Buckhorn Disinfection Byproducts / Backwash Disposal Project Board of Directors Meeting June 14,...
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Transcript of Buckhorn Disinfection Byproducts / Backwash Disposal Project Board of Directors Meeting June 14,...
Buckhorn Disinfection Byproducts / Backwash
Disposal Project
Board of Directors MeetingJune 14, 2012
Project Purpose and Issues
Backwash Management Strategies
DBP Reduction Alts and Recommendations
Recommended Phasing Plan
Presentation Outline
Project Purpose: Assure Compliance with Stage 2
Disinfection Byproduct (DBP) Rule (a)
& Develop An Integrated Backwash Management Strategy
Key Project Issues: Elevated DBPs in the Buckhorn WTP
Distribution System Insufficient Pond 7 Storage Capacity
for Backwash Waste Water Disposal
Project Purpose and Issues
(a) Effective October 1, 2013.
1. Expand Pond 7 to Contain 100-Yr Storm Event per WDR
2. Remove Solids at WTP to allow Recycle to WTP and/or Discharge Treated Backwash Water (BWW) to Pond 7
a) No WDR Required
3. Select Best Long-Term and Most Cost Effective Backwash WaterManagement Strategy
Backwash Water Management Strategies for the Buckhorn
WTP
Comparison of Solids Removal Alternatives
Alternative
Comparison Criteria (Score 1 to 5, 5 = best)
ScoreRegulatory Construction Cost
ApplicabilityParticulate Chemical
Compliance Removal Compatibility
1. Bag Filter w / Recycle 35
($255k) 1 1 5 15
2. Bag Filter w / Discharge 21
($760k – $910k) 3 1 5 12
3. Mech. Dewatering w / Recycle 33
($525k) 1 1 1 9
4. Mechanical Dewatering w / Discharge 22
($660k) 1 1 5 11
5. Conventional Drying Beds 31
($1,525k) 3 5 416 (site
constraints)
6. Proprietary Drying Beds 54
($355k) 5 5 4 23
7. Reuse Old Plant (Conv. Drying Beds) 31
($1,515k) 2 5 4 15
8. Leachfields 15
($200k) 1 5 5 17
9. Micro Screen 32
($595k – $900k) 2 3 5 15
10. Expand Pond 43
($500k - $650k) 3 5 5 20
Proposed Flow Schematic
Potential Site Layout
Recommended DeskinsTM System
(Solids Removal and Dewatering)
Stage 2 DBR Rule Compliance
Historical TTHM/HAA5 Results
TOC Removal Coagulation/Filtration Adsorption Oxidation
Reduce Chlorine Dose Maintain Disinfection CT Maintain Residual Disinfectant throughout System
Distribution System Modifications Reduce Water Age Tank Materials
DBP Removal Strategies
Buckhorn WTP Distribution System
DBP Sample Location
Comparison of DBP Reduction Alternatives
DBP Reduction Alternative
Capital Cost(1-5, 5 = Lowest)
Operating Cost(1-5, 5 = Lowest)
DBP Reduction(1-5, 5 = Greatest)
Complexity(1-5, 5 = Simplest)
Total Score
TOC REMOVAL
Chlorine Dioxide
2($180,000)
1($30,000/yr)
3 3 10
ACH4
($25,000)3
($20,000/yr)4 5 16
Ferric Chloride
3($45,000)
2($25,000/yr)
3 3 11
REDUCE CHLORINE RESIDUAL
Clearwell Baffling/Chlorine Booster Stations
1($160,000)
3($20,000/yr)
5 2 10
pH Adjustment
Location
4($20,000)
5($0/yr)
3 5 17
Reduce CT Provided
5($0)
5($0/yr)
3 5 18
DISTRIBUTION SYSTEM MODIFICATIONS
Tank Mixing3
($175,000)5
($0/yr)2 4 14
ACH DBP Reduction
Recommended Phasing PlanGoal: ACH feed system operational Summer
2013; highest DBP concentrations have historically occurred during summer seasona
Step / Activity Est. Construction Cost ($)
2012 2013
J J A S O N D J F M A M
1. Solids Removal Project
355,000 Design B Construct & Startup
2. Full Scale Testing to Minimize Chlorine Dose
0b
3. Tank A Modifications
50,000 D B Construct
4. ACH Improvements 25,000 D B C & SU
Total Est. Construct Cost
430,000
a First set of Stage 2 DBP compliance testing to be conducted prior to October 1, 2013
b Testing conducted by Agency operators and staff
Questions ?