Kollmorgen Letter 20120517Edward S. Huntley, P.E.
Director
May 17, 2012
Mr. Jay P. Viamari, P.E.
Project Manager
Tighe & Bond
53 Southampton Road
Westfield, MA 01085
ClTY OF NORTHAMPTON, MASSACHUSETTS
DEPARTMENT OF PUBLIC WORKS
125 Locust Street
Northampton, MA 01060
413-587-1570
Fax 413-587-1576
Re: Kollmorgen -Stormwater Permit -Remaining Compliance Issues
Dear Mr. Viamari:
The Northampton Department of Public Works (DPW) has received your April 16, 2012 letter and
attached Table l, Water Quality Volume Provided describing how the outstanding items for compliance
with the Stormwater Management Permit for the project will be corrected. The DPW has the following
comments:
Recharge Volume
The proposal to raise the grates for catch basins 17 and 18 is an acceptable solution to provide capacity
that meets minimum water quality volume for the project in compliance with Standard 3 of the
Massachusetts Stormwater Management Standards. In addition the DPW requests that during future
maintenance and reconstruction of the bioretention areas, the water quality volumes of these structures
be maintained in accordance with the "Actual Water Quality Volume" specified in Table 1, Water
Quality Volume Provided (rev. 04-2012) prepared by Tighe & Bond. For example, if the bioretention
areas require additional mulch or stone or full reconstruction including replacement of soil media and
plants, the reconstructed volume of each of the bioretention areas will be no less than the Actual Water
Quality Volume Provided in Table 1.
Erosion and Sediment Control
The site was inspected on September 22 and 23, 2011 by Jay Viamari, P.E., Tighe & Bond and John
Weatherwax, Kollmorgen and documented in 2011 Inspection and Maintenance Review. It was noted
that erosion repair and/or sediment removal was required in many of the swales and bioretention areas.
In the April 16, 2012 letter from Jay Viamari, PE, it was noted that "The contractor for the project is
planning to remove the sediment that has migrated into the bioretention areas." Sediment that has
migrated into the bioretention systems must be removed as soon as possible to maintain the function of
these systems and avoid costly reconstruction if they fail. The DPW requests written confirmation that
the maintenance work on the swales and bioretention areas has been completed.
Pg.1/2
The swales and bioretention areas have experienced numerous issues with erosion and ineffectiveness of
the wood mulch. Part of the problem may be that the original design called for grass swales which were
constructed with plantings and mulch instead of grass. The mulch that was installed may not be
appropriate for use in swales. The use of stone and further establishment of the vegetation will certainly
improve the problem, but erosion and sediment control in the swales and bioretention areas must
continue to be monitored and corrected in a timely way.
Record Plans and Next Steps
At the completion of work proposed to raise the catch basin grates, please submit final Record Plans for
DPW approval that include all changes made to the stormwater system that were undertaken to address
the issues described above. Record Plans must include a professional engineer stamp with signatures
and dates that are consistent with the latest revision dates on the record plans.
Please· notify Doug McDonald at the DPW (587-1582) regarding the construction schedule and if there
are questions.
cc. Charlene Pellegrino, VP, Kollmorgen Electro Optical
Andrew Crystal, LEED AP, Western Builders
John Weatherwax, Kollmorgen
Louis Hasbrook, Northampton Building Department
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