. 2003 Stormwater Report; these
were added features and were not needed to meet the requireillents of the Stormwatef
Management Policy and no credit was taken for those in the former design plan. Tlw
removal of the Planted Rock Filters simplifies the design of Basin I and the outfall of
Basin 2. Which Should cleat'up some of the confusion various reviewers had in how those
systems worked with the drain system.
The sub-drainage systern recommended by Ms. E-gleston for-Basin 1 remains an
appropriate design feature for that stormwater-BLIP and we have added that to the pkmr
The pipe system now provides a hydraulic connection between tine two portions of the
basin as well.
j' 21652
North Andover Conservation Commission
September 24, 2003
RE: Poster Farm Elementary School —DEP File No. 242-1205 Page 3
Item It -- Southern Stormwater Basin (Page 3, 5'i'Bu]let).
This was discussed in Item 3 above. Additional detail has been provided and the design
has been simplified with the elimination of the Planted Rock Filters. The computer model
of the Basin in the Hydrologic Model is now clarified.
Item 5 — Parking Lot Grading (Page d, 51'Bullet).
Some additional spot grade information has been added to the plan to make it clear that
there is not to be a trapped low area at the corner of the handicapped spot.
Itern 6—Catch Basin 12 (Page 5, 1"Bullet).
This Item is no longer applicable due to the removal of the Planted Rock filter.
Item 7 —Stormceptor_(Page 5, 2nd Bullet). Same response to tlri.s Item.
\:1s. Eggleston points out that if a substitute is to be made as an "equal" to the specified
Stormceptor, there may need to be a different design Configuration to accommodate the
change. This is important and is the same thing that was recently clone in the High School
project. In order for a proposed substitute to be approved as an "equivalent", our process
for that project was that the substitution must first be approved by the project engineer to
make sure that the unit will properly fit into the system, and that it meets the requirements
for the required TSS removal. Following that, it must also be approved by [lie
Conservation Commission and (lie Town Engineer. We would recommend that this be
included in the Order of Conditions for the project.
Item S — Drywell Infiltration Systems (Page 5, 3ra Bullet).
As recommended, the inlet and outlet pipes fo=- the multiple drywell systems have been
changed to the opposite ends of the system, rather than the same dryWell.
Item 9 —Additional Soil Testina (Page 5, Wh Bullet).
As recommended, additional testing was conducted on September 12. 2003 in the actual
proposed location of the infiltration structures to confirm the soil conditions, The
information is contained in the Attachment 2 and the testing has confirmed the anticipated
soil conditions at the infiltration BMP locations.
Item 10—Replacement of Culvert at the Cart Path (Page 5, 5th Bullet).
Same 1•esponse as follows: Ms. Eggleston points out that the existing culvert (actually a
stone crossing) needs to replicate existing low flow capacity because it plays a role in the
outflow from the vernal pool. The elevation of the culvert is several feet below the
upstream vernal pool and the actual outflow is controlled at a point about 200 feet
upstream from the culvert, so it does not directly control the outflO\V of the ver11,11 pool.
However the concern is valid and we do concur that a change in the location and
configuration of the stone culvert could have an impact on the hydrology of the area, which
could certainly impact the vernal pool. This is why we have chosen to replace the stone
crossing with one that, as best as we can determine, will replicate the existing stone
5
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21652
North Andover Conservation Commission
September 24, 2003
RE: Foster Farm Elementary School --DEP File No. 242-1208 Page 4
structure. The improvement will be a filter fabric to separate the top of the stone from the
walking path surface gravel to protect the stone and provide a dryer walkinC' surface,
Item It—--Dr7 ywell Inlets.(Page 5, G°i Bullet),
Information has been added to the plan to make it clear which units have Beehive Inlets
and which units have solid covers.
Item 12—Double Inlet Catch Basin (Page 5, 7"i Bullet).
To clarify which catch basins have double inlets, we added the symbol "DICB" to each
catch basin label where a double inlet is required and have also added this to the legend on
the plan.
Item 13 -- Inspection Ports for the Ctrltec Systems (Page S,
As recommended, inspection ports have been added to the plan for these systems.
Item 1 1.=Erosion and Sediment Control (Page 7, Standard S).
We conc►€red with the comment that temporary use of the vicirr'€ty of the northeast
retention/detention basin for the stockpiling of soil materials and also construction actiN ity
in general on the site will cause soil compaction in that urea. To mitigate that impact, we
have amended the plan to keep any stockpiling activity off the area of the proposed
infiltration systems. In the site preparation specifications for the construction of the
Northeast Basin, it will be required that the upper soil layer in the basin area to be
uncompacted by deep plowing and regrading of the subgrade material prior to installation
of the topsoil and finish grading of the basin bottom.
With respect to the Conservation Commission being provided the opportunity to review
and approve the Stormwater Pollution Prevention Plan (SWPPP) when it is developed. we
concur and recommend that be included in the Order of Conditions. The Order of
Conditions is always included as part of tite bidding and contract documents, so this will
make all contractors bidding on the project aware of the requirement of the Order.
As for construction monitor'inR of the erosion controls, the current arrangement for the
High School project appears to be wonting well for that purpose. and is being used as a
model in other Towns. We would recommend similar conditions be placed in the Order
for this project.
Item 15aeration and Maintenance Plan (Page S. Standard 9).
We agree that the COMMission should be provided the opportunity for input o€7 the
preparation of the O&IN/I Manual for the Stormwater-Management System along with the
Town Engineer. We recommend that be included as a Condition in the Order of
Conditions.
�.T SCJJO1= ELD 131101411,T
Ri 21652
North Andover Conservation Commission
September 24, 2003
RE: Foster Farm Elementary School --- DEP File No. 242-1205 P lie• 5
Also as recommended, a snow storage plain for the future management of the site has been
prepared and included with the attached materials for your review. Obviously this is a
preliminary discussion document that outlines the general pnramete€•s fo€-setting t€p a S11oW
mans gent plan for the site. Similar to the Stornwater Operation and kVda€ntenanCe Plan,
a more detailed plan will need to be developed at the completion of the construction which
will likely be several years in the future and will need to consider the egUipment available
tit that time, acceptable t€se of deicers, etc. We recommend that this be part of the
preparation of the final Stormwater 0&,\,l Manual that should be required and approved by
the Commission as a condition in the Order of Conditions.
In addition to addressin` the Conservation Commission's concerns, other revisions have been
made to the: plan in response to the Planning Board comments. Those 1nChi& some coordination
of the drawin(,s by the various project consultants. With respect to Stormwater, that information is
detailed in the attached letter report to Di\isco Design Partnership (9/22/03).
We believe that this hats addressed the comments and look: forward to reviewing these with )'ou at
the continuation of the wetlands hearing. In the meantime, if there are any questions regardintig any
of these materials, please do not hesitate to contact us.
Very truly yours,
Schofield Brothers of New England, Inc.
Fredric W. Kin-. P.E.
Senior Engineer 1 Wetland Specialist
Cc: DiNj isco Design Partnership(for further distribution)
Eggleston Environmental
DEP— NI ERO
Attachments