Proposed - Massachusetts Water Resources Authority
Proposed - Massachusetts Water Resources Authority
Proposed - Massachusetts Water Resources Authority
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S. 130 Siphon Structure Rehabilitation<br />
Project Purpose and Benefits<br />
Contributes to improved public health<br />
Provides environmental benefits<br />
Extends current asset life<br />
Improves system operability and reliability<br />
Master Plan Project 2009 Priority Rating 2 (see Appendix 3)<br />
Design and construction of improvements to headhouses and structures.<br />
Project History and Background<br />
Siphon chambers are located at the upstream and downstream ends of depressed sewers. Depressed sewers are<br />
constructed to avoid obstructions in sewer alignments such as rivers and subsurface utilities. Upstream siphon<br />
chambers allow attainment of proper water elevation so that the depressed sewer flows under pressure. Downstream<br />
chambers provide transitions between depressed sewers and downstream gravity sewers.<br />
Connecting structures are facilities at which flows from sewers are redirected to converge with or receive flows from<br />
other sewers.<br />
There are 92 siphon chambers and 111 connecting structures in the MWRA wastewater system. Hydraulic flows<br />
through many of these siphon chambers and connecting structures are below design capacities. The poor flow<br />
conditions, caused by irregular maintenance due to the inaccessibility of many structures, contribute to significant<br />
surcharges and overflows. Wastewater detention time at many structures also contributes to serious odor problems.<br />
MWRA completed a study in 1998 to evaluate rehabilitation of these structures to permit greater accessibility to<br />
provide regular maintenance in order to alleviate the above problems. 83 siphon chambers and 63 connecting<br />
structures were included in the study which recommended rehabilitation and improvements to 127 of these<br />
structures. MWRA has prioritized the design and construction of improvements to these structures. Phase 1 will<br />
rehabilitate the most deteriorated structures.<br />
Scope<br />
Sub-phase<br />
Planning<br />
Design/CS/RI<br />
Construction<br />
Scope<br />
Identification of methods to improve accessibility and structures. Inspection of the siphon<br />
chambers and diversion structures along with recommendations for rehabilitation.<br />
Design, Construction Services and Resident Inspection for up to 16 sites.<br />
Construction for up to 16 sites.<br />
Expenditure Forecast (in $000s) and Project Status<br />
Total<br />
Budget<br />
Payments<br />
thru FY11<br />
Remaining<br />
Balance<br />
FY12 FY13 FY09-13 FY14-18 Beyond<br />
FY18<br />
$2,671 $940 $1,731 $0 $30 $30 $1,701 $0<br />
Interception and Pumping - 22
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