Proposed - Massachusetts Water Resources Authority

S. 131 Upper Neponset Valley Sewer System
Project Purpose and Benefits
Contributes to improved public health
Provides environmental benefits
Improves system operability and reliability
The Upper Neponset Valley Sewer is hydraulically deficient resulting in frequent community system back-ups and
interceptor overflows during wet weather to adjacent residential areas and water bodies in Brookline, Boston,
Newton, and Dedham. Construction of a new replacement interceptor will reduce chronic wastewater overflows
and surcharging during wet weather and improve service and water quality.
Project History and Background
The Upper Neponset Valley Sewer constructed between 1896 and 1902, extends approximately four miles through
West Roxbury and Newton, and receives wastewater from West Roxbury, Brookline, Newton, and a small portion
of Dedham. Based on the results of the 1994 Combined Sewer Overflow Master Plan, work on Section 530 in
Newton and West Roxbury has been added to this project because the hydraulic improvements are needed in this
section.
The 1984 Wellesley Extension Sewer Facilities Plan/Environmental Impact document estimated that the UNVS
overflowed an average of six to ten times per year with occurrences lasting as long as ten days. The Facilities
Plan/EIR indicated that installation of a new interceptor would be the most cost-effective solution to these problems.
With the increased capacity of the new interceptor, chronic wastewater overflows during wet weather will be
reduced, improving water quality. The project will increase the hydraulic capacity in the Upper Neponset Valley
Sewer by 8 mgd, through the construction of replacement sewers, to the level of service provided to all MWRA
sewer member communities. The project will eliminate surcharging and overflows during the one-year, six-hour
DEP designated design storm, with no increase in downstream overflows. It will also reduce overflows for 5-year
and above storms. The project includes design and construction of sections 685 and 686 replacement sewers for
sections 526 to 529. This construction contract was awarded in March 2005 and was completed in March 2008.
The project also includes design and construction of Section 687 to replace Section 530 which was awarded in
October 2006 and completed in November 2007.
Scope
Sub-phase
Designs/CS/RI
Resident
engineering &
inspection
Boston Paving
Replacement
Sewer Sections
685-686
construction
Replacement
Section 687
construction
Scope
Completion of design and provision of construction services during the construction phases.
Resident engineering and inspection during construction of the two contracts
Payment to the City of Boston for paving work on city streets.
Installation of 15,780 feet of new sewers within public roadways to reduce overflows to
adjacent residential areas and water bodies in West Roxbury.
Installation of 8,500 feet of new sewers to reduce overflows to adjacent residential areas and
water bodies in West Roxbury and Newton
Interception and Pumping - 20