5223-11-13-m719-ltr
One Financial Plaza | 1350 Main Street, Suite 1012, Springfield, MA 01103 | 413.241.6920 | www.MMInc.com
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May 7, 2019
Mr. Douglas McDonald, Stormwater Manager
City of Northampton
Department of Public Works
125 Locust Street
Northampton, MA 01060
RE: CED Northampton Solar
Stormwater Permit Conditions
Burts Pit Road
Northampton, Massachusetts
MMI #5223-11-13
Dear Doug:
On behalf of CED Northampton Solar, LLC (CED), we are providing the following responses and attached
revised documents as stipulated in the conditions of approval of the Stormwater Permit application that
was submitted on November 26, 2018, for the CED Northampton Solar facility on Burts Pit Road.
Our responses to the permit conditions are as follows:
Standard Permit Conditions
C1. All clearing, grading, drainage, construction, and development shall be conducted in strict
accordance with the following plans and information submitted with the application and as
amended by any conditions attached to this permit:
a. Site Plans for CED Northampton Solar, LLC, Burts Pit Road, Northampton, MA,
Sheets 01, LD, IN, EX-1, EX-2, EX-3, EX-4, LA-1, LA-3, LA-4, SE-I, SE-2,
SD-1 and SD-2 Dated 11/26/2018, Sheet LA-2 Dated 12/13/2018, Stamped by
Michael R. Gagnon, P.E., Milone & Macbroom.
b. Stormwater Report for CED Northampton Solar, LLC, Burts Pit Road,
Northampton, MA, Dated 11/26/2018, Stamped by Michael R. Gagnon, P.E.,
Milone & Macbroom.
c. Post-Construction Stormwater Management Operation and Maintenance Plan for
CED Northampton Solar, LLC, Burts Pit Road, Northampton, MA, Dated
11/26/2018, Prepared by Milone & Macbroom.
d. Stormwater Pollution Prevention Plan (SWPPP) for CED Northampton Solar, LLC,
Burts Pit Road, Northampton, MA, Dated 11/26/2018, Stamped by Michael
R. Gagnon, P.E., Milone & Macbroom
R1. Noted. All work will be conducted in accordance with the documents as included with the
stormwater permit submission on November 26, 2018, and the attached May 7, 2019
construction drawing set.
Mr. Douglas McDonald | Page 2
May 7, 2019
C2. The Northampton Department of Public Works (DPW) or its authorized representative shall be
provided access to the property to conduct inspections before, during, and after construction
activities as necessary. The applicant shall arrange with the DPW to schedule the following
inspections: Initial Inspection, Erosion Control Inspection, Bury Inspection, and Final Inspection.
The DPW may also conduct random inspections to ensure effective control of erosion and
sedimentation during all phases of construction.
R2. DPW will be able to access the site during normal working hours. Otherwise, during
nonworking hours, the gate is locked at the Ryan Road entrance. CED will coordinate
inspections with DPW as requested.
C3. The applicant shall retain a Project Engineer (the design engineer or another professional engineer
of record in the Commonwealth of Massachusetts) to document the construction of the proposed
stormwater system and site development during all phases of the project. The Project Engineer
through routine inspections and surveys shall check elevations, inverts, grading, layout,
impervious areas and other critical aspects of the stormwater system as they are being
constructed during all phases of the project. All proposed changes to the approved stormwater
facilities and site development shall be documented by the Project Engineer and submitted to the
DPW for review and approval by the DPW prior to construction. At the completion of the work,
including construction of all stormwater management facilities and landscaping, the applicant
shall submit to the DPW as-built plans stamped by a professional engineer of record in the
Commonwealth of Massachusetts and a statement from a professional engineer of record in the
Commonwealth of Massachusetts certifying that the materials and construction of the stormwater
management system was constructed in accordance with the approved plans and functions as
designed. The as-built plans must include surveyed information documenting the as-built
elevations, inverts, grading, layout, impervious areas and other critical aspects of the stormwater
management system.
R3. CED intends to retain a project engineer for the duration of construction to observe
construction of the facility including stormwater management controls as shown on the
project drawings. As-built drawings will be submitted at the completion of the project as
requested.
C4. Annual Reports that are stamped by a Registered Professional Engineer documenting the actions
completed as required by the Operation, Maintenance and Inspection Agreement shall be
submitted to the Northampton Department of Public Works by October 1st of each year (see
Specific Condition I below).
R4. Noted. CED will provide annual reports stamped by a registered professional engineer as
requested.
C5. If construction of the proposed stormwater system has not started within five years of the issue
date of this permit, then the permit will expire and a new permit will be required. Construction is
defined as clearing, grading, excavation, filling, and installation of drainage structures on the lots
specified in this permit.
R5. Noted.
Mr. Douglas McDonald | Page 3
May 7, 2019
Specific Permit Conditions
C1. Prior to start of construction and issuance of any Building Permit, the applicant shall record an
executed Stormwater Operation, Maintenance, and Inspection Agreement that is binding on all
subsequent owners of land served by the private stormwater management facility by recording it
in the land records of the Registry of Deeds. The maintenance schedule and responsibility for
maintenance of all components of the proposed stormwater management system must be
adequately specified in Attachment A to this Agreement. The proposed Schedule for Inspection
and Maintenance that was included in the Post-Construction Stormwater Management
Operations and Maintenance Plan can be used for Attachment A but must be revised to include
additional specification of ongoing inspection and maintenance throughout the site of erosion
and concentration of flows in rills and gullies that may result from flow of stormwater off the solar
panels. The DPW can provide additional guidance on required revisions to the maintenance
schedule. The final agreement shall be approved by the Northampton DPW and signed by the
owner and the Mayor of Northampton. The final agreement shall be recorded at the Registry of
Deeds at the owner's expense. Section 281-8 of the Northampton Stormwater Management
Ordinance provides additional guidance for the requirements of this agreement.
R1. An executed Stormwater Operation, Maintenance, and Inspection Agreement will be
recorded at the Registry of Deeds by CED prior to the issuance of a building permit. The
agreement is revised to include ongoing inspection and maintenance along the drip edge
of the solar array panel rows should any erosion or rills develop.
C2. This project will be required to submit one or more Notice of lntent (NOI) to the U.S. EPA for
coverage under the NPDES Stormwater Construction General Permit. A copy of the final NOI and
final Stormwater Pollution Prevention Plan (SWPPP) shall be submitted to the Northampton DPW
for approval prior to the start of construction and prior to issuance of a building permit for each
phase of construction.
R2. An EPA NOI was filed with the EPA for coverage under the NPDES Stormwater Construction
General Permit as attached for stump removal and grubbing of the site. The final SWPPP is
also enclosed as referenced in the NOI. Both the NOI and SWPPP are also applicable to the
construction of the facility and will be revised as necessary to include pertinent contact
information for the site contractor for the construction of the facility.
C3. The proposed hydrologic calculations included in the drainage report are not completely
consistent with the proposed development plans. A portion of Subcatchment Pr-04 will not reach
the proposed Stormwater Basin but the calculations specify it this way. A revised Plan Sheet LA-2
was submitted on 12/13/2018 that clarified the grading to show flows from the portion of
Subcatchment Pr-04 with stormwater panels graded to flow to the basin. Prior to construction,
revised pre and post construction calculations should be submitted to eliminate any inconsistency
between the plans and the calculations.
R3. The hydrologic analysis is revised to show the southwesterly area of the site broken out as a
separate subcatchment area Pr-05, which drains toward the westerly wetland area. The
previous analysis inadvertently showed the westerly area of subcatchment Pr-04 draining
Mr. Douglas McDonald | Page 4
May 7, 2019
toward the basin. As shown in Table 4-1 of the revised analysis report, peak flows at
Analysis Point 1 are still reduced for developed conditions for all storm events.
C4. The access drive to the site runs across an adjacent property (Assessors# 035-029-001). A portion
of this drive will be paved as part of a separate development for 1010 Ryan Road which received a
separate Stormwater Management Permit on 8/9/2018. A portion of the drive is not proposed to
be improved and is in poor condition. If this roadway will be paved in the future, an amendment
of either this Stormwater Management Permit or the Stormwater Management Permit for 1010
Ryan Road will be required to complete this work.
R4. Noted. The section of access drive east of the adjacent site development will not be paved
as part of this project.
C5. The Stormwater Report includes test pit logs that indicate groundwater near the proposed
Stormwater Management Basin at elevation 272.1 at MM-6 and 273.7 at MM-7. The proposed
Stormwater Management Basin has been designed with a bottom elevation at 271.75. Prior to the
start of construction, additional test pits should be completed in the location of the proposed
Stormwater Management Basin to confirm the elevation of groundwater in this location. The
results of the test pits must be submitted to the DPW for review. If groundwater is found to be
higher than the proposed bottom elevation of the basin, the elevation of the bottom of the basin
must be revised to be above groundwater and grading of the surrounding area revised as
necessary.
R5. Two test pits were conducted in the area of the stormwater management basin on April 30,
2019. As shown on the attached test pit report, groundwater was observed at 2.4 feet and
2.0 feet below the ground surface for test pits 1 and 2, respectively. Thus, the observed
groundwater elevation of 270± is below the bottom elevation of the basin at 271.75. We
expect that this nearly represents the season high groundwater elevation given the time of
year and the amount of rainfall of 7.3" as recorded at Northampton Airport for the month
of April 2019.
C6. Construction plans and specifications shall be submitted to the DPW for approval prior to
issuance of a building permit and prior to the start of construction. Sheet SE-2 should be revised
to the match the proposed grading shown on revised Sheet LA-2.
R6. May 7, 2019 construction plans are attached.
C7. The stormwater management basin, swales and non-piped components of the proposed
stormwater system shall be constructed as proposed and stabilized prior to receiving drainage
flows from the proposed development.
R7. The stormwater management basin and associated stormwater controls will be constructed
prior to slope grading of the site as outlined in the construction sequence in the
stormwater report.
C8. The proposed stormwater management system is designed to mitigate peak stormwater flows. If,
after construction of the proposed system, the system is found to increase stormwater flows or
Mr. Douglas McDonald | Page 5
May 7, 2019
pollutants in these flows to adjacent properties, roadways and stormwater systems, the owner
shall redesign and reconstruct the drainage system to prevent any increased stormwater flows or
pollutants in these flows to adjacent properties, roadways and stormwater systems.
R8. Noted.
Please do not hesitate to contact me should you have any further comments or questions.
Very truly yours,
MILONE & MACBROOM, INC.
Michael R. Gagnon, PE
Senior Project Specialist, Civil Engineering
cc: Gavin Nagle, CED Northampton Solar, LLC
Enclosures
5223-11-13-m619-ltr.docx