uv disinfection for unfiltered surface water regulatory compliance
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UV Disinfection for Unfiltered Surface Water Regulatory Compliance. Kevin Castro, PE | GHD. Image placeholder. Image placeholder. Image placeholder. UV Disinfection for Unfiltered Surface Water Regulatory Compliance. Kevin Castro, PE | GHD. Presentation outline. Background - PowerPoint PPT PresentationTRANSCRIPT
UV Disinfection for Unfiltered Surface Water Regulatory ComplianceKevin Castro, PE | GHD
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UV Disinfection for Unfiltered Surface Water Regulatory ComplianceKevin Castro, PE | GHD
2013 NYC Watershed/Tifft Science & Technical Symposium
Presentation outline
• Background• Regulatory Requirements• Water Quality• Basis of Design• Procurement/Construction• Benefits/Results• Lessons Learned• Questions
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2013 NYC Watershed/Tifft Science & Technical Symposium
Village of Skaneateles, New York
• Village demands– 0.6 mgd average daily demand– 1.2 mgd maximum daily demand– 2.0 mgd pump capacity
• Served off City of Syracuse Skaneateles Lake supply
• FAD since 1991• 3 log giardia inactivation through chlorination
(using City of Syracuse chlorination)• Population served ± 3,000
2013 NYC Watershed/Tifft Science & Technical Symposium
Skaneateles/Syracuse water supply system
2013 NYC Watershed/Tifft Science & Technical Symposium
Regulatory requirements
• SWTR– 1991 FAD– 3 log giardia inactivation through
chlorination– 4 log virus inactivation through
chlorination– Contact tank and contact
transmission main constructed 1995
• LT2ESWTR– 2 or 3 log cryptosporidium
inactivation– Two barriers: UV/Cl2
2013 NYC Watershed/Tifft Science & Technical Symposium
Water quality
• Turbidity– Average = 0.8 NTU– Range = 0.5 to 10 NTU– Syracuse intake shutdowns control turbidity
• UVT– Average = 97%– Minimum value = 92%– ICR = 96 to 98%– Limited historical data– Design Range = 90 to 98%
• Cryptosporidium– 1 oocyst detected since 1986
• 2 log cryptospordium inactivation required• Fouling Potential - Low
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2013 NYC Watershed/Tifft Science & Technical Symposium
Basis of design
• 2 log cryptospuridium inactivation = 5.8 mJ/cm2• 3 log giardia inactivation = 11 mJ/cm2• Designed for 3 log giardia inactivation• UVT – 90% minimum
- 95% average• Turbidity < 10 NTU• Lamp Technology – Medium Pressure or LPHO• Two 100% redundant UV reactors
2013 NYC Watershed/Tifft Science & Technical Symposium
Basis of design (cont’d)
• Max flow = 2 mgd• Ave flow = 1 mgd• Min flow = 0.5 mgd• Reduce giardia chlorine contact time requirements• Max headloss – 7 inches• Improved monitoring (UVT, Turbidity, Cl2)
2013 NYC Watershed/Tifft Science & Technical Symposium
Procurement
• Preselection vs. pre-purchase• Preselection approach chosen to give contractor ultimate responsibility for
system performance.• Life cycle cost bid
- Equipment costs- Lamp/ballast costs- Power costs
2013 NYC Watershed/Tifft Science & Technical Symposium
Procurement
• Procurement results• Trojan awarded selection
Equipment PV – Lamp Replacement
PV – Ballast Replacement
PV - Annual Power
Total Life Cycle Cost
Svern Trent $121,594 $5,173 $14,200 $9,884 $150,851
Trojan $117,000 $21,460 $5,976 $8,045 $152,481
Calgon $141,860 $9,079 $5,970 $9,986 $166,895
2013 NYC Watershed/Tifft Science & Technical Symposium
Construction
• Space available with BPS• Pump replacement *• VFDs provided *
- Reduce pump flow to 1 mgd (90% speed)- Reduce pump energy cost by $4,000/year- Reduce pump starts to < 4/day- Eliminate cavitation of pumps on low lake
level• SCADA for monitoring/control/reporting
*Provided through ARRA grant
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2013 NYC Watershed/Tifft Science & Technical Symposium
Construction
UV Disinfection UV Controls
2013 NYC Watershed/Tifft Science & Technical Symposium
Construction
Pumps
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SCADA
2013 NYC Watershed/Tifft Science & Technical Symposium
Construction
Turbidity/Chlorine/UVT Monitoring
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Chlorine Booster System & Monitoring
2013 NYC Watershed/Tifft Science & Technical Symposium
Results/benefits
• 2 log cryptosporidium inactivation – compliance• 3 log giardia inactivation through UV/Cl2• 4 log virus inactivation through Cl2• Use transmission main and contact tank for improved fire protection
(currently under development)• Reduced pump starts to < 4/day• Reduced energy/cost for pumping• Improved monitoring/reporting of CT, turbidity, Cl2 residual• < 0.1% off-spec water since March 2012
2013 NYC Watershed/Tifft Science & Technical Symposium
Lessons learned
• Validation layout ≠ Approved layout• Alarm management during maintenance
- Nuisance alarms during lamp and UVT transmitter maintenance
• Preselection was effective procurement approach
• Avoid pre-preselection design layouts ($$)• Define distances for power/instrumentation
cabling• LT2ESWTR allows off-spec water
2013 NYC Watershed/Tifft Science & Technical Symposium
Questions?
Please contact Kevin Castro at [email protected]
2013 NYC Watershed/Tifft Science & Technical Symposium
www.ghd.com