The Ridge Stormwater Compliance Status 08172011
Memorandum
To: Carolyn Misch, Office of Planning and Development
From: Doug McDonald, Stomwater Management Coordinator
Date: August 17, 2011
Re: Status of The Ridge Stormwater Management Permit Compliance
On October 28, 2004, a Stormwater Management Permit for the project was issued by the Department of Public Works (DPW). On November 13, 2009 the DPW issued a letter to Todd Cellura summarizing
three issues related to Stormwater Permit Compliance for the project (see attached). The DPW has received the following submissions relating to the Stormwater Management Permit:
Letter and Drainage Calculations, Colonial Village Definitive Subdivision, Stormwater Permit Revisions, dated July 7, 2010, prepared by Brain Darnold, E.I.T., The Berkshire Design Group,
Inc.
Letter, Draft Stormwater Management Operation, Maintenance, and Inspection Agreement, and Drainage Calculations, dated January 14, 2011 and January 20, 2011, prepared by Brain Darnold,
E.I.T., The Berkshire Design Group, Inc.
The DPW also received a preliminary Record Plan (1 sheet), dated December 2, 2010, by The Berkshire Design Group, Inc and the DPW commented separately in a Memo issued January 24, 2011.
Since that time the DPW has met and communicated through email with individuals from Berkshire Design Group and Todd Cellura to resolve the stated issues.
In addition to the comments in the January 24, 2011 Memo from the DPW, below is a description (in italics) of the status of the 3 issues described in the November 9, 2010 letter from
the DPW:
A Stormwater Operation, Maintenance, and Inspection Agreement must be finalized, approved by the DPW, executed, and recorded at the Registry of Deeds. This requirement was described
in Specific Permit Condition 1 of the approved Stormwater Management Permit.
A draft Stormwater Operation, Maintenance, and Inspection Agreement was submitted to the DPW on 1/14/2011. The DPW is unable to approve the draft agreement until documentation is provided
by a Registered Professional Engineer that the infiltration basins and all components of the drainage system have been constructed and is functioning in conformance with approved plans
and
specifications. If changes to the approved stormwater system are proposed and approved, then the Stormwater Facilities Maintenance Schedule must be consistent with the structures that
have been approved and constructed.
The plans and drainage calculations approved by the Stormwater Management Permit for this project include the construction of the roadway and sidewalk, but do not include the build out
of the lots. The build out of the lots is considered part of a common plan of development and therefore must be included as part of the existing Stormwater Management Permit for the
site. The owner(s) of the site must make a formal request to the DPW to amend the existing Stormwater Management Permit to include the existing and expected build out of the lots. Stormwater
management measures must be proposed by the owner(s) to bring the site into compliance with the Northampton Stormwater Management Ordinance. Revised plans and drainage calculations that
include all existing and expected build-out of the lots and proposed stormwater management mitigation measures must be submitted to the DPW for approval.
The Berkshire Design Group, Inc submitted Stormwater Permit Revisions to the DPW on July 7, 2010 that included revised drainage calculations including build out of the lots. The drainage
calculations included some changes based on observed conditions of the infiltration basins, but assumed the basins and the drainage system had been constructed according to approved
plans and specifications. Again, the DPW cannot complete a review of these documents until documentation is provided that the drainage system was constructed and is functioning in conformance
with approved plans and specifications.
Detention Basin #2 has been observed by DPW personnel with standing water for prolonged periods of time (over 72 hours) indicating that the basin is not functioning as an infiltration
basin as specified in the approved plans and specifications. An inspection must be conducted of Basins 1 and 2 by a Registered Professional Engineer to confirm the dewatering rate and
overall function according to the approved design of each basin. If the basins are found to not be functioning according to the approved design then maintenance must be completed to
bring these basins into proper working order. If maintenance does not correct the problem(s), the owner must propose additional measures to bring the site into compliance with the Northampton
Stormwater Ordinance and demonstrate these measures in revised drainage calculations for the site.
On January 20, 2011 the Berkshire Design Group, Inc submitted a description of observations of the two infiltration basins and revised drainage calculations assuming the basins functioned
differently than the approved design or did not function at all. Again, the DPW cannot complete a review of these documents until it is confirmed what was constructed on a Record Plan
and other documents. Additional information must be submitted by a Registered Professional Engineer including but not limited to the following: the constructed elevations of all components
of the two basins, forebays, outlet structures, and related pipes and structures; the constructed volume of the two basins and two forebays; and an assessment of the actual functioning
of the basins as infiltration basins given that ledge underlies the south basin and the north basin has been observed holding water after an extended period of time. As stated above,
if the basins are not functioning according to the approved design and maintenance does not bring the basins into proper working order, the owner must propose additional measures to
bring the site into compliance with the Northampton Stormwater Management Ordinance. Additional detailed comments regarding the basins and other components of the drainage system are
provided in the Memo dated January 24, 2011.