AWWA WQTC64033

One of the greatest impacts of the 1991 Lead and Copper Rule on utilities across the United States has been the wholesale removal of lead service lines (LSL) from distribution systems. While the removal of LSLs is expected to reduce the lead exposure to consumers, there is considerable debate on the relative improvement in lead levels and the contribution of various lead sources on lead levels in the first liter sample. As part of an AwwaRF study, "Contribution of Service Line and Plumbing Fixtures to Lead and Copper Rule Compliance Issues", an in-depth analysis 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 Resources Authority (MWRA). The objectives of the field-testing program are to: conduct sequential sampling of stagnant water samples from kitchen faucets to identify sources of lead in service and premise plumbing and assess the contribution of these sources 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 line replacement (LSLR) and associated monitoring at both BWSC and Madison. Premise piping surveys were conducted at each site prior to sampling to determine the length, diameter and type of piping between the kitchen faucet and the end of the lead service line. This data was used to calculate the water volume that must pass through the kitchen faucet in order to determine how many sequential samples would need to be collected in order to reach water that had been in contact with the lead service during the stagnation period. Water sampling was conducted at the kitchen 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 the LSL and to establish baseline conditions for LSLR impact; Stage 2 - immediately before and after LSLR, and for three consecutive days following the replacement to quantify short-term impacts; 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 dissolved lead analyses as soon as possible after collection. Selected samples were also analyzed for temperature, pH, conductivity, free and total chlorine, HPC, alkalinity, copper, zinc, and calcium. At Madison, results indicate that lead occurrence is defined by the random release of lead particulate matter that forms when a lead service line is or has been in a plumbing system, along with the presence of iron and manganese scale layers. AT BWSC, lead levels measured from sequential samples collected at the taps where lead service line replacement had occurred indicate that: initial lead levels may be very high immediately after LSLR and flushing for 15 minutes immediately after replacement may not be adequate to reduce the lead levels to acceptable levels on the day of replacement; high total lead levels measured on the day of replacement, and for up 2 days after, may have been due to the presence of particulate lead dislodged from the surface scales of the premise piping and components during replacement; some sites experienced lower lead levels immediately after LSLR, however other sites did 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 months after full LSLR. Includes extended abstract only.