AWWA WQTC64120

One of the greatest impacts of the 1991 Lead and Copper Rule on utilities across theUnited States has been the wholesale removal of lead service lines (LSL) from distributionsystems. While the removal of LSLs is expected to reduce the lead exposure to consumers, thereis considerable debate on the relative improvement in lead levels and the contribution of variouslead sources on lead levels in the first liter sample. As part of an AwwaRF study, "Contributionof Service Line and Plumbing Fixtures to Lead and Copper Rule Compliance Issues", an in-depthanalysis of multiple LSL replacements is being conducted at Madison Water Utility in Madison,Wisconsin and in the Boston water supply area by the Boston Water and Sewer Commission(BWSC) in concert with their regional water supplier, the Massachusetts Water ResourcesAuthority (MWRA). The objectives of the field-testing program are to:conduct sequential sampling of stagnant water samples from kitchen faucets to identifysources of lead in service and premise plumbing and assess the contribution of thesesources to lead levels at the tap prior to and several weeks after LSL replacement,(sometimes referred to as profiling); and,evaluate immediate and long-term differences in lead levels after LSL replacement.Four residential homes with lead service lines were chosen for lead service linereplacement (LSLR) and associated monitoring at both BWSC and Madison. Premise pipingsurveys were conducted at each site prior to sampling to determine the length, diameter and typeof piping between the kitchen faucet and the end of the lead service line. This data was used tocalculate the water volume that must pass through the kitchen faucet in order to determine howmany sequential samples would need to be collected in order to reach water that had been incontact with the lead service during the stagnation period. Water sampling was conducted at thekitchen faucet using the cold water portion of the faucet, and was conducted in three stages:Stage 1 - prior to LSLR to identify lead contributions from premise plumbing and theLSL and to establish baseline conditions for LSLR impact;Stage 2 -immediately before and after LSLR, and alsofor three consecutive days following the replacement to quantify short-termimpacts; and,Stage 3 - monthly for 2 months following LSLR to determine long-term impacts.An initial flushed sample was collected, after which the water was allowed to stagnate fora minimum of six, and not more than 8, hours. Flushed samples were collected by allowing thewater to run long enough to ensure that freshwater from the water main was flowing through thefaucet. Multiple sequential stagnant water samples were collected at the end of the stagnationperiod. On the day of LSLR an initial flushed sample was collected prior to replacement, andanother flushed sample was collected after the replacement was completed. For all samples, anyaerator on the kitchen faucet was left attached during sampling.Samples were analyzed for total and dissolved lead, with samples filtered for dissolvedlead analyses as soon as possible after collection. Selected samples were also analyzed fortemperature, pH, conductivity, free and total chlorine, HPC, alkalinity, copper, zinc, andcalcium.At Madison, results indicate that lead occurrence is defined by the random release of leadparticulate matter that forms when a lead service line is or has been in a plumbing system, alongwith the presence of iron and manganese scale layers. Specifically:particulate lead was the significant fraction of the total lead found in the water;in flowing samples, particulate lead was below the Action Level of 15 µg/L before thelead service line was replaced, and increased immediately after replacement, and within oneday of lead service line replacement, the total and particulate lead levels fell to at or nearthe Limit of Detection at 1 µg/L;for stagnation samples, most of the lead captured i

Product Details

Edition:

Vol. - No.

Published:

11/01/2006

Number of Pages:

3

File Size:

1 file , 310 KB