Bristow Water District – PWS# 41XXXXX
Stage 2 DBPR Compliance Monitoring Plan (CMP)
The Bristow Water District is required to monitor quarterly. As described in our IDSE report, Stage 2 DBPR compliance monitoring will begin the second week of November 2013, and then approximately every 90 days thereafter. We will be taking individual TTHM and HAA5 samples (instead of dual sample sets) at the locations with the highest TTHM and HAA5 concentrations, respectively. More specifically, an individual sample will be collected quarterly from sample point SM-1 (4747 Alias Dr) and tested for TTHMs, and an individual sample will be collected quarterly from sample point S1-1 (47000 Rambaldi Rd) and tested for HAA5s.
Each quarter we will calculate a locational running annual average (LRAA) for TTHM and HAA5 at each monitoring location, beginning in the fourth quarter of 2013. Compliance calculations will start at the end of the third quarter of 2014. Compliance will be achieved if the TTHM and HAA5 LRAA at each monitoring location for the four most recent quarters is less than or equal to 0.080 mg/L for TTHM and less than or equal to 0.060 mg/L for HAA5. The LRAA will be calculated prior to the fourth quarter of data if fewer than four quarters of data would cause the MCL to be exceeded, regardless of the monitoring results in subsequent quarters.
Compliance is calculated for each LRAA as: (Q1 + Q2 + Q3 + Q4)/4 < MCL for each location.
If, after 4 quarters of monitoring and the city has an LRAA calculation of equal to or less than .040 mg/L for TTHM and .030 mg/L for HAA5 and an annual average raw TOC of less than 4.0 mg/L the city may request reduced monitoring. If the city is approved for reduced monitoring we would collect one TTHM and one HAA5 sample per year. The TTHM sample will be collected from the location and during the quarter with the highest TTHM single measurement. The HAA5 sample will be collected from the location and during the quarter with the highest HAA5 single measurement. They may occur in different quarters. Alternatively, if the highest TTHM and HAA5 measurements occur at the same location and quarter, one dual sample set per year is allowed. We will then continue to monitor at the reduced frequency until we have any sample (TTHM or HAA5) that exceeds the maximum MCL at any sample location, our LRAA calculation exceeds .060 mg/L for TTHM or .045 mg/L for HAA5 at any location, our annual average TOC exceeds 4.0 mg/L, or we are otherwise instructed to return to routine sampling. Routine sampling would be returning to individual TTHM and HAA5 samples on a quarterly basis.