Comparison of At-the-Tap and Profile Sampling for Lead

Transcription

1 New York City Department of Environmental Protection Bill de Blasio, Mayor Emily Lloyd, Commissioner Comparison of At-the-Tap and Profile Sampling for Lead Carla Glaser NYC DEP Bureau of Water Supply Division of Distribution Science & Planning New York's Water Event 2016 Saratoga Springs, New York April 12-14,

2 Objectives Overview of NYC Lead and Copper Rule (LCR) Program Compare 90 th percentile concentrations of lead for compliance samples vs. Free Residential Program (FRP) samples Compare lead levels of samples taken at different draw intervals Lead service line profiling Comparison of two homes Effects of partial lead service line (LSL) replacement 2

3 Introduction Brief explanation of lead program 1991: LCR promulgated Compliance Program, LCR mandated at-the-tap lead monitoring begun 1992: Department of Environmental Protection (DEP) began applying corrosion control treatment 1992: DEP began FRP, offering any resident of NYC free at-the-tap lead testing kits Since the beginning of the FRP, DEP has distributed over 100,000 kits On average DEP receives about 2,000 requests for kits a year When samples have lead concentrations above the LCR Action Level of 15 µg/l, DEP sends a retest kit 3

4 Number of Requests 1/1/2016 1/3/2016 1/5/2016 1/7/2016 1/9/2016 1/11/2016 1/13/2016 1/15/2016 1/17/2016 1/19/2016 1/21/2016 1/23/2016 1/25/2016 1/27/2016 1/29/2016 1/31/2016 2/2/2016 2/4/2016 2/6/2016 2/8/2016 2/10/2016 2/12/2016 2/14/2016 2/16/2016 2/18/2016 2/20/2016 2/22/2016 2/24/2016 2/26/2016 2/28/2016 3/1/2016 3/3/2016 3/5/2016 3/7/2016 3/9/2016 3/11/2016 3/13/2016 3/15/2016 3/17/2016 3/19/2016 3/21/2016 3/23/2016 3/25/2016 3/27/2016 3/29/2016 3/31/2016 4/2/2016 4/4/2016 4/6/2016 Public Response to Flint 700 Lead Test Kit Requests in NYC for Since Flint has been in the news, the number of kit requests have increased significantly The news about Flint hit the national media in mid- January total number of kit requests 2,313 Through the beginning of April 2016 number of kit requests over 5, Date 4

5 Sampling All at-the-tap samples are collected by the residents themselves Depending on program, kits contain different number of bottles Compliance 1 bottle FRP 2 bottles Retest 3 bottles In all kits, the first bottle is used to collect a first draw sample, the second bottle (if provided) is for a 1 to 2 minute flush sample, and the third bottle (if provided) is for a 5 minute flush sample The volume of all the bottles is one liter Any resident of New York City can request a free lead test by calling 311 or visiting 5

6 Sampling cont. All sampling instructions are based on LCR Before sampling, water should remain off for a minimum of 6 hours Sample(s) are collected from either the kitchen or bathroom tap, and if multiple bottles are filled all samples should be collected from the same location By-pass any filter (if present) Internal Plumbing Water main Meter Service Line 6

7 Compliance VS FRP At-The-Tap LCR Compliance & Free Residential 1st Draw 90th %tile History Jun Jun Jun Jun Jul - Dec 2005 Jan - Jun 2005 Jul - Dec 2006 Jun Jun Jun Jun Jun Jan - Jun 2011 Jul - Dec 2012 Jun June June June - LCR Compliance - 1st Draw 90th %tile Free Residential - 1st Draw 90th %tile LCR Action Level FRP data reflect the same trends detected as LCR data FRP has a large enough sample set to be indicative of system wide changes in lead levels Since 2000, just under 50% of FRP households detected lead ( 1µg/L) 7

8 No. of Samples Lead Level (µg/l) FRP 1 st Draw Residential At-The-Tap Lead Testing Results 1st Draw by Year YEAR 0 No. Samples Pb1 >15 µg/l Pb1_90th% 8

9 No. of Samples Lead Level (µg/l) FRP 1-2 Minute Flush Residential At-The-Tap Lead Testing Results 1-2 Minute Flush by Year YEAR 0 No. Samples Pb2 >15 µg/l Pb2_90th% 9

10 1 st Draw vs. 1-2 Minute Flush 70% Highest Pb Levels by Percent 60% 50% 40% 30% 20% 10% 0% % 1st Draw > 1-2 Minute Flush % 1st Draw < 1-2 Minute Flush % 1st Draw = 1-2 Minute Flush 10

11 Public Outreach All residents sent letter with test results within 30 days of sample receipt Letter includes information on ways to minimize lead in drinking water and conservation. To avoid lead in drinking water, before using water for drinking or cooking, the tap should be run for a few minutes if it has not been used in the past six hours, or more Please do not waste water. Use the water you flush out for washing or watering plants All results are provided routinely to the local health department, and any lead results higher than 15 µg/l are immediately reported 11

12 Lead Service Line Profiling To provide information regarding differences in lead concentration during flushing and following stagnation, from 2010 to 2015, DEP performed a series of lead profiles at two homes with LSLs Samples were collected of the calculated volumes of the internal piping and services lines to: capture lead release from the two homes profile the full impact of Pb service lines and/or internal plumbing determine what was the highest Pb concentration after stagnation determine when was the highest Pb concentration observed at the tap determine the impact of high velocity flushing on Pb concentration 12

13 Profiling Experimental Design A series of incremental 1-L samples were collected to capture 3 times the calculated volume of each home s service line to the sampling tap starting from the initial draw (after 6 hours of stagnation) Samples were collected by the residents from a cold water tap, after a minimum of 6 hours stagnation, and promptly brought to DEP s Laboratory The total number of liters collected at each home was dependent on the plumbing of the individual homes which was calculated to be 15 liters for Home A, and 20 liters for Home B Home A collected bottles Home B collected bottles Five (5) sampling events were conducted between 2011 to 2015 from each home July 2014 samples were collected following a 30 minute high velocity flushing of the entire home one (1) day prior to sample collection 13

14 Volume Estimation for Profiling Home Service Line Dimensions Service Line Volume (Liters) Internal Piping Dimensions/Material Internal Piping Volume (Liters) 3 Total Volume (Liters) A 13 ft long 1 dia ft long ¾ dia., copper B 80 ft long ¾ dia ft long ¾ dia., lead

15 Comparison of Homes Lead Results Home A vs. Home B There was a notable difference in the Homes Pb concentrations Home B s Pb levels were up to 139% higher than Home A s Home A s Pb levels averaged 12.7 µg/l and ranged between 2.6 to 43.1 µg/l Home B s Pb levels averaged 20.8 µg/l and ranged between 4.2 to 75.4 µg/l Difference was due to lead service line length and internal plumbing Home B had a longer lead service line 80 ft vs. 10 ft in Home A Pb was more prevalent throughout Home B in the joints, and valves in comparison to Home A 15

16 Lead (µg/l) Results of Lead Profiling Lead (µg/l) Home A - Lead Profile Total - 5/6/2015 Total - 9/25/14 Total - 8/26/14 Total - 7/28/2014, post high velocity flushing Total - 11/12/ L Sample Bottle Sequence Major differences between the two homes: Home B exhibited a much higher lead peak at 62 µg/l than Home A at 43 µg/l Timing of the lead breakthrough for Home A occurred after over 100% of the estimated service piping volume of water was collected, while Home B s peak occurred at the beginning of the sampling Profile results were consistent for both homes except after high velocity flushing Home A showed peak lead concentrations in the 7L sample at 33 µg/l Home B was highest at the 1L mark at 75 µg/l, with a second peak at the 6 L sample of water Home B - Lead Profile L Sample Bottle Sequence Total - 5/7/2015 Total - 9/25/14 Total - 8/22/14 Total - 7/28/14, post high velocity flushing Total - 11/5/11 16

17 Profiling Summary First Draw Does Not Capture Highest Lead Concentration Home A s average peak lead level was 38 µg/l Home B s average peak lead level was 54 µg/l Peak lead levels were much higher than the 15 µg/l LCR action level and higher than the median immediate first draw sample levels of 3 and 16 µg/l respectively for Home A and Home B Highest peak lead profile levels for Homes A and B occurred at or after 100% of the piping volume flushed through and not from the immediate first draw sample Home A s lead peaked at the 10 L sample ~2 minutes 40 seconds Home B lead peaked at the 7 L sample ~ 1 minutes 40 seconds Lead results following the high velocity flushing showed peak lead levels in Home A s 7 L sample at 33 µg/l and for Home B in the 1 L sample at 75 µg/l For Home A return to pre-flush lead levels after 2 months For Home B slight reduction in lead maintained from 1 to 10 months 17

18 Partial LSL Replacement Power utility work in the street replacing the natural gas line was performed in front of Home B in tember of 2015 In the process, the construction crew cut the LSL of Home B and partially replaced it (The New York City code states that you cannot partially replace an LSL, so this work was not approved by any city agency) Once the partial replacement came to light, DEP took the opportunity to perform additional profile sampling events at Home B 18

19 Lead (µg/l) Partial LSL Replacement Lead (µg/l) Home B - Lead Profile Total - 2/24/2016, post partial SL replacement Total - 12/9/2015, post partial SL replacement Total - 10/22/2015, post partial SL replacement Total - 5/7/2015 Total - 9/25/14 Total - 8/22/14 Total - 7/28/14, post high velocity flushing Total - 11/5/ First profile after PLSLR showed much higher lead levels, peaking at 226 µg/l 1-L Sample Bottle Sequence For the second and third profile sampling, after PLSLR, the curves fell to previous levels Home B - Lead Profile Total - 2/24/2016, post partial SL replacement Total - 12/9/2015, post partial SL replacement Total - 10/22/2015, post partial SL replacement Total - 5/7/2015 Total - 9/25/14 Total - 8/22/14 Total - 7/28/14, post high velocity flushing Total - 11/5/ L Sample Bottle Sequence 19

20 Conclusions Individual sites do not always have consistent at-the-tap lead levels, nor does their first flush sample always have the highest lead concentration With a large enough sampling pool, it is not necessary to find high risk sites (as defined by the LCR) to detect trends in at-the-tap lead values or to evaluate the effectiveness of a corrosion control program. Collecting only first draw samples misses a large percentage of peak lead values Highest Pb levels in a home with a lead service line may be as much as 200% higher than in the immediate first draw sample At the tap lead testing results obtained by the current EPA LCR compliance sampling protocol does not always quantify the worst case lead level nor give a predictable peak lead value Partial LSL replacement does increase lead levels, for a limited period of time, but did not shift the timing of the peak level Pb levels returned to pre-replacement levels within three months 20

21 Questions? 21