Weston & Sampson is providing planning, design, and construction oversight for the MWRA’s rehabilitation of Water Sections 50 & 57 and Sewer Sections 19, 20, & 21.
The sections include 8,000 linear feet of 48-inch steel water main; 12,000 linear feet of 20-inch cast iron water main; 10,300 linear feet of horseshoe-shaped brick sewer ranging in size from 53-inch x 56-inch to 56-inch x 61 inch; and 350 linear feet of 48-inch diameter cast iron siphon. The project includes water and sewer crossings underneath the Malden River, a bridge crossing over the Mystic River, and an above-ground crossing of Winter Brook.
Our team is responsible for conducting a detailed survey with a flyover; review of record drawings/maintenance data; site walk; review of engineering studies in abutting areas; modeling/evaluation of water main performance requirements and points of control; in-field soil corrosivity sampling and water main external condition assessment; manhole/TV/sonar inspections; corrosivity evaluation; bypass pumping evaluation; geotechnical/hazardous material explorations; environmental, permits, traffic, and real estate/easement assessments; rehabilitation alternative evaluation; design bid packages; as well as construction administration and resident inspection services.
Weston & Sampson evaluated pipe rehabilitation and replacement alternatives and alignments, to achieve the MWRA’s long-term goals for reliable water and sewer system performance in the project area. Our team evaluated alternatives to identify the highest value alternative, considering cost, schedule, risks, and other factors. The recommended alternative aims to achieve their goals for improved water quality, service reliability, and corrosion protection in Water Sections 50 & 57, as well as improved structural integrity and flow conveyance properties in Sewer Sections 19, 20, & 21. Alternatives included:
- Replacement – open cut, pipe bursting, directional drilling
- Sliplining – steel, polyethylene
- Cured-in-place pipe – steam, water, UV, styrene-free, epoxy-based
- Spray-in-place pipe – cleaning and cement lining, epoxy, geopolymer
- Carbon fiber reinforced polymer
Final design included sliplining of the 48-inch steel main with 40-inch cement lined steel pipe (Section 57) and replacement of the 20-inch cast iron main (Section 50) below grade at the Winter Brook crossing. The river crossing includes vertical shafts and horizontal pipe that will be lined with epoxy. The project is currently paused while the City of Medford and National Grid Gas negotiate construction mitigation measures.
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CLIENT: Massachusetts Water Resource Authority
- 8,000 linear feet of 48-inch steel water main
- 12,000 linear feet of 20-inch cast iron water main
- 10,300 linear feet of horseshoe-shaped brick sewer ranging in size from 53-inch x 56-inch to 56-inch x 61 inch
- 350 linear feet of 48-inch diameter cast iron siphon