THE COMMONWEALTH OF MASSACHUSETTS
WATER RESOURCES COMMISSION
for Determination of Applicability
the Interbasin Transfer Act
Chapter 21 Sections 8B-8D
Massachusetts Water Resources Authority
Upper Neponset Valley Relief Sewer Project
May 8, 2003
May 8, 2003,
the Massachusetts Water Resources
decided unanimously that the Interbasin Transfer Act does not apply to the
Upper Neponset Valley Relief Sewer project (UNVRS), as proposed by the Massachusetts
May 3, 2002,
the WRC received a request for
determination of applicability under the Interbasin Transfer Act (M.G.L.
Chapter 21 §§ 8B‑8D) from the MWRA for the Upper Neponset Valley Relief
Sewer project (UNVRS). This request was
submitted as part of the DEIR. This
project will address capacity issues in the MWRA sewer line which serves Newton, Brookline, the
West Roxbury section of Boston,
in the Charles River
basin. Wastewater from these communities is
transported for treatment at MWRA’s Deer Island
facility and discharged to the Massachusetts Coastal basin.
review of the information submitted by MWRA, the WRC
requested that additional information to fully evaluate this request be
provided in the FEIR for this project. This
was submitted in February 2003.
review focused only on possible increases in capacity designed to transport inflow
and infiltration flows over and above the existing rates of I/I from Newton, Brookline, and Dedham, as well as any
potential increases in capacity to accommodate potential increases in sanitary
flows from Dedham. The reasons for this are:
- Newton and Brookline receive all of
their water supply from the MWRA Water Supply System in the Chicopee and Nashua River basins. Because the source of the sanitary
wastewater does not originate in the basin where the “action to increase
over the present rate of interbasin transfer” is
occurring, sanitary flow from within these communities is not subject to
Interbasin Transfer Act review.
- Dedham receives a portion
of its water supply from sources located in the Charles River basin. These are considered local sources and
are subject to review under the Act.
- Boston (West Roxbury) also receives all
of its water supply from the MWRA Water Supply System. In addition, any increased capacity for
I/I flows from West Roxbury are not subject to review because
of the intratown exemption. West Roxbury is a neighborhood
located in the City of Boston. The Deer Island Treatment Plant is
located in Boston. Wastewater is discharged from this plant
to the Massachusetts Coastal basin.
Boston has land area in
Boston Harbor and Massachusetts
original Upper Neponset Valley Sewer (UNVS) was constructed between 1896 and
1902. It serves the communities of Brookline and Newton and portions of Dedham and Boston (West Roxbury). The UNVS is tributary to the MWRA’s Wellesley Extension Sewer (WES). In 1984, the MDC, MWRA’s
predecessor, conducted a study of the WES and found that the tributary UNVS was
1999, the MWRA began the MEPA process for the Upper Neponset Valley Relief
Sewer (UNVRS), to address capacity issues within the UNVS. The existing UNVS experiences wet weather
overflows into wetlands and brooks, which eventually reach the Charles River. Sections 529 through 526, which serve West Roxbury, Dedham, Brookline and Newton, are gravity fed
sewers. The slope of the gravity fed
sewer pipe segment determines its capacity.
The segments of the pipes are of different sizes and slopes. This causes “bottlenecks” in the flow and has
contributed to the overflow problems. The
MWRA is proposing to replace the existing Sections 529 through 526 of the UNVS
with a one pipe system that will be known as the VFW Interceptor. This will improve the efficiency of the
system, thus reducing overflow events. The
existing sections will be filled with concrete to prevent collapses. They will no longer be able to transport
wastewater flows. Section 530, which
serves portions of Brookline and Newton, will be replaced and brought
up to current design standards.
the capacity of the junction of Section 526 with the WES represents the “present
rate of interbasin transfer in a wastewater
conveyance system”, as defined by the regulations. The MWRA has stated that the capacity of this
juncture is 22.6 mgd.
According to the FEIR, the junction of the VFW interceptor with the WES
will be 20.56 mgd.
It is expected that flows within the system will increase, due to
increasing efficiency, however, the overall capacity
of the system (i.e. the “ability” to transfer wastewater) will decrease. In addition, the WES has sufficient capacity
to accept flows from the UNVRS.
the capacity of the junction of the UNVRS with the WES, as described in the
FEIR, is decreasing from 22.6 mgd to 20.56 mgd and because the WES has sufficient capacity to accept
all the flows from the UNVRS, the
Interbasin Transfer Act does not apply to the Upper Neponset Valley Relief Sewer project as proposed. If in the future, the design for this project
is modified or the capacity enlarged beyond what was stated in the EIR for this
project, further Interbasin Transfer Act review may be warranted.