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Potable Reuse as a New Source of Supply for Gulf Coast Water Authority
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Potable Reuse as a New Source of Supply for Gulf Coast Water Authority

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Presented at TWCA Mid Year Conference - June 13, 2014

Presented at TWCA Mid Year Conference - June 13, 2014
GCWA: Ivan Langford III – General Manager
Carollo Engineers: Meera Victor – Project Manager

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    Potable Reuse as a New Source of Supply for Gulf Coast Water Authority Potable Reuse as a New Source of Supply for Gulf Coast Water Authority Presentation Transcript

    • GCWA: Ivan Langford III – General Manager Carollo Engineers: Meera Victor – Project Manager
    • GCWA1113_interview.pptx Map GCWA serves municipal, industrial, and irrigation users in Brazoria, Fort Bend, and Galveston Counties City of Houston
    • GCWA1113_interview.pptx Map Shannon P/S – 60 MGD (Average Capacity) Oyster Creek
    • GCWA1113_interview.pptx Map 2nd Lift P/S – 50 MGD (Average Capacity)Oyster Creek
    • GCWA1113_interview.pptx Map Thomas Mackey WTP – 50 MGD Oyster Creek
    • GCWA1113_interview.pptx Brazos River @ Juliff Intake in 2009 tells the story of drought situation
    • GCWA1113_interview.pptx Multiple options to supplement supply were investigated 1. Desalination 2. Obtain additional treated water from Houston 3. Participate in raw water supply from east Texas 4. Participate in Allen’s Creek Project 5. Potable Reuse Near-term, lowest cost option Longer term, higher cost option Not Practical
    • GCWA1113_interview.pptx Map Thomas Mackey WTP Approximately 8.5 miles to Canal A Over 32 miles to Thomas Mackey WTP Treated effluent from Houston’s SW WWTP provides a possible supply source Houston SW WWTP (60 MGD max/30 MGD ave)
    • GCWA1113_interview.pptx WWTP discharge to A Canal is a “grey” area of TCEQ regulations  Waters of the State  Discharges Permitted under 30 TAC §307 and §309 (TPDES)  A WTP intake can be located as close as 500 feet away Brazos River  Not Waters of the State  Intent to reuse requires permitting on an individual basis  Dilution and environmental buffer are important GCWA Canal
    • GCWA1113_interview.pptx This project puts GCWA on path towards supply augmentation with potable reuse T1&2 – Data/gaps/monitoring T3 - Regulatory T4&5 – Goals & Standards T6 – Presentations T7 - Reporting Water shortages Water Quality Study Negotiate Implement Strategies Augment Supply Ongoing monitoring & verification
    • GCWA1113_interview.pptx Increasing risk requires more safeguards to make supply safe IncreasingRisk (acute&chronic) Increasing Safeguards (treatment & barriers) Conventional WTP (4 log virus, 3 log Crypto) Higher level of treatment & barriers needed for higher risk Brazos R. designated “high” per TCEQ SWA WWTP discharge into canal increases risk
    • GCWA1113_interview.pptx Regulators and end-users must be confident in approach Does it provide sufficient treatment to mitigate risk? Can I trust this source of supply?
    • GCWA1113_interview.pptx Environmental barrier & monitoring make supply reliable (trustworthy)  Response Retention Time (RRT)  Treatment (Attenuation)  Verify performance  Early warning Environmental Barrier Water Quality Monitoring
    • GCWA1113_interview.pptx 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 10 100 1000 10000 PercentNotExceeded Fecal Coliform Existing raw supply already impacted Fecal Coliform in Brazos River at Richmond Station (1980-1995) In-stream standard Type I reuse standard
    • GCWA1113_interview.pptx WQ evaluations will establish possible range of blended quality 0 50 100 150 200 250 300 350 Oyster Cr @ A Canal Oyster Cr @ Hwy 90 Possible Blend - Low Possible Blend - Max E.coli(CFU/100ml) Historic Sampling Possible Blended Canal WQ Under some conditions, blended quality might be higher than Oyster Cr.
    • GCWA1113_interview.pptx Potable Reuse in Texas  §290.D.42(g) - Innovative/ alternate treatment clause: “Any treatment process that does not have specific design requirements in 290.42(a) – (f) of this title.”  Case-by-case approval • Treatment requirements based on pathogen log reduction credits • Pilot or “full scale verification” required
    • GCWA1113_interview.pptx Regulatory Approaches to Direct Potable Reuse (DPR) Severely impaired High quality sewage WWTP effluent Defined: 10-4 risk drinking water TCEQ Approach (8/6/5.5) California / WRRF Approach (12/10/10) site- specific quality site- specific quality
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Dilution Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 Negligible
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Dilution 2. Canal A (Environmental Buffer) Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 Negligible Variable (safety factor)
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Dilution 2. Canal A (Environmental Buffer) 3. Thomas Mackey WTP (Conventional WTP) Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 Negligible Variable (safety factor) 4 / 3 / 2
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Dilution 2. Canal A (Environmental Buffer) 3. Thomas Mackey WTP (Conventional WTP) Total of All Barriers/Treatment Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 Negligible Variable (safety factor) 4 / 3 / 2 4 / 3 / 2
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Dilution 2. Canal A (Environmental Buffer) 3. Thomas Mackey WTP (Conventional WTP) Total of All Barriers/Treatment Potential Deficit Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 4 / 3 / 3.5 8 / 6 / 5.5 Negligible Variable (safety factor) 4 / 3 / 2 4 / 3 / 2
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Existing Systems Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 4 / 3 / 2
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Existing Systems 2. Possible Barriers a. Enhanced disinfection (chlorine dioxide + chlorine) Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 4 / 3 / 2 4+ / 2+ / 2+
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Existing Systems 2. Possible Barriers a. Enhanced disinfection (chlorine dioxide + chlorine) b. Optimized filtration (0.15 NTU 95% time) Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 4 / 3 / 2 4+ / 2+ / 2+ 0 / 0.5-1.0 / 0
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Existing Systems 2. Possible Additional Barriers a. Enhanced disinfection (chlorine dioxide + chlorine) b. Optimized filtration (0.15 NTU 95% time) c. UV disinfection Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 4 / 3 / 2 4+ / 2+ / 2+ 0 / 0.5-1.0 / 0 <1 / 3+ / 3.5
    • GCWA1113_interview.pptx TCEQ BASELINE GOALS 1. Existing Systems 2. Possible Barriers a. Enhanced disinfection (chlorine dioxide + chloramines) b. Optimized filtration (0.15 NTU 95% time) c. UV disinfection Total of All Barriers/Treatment Barrier/Treatment Log Removals* * Virus / Crypto / Giardia Multiple barriers will ensure safety of supply 8 / 6 / 5.5 4 / 3 / 2 4+ / 2+ / 2+ 0 / 0.5-1.0 / 0 <1 / 3+ / 3.5 8+ / 6+ / 5.5+
    • GCWA1113_interview.pptx UV inactivates Crypto & Giardia at low doses and reasonable cost 0 20 40 60 80 100 2 log virus 3.5 log Giardia/Crypto UVDose(mJ/cm2) $0.05/gal $0.20/gal Budgetary Cost Range for UV @ WTP
    • GCWA1113_interview.pptx Conclusions 1. Potable reuse offers the quickest, least expensive approach for augmenting the GCWA water supply 2. This study will establish reuse water quality to ensure safety and reliability of supply 3. Multiple barriers are needed to make supply safe and trustworthy 4. Supplemental treatment with UV disinfection or another technology might be required
    • GCWA: Ivan Langford III – General Manager Carollo Engineers: Meera Victor – Project Manager