South Central Connecticut Regional Water Authority
NEW HAVEN SERVICE AREA IMPROVEMENTS STUDY, 50-YEAR POPULATION AND WATER USE STUDY, AND CAPITAL EFFICIENCY PLAN™
We have provided civil engineering consulting services and completed numerous studies for the South Central Regional Water Authority (RWA) headquartered in New Haven, Connecticut, serving 17 Cities and Towns and serving a population of over 400,000 people. Phase 1 of the New Haven Service Area Improvements Study was completed in 2009. The purpose of the study was to determine the lowest cost set of recommended capital and operational improvements to incorporate additional service areas into the New Haven Service Area. Our services included evaluating potential improvements to the distribution system as to whether they met RWA’s pressure, tank fluctuation, and fire flow criteria and recommending a conceptual baseline solution, which was optimized during Phase 2 of the study. Phase 3, which completed the study, included a Preliminary Design Report with our final recommendations.
We recently completed a 50-Year Population and Water Use Study for RWA in 2009. The study examined trends in water use and population growth in each of the towns and service areas served by RWA and projected future water use for average day, maximum day, and maximum month demand throughout the distribution system. The projections were completed in accordance with guidelines from the Connecticut Department of Public Health and are suitable for use with RWA’s next water supply plan update.
RWA recently purchased a water distribution system with approximately 125 miles of water mains and customers located in Ansonia, Derby and Seymour, Connecticut. Tata & Howard was contracted to complete a Capital Efficiency Plan™ of the new system. Our services included updating and verifying the existing hydraulic model, evaluating the condition of the existing distribution system infrastructure to determine the adequacy of meeting present and future demands, calculating needed storage requirements, assess and prioritizing system improvements, reviewing and evaluating typical fire flows throughout the system, creating a pipe asset management rating system, and recommending improvements to the distribution system.
PIPE CONDITION ASSESSMENT
Tata & Howard provided Pipe Sample Testing for the South Central Connecticut Regional Water Authority (SCCRWA) in conjunction with the SCCRWA’s cement lining projects. Work included extracting, sandblasting, crushing and analyzing one foot length cast iron water main samples. Samples ranged from 4-inch to 16-inch in diameter. Approximately 200 water main samples have been analyzed to date. The pipe testing program began in 2007 as part of the SCCRWA’s cement lining project in New Haven, CT where one foot long pipe samples were extracted and analyzed at the end of the cement lining project. All samples were sandblasted, crushed, and analyzed. The analysis includes visual inspection of the sandblasted sample and pipe crushing using the ANSI A21.6-13 Ring Test Method. Pipe class and remaining factor of safety of each pipe sample can be estimated using this method.
Each sample is inspected for internal corrosion, external corrosion, wall perforations, air inclusions and wall thickness. Pipe class is estimated for each sample and pipe crushing loads are compared to the crushing load of new pipe with a 2.5 pipe manufacturer’s minimum factor of safety. By comparing the measured break load to the 2.5 manufacturer’s minimum factor of safety, the remaining factor of safety for the pipe sample can be estimated. By estimating the remaining factor of safety, decisions can be made on method of rehabilitation or replacement. Tata and Howard’s research has shown that pipe with an older installation date does not necessarily relate to a lower estimated remaining factor of safety. Therefore, pipe sample testing is effective in assisting the SCCRWA in determining whether to rehabilitate or replace a particular main.
A water audit was conducted according to the guidelines outlined by the American Water Works Association (AWWA) in Water Audits and Loss Control Programs, Manual of Water Supply Practices M36, Third Edition, published in 2009. The data reviewed and analyzed included the volume pumped for each source, source meter errors/calibration, the volume of water imported/exported, billed and unbilled consumption, recorded leakage, main breaks, and unauthorized consumption. Key performance indicators, including Infrastructure Leakage Index and nonrevenue water, were evaluated to track management of the water utility. Based on the results of the audit, recommendations were made to improve system operation and reduce nonrevenue water. Although the RWA’s unaccounted-for water rate around 15%, the audit confirmed that the RWA’s Infrastructure Leakage Index or ILI was at industry best practice levels, confirming that apparent losses made up the majority of RWA’s water loss.
The recommendations in the audit report included verification of flows at ten production meters, where serious over-reporting of flow was identified. As a result of this work, two of the production meters were replaced in 2013, including a 54-inch diameter venturi tube at the RWA’s main source. The audit report also confirmed statistical analysis of customer meter testing that led to a decision to focus meter replacement work on piston-type meters while leaving older but more statistically accurate nutating disc-type meters in service for longer periods.