HomeMy WebLinkAbout2005-03-16 Engineer Review SPR WITHDRAWN 1 ,
,'VHB Pro,.No. 06716.98
Site Plan--Willow Street=North Andover,MA
APPENDIX_A
Scope of Services
The scope of services consists of an engineering review of the site plan. The major tasks are listed below:
1. Plan Review: Review the site plans for conformance to the Zoning Bylaw (December 2002) and
standard engineering practice. Prepare one (1) engineering review report listing written comments.
Provide one(1) `follow-up' letter that addresses the Applicant's responses to the engineering report.
2. Drainage Review: Review the drainage design report for conformance to the Zoning Bylaw, DEP's
Stormwater Management Policy and standard engineering practice.Written comments will be included in
the engineering review report.
3. Environmental Review: Provide a general review the Notice of Intent application and Wetland Replications plan
for proposed development. Written comments will be included in the engineering review report.
4. Project Management: Provide a preliminary review of the plan submission for the purpose of
establishing a detailed budget with upset limits for engineering services for the scope of services
contained herein.Plan,monitor and coordinate the review efforts.
Services Not Included
The following additional services are not provided in this scope of work:
1. Review of traffic studies or data. No traffic information was provided.
2. Review of architectural plans.
3. Geotechnical review.
4. Culvert design or analysis.
5. Review of mechanical design.
6. Construction inspection.
7. Attendance at public meetings.
Should services be required in these areas,or areas not previously described,the ENGINEER will prepare a
proposal or amendment,that contains the Scope of Services,Compensation, and Schedule to complete the
additional services.
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TOWN OF NORTH ANDOVER PLANNING BOARD
ENGINEERING REVIEW OF SITE PLAN
FOR CONFORMANCE WITH THE
TOWN OF NORTH ANDOVER ZONING BYLAW
Site Plan Title: Willow Street--Map 25,Parcel 4 VHB No,: 06716,98
Site Plan Location: Willow Street
Applicant: Dr.Sudarshan Chatterjee.55 South Bedford Street,North Andover,MA
Applicant's Engineer: CAQ Engineering Associates,Inc.,236 Pleasant Street,Methuen,MA
Plan Date: September 24,2004 Review Date: 12-16.04
Revised November 8,2004
The plan was reviewed for conformance to the 1972 Town of North Andover Zoning Bylaw(last amended
December 2002),the North Andover Wetlands Protection Regulations(NAWPR)and standard engineering
practice. The Applicant has submitted the following information for VHB's review:
• Technical Supplement to Site Plan Application Notice of Intent dated September 27,2004
• Site Development Plans dated September 24,2004 and Revised November 8,2004
• Wetland Replication Plan dated November 16,2004
The following comments note non-conformance with specific sections of the Zoning Bylaw,NAWPR and
questions/comments on the proposed design and.VHB's recommendationstsuggestions.
Section 4.1—Ristrict Use Regulations
4A25 Although the application for Site flan Special Permit indicates that the proposed site is
in a General Business zone,it appears that,by comparing the Site Plan and the Town of
North Andover Zoning Map,the site is actually in a Residential District 6 zone. The
Applicant should provide sufficient information(i.e.updated zoning map,more
accurate locus map,addition of zoning division lines to the site plans)to indicate what
zone the site is in. The proposed office building would not be permitted in a
Residential District 6 zone.
Section 8.3--Site Plan Review
8.3.5.e.ii VHB suggests using a different line type to depict the property lines.
8.3.5.e.iv -It appears that 25'and 50'Wetland Buffer Zone lines are shown,however they are not
clearly labeled;
-The Applicant should make it clear on the plans that the entire site is within the 100'
Buffer Zone to Bordering Vegetated Wetland;
-Are there any easements relative to the existing drainage ditch and replication area that
would affect the development on the proposed site?
8.3.5.e.v Contours at 2' intervals are not provided on the plan. Furthermore,there appears to be
a limited number of spot grades within the construction area. The Applicant should
verify that the contours accurately reflect the topography of the site,
8.3.5.e.vii See drainage comment below.
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8.3,5.e.xiii A driveway is proposed,however it is not clear if any curb is proposed. A driveway
detail should be provided that identifies the materials and dimensions proposed.
8.3.5.e,xv -There appears to be a.slight discrepancy between the plan and planting schedule
regarding the number of proposed trees/shrubs;
-Are there any existing trees on the site that are larger that 12"diameter than can be
saved'? Are there any that need to be removed? These should be indicated on the plan;
-Materials are not specified on the plans;it is unclear what areas are asphalt,concrete,
loam and seed or other. The Applicant should label all necessary areas.
8.3.5,e.xvi -It is unclear whether the 8'chain link fence is proposed all the way around the
dumpster or only on one side. This section specifies that the outdoor refuse storage
area be fully enclosed;
-The fence should be shown on the Layout and Utilities Plan;
-A gate should be proposed to access the dumpster area. A detail of this gate should be
added to the plans.
8.3.5.e.xvii Light fixtures are proposed,however a detailed lighting plan was not included in this
submission.
8.3.5.e.xviii See drainage comments below.
8.3.5.e.xix A traffic impact study was not included in this submission.
8.3.5.e.xx A profile of the proposed sewer line was not provided. VHJ3 also requests a detail for
the connection of the proposed sewer line to the existing sewer line under Willow
Street.
8.3.5.e.xii A fiscal impact study was not included in this submission.
8.3.5.e.xiii A community impact analysis was not included in this submission.
General Comments
1. The Applicant should verify that all information provided in the Application,Plans and any
Technical Supplements is consistent. (For example,the plans indicate that the Proposed
Compensatory Wetland area is 1207 SF,however WPA Form 3 section C.6 indicates that an area
of 1130 SF is being replaced.)
2. The Locus Plan on the cover sheet is difficult to read,the Applicant should consider making the
plan clearer.
3. The proposed retaining wall label refers to S-2,however the Retaining Wall detail is on sheet S-4.
4. It is not clear whether curb is proposed at the edge of parking lot. The Applicant should clarify by
labeling us Proposed Curb or Edge of Pavement.
5. The Applicant should verify the existing sewer line information. The sewer manhole(SMH)with
a rim elevation of 98.3' is within 15 feet of it spot grade indicating an elevation of 102.64'.
6. The Applicant should add a Wheelchair Ramp detail.
7. The Applicant should add a Sidewalk detail(VHB assumes hatched areas on north and south ends
of the proposed building are sidewalk).
S. A Curb Installation detail should be added if curb is in fact being proposed.
9. It is unclear what the ingress/egress lines are indicating, The Applicant should clarify.
10. What is the 8'x20'steel plate for'? The Applicant should clarify.
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11. Note that the front building setback dimension for the General Business zone is 25',not 20'. The
Applicant should correct the plan.
12. If the Applicant is proposing curb at the driveway entrance,the Paved'Water Way should be
moved further past the end of the proposed curb,or curb transition pieces should be proposed on
the plans,
13. All water and sewer pipe sizes and lengths should be labeled on the plans.
14. All water connections and gates should be labeled on the plans.
15. Section 23.2.2 of the Massachusetts Architectural Access Board(MAAB)regulations states that j
"one in every eight accessible spaces,but not less than one,shall be van accessible". The
Applicant should verify that a van accessible space is provided and should ensure that the
dimensions of the space meet the requirements of MAA.B.
16. The Site Location appears to be indicated inaccurately on the soils map provided in the NOI
application. Although it appears that the correct site is the same soil group as the one described in
the report,VHB suggests modifying the soils map to accurately indicate the proposed site.
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17. The Applicant should verify that standing water against the proposed retaining wall will not affect
the structural integrity of the wall.
Drainage Comments
. The System Design Overview section of the NOI Technical Supplement states that a Drainage
Swale,Detention Basin and a Constructed Wetland are used to mitigate impacts,however only a
vegetated wet pond with a sediment forebay,as defined by the DEP Stormwater Management
Handbook,is used.
2. Where does water flow once it leaves the driveway? What direction is Willow Street sloping?
Does Willow Street have a normal crown?
3. Does the runoff from the proposed driveway flow to the existing drainage system on Willow
Street? If so,the Applicant should verify that the existing drainage system on Willow Street has
enough capacity to accommodate the added flow.
4. Upon review of the plan,it appears that the Proposed Compensatory Wetland is actually only 600
SF in size,not 1207 SF as indicated on the plans.
S. It is unclear how the Applicant calculated the 600 SF of tilled wetland. 'rho Applicant should
clearly indicate this area on the plan.
G. The Applicant should clearly label the wetland limit lines.
7. Do the flags labeled with"C"delineate the wetland associated with the existing drainage ditch'? If
so,what is the delineation on the opposite side of the ditch? The Applicant should clarify,
especially in the area of the proposed driveway,what areas are considered wetlands.
8. Has a culvert analysis been done for the proposed box culvert at the driveway? Will the capacity
of the existing drainage ditch be affected by the proposed culvert?
9. The Applicant is proposing a Precast Concrete Box Culvert in an existing drainage ditch in order
to access the site. VHB offers the following comments;
• The construction detail provided should be more detailed. The Applicant should indicate
existing and proposed ground elevations,water,sewer and other utility crossings. The
Applicant should explain the 8'x20'steel plate.
• The detail should identify the proposed material that will be used for the bedding of the
culvert and the backfill.
• As vehicles will traverse the culvert,it should be designed to accommodate HS-20 loading.
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+ Will guard rail be required to protect errant vehicles from entering the ditch'?
• It appears that this proposed culvert will be located within the roadway layout and presumably
on Town property. The proposed culvert design should be review by the Town Engineer and
the Department of Public Works. Future maintenance and liability will be the responsibility of
the Town.
10. The Concrete Outlet Control Structure detail does not indicate the length of the 12"RCP or its
slope.
11. Length and size of proposed drainage pipes should be shown on the Layout and Utilities Plan.
12. The Applicant should provide capacity calculations to demonstrate that the 12"RCP outlet pipe is
adequately sized.
13. An emergency spillway has not been provided for the Wet Pond,as required by the DEP
Stormwater Management Handbook. The emergency spillway's bottom elevation should be higher
than the top of the galvanized steel grating of the outlet control structure.
14. The Applicant should also provide calculations to demonstrate that the emergency spillway is sized
to take the entire 100-yr storm(assuming that the outlet structure completely fails).
15. The Wet Pond Design section of the DEP Stormwater Management Handbook calls for a minimum
10' wide maintenance access to the outlet structure without crossing the emergency spillway.
16. The invert of the 12"RCP pipe is indicated as 98.75',however a proposed 100'contour is shown
at the end of the pipe, The Applicant should verify if the pipe needs to be lengthened.
17. It appears that the proposed grades at the bottom of the proposed wet pond are lower than some of
the existing spot grades near the site. Have any test pits been taken to verify ground water
elevation,infiltration rates,etc...? If the proposed wet pond will contain standing water,the
Iydrocad model must take this into account.
18. A detail of the proposed wet pond should be provided,including a cross-section.
19, A detail of the proposed Rip-Rap areas should be provided in the plans, Does water run directly
off the pavement to the sediment forebay? The Applicant should verify that the proposed rip-rap
stones are adequate to prevent erosion.
20. The sediment forcbay appears to be too small. DEP Stormwater Management Handbook calls for
0.1 inch over the impervious area of the proposed catchment area(in this case: 0,939AC x 0,lin=
0.0393AC,in= 145CF). It appears the Applicant has provided less than 50 CF.
21. Pre-and Post-development total areas are inconsistent. There is a difference of 0.63 AC,or over
2700 SF. The Applicant should verify.
22. The Fxisting and Proposed Watershed plans are not to scale and do not indicate the critical paths
used for calculating the times of concentration(Tc). They also do not indicate any contours. V1IB
was not able to properly review the catchment areas or Vs.
23, The Applicant used a time span of 5-20 hours in the Hydrocad model. Typically,a model should
have a time span that goes from zero discharge to peak discharge,and back to zero discharge
(beginning and ending of storm event). VHB suggests using a minimum time span of 0-24 hours.
24. The labels 1S and 2S appear to have been mixed up in the Proposed Watershed plan.
25. Areas 1S and 2S do not appear to have been delineated correctly. The Applicant should review
these areas,and take into consideration Comment no.26.
26. Although there are a limited number of spot grades on the site,it appears that an existing high
point may exist across the proposed site. If this is the case,2 design points,one at the northern tip
of the site(proposed wet pond area)and one at the southern tip(downstream of existing drainage
ditch)are required. The Applicant should verify the topography of the site and make any
necessary adjustments to the Hydrocad model.
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27. In the Applicant's Stormwater Management Program,the Drainage Analysis section compares
total runoff from the site. The correct procedure would be to compare runoff at separate design
points. Post-development runoff for all storms,2-yr, 10-yr and 100-yr would have to match or be
lower than pre-development flows. Assuming that the Applicant's Hydrocad model and
Catchment areas are correct,the Applicant would show a net decrease in runoff at the northern tip
of the site(outlet of the wet pond),however there would be a net increase in runoff at the southern
end(edge of proposed driveway). VHB suggests taking into account all previous comments to
modify the catchment areas,times of concentration,detention basin(wet pond)dimensions and re-
run calculations.
DEP Stormwater Management Standards
Standard#1
1. It is unclear how much reveal(if any)is provided by the wall or possible proposed curb. All
runoff from the parking lot must be contained and flow to the detention basin for treatment before
reaching the wetland. Please clarify.
2. The above comment also applies to the driveway runoff, The Applicant must justify that the runoff
is treated before reaching a wetland.
Standard#2
1. See Drainage comment 27.
Standard#3
1. It is unclear how the Applicant calculated the volume to be recharged. The total impervious area
of the site is 18,687 SF and the recharge rate for C soils is 0.1 in,for a volume of 156 CF.
2. 'rho Applicant states that the Constructed Wetland will provide infiltration to meet Standard 0.
However,as questioned in Drainage Comment 17,there is the possibility of high ground water
levels which would prohibit infiltration. Test pits should be taken to verify the ground water
elevation.
Standard#4
1. The Applicant is claiming an 809f,TSS removal rate.The detention basinlwet pond doesn't have a
forebay.Without a forebay,it can't be claimed as a wet pond(70%only as a sediment trap
(25%),As of now,the sediment trap and the pavement sweeping equal a 32.5%TSS removal rate.
Standard#9
1. The Applicant should identify the stormwater management system's owner and the party or parties
responsible for operation and maintenance,as stated in Standard#9.
Environmental Comment
Site Plans
In addition to the comments provided under Section 8.3—Site Plan Review,according to North Andover
Wetlands Protection Regulations,the site plans should also provide the following:
I. No existing conditions plan has been provided by the Applicant.
2, The entire property with property boundaries as well as abutting properties should be shown on
plans.
3. Existing features such as ledge,trees,paths,utilities,and drainage are not shown of the plans.
4. There are no sequencing details or species listed for the replication area.
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5. It appears that the entire project lies within the 100-foot buffer zone to Bordering Vegetated
Wetlands.This should be stated on plans.
Notice of Intent Narrative
1. The Narrative states that the Applicant is filing the Notice of Intent due to filling wetlands on the
site, However,the Applicant must rile anyway due to work in the 100-font buffer zone.
2. The Applicant states that the site does not lie within the FEMA 100-year floodplain zone.
Documentation should be provided to verify this claim,Based on the Flood Insurance Rate Maps
for the Town of North Andover,Community Panel Number 250098 0006C,dated June 1993,it
does appear that the site is very close to or within the 100-year flood zone.
3. The Applicant states that this project is a limited project.Documentation as to the limited project
status of the project under the Wetlands Protection Act,and its implementing regulations 310
CMR 10.53 3.(c)should be provided,
4. According to the North Andover Wetlands Protection Regulations,the Applicant should show
clearly that proposed work in the buffer zone will not adversely impact the said interests of the
Wetlands Protection Act or the interests identified in Section 178.1 of the North Andover
Wetlands Bylaw,
5, The Applicant should state the am+.m of work proposed within the 25-foot No Disturb Zone and
the 50-foot No Build Zone,
6. The Applicant states that the wetland replication area is at a 2:1 ratio.On the WPA Form 3,
Section C,the area of Bordering.Vegetated Wetland altered is 600 square feet.The replacement
area is 1,130 square feet.On the site plans,the replacement area is listed as 1,207 square feet,
There needs to be uniformity in the amount of area replaced.
7. Would the fill area at the drainage ditch be considered Bank impacts rather than BVW impacts?
The Applicant should verify.
8. The North Andover Wetlands Protection Regulations Section 5.1 states that the Commission may
require an alternatives analysis for any work within the 25-foot No Disturb Zone(the entrance
roadway).
Drainage Calculations
1. The claim of using constructed wetlands as any TSS removal should be disallowed.It should only
be used as a replicated wetland.
2. Infiltration cannot occur within the constructed wetland.The mitigation area(wetland replication)
cannot be used for water quality improvements.
Operations and Maintennnce Plan
. The Operations and Maintenance Plan does not provide enough detail for the future site manager.
1 VHB recommends that the proposed pavement sweeping be done more than once per year.
3. There are no provisions for recording maintenance events.
4, The Plan doesn't specify any ongoing monitoring of replicated wetland. According to the North
Andover Wetlands Protection Regulations,Section 6.1,the replacement area should be monitored
2 times per year.
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S. The site appears to be maximized and has been designed to fit within the surrounding wetland area.
As a result,the site is `tight'and there is little room for error. VHB recommends that the
Applicant retain a surveyor to layout the proposed haybale/silt fence to ensure that these are
constructed as shown on the design plans. Further,VHB recoErunends that the Town verify the
location of the haybale/silt fence prior to construction.
It is rccommended that the Applicant provide WRITTEN RESPONSE S to the issues and comments
contained herein.
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Reviewed by: „` - r ' Date:
Darryl Gallant
Civil Engineer—Highway and Municipal
Reviewed by: Date:
Susan McArthur
Environmental Group
Reviewed by: �' �' "� J Date:
Timothy B:McIntosh,P.E.
Project Manager—Highway and Municipal
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