HomeMy WebLinkAboutCorrespondence - 102 PETERS STREET 1/30/2012 andover 1 East River Place
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January 30, 2012
North Andover Conservation Commission 'E. Da a W 1
Town Offices
1600 Osgood Street
North Andover, MA 01845
FEB 3 20'12
RE: DEP File No: 242-1539 NORTH ANDOVER
102 Peters Street PLANNING DEPARIMENT
North Andover, MA
Ladies and Gentlemen:
We are in receipt of review comments made by your Consultant, Ms. Lisa Eggleston, P.E., for the project
captioned above,contained in her letter to the North Andover Planning Board and Conservation Commission
dated January 23,2012. Ten copies of the revised plans, sheets 1, 2 and 3 of 3, revision dated January 25,2012
and 2 copies of the Supplement to the Stormwater report, dated January 25, 2012 are attached. The plans and
calculations were revised and our responses to the review comments are as noted below:
Comment: 1. The proposed project would increase the impervious cover on the site from approximately 11
percent to about 43 percent, however it does not appear that any serious consideration was given to the use of
Low Impact Development(LID) techniques as is required by the DEP Stormwater Standards. In particular, the
use of bioretention and✓or pervious pavement would be appropriate and potentially more effective alternatives to
the best management practices(BMPs)proposed.
Response: Contrary to the stated comment, low impact techniques were considered and have been implemented.
The intent of low impact is to decentralize stormwater management systems and use several decentralized systems
close to the impervious surfaces and dispersed through out the project site or at the lot level. The project is a small
one with no direct discharge to a wetland. For this particular project, the area to work with is very small, but the
proposed systems are dispersed on the lot. In addition, the roof drywell system will infiltrate much more volume
than required by regulation and its Surface outlet will then discharge to lawn areas consistent with "disconnecting"
impervious area as encourage by LID. The use of the bioretention noted above requires pretreatment which is
typically provided by lawn/grass filter strips of lengths not compatible with those available on this small lot.
Pervious pavement was deemed not practicable due to the small footprint of development and the onerous
maintenance requirements.
Comment:2. The submittal packet includes 4ydroCAD 8.0 analyses and a tabular summary of the peak flow
rates under pre-and post-development conditions for the 1,2, 10 and 100 y design storms,indicating that the
rate of runoff from the site would not be increased as a result of the project.As outlined below,I do have a
number of concerns about the hydrologic model on which this is based.In addition though,the applicant has
not addressed changes in the volume of runoff'that would result from the project, as is required by both the DEP
Stormwater Standards and the Wetlands Bylaw. Based on the calculations submitted,the proposed
(kywel1✓infiltration pit located in the existing driveway would overflow in all of the design storm conditions, with
the excess flow draining directly onto Peters Street. The total volume of flow discharged to Peters Street in each
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storm would be approximately double what it is under existing conditions, while the volume of runoff toward the
wetland area would be about half of the present volume.
Response: As noted above, the peak rates of flow are not increased in compliance with DEP and North Andover
stormwater standards. In addition,the project is a small one. A comparison of the net increase in runoff volume,
pre developed vs. post developed conditions, for the entire property, for the 100-year event, will reveal a net
increase of only 0.01 ac-ft, or 435.6 cubic feet, a trivial amount. Additionally, the terminal drywell is intended to
slowly release the outflow from the parking lot detention system, not to eliminate it. Small, typical rainfall events
will likely infiltrate and result in no outflow so any infiltration that may occur would be an additional benefit. In
any event,the discharge is mitigated as required and will discharge to the gutter of Peters Street,thence to an
existing catch basin about 70 feet downhill from the site, in Andover and complies with the stormwater
management standards for peak rate mitigation.
Comment:3. No credit should be taken for infiltration or storage volume within groundwater. While the HSG B
soils at the site are suitable for infiltration, it appears from the limited soils data provided that all three proposed
subsurface infiltration structures would be in or near the groundwater table during high groundwater
conditions. The DEP Handbook calls for a minimum of two feet of separation from infiltration structures to the
estimated seasonal high groundwater elevation (ESHGW). This is particularly important where the infiltration
system is also being used to meet the 80 percent TSS removal requirement, as is the case for the
detention/infiltration system beneath the proposed parking area. Based on the data from Test Pit #2, the
ESHGW would be approximately commensurate with the invert of the detention/infiltration system,providing
no separation or dead storage during high groundwater conditions.
Response: Based on the soil testing done at the site, the system will be at or above the seasonal high groundwater
table. The system may not always be 2 feet above the ESH WT, but it will be for significant portions of the average
year. In addition, since the parking lot and drainage system is well outside of the nearby wetland buffer zone and
does not discharge directly to that wetland or directly to any other, the discharge will not result in an untreated
discharge to or the erosion of a wetland.
Comment 4. Neither of the two test pits conducted on the site were within the locations proposed for infiltration
and, in the case of the overflow drywell/infiltration pit, the closest test pit is 75 ft away and four feet higher in
elevation. Site specific testing within each proposed infiltration location will be needed prior to system
installation to verify soil suitability and ensure adequate depth to groundwater and/or bedrock.
Response: Again, the lot is small and not a lot of testing was necessary, nor is additional testing required. The
intent of the soil testing is to determine the estimated seasonal high water table, depth to ledge if any, and to verify
the soil texture of the soil as delineated by the NRCS USDA soil map. For this site, the USDA Web Soil Survey
shows the soil to be a Charleton fine sandy loam series. Field soil testing done determined the soil to be a loamy
sand (less silt)rather than a sandy loam. The soil in the vicinity of the roof drywell(see test pit 1 data)was a single
grain sand and gravel while the soil near the house (test pit 2) was less gravelly but also a loamy sand. Assuming
an HSG "B" Rawls Rate for the soil deposit, as was done for the calculations, is conservative. A higher sand rate
could have been used based on field testing.
Note that the test pits were taken as close to the proposed locations as possible. The proposed parking lot system
will fall within the footprint of the existing house so testing at that location was not practicable due to the presence
of the existing structure. The foundation hole will be backfilled with clean sand and gravel. The roof drywell
location, toward the rear of the lot, is within an area currently wooded with a few large trees and we didn't want to
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clear them away for the purposes of conducting a soil test. Also note that the symbol on the plan indicates the
approximate center of the pit. The revised plan shows the approximate limits of the actual testing hole.
Comment S. The proposed project calls for the infiltration BMPs to attenuate large storm flows (10 yr and
larger), therefore the DEP standards require that a mounding analysis be performed since the separation to
seasonal high groundwater is less than 4 feet. In the event that a calculated mound reaches the infiltration
structure, additional storage volume would be lost.
Response: The pipe detention system does not rely on infiltration to attenuate the peak rates of runoff. The
attached HydroCAD model has been modified to eliminate the exfiltration and the stone storage below elevation
189 to demonstrate this. In addition, because the terminal drywell is intended to be a slow release outlet, the
exfiltration for this structure was also eliminated. There is no effect on the pre developed vs. post developed rates
of runoff with this modification. Any infiltration that occurs will be an added benefit.
The roof drywell system does rely on the storage and slow release, via infiltration, of the structure to attenuate peak
rates of flow, but the volume provided greatly exceeds that needed for recharge. This drywell is fitted with a catch
basin grate intended to discharge to the permeable surface of the lot in the event of surcharge. In addition, there are
to be bypass outlets on the downspouts in the event of surcharge which again discharge to lawn areas on the lot in
keeping with the LID technique of"disconnecting" the roof from the site drainage system. Note that the time to
drain calculation assumed that the drywell system was full and drained at a Rawls Rate of 0.52 in/hr resulting in a
time to drain of 44 hours which is less than the 72 hours required by the regulation. Using the Rawls Rate of 1.02
in/hr for sandy loam (per NCRS soil map), the time to drain is roughly half that at 22.5 hours. Using a Rawls rate
of 2.41 in/hr of a loamy sand (per field testing)results in a time to drain of about 10 hours.
Comment 6. It is not clear why the overflow drywelUinfiltration pit is modeled with an exfiltration rate of 0.17
inches/hr, rather than the 0.52 inches/hr used elsewhere. Are the soils different in that location, or is the
reduced infiltration rate based on the fact that the drywell is located beneath the existing driveway, therefore the
soils may be compacted?
Response: The overflow/outlet drywell is intended to be an outlet. Any infiltration from this structure would be an
added benefit because exfiltration is not relied upon to attenuate flow rates. The rate of 0.17 in/hr was used as that
is the minimum rate per the MADEP stormwater regulations for recharge calculations and because no testing was
done near it. Testing here was not practicable as it is in the existing paved driveway and because infiltration here is
not needed. As noted above, exfiltration was deleted from the analysis of this structure in the attached HydroCAD
calculations. The exfiltration at the pipe detention was also eliminated in the attached calculations as noted above.
The exfiltration rate for the roof drywell system used in the HydroCAD calculations was 1.02 in/hr consistent with
the Rawls rate for a sandy loam and the as mapped Carleton series. The time to drain the roof drywell was
conservatively calculated using the 0.52 in/hr Rawls rate for HSG B loarn soil.
Comment 7. The rate of flow from the proposed detention/infiltration system in the HydroCAD analysis appears
to be driven more by the modeled tailwater conditions in the downstream drywell (with its limited exfiltration
capacity) than by the outlet orifice. I recommend running the analysis without the tailwater conditions to better
assess the effectiveness of the detention system.
Response: The calculations are accurate as the elevation of the outlet drywell (Rim= 188.8)which is below the
outlet orifice elevation of 189.0. The HydroCAD model was run using the Dynamic Storage Indication method.
This method performs the same calculations as the static Storage-Indication method, except that the stage-
discharge and storage-indication curves are re-evaluated at each time step,based on the current elevation of any
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downstream nodes. This allows the routing to respond to ongoing tailwater changes, rather than assuming static
tailwater conditions.
Comment 8. In accordance with the DEP handbook, exfiltration from the three infiltration structures should be
modeled over bottom area only,not the wetter!area.
Response: Exfiltration for the parking lot pipe detention system and the outlet drywell has been deleted. The
exfiltration for the roof drywell was calculated in the model over the horizontal area not the wetted area. The time
to drain for the roof drywell was calculated over the bottom area using the Rawls rate of 0.52 in/hr in accordance
with the stormwater standards.
Comment 9. It appears that post-development subcatchment "Developed 2"in the HydroCAD model should be
routed to Pond PI (the catchbasin),rather than directly to the subsurface detention system.
Response: Noted and revised.
Comment 10. The pavement area in post-development subcatchment "Developed 2"should have a CN of 98,not
95.
Response: Noted and revised. The revision to CN=98 has no impact on peak rates but the storage elevation in the
pipe detention system for the 100-year storm is now 190.52 (was 190.44).
Comment 11. The stone depth in the proposed detention/infrltration system is modeled as being 92.25 ft high, it
should be 4.25 ft.
Response: The height should have been 4.25 as noted, however there is no impact on the calculations as the depth
of water storage for the 100-year storm was 190.44 (now at 190.52-see above) which is below the top of stone
elevation of 192.50. As was noted previously, the storage below elevation 189 (new stone height= 3.5 ft)and the
exfiltration from the detention system has been eliminated to demonstrate that the design does not rely on
exfiltration to attenuate the peak rates of flow.
Comment 12. Consideration should be given to raising the outlet invert from the subsurface detention system to
increase the dead storage volume in the system and enhance infiltration.
Response: We did consider this, however; raising the system by 2 feet would create an unnecessarily steep parking
lot.
Comment 13. The overflow drywell/infiltration pit closest to Peters St is modeled as having a rim elevation of
188.8,but the plan shows a rim elevation of 189.9 and the detail gives a rim elevation of 188.9.
Response: The rim is intended to be at 188.8. The detail and drawings were revised to reflect this.
Comment 14.As indicated above, the proposed treatment train (deep sump catchbasin followed by infiltration)
does not meet the 80 percent TSS removal requirement because there is not adequate separation to groundwater.
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In addition, however, there is a high rate of failure of subsurface infiltration structures where there is only
minimal pretreatment such as is proposed for this project. Consideration should be given to either augmenting
the solids removal provided before infiltration, or implementing a more aggressive sweeping program to reduce
the solids loading to the drainage system.
Response: Based on the soil testing done at the site, the system will be at or above the seasonal high groundwater
table. The system may not always be 2 feet above the ESH WT, but it will be for significant portions of the average
year. The system is outside of the buffer zone of any nearby wetland and does not discharge directly to one.
However, the applicant is not averse to implementing a sweeping program to augment suspended solids removal.
The operation and maintenance plan and the long term maintenance plan have been revised to require sweeping
every 60 days, beginning in the spring and going through the summer and fall, for a minimum of 4 times per year.
Comment 15. The drywell details shown on Sheets 2 and 3 should be labeled as to which system they correspond
to.
Response: The roof drywell detail on sheet 2 of 3 has been labeled "Precast Concrete Drywell-Roof' and the
terminal outlet drywell detail on sheet 3 of 3 has been labeled"Outlet Drywell Detail".
Comment 16. The ESHGW elevation should be shown on each infiltration system detail.
Response: The estimated seasonal high water ground water elevations have been added to the details,as requested.
Comment 17. The depth ofstone under the detention/infiltration system should be shown on the design details.
Response: The depth of stone has been added to the details, as requested.
Comment 18. The outlet pipe from the proposed drain manhole is shown as being 8 inches on the DMH detail,
and 10 inches on the drywell detail.
Response: The 10 inches refers to the precast opening in the drywell structure. The detail was revised to indicate
the 8"PVC pipe at invert 186.58, on sheet 3 of 3, for clarification.
Comment 19. Inspection ports are needed on the detention/infiltration system, and inspection of that system
included in the O&M Plan.
Response: Clean outs were shown on the system detail on sheet 2 of 3. Cleanout details have been added to sheet
3 of 3.
Comment 20. The O&M Plan should include an O&M schedule and log form(for long-term maintenance tasks)
as required per the DEP regulations. I generally find it useful to include a simple sketch plan showing the
locations of the BMPs to be maintained
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Response: An O&M schedule and log form were included in the stornnvater report. Copies are included in the
attached stormwater report supplement. A site plan sketch has been included with the log, as suggested.
Comment 21. The Long Term Pollution Prevention Plan calls for snow to be stored just off the edge of
pavement, hence most of the snowmelt will bypass the stormwater treatment train.
Response: The project has no direct discharge to a nearby wetland. The snow banks along the easterly and
southerly edge of the lot will melt and discharge onto the parking lot. Any snow on the west side of the lot would
melt onto lawn and landscaped areas and be filtered prior to reaching any pavement or drainage system.
Comment 22. The proposed project ►rill not entail disturbance of more than one acre, thus it is not subject to
coverage under the EPA Construction General Permit. The Construction Period Pollution Prevention and
Erosion and Sediment Control Plan should identify proposed stockpile locations and identify measures to
protect the proposed detention/infiltration area during construction.
Response: Agreed. The project is small and not subject to an NPDES Permit. Stockpiles, if needed, will be located
depending upon the construction sequence and aren't necessary to show on this small scale project as it is likely
that soil will be removed from the site daily. Note 5 has been added to the Construction Period Pollution
Prevention and Erosion and Sediment Control stating that any stockpiles shall be protected to avoid sedimentation
of off site properties and the protection shall consist of staked haybale or secured silt fence barrier around the
perimeter or by surface protection with mulch or tarps. Note 6 has been added to require the use of a catch basin
silt sack or equivalent, appropriately modified to catch influent from the vane drain, to minimize sedimentation of
the catch basin and pipe/detention system.
Should you have any comments or require any additional information concerning the above, feel free to contact us.
Sincerely,
ANDOVER CONSULTANTS,INC.
<��1-C ----
James S. Fairweather I1, P.E.
Project Engineer
Enclosures
cc
MADEP-NERD
Planning Board
Dundee Properties
102 Peters Street
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February 6, 2012
North Andover Planning Board L9 @ I a a \VJ R."
Town Offices
L
1600 Osgood Street
North Andover, MA 01845 FED "7 ?012
NORTH ANDOVER
PANG
RE: Site Plan Special Permit F NM DEP ARTMENT
102 Peters Street
North Andover,MA
Members of the Board:
We are in receipt of review comments made by your consultant, Hancock Associates., for the
project captioned above. The comments were made in a letter to the North Andover Planning Board
dated January 25, 2012. Two full sized copies of the revised plans, sheets 1, 2 and 3 of 3,revision
dated February 2, 2012 and five copies of the plan reduced to 11" x 17" are attached for your
review. The plans were revised per the review comments as noted below:
Comment 1:Section 8.1 - Off'Street Parking: The parking calculations, as provided, do not
adhere to the off street parking bylaw for Offices and Medical Offices and Research Facilities.
The minimum spaces required are as follows:
Use Minimum Spaces Required
Offices I space per 300 square feet of GFA.
Medical Offices and Research facilities 3 Spaces per 1000 square feet GFA plus one space
per employee.
Response: The parking calculations depicted on the plan complies with Section 8.1.4 a) of the
September 13, 2010 Zoning Bylaw.
Comment 2. Section. 8.14- One (1) handicapped parking space shall be provided for every twenty
(20)parking spaces provided on site. The handicapped space shall be 12'x 20'and be indicated
by a ground mounted sign and pavement markings. The handicapped parking space does not
conform to the dimensional requirements set,forth in this section.
Response: The accessible space and aisle dimensions comply with Section 8.1.4 b) of the
September 13,2010 Zoning Bylaw. This section requires compliance with the Rules and
Regulations of the Architectural Access Board (AAB), 512 CMR. The space is 9 feet wide with an
adjacent aisle of 9 feet which exceeds the required 8 foot wide space and 8 foot aisle required by the
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AAB for a van accessible space, The length is 18 feet,the same as the standard spaces,also per the AAB regulations 521
CMR 23.
Comment 3. Section 8.5.c-All site plans shall be prepared by a certified architect, landscape
architect, and/or a civil engineer registered in the Commonwealth of Massachusetts.All
landscape plans shall be prepared by a certified landscape architect registered in the
Commonwealth of Massachusetts.All building elevations shall be prepared by a certified
architect registered in the Commonwealth of Massachusetts.All plans shall be signed and
stamped, The 11 'W7"Front Elevation prepared for Dundee Properties, LLC by Maclaren
Associate's, LLC, dated 0712112011 does not contain the requisite signature and stamp
Response: The architect has provided a stamped and signed copy.
4. Section 8.5.e.i-NORTH ARROWILOCA TION MAP. A north arrow and a location map
showing surrounding roadways and land uses adjacent to the site (I"=1500). Location Map
should show at least one intersection of two existing Town roadways. The 'Locus Plan'contained
within the Proposed Site Plan, dated 1211312011 is at a scale of I"=800'and does not adhere to
the requisite scale of I"=1500'setforth in this section.
Response: The locus scale of I"= 800 feet is larger than the required I"= 1500 feet making the
locus easier to read which is more appropriate for the small project proposed.
5. Section 8.5.e. v- TOPOGRAPHY. The present and proposed topography of the site, utilizing
two foot (2) contour intervals. The contours shall extend at least fifty (50)feet beyond the site
boundaries by estimation of the professional submitting the plan. The present and proposed
topography do not extendfifty(50)feet beyond the boundaries of the site as required by this
section.
Response:. By our estimation, the topography of offsite areas is appropriately accounted for this
small project.
6. Section 8.5.e. vi-ZONING INFORMATION. All applicable Zoning Bylaw. information shall
be provided regarding the site's development This information shall be placed in a table and list
all parking, setbacks,percent of lot coverage,floor-area-ratio, number of dwelling units, total
amount of square feet, size of signs and any other applicable zoning information necessary for
the proper review of the site plan by the Town Planner and Planning Board. It is not cleat-from
the submitted plans whether signs are proposed and if they comply with the Zoning Bylaw
Section 6.0-Signs and Outdoor Lighting Regulations.
Response: There are no specific tenant(s) for the project at this time. Signs will be provided per the
tenant's requirements. Signs will be in compliance with the zoning bylaw and the appropriate
permits filed for when the sign design has been determined.
7.Section 8.5.e.xii-LOCATION OF WALLS/SIGNS:Identification of the location,height and materials to be used for all
retaining walls and signs located on the site.Signs will be reviewed using the guidelines set forth in Section 6.7(H)of the
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Zoning Bylaw.It is not clear from the submitted plans whether signs are proposed and if they comply with the Zoning
Bylaw Section 6.0-Signs and Outdoor Lighting Regulations.
Response: See response above.
8. Section 8.5.e.xiv- OUTDOOR STORAGEIDISPLA YAREAS. Identification of the location
and type of outdoor storage and display areas on the site. It is not clear from the submitted plans
whether outdoor storage or display areas are proposed.
Response: There will be no outdoor storage or display areas for this business office/medical office.
9. Section 8.5.e.xv-LANDSCAPING PLAN. Identification of the location and landscape
schedule of all perimeter and interior landscaping, including but not limited to proposed paving
materials for walkways,fences, stonewalls and all planting materials to be placed on the site. In
addition, all existing trees over 12 inches DBH, to be saved or removed shall be shown on the site
plan. Any landscaping required by the Town Bylaws shall be indicated on the site plan in tabular
form showing the amount required and the amount provided. It is unclear from the submitted
plans whether there are existing trees over 12" in diameter and if they are to be saved or
removed. The "Plant List"located on the Conceptual Landscape Plan does not contain the
amount of plantings required by the Town Bylaws.
Response: There are no existing trees on the lot that will be retained. The landscaping plan,
attached, has been revised to reflect this. In addition, new plantings will be provided consisting of
native species to replace the invasive species removed. The additional plantings at the rear of the
lot are being provided at the request of the Conservation Commission. The landscaping plan lists
the quantity of each plant.
10. Section 8.5.e.xvi-REFUSEAREAS:Identification of the location of each outdoor refuse
storage area, including the method of storage and screening.All refuse areas must be fully
enclosed. The method of refuse storage and area screening are not detailed on the submitted
plans.Additionally, the location of the dumpster pad may make refuse removal problematic
during normal business hours depending on the type of'container proposed. The Applicant
should demonstrate that an SU-30 vehicle can access the dumpster at this location.
Response: The dumpster and pad have been removed. Because the project is small, a dumpster will
not be needed.
11. Section 8.5.e.xvii-LIGHTING FACILITIES. Identification of the proposed illumination,
indicating the direction and the degree of illumination offered by the proposed lighting facilities,
including an example of the light fixture to be used. It is unclear from the submitted plans
whether any illumination is proposed and if the type, direction and degree of illumination
conform to the guidelines set forth in Section 6.0-Signs and Outdoor Lighting Regulations of
the Zoning Bylaw.
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Response: No lighting for the parking lot is proposed. The architect's final plans will include
details of any lighting located on the exterior of the building. A cut sheet of a typical wall mounted
light proposed for use is attached for your review.
12. Section 8. 5. e.xxi- UTILITIES:All utilities, including water line locations, sewer line
locations and profiles, and storm drainage systems;It is the opinion of this office that a sewer
line profile, when considering the proposed length, should not be required. However, details
identifying all inverts, cleanouts and manholes are not adequate for construction as shown on
the submitted plan set and should be updated accordingly.
Response: The sewer connection inverts and size information has been added to the plan.
13. Section 6.a.iiid-Electric, telephone, cable t. v., and other such lines and equipment must be
placed underground. Underground utilities have not been specified or their proposed locations
shown on the submitted plan set.
Response: The underground electric, telephone and cable utilities will be installed below grade and
are now shown on the plan.
14. Hancock understands Lisa Eggleston is reviewing the design of the stormwater management
system. We defer to Al's. Eggleston's regarding this matter.
No response needed.
15. Section 8.5.e.xix- TRAFFIC IMPACT STUD Y.• Identification of existing traffic levels, along
with the expected traffic impacts to occur based upon the proposed project. Projects which access
state highways, a traffic impact study shall be filed with MEPA concurrently with the Planning
Board review.A copy of the MEPA study shall be fled with the application to the Planning
Board. The Applicant should report to the Board regarding the applicability of this section and
the status offilingfor the Highway Access Permit with MassDOT. Hancock understands
MassDOT design guidelines call for 30 foot radius soundings on state controlled roadways. The
plans call for 15-foot radii.
Response: The project does not need an Access Permit from Mass Highway as Peters Street is a
County Layout under local control, nor is a filing with MEPA required. The driveway entrance/exit
design complies with section 81.5. c) of the zoning bylaw.
16. The Traffic Memorandum from DJK states that the site distance should be enhanced through
the control of vegetation within a triangle defined by a point on the proposed access drive 14.5
feet back from the travel way and extending 360 feet westerly down Peters Street (Haverhill Street
in Andover). It is unclear from the plan as to whether this triangle crosses private properties and
therefore not within the control of the Applicant. DJK should expand upon the sight distance
discussion addressing this issue, whether clearing easements are proposed and in the absence of
permission to keep this area clear, the resulting sight distance and its adequacy.
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Response: The proposed plantings on the lot were adjusted to be outside of the described sight
triangles. The sight lines are depicted on the attached sketch. There is no sight line obstruction on
the abutting private lot looking east. Minor trimming of existing vegetation in the right of way
looking west is necessary.
17. The Traffic Memorandum does not speak to the site drive proximity to the signalized
intersection of Peters Street and Turnpike Street and the interaction of vehicle movements with
vehicles queued at the intersection. The Peters Street eastbound roadway configuration features
two lanes with a dedicated left turn lane, a rumble strip and striped transition area. The site plans
do not depict these traffic control features. DJK should expand the memorandum commenting on
the safety of all turning movements into and out of the site relative to these issues.
Response: Dermot J. Kelly, PE, PTOE has provided the following response to this comment:
"During the morning peak hour, the proposed project will genet-ate between 4 to 5 vehicle-trips per
hour (vph) with 3 to 4 vph entering the site depending on what portion of the project is medical
office compared to general commercial office space. Additionally, the entering traffic will be split
with some traffic entering from the right with the remaining trc?f
,fic entering from the left.
Consequently, it can be assumed that there will be only I or 2 vph entering the site as a westbound
left turn. If'a westbound left turning vehicle has to wait to enter the site due to a queue of
eastbound vehicles backing up from the Route 114 traffic signal, this will not create a significant
westbound queue which would in turn cause traffic to back tip onto Route 114. Similarly, during
the evening peak hour, the proposed project will generate between 4 to 7 vph with only I vph
entering the site. Again, a single vehicle would not cause traffic to back up onto Route 114. "
18. The proposed building is shown less than one foot from an excising sewer easement. It is
unclear from the plans if the intent is far the building to be at 15 feet from the property line or if
the dimension shown is labeling the easement width. Hancock is concerned that building footings
would encroach into the easement.
Response: The building will be constructed outside of the easement.
19. Sewer connection for a commercial property should be made via a manhole structure to allow
North Andover Sewer Department access and sampling. Installation of a manhole at this location
given the proposed building location will be difficult. Hancock recommends the building size be
decreased by two feet to accommodate this concern as well as that outlined in the comment above.
Additionally, where the easement is a Town of North Andover easement, the Sewer Department
should provide comment regarding adequate protection of the sewer line.
Response: We called Mr. Timothy Willett, DPW Operations Manager of the North Andover DPW
water and Sewer Department to determine if a manhole would be required. Mr. Willett stated that a
sampling manhole is not required.
20. Shrubs and two trees are proposed within the Sewer Easement. The Applicant's Landscape
Architect should confirm these plantings would have no adverse impact to the sewer line or
relocate the plantings.
102 Peters Street
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Response: The landscaping plan has been revised to move some of the plants away from the sewer.
The sewer depth is approximately 7 feet deep along the side of the lot. The remaining Inkberry
shrub screening line, within the easement and along the easterly property line, won't affect the
sewer. A revised landscaping plan dated February 1, 2012 is attached for your review.
21 The architectural plans depict a hip roof. The site plan shows a single roof leader exiting the
rear of the building in the center. The Applicant's Architect and Engineer should confirm how
roof runoff would get to this pipe.
Response: The plan has been revised to depict perimeter drains to pick up the downspouts which
drain to the drywell.
Should you have any comments or require any additional information concerning the above, feel free
to contact us.
Sincerely,
ANDOVER CONSULTANTS, INC.
mesS. Fairweather 11, P.E.
Project Engineer
Enclosures
cc
Hancock Associates
Conservation Commission
Dundee Properties
102 Peters Street
Page 6 of 6
'I East River Place
andover
Metht.ien, Massachusetts 01844
consultants Tel. (978) 687--3828
inc. Fax (978) 686-5100
www.ar)dovel'COnSLIltarits.corii
February 21, 2012
North Andover Planning Board
Town Offices
1600 Osgood Street
North Andover, MA 01845
RE: Site Plan Review Special Permit
102 Peters Street
North Andover,MA
Members of the Board:
We are in receipt of review comments made by Gene Willis, PE, Director of Engineering, for the
project captioned above. His comments were made in a letter to the North Andover Planning Board
dated February 7, 2012. We also met with Mr. Willis, at his office, on February 14, 2012 to review
the project in conjunction with his review comments. We have summarized his comments along
with our responses below:
Comment 1: The increased volume of storinwaterflowing onto Peters St. (per Eggleston
Environmental comment#2) is unacceptable to DPW. The overflow structure proposed in NW
comer of lot should be relocated to the south and away from the Peters St. right-of-way so as to
result in zero change in stormwater flow to Peters St.
Response: The plans were revised to relocate the outlet away from Peters Street as noted. A
preliminary copy of the revised plans was hand delivered to Gene on February 15, 2012 and an
updated copy emailed to him on February 16, 2012. In a telephone conversation with me today,
Gene requested that the drywell that was removed on the preliminary plans sent to him be restored
but placed just downstream of the detention outlet and upstream of the new stone trench. The plans
will be revised to reflect his request. Also note, the post-developed peak rates of runoff from the site
were and still are attenuated to rates less than or equal to the pre-developed condition in compliance
with the state and local stormwater regulations.
Comment 2: Currently traffic travelling east on Rte 133 cues across the frontage of the lot during
almost every red cycle of the traffic light at.Rte 114. This should be addressed.
Response: Gene has requested that traffic engineer respond to this comment in writing for his
review.
Comment 3: There should be a confirmatory easement with meets and bounds, given to the Town
of North Andover for the existing sewer easement shown on the plan. This sewer easement
should be recorded at the registry of deeds.
Response: A copy of the existing deed and a copy of the recorded plan depicting the existing
Planning Board page I ?fi3
Vil Engineers e Land Surveyors o Land Planners
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consu"ants
easement were delivered to Gene on February 15, 2012. The deed is recorded in the Northern Essex
Registry of Deeds in Book 1087, Page 346.
Comment 4.- The building footing should be a minimum 121 off the 10"sewer main shown on the
plan.
Response: The building and footing will be constructed outside of the easement.
Comment 5: The sewer set-vice connection (per Hancock Associates comment# 19) should be via
a sewer manhole.
Response: At our meeting we informed Gene that Tim Willet of the North Andover Water and
Sewer Department told me, via a telephone call on February 1, 2012, that a sewer manhole
connection was not required for this project. Mr. Willis agreed.
Comment 6.- There should be no trees planted in the sewer easement.
Response: Trees will not be planted in the sewer easement. Gene indicated that shrubs would be
ok. The inkberry screening shrub line will remain as originally shown.
Comment 7. The abandoned existing water service must be terminated at the main.
Response: The plans were revised to note that the existing water service will be abandoned at the
main.
Comment 8: The discrepancy between the location of the town line shown on the plan (PIN
FND.) and the granite bound with hub and scored line shown on the plan (ROAD STONE)
should be resolved.
Response: The monuments were located by an instrument survey. The noted road stone is not on
the Street Right-of-Way but as shown on the plan. Road stones are not necessarily accurately
placed on street lines or town lines which is the case for this stone.
Comment 9: The hub and scored line in the above granite bound should be survey located and
shown on plans.
Response: The bound and monuments depicted on the plans were all located by instrument survey
and are as depicted on the plan. Bound monuments that were located already in place are denoted
as "(FND.)". Other property monuments set to define the property comers are denoted as"(SET)".
Comment 10: The drill hole in the granite monument labeled TOWN CORNER should be survey
located and shown on plans.
Response: The Town Corner was also located by an instrument survey. At our meeting with Gene,
we discussed that the monument was found but that the granite monument is tipped (not plumb).
We told Gene that we would create a plan to show the Town Comer on the State Plane Coordinate
System with its latitude and longitude noted. We told gene that because the monument was tipped,
the survey crew located the four comers of the bound where they enter the ground. A plan with the
Town Corner on the State Plane Coordinate System and a detail of the stone marker as found was
prepared and emailed to Gene on February 21, 2012.
Comment 11: The test pit soil logs should be displayed on sheet I of 1. Response: The plans were
revised to include the soil testing data on sheet I of 3, as requested.
Planning Board page 2 of 3
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12. The existing di-ainage in Petei-s St. should be shown.
The plans were revised to depict the location of the existing catch basin just over the Town Line
with Andover. Also, in the telephone conversation with Gene,today, he informed me that there is
no existing drainage within the section of Peters Street in front of the project.
Should you have any comments or require any additional information concerning the above, feel free
to contact us.
Sincerely,
ANDOVER CONSULTANTS, INC.
James S. Fairweather 11, P.E.
Project Engineer
Enclosures
CC
Gene Willis, PE
Dundee Properties
Planning Board page 3 of 3
'I East River Place
andover Meth(,ieri, MassachUsetts 01844
N consultants Tel, (978) 687-3828
Fax (978) 686-5100
www.aridover,consi.iltar)ts.co i,i
...............
February 28, 2012
North Andover Planning Board
Town Offices
1600 Osgood Street
North Andover, MA 01845 HE 29
VAR
I 'I i
PEA : Site Plan Special Permit P NORTHANDO LANNNG:DE2)ARTMENT
102 Peters Street
North Andover, MA
Members of the Board:
We are in receipt of a second peer review made by your consultant, Hancock Associates., for the
project captioned above. The comments were made in a letter to the North Andover Planning Board
dated February 22, 2012. Many of their initial comments made in their first review have been
addressed. Comments 4, 5, 9, 10, 11, 16, 18, 20 and 21 of the second review require additional
response. Our responses are summarized below:
Comment 4: The Location map still does not conform to the required scale of I"=1500'. The
intent of the locus scale is to seethe project site within the context of the surrounding area. The
Board should decide if given the location, they need to see more of the surrounding area within
the locus map. The Applicant should request a waiverfirom this submission requirement.
Response: We believe that the intent of the Locus has been satisfied. However; on behalf of the
Applicant, Dundee Properties, we respectfully request that the Board waive the scale requirement of
1"=1500' and accept the submitted locus scale of I"=800'.
Comment 5: While the plan does not conform to the requirements for the extent of topography
shown, Hancock believes that suitable information is provided to complete our review, the
Applicant should request a waiver from this submission requirement.
Response: As previously noted, we believe that the offsite topography for this small project as
appropriately accounted for. However, on behalf of the Applicant, we respectfully request that the
Board waive the requirement of depicting offsite topography for 50 feet beyond the project
boundary.
Comment 9: The plan entitled Conceptual Landscape Plan by Huntress Associates, Inc. dated
August 4, 2011, revised February 1, 2012 depicts a region of existing trees to remain at the
southern property line. The plan does not speak to the required identification of existing trees 12
102 Peters Street-February 27, 2012 revision
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inches in diameter or larger. The plan also does not include a tabular list containing the amount
of lyyyjMdplantings.
Response: The landscaping plan is being revised to coordinate with the comments from the DPW
to remove trees from the sewer easement and to account for the proposed stone trench in the
northwest comer of the lot. There are no existing trees of 12" diameter or larger that will remain at
the southern end of the lot. Per Section 8.4 of the North Andover Zoning Bylaw, "Screening and
Landscaping Requirements for Off-Street Commercial and Industrial Districts", the revised plan
conforms to this section as there is no quantity of required plantings for a project this small. The
revised Landscaping Plan will be forwarded when completed.
Comment 10:Hancock is in agreement that the size of the project may not require a dumpster.
However, refuse generated from the proposed business or medical office will require some sort of
storage and the plan does not address its type, location or required screening.
Response: The trash will be stored inside the janitor's closet internal to the building until trash day
at which time it will be brought to the curb for pickup.
Comment 11: The plans still do not depict the direction and degree of illumination proposed.
Response: Site lighting will consist of wall packs mounted on the structure as previously stated. A
copy of the proposed fixture was also previously submitted. Additional information concerning the
lighting is included in the attached email prepared by the project architect, Maclaren Associates,
LLC, dated February 28, 2012.
Comment 16: The "sketch"that was provide is not to scale and does not depict the full extension
of the sight line on Peters Street. The DJK Memorandum was not updated to specifically address
any action to enhance sight distance. The landscape plan identifies two (2) red maple trees
located on both sides of the entrance. From the "sketch"provided, the sight lines appear to
conflict with both of these plantings. Hancock recommends that the full sight distance lines be
shown on all plans and clearly identify any measures that will be taken to enhance sight distance
on the subject property and abutting parcels.
Response: The sight line issues discussed in the DJK Memorandum were intended as project
recommendations to coordinate with proposed site landscaping. It is not necessary to depict the full
extent of the sight lines as they are very conservative for this stop controlled parking lot and
because the intent of coordination has been met. See the attached Landscaping Plan which depicts
the sight lines referenced. A note has also been added to the site plan noting to remove vegetation
within the right-of-way that may interfere with exiting vehicles looking west.
Comment 18:It remains unclear from the details provided how the building structure below
grade would not encroach into the sewer easement. Standard construction details have footings
extending beyond the face of the structure.
Response: The building wall is located about 10 inches from the sewer easement. See the attached
email from Maclaren Associates, LLC addressing the extension of the footing beyond the east wall.
Comment 20:Hancock is not in receipt of comments from the Applicant's Landscape Architect
attesting that the plantings in the sewer easement will not adversely impact the sewer line.
102 Peters Street-February 27, 2012 revision
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Response: At a meeting with Mr. Gene Willis, PE, Director of Engineering of the North Andover
Public Works Department, Mr. Willis requested that all trees be removed from the easement. The
trees have been removed from the easement. When asked if shrubs were o.k., Mr. Willis stated that
shrubs were o.k.
Comment 21: The plans do not clearly identify the perimeter drain, there are no elevations or
slopes identified and the size and type of material have not been specified.
Response: The perimeter roof drain information has been added to the plans. The roof drains are 6-
inch diameter, schedule 40 PVC pipes with a slope of 0.5% (0.005).
In addition to the Hancock letter, we are also in receipt of a second comment letter from Gene
Willis, Director of Engineering for the North Andover DPW to the Board and dated February 24,
2012. Mr. Willis had two comments and our responses to his second set of comments are noted
below:
Comment 1: The overflow structure proposed in the NW corner of the lot was not relocated to the
south and away from Peters Street right-of way but replaced by a stone swale. Over time, the
voids in the stone will fill with sediment resulting in zero storage volume. The originally
proposed drywell should be included in the final design.
Response: The drywell has been restored to the project as requested and is depicted on the revised
Site Plans, revision dated February 27, 2012.
Comment 2: The hydraulic modeling of the site, as well as the subsequent report, has not been
reviewed by DPW.
Response: Noted. The project's stormwater components are being review by Eggleston
Environmental. A copy of the revised stormwater calculations and report will be submitted to DPW
for their records.
Finally, we have also received a second set of comments from Lisa Eggleston, PE of Eggleston
Environmental detailed in a letter to the Planning Board and Conservation Commission dated
February 24, 2012. We offer the following in response:
Comment ].- The design revisions call for moving the overflow drywell approximately 35 feet
back on the site (away from Peters Street) and incorporating an overflow swale with a stone
trench to further enhance infiltration and direct the overflow onto the shoulder of Peters Street.
This should mitigate any increases in runoff volume generated by the development and prevent
the direct discharge of flow onto Peters Street. It will also provide some degree of treatment far
snowmelt off of the west side of the proposed parking area.
Response: The drywell has been relocated away from Peters Street as was suggested in Ms.
Eggleston's February 7, 2012 email to Judy Tymon and Jennifer Hughes, and per comment #1 in
Mr. Willis's comment letter to the Board dated February 7, 2012. The stone trench and sod berm
were added to increase the surface storage on the lot and provide for additional avenues of
infiltration to provide the additional treatment and mitigation noted above.
102 Peters Street-February 27, 2012 revision
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Comment 2: The Stormwater Report should be revised to reflect the modifications to the outlet
design. Calculated storage in the outlet drywell and overflow trench should be limited to that
which is above the ESHGW level in that location, so that the modeled discharges are
representative of "worst case" conditions. Based on the existing grades on the site and the
ESHGW elevation in the two test pits, it appears that this would be somewhere around elevation
188.0.
Response: As has been stated before, the drywell and stone trench are additional features provided
to enhance potential infiltration over and above that provided by the perforated pipe detention
system. The infiltrative capacity of the perforated pipe detention bedding, drywell and stone trench
are not needed to mitigate peak flows. Note that the attached calculations do not model exfiltration
for the parking lot drainage system components. The post-developed peak rate is mitigated by
storage in the pipes and the rates depicted in the pre vs, post developed runoff rate comparison do
represent worst case scenarios.
The available storage in the perforated pipe bedding is approximately 150 cf. The storage within
the drywell, above elevation 186.5 (bottom of adjacent trench) is 22 cf, while the stone trench
provides void space of 120 cf. The surface storage detained behind the proposed sod berm is
approximately 24 cf. The total volume provided by the drywell, trench and surface storage is equal
to 166 cf which is more than the 150 cf required for WQV of the tributary parking lot.
Comment 3: During periods of seasonal high groundwater there will be no (lead storage in the
detention system beneath the parking lot, hence no water quality treatment via infiltration. It is
my understanding that the overflow trench has been designed to capture and infiltrate the water
quality volume, however calculations are needed to demonstrate this.
Response: See the above. The potential available water quality volume in the stone trench and
drywell area exceeds that required. Note that the peak rates are mitigated in compliance with the
state and local stormwater regulations and that there is no direct discharge to a wetland area.
Comment 4: The plans should show the perimeter drain proposed for the collection and
conveyance of roof runoff.
Response: The roof drain information has been added to the revised plan as suggested.
Comment 5: A design detail of the overflow swale/trench is needed. The side slopes of the swale
should be vegetated or otherwise stabilized. I have not seen the landscaping plan, but presume
that it may also need to be revised to show the swale.
Response: A detail has been added to sheet 3 of 3, as suggested. The stone trench is rectangular at
24 feet long by 5 feet wide and 30 inches deep. The swale is 5 feet wide with 2 to I side slopes.
The Landscaping Plan is being revised to coordinate with the swale and stone trench.
Comment 6: 1 suggest rewording item #3 in the O&M Plan to say that the catchbasins should
be cleaned when the sediment level is within two feet of the outlet pipe; this is easier to measure
than the depth of sediment accumulated. The O&M Plan should also include maintenance of
the overflow swale/trench.
Response: The O&M plan has been revised to reflect cleaning required per the depth from invert,
102 Peters Street-February 27, 2012 revision
Page 4 of 5
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as suggested. Also, maintenance of the stone trench has been added to the checklist and the
inspection schedule.
We believe that, with the latest revisions, all the comments made by your consultants and the DPW
have been appropriately incorporated into the design and respectfully request that the project be
issued the necessary approvals and permits for construction. Should you have any comments or
require any additional information concerning the above, feel free to contact us.
Sincerely,
ANDOVER CONSULTANTS, INC.
James S. Fairweather 11, P.E.
Project Engineer
Enclosures
cc
Conservation Commission
Eggleston Environmental
Hancock Associates
MADEP-NERD
Dundee Properties
102 Peters Street-February 27, 2012 revision
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