The primary goal of the Area-Wide Optimization Program (AWOP) is to reduce the effluent turbidity of water systems in order to maximize public health protection without major capital expenditures. This goal is accomplished by working with the water treatment system to optimize or refine coagulation, flocculation, sedimentation and filtration.

AWOP is based upon a 1997 agreement with the U.S. Environmental Protection Agency Region 4, the Optimization Institute in Cincinnati, Ohio, and the states of Alabama, Georgia and South Carolina.

Optimization Performance Criteria for Surface Water Treatment Systems

Optimized water treatment performance for protection against microbial contaminants is determined by specific measurements and targets. Any water treatment system that meets all of the following criteria will be considered optimized (for their existing treatment scheme).

I. Minimum Data Monitoring Requirements

• Daily raw water turbidity.
• Settled water turbidity at four-hour increments from each sedimentation basin.
• Online (continuous) turbidity from each filter.
• One filter backwash profile each month from each filter.
• HPC* top and bottom of each filter (for initial evaluation, then monthly).

     Additional Data Monitoring (to be collected by visiting technical assistance officer from the Division of Water):

• Total Organic Carbon for raw and finished water.
• Trihalomethanes (a complete set for initial evaluation).
• Bacteriological samples from raw, top and bottom of filters, plus representative of the distribution system to be analyzed for total coliform, fecal coliform, fecal strep and HPC (for initial evaluation).

II. Sedimentation Performance Criteria

• Settled water turbidity less than 1 NTU, 95 percent of the time, when annual average raw water turbidity is less than or equal to 10 NTU.
• Settled water turbidity less than 2 NTU, 95 percent of the time, when annual average raw water turbidity is greater than 10 NTU.

III. Filtration Performance Criteria

• Filtered water turbidity less than 0.1 NTU 95 percent of the time (excluding 15-minute period following backwashes) based on the maximum values recorded during four-hour increments.
• Maximum filtered water measurement of 0.3 NTU.
• Maximum filtered water turbidity immediately following backwash of less than 0.3 NTU.
• Maximum backwash recovery period of 15 minutes (i.e., return to less than 0.1 NTU within 15 minutes).
• Maximum filtered water measurement of less than 10 particles (in the 3 to 18 um range) per milliliter (if particle counters are available).
• HPC* counts should go down from top to bottom of filter (target HPC level at bottom of filter to be 0 colonies/ml).

IV. Disinfection Performance Criteria

• CT values to achieve required log inactivation of Giardia and virus.
• Assure the most advantageous use of chlorine by substitution of potassium or sodium at the intake, or rapid mix for oxidation of Fe, Mn, precursors, etc. Use of PAC (powdered activated carbon) for precursor removal may also be considered.

V. Distribution System Performance Criteria

• Perform a thorough, systematic flushing procedure at least twice a year. Make use of DPD chlorine test kit during flushing to assure same water quality from plant to first blowoff, and then beyond to each hydrant. Storage tanks shall be cleaned as necessary.
• Maintain water quality throughout distribution system so as to exert the least chlorine demand possible.
• Target a 24-hour turnover in storage tanks.
• Assure that purchasing systems are not overchlorinating through booster stations (if DBPs are a concern).
• Target HPC levels to be 0.
• Total coliform levels should be 0.
• Fecal coliform levels should be 0.
• Fecal strep levels should be 0.

* If you are not currently sampling for HPC, we recommend that you use the R2A (spread plate) method and incubate for 5 days.

If your surface water system is not achieving the performance criteria listed above, some things you could do now are:

• Improve baffling of your sedimentation basins and clearwells.
• Evaluate current chemical performance by running jar tests to achieve optimum coagulation.
• Evaluate filter performance after backwash.
• Improve chemical mixing at the rapid mix.
• Conduct inspections to assess current condition of the filter and media. 

For more information about AWOP, contact Julie Roney at 502-564-3410.