AWWA WQTC64033

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, andfor three consecutive days following the replacement to quantify short-termimpacts; and,Stage 3 - Monthly for 2 months following LSLR to determine long-term impacts. 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. AT BWSC, lead levels measured from sequential samples collected at the taps where leadservice line replacement had occurred indicate that: initial lead levels may be very high immediately after LSLR and flushing for 15 minutesimmediately after replacement may not be adequate to reduce the lead levels toacceptable levels on the day of replacement;high total lead levels measured on the day of replacement, and for up 2 days after, mayhave been due to the presence of particulate lead dislodged from the surface scales of thepremise piping and components during replacement;some sites experienced lower lead levels immediately after LSLR, however other sitesdid not exhibit lower lead levels until 3 days after LSLR; and,total lead levels were generally reduced to well below the action level by 1 to 2 monthsafter full LSLR. Includes extended abstract only.

Product Details

Edition:

Vol. - No.

Published:

11/01/2006

Number of Pages:

3

File Size:

1 file , 310 KB