• •  EPA Method 1623
• •  Budget Planning for LT2
      (Please Call)
• •  Sample Collection

LT2 Update – June 2007

Background

The Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR or LT2) was signed on December 15, 2005. The final rule was promulgated on January 5, 2006 and became effective in March 2006.

The LT2 Rule applies to all public water systems (PWSs) whose source water is surface water or ground water under the direct influence of surface water. The Rule applies to approximately 14,000 systems serving approximately 180 million people nationwide.

The intent of LT2 is to provide more uniform public health protection by linking the level of required water treatment to the level of source water contamination. Current regulations require PWSs who filter their water to provide a 2-log (99%) reduction in Cryptosporidium levels. This level of treatment is appropriate for many PWSs that have little or no Cryptosporidium in their source water but EPA has determined that additional treatment is required for PWSs that have high levels of Cryptosporidium in their source waters and for all unfiltered PWSs.

The objective of the LT2 monitoring is to determine the concentration of Cryptosporidium in source water and, for PWSs with high levels of Cryptosporidium in their source water(s) to require additional treatment as specified in the Rule. LT2 also seeks to examine the correlation between Cryptosporidium, E. coli and turbidity for use with smaller systems.

LT2 compliance monitoring periods are staggered by PWS size. Schedules 1 – 3 involve large systems (≥10,000 population served) using surface water, including both community and non-community systems. Schedule 4 monitoring involves smaller (< 10,000 population served) PWSs. Ground water systems (not under the influence of surface water) are exempt from LT2, as are surface water systems that already provide ≥5.5 log treatment for Cryptosporidium.

Mandatory monitoring starting dates are summarized in the table below.

Monitoring Requirements

For Schedules 1 – 3, sampling will be required for two years (24 months) and will include monthly Cryptosporidium, E. coli and turbidity samples (optionally, samples may be collected more frequently). Source water samples must be collected at a location prior to treatment. Treatment plants utilizing pre-sedimentation, raw water off-stream storage or bank filtration may sample the effluent of those processes. In general, data will be collected and assessed for each separate and distinct source water site. No finished water sampling is required.

Schedule 4 plants will be required to initially conduct 12 months of monitoring for E. coli. Following this, an additional 12 – 24 months of monitoring for Cryptosporidium will be required only if the E. coli trigger levels (annual mean E. coli concentration exceeding 10 / 100 mL for PWSs using lake or reservoir sources or exceeding 50 / 100 mL for PWSs using flowing stream sources) are exceeded during the E. coli monitoring period.

Small, filtered Schedule 4 PWSs who anticipate exceeding the trigger levels may choose to skip the initial E. coli monitoring and perform Cryptosporidium monitoring. They must notify EPA of their intent to do this no later than three months prior to the date the PWS is required to begin monitoring. Small filtered PWSs that monitor for Cryptosporidium must monitor using one of the following two sampling frequencies: 1) Sample at least two times per month for a period of one year or 2) sample once per month for a period of two years.

Samples for Cryptosporidium analysis must be at least 10L in volume or as much volume as two approved filters can accommodate before clogging or adequate volume to generate at least 2.0 mL of packed pellet volume. The samples can be grab samples or field-filtered samples of up to 50L. ASI uses two types of filters (IDEXX Filta-Max xpress and Pall Gelman Envirochek™ HV) for concentration of water samples for analysis by Method 1623.  Both filters, and their associated elution procedures, are fully approved by the EPA for LT2 Cryptosporidium compliance samples.

Cryptosporidium samples are required to be analyzed by an EPA approved LT2 Cryptosporidium laboratory. Samples must be analyzed by EPA Method 1623 (or 1622); Cryptosporidium and Giardia in Water by Filtration/IMS/FA; December 2005 (EPA 815-R-05-002. ASI is a fully approved EPA LT2 Cryptosporidium laboratory.

Similarly, E. coli analyses for LT2 must be performed by a laboratory approved by EPA to perform quantitative LT2 E. coli analyses. Several E. coli methods are approved by the EPA; ASI uses Standard Method 9223B (IDEXX Colilert™/Quanti-Tray™ exclusively. ASI is a fully approved EPA LT2 E. coli laboratory.

ASI reports LT2 Cryptosporidium and E. coli results to its client via mailed reports, and also enters LT2 compliance sample data into the EPA Data Collection and Tracking System (DCTS) on the EPA Central Data Exchange (CDX) website. The PWS is then able to review and approve its data for release to the EPA.

Water Treatment Plant (WTP) Bin Classification

After the results are compiled, state or federal authorities will classify water treatment plants into one of four treatment bins according to the average concentration of Cryptosporidium reported in the LT2 data. The four bins for Filtered PWSs are defined below.

The mean Cryptosporidium concentration is calculated from a PWSs individual sample data. The method of calculation varies with the frequency and duration of monitoring, as described below.

1. PWSs with 24 – 47 monthly results over at least 24 months: Mean Cryptosporidium concentration is calculated from the 12 consecutive months out of 24 that yield the highest average.
2. PWSs with at least 48 results (≥2 samples per month for at least 24 months): Mean Cryptosporidium concentration is calculated from the overall arithmetic average. (Note: Certain water suppliers, for instance those with expected seasonal fluctuations (rain events, etc.), might want to consider monitoring more than once per month (i.e. twice or more per month). These additional data can lead to a bin classification more representative of actual long term average Cryptosporidium concentrations.
3. PWSs that operate only part-year and monitor less than 12 months per year: Mean Cryptosporidium concentration is calculated as the highest arithmetic mean of all concentrations from any year of monitoring.
4. PWSs that serve less than 10,000 people and monitor for Cryptosporidium for 1 year (2 samples per month): Mean Cryptosporidium concentration is calculated as the arithmetic mean of all sample concentrations.

It should be noted that all data will be reduced to oocyst concentration per liter for entry into the LT2 database, average calculation and bin assignments. All "non-detect" data (e.g., 0/10L, 0/50L, etc.) will be reduced to 0/L, so there is no mathematical advantage to larger sample volumes. Systems will have three years following bin classification to meet the treatment requirements associated with the bin.

Grandfathered Data

Many water suppliers have been monitoring prior to rule promulgation and have submitted complete LT2 data packages to EPA using “grandfathered” data. ASI has assisted nearly 80 Schedule 1 and 2 PWSs in this process. In addition, many Schedule 3 and some Schedule 4 PWSs have already started their LT2 monitoring prior to their regulation-mandated start dates and intend to submit grandfathered data to the EPA. The EPA intends to use grandfathered data for bin classification, provided all requisite Method QA/QC and other criteria are met. Use of grandfathered data offers flexibility in data management and provides the utility with a choice of data monitoring periods to submit instead of monitoring only under the LT2 Rule. Submission of E. coli and turbidity data is requested with grandfathered data, but not required.

Public Water Suppliers must report that they intend to submit previously collected monitoring results no later than three months prior to the date the PWS is required to begin monitoring. The PWS must report its "grandfathered" data no later than two months after the date the PWS is required to begin monitoring.

Analytical Services, Inc.

ASI is an approved laboratory for analysis of LT2 compliance samples for both Cryptosporidium and E. coli.

Please contact our Client Services Representative representative, Hannah Towne (htowne@analyticalservices.com or 800.723.4432x18), with questions or for additional information. Also see our Technical Advisory concerning EPA Method 1623.

Additional planning information can be found at the EPA’s website: www.epa.gov/safewater/disinfection/lt2/compliance.html

ASI strongly urges PWSs to stay in touch with EPA, AWWA and their State Administrators throughout their planning process for LT2.

P.O. Box 515 (mailing)
130 Allen Brook Lane (shipping)
Williston, VT 05495 USA
Toll Free: 800-723-4432
Local: 802-878-5138
Fax: 802-878-6765
htowne@analyticalservices.com

Copyright © 2006
Analytical Services, Inc.