1 / 25

Have You Got Your Microbial Toolbox Ready?

Have You Got Your Microbial Toolbox Ready?. Sarah Clark, P.E. HDR Denver Office. Effective. Proposed. Final. Drinking Water Regulatory Schedule. Financial. Operations. Schedule. FEASIBLE ALTERNATIVES. Regulatory. Water Quality. Why Utilities Should be Concerned:

jorn
Download Presentation

Have You Got Your Microbial Toolbox Ready?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Have You Got Your Microbial Toolbox Ready? Sarah Clark, P.E. HDR Denver Office

  2. Effective Proposed Final Drinking Water Regulatory Schedule

  3. Financial Operations Schedule FEASIBLE ALTERNATIVES Regulatory Water Quality Why Utilities Should be Concerned: The Practical Effects of New Rules Water utility flexibility is shrinking Source: Balancing Multiple Water Quality Objectives, AWWARF, 1998

  4. Bin Classification for Filtered Systems

  5. % with no brackets indicate actual; in brackets is the expected assignment based on maximum RAA of 24 samples 52-80% (49-71%) 14-23% (15-19%) 0-6% (1-7%) 4-23% (12-23%) Mean Cryptosporidum Concentration in Source Waters Number of Source Waters 0.03 0.1 1.0 Oocysts/Liter

  6. LT2 Source Water Monitoring

  7. National Microbial Monitoring Costs Total National Cost = $39,250,700

  8. Measure 24 samples and calculate the highest running annual average Measure 48 samples and calculate the simple mean Finding Your Crypto Bin Chose One:

  9. “Binning” based on 48 samples is much more likely to put you in your “true” bin than “binning” based on 24 samples.

  10. LT2 Treatment Requirements *Use any technology or combination from the Toolbox **At least 1 log by ozone, chlorine dioxide, UV, membranes, bag/cartridge filters, or in-bank filtration.

  11. What is the Microbial Toolbox? • Tools for an individual plant to use in reducing risk of Crypto in finished water • Minimizes cost of treating for Crypto by reducing the number of plants shifting to advanced technologies • Tools provide some flexibility for treatment plants to meet multiple water quality objectives

  12. Key to Table Symbols • X indicates potential log credit based on proper design and implementation accordance with EPA guidance. • Arrow indicates estimation of potential log credit based on site specific or technology specific demonstration of performance • (1) Criteria to be specified in guidance to determine allowed credit • (2) Inactivation dependent on dose and source water characteristics • (3) Additional monitoring for Cryptosporidium after this action would determine new bin classification and whether additional treatment is required.

  13. Current EPA Proposed Toolbox

  14. What Tools are Plants Most Likely to Use? • Least expensive • Most direct credit from States (without extra measurement and reporting) • Membranes • Disinfectants

  15. Expected LT2 Direct Credit for Cryptosporidium Removal • Off-stream storage • 0.5 log credit for 21-day storage • 1.0 log credit for 60-day storage • Pre-sedimentation with continuous coagulant addition – 0.5 log credit • Lime softening • 3-log credit for single-stage plants, as for conventional plants • Additional 0.5 log credit for two-stage softening

  16. Expected LT2 Direct Credit for Cryptosporidium Removal cont. • Improved filtration • 0.5 log credit where CFE turbidities are maintained below 0.15 NTU, 95% of time • Roughing filters – 0.5 log credit • Multiple filtration processes – 0.5 log credit • Slow sand filtration • 3.0 log credit as baseline • 2.5 log credit if added to a clarification/filtration system • Bank filtration – 0.5 or 1.0 log credit based on demonstration

  17. Guidance Will Also Provide Details for Testing • EPA intends to provide draft guidance with the proposed rule, including • Requirements for completion of a Cryptosporidium challenge test on a full-scale membrane module • Requirements for UV reactor validation • Requirements for demonstrating credit above the minimum specified in the rule

  18. Demonstration of Performance

  19. What Can Utilities Do Now to Prepare for LT2ESWTR? • Consider beginning Cryptosporidium monitoring before the required date • Review Cryptosporidium data you already have to get an idea of your “bin” - but don’t be too optimistic about your bin if your data is slim • Review each plant with the microbial toolbox in mind to determine your options • Plan ahead for the expenses of monitoring and treatment changes

  20. Sources of Information • Proposed LT2 Rule expected in December 2002 or January 2003 • Guidance manual expected for review along with the rule • AWWA Microbial Toolbox Report • Pre-proposal draft of the LT2 Rule • Call Sarah Clark – 303-764-1560 or sarclark@hdrinc.com

More Related