tom singleton associate vp, director, integrated water resources an atkins company linking tmdls...
TRANSCRIPT
Tom SingletonAssociate VP, Director,Integrated Water Resources
an Atkins company
Linking TMDLs & Environmental Restoration
Presentation Overview• Total Maximum Daily Loads (TMDLs)
– state-wide water quality conditions
• Sustainable water resource management– definition
• Model world & reality– need to link water quality benefits with management actions– not all loads are equal
• Science & engineering– it takes both
• Uniqueness of place– the right projects in the right places
1160 Impaired Waters
• 46% nutrients• 48% bacteria
16.8 million acres or26,000 square milesof impaired watersheds
$100-200 billion to restore water quality (FSA 2010)
Sustainable Water Resource Management
Water Supply
Water Quality
Natural Systems
Built Environment
Flooding
Comprehensively managing the highly complex relationships between communities & the land & water resources that sustain them
Most models overstate loads
• Especially run-off volume– SCS curve number developed to size pipes not estimate annual runoff
• Assume entire load reaches receiving water– fail to consider volume & pollutant attenuation within the watershed
• Delivery ratio:– fraction of runoff that reaches receiving water– as low as 8% due to high internal storage in lakes & wetlands,
especially in headwaters of watersheds
• Need to reality test model estimates
Source: Harvey Harper, FSA 2010
Insufficient information to properly characterize pollutants & select BMPs
• Untreated stormwater– dissolved species – nutrients, heavy metals– particulates – suspended solids, nutrients, heavy metals
• End of pipe runoff– doesn’t account for pre-treatment & characteristics of runoff reaching
the receiving water
• Need to verify loading conditions before selection & design of BMPs– inexpensive field verification monitoring
Source: Harvey Harper, FSA 2010
Need to link water quality benefits with management actions
• What is working, where it is working, & why it is working
• Need to be able to distinguish between successful & unsuccessful management strategies:– water quality benefits realized, but not predicted by models– water quality benefits predicted by models, but not realized
• Critical to document success:– past management actions are working– reasonable expectation that ongoing & planned management
actions will lead to the restoration of water quality in due time
Need to link water quality benefits with management actions
• Document water quality benefits of past management actions– review existing water quality & biological indicator status & trend
reports– compare with pollutant loading model output to determine if changes
in modeled loads are reflected in water chemistry– identify successful & unsuccessful management strategies (what)– identify where water quality assessments & models are accurately
reflecting no trends, improving trends, or degrading trends (where)– identify the causes of disagreement between the assessments & the
models– credit for load reductions & water quality restoration
Not all nutrient loads are equal
• Stormwater & wastewater– differ in makeup, concentrations, & impacts– stimulate different amounts of biological productivity– yet, treated the same for most loading models
24%
14%62%
Nitrogen species in stormwater
NOx NH4 ON
57%
5%
38%
Nitrogen species in wastewater effluent
NOx NH4 ON
Nutrient Sources & Biological Productivity
• Wastewater:– low volume, high concentration (up to 20 mg TN/liter), mostly inorganic– highly stimulating in both form of delivery & composition
• Stormwater runoff:– high volume, moderate concentration (1-2 mg TN/liter), mostly organic– moderately stimulating in form of delivery & composition
• Direct atmospheric deposition:– high volume, low concentration, mostly inorganic– least stimulating in form of delivery & composition
• Conclusion:– a pound reduction of N from wastewater is worth more than a
pound reduction of N from stormwater or atmospheric deposition
Water Quality Trading• Although expensive, wastewater reductions:
– easier & less expensive per pound to implement & the benefits are much greater & easier to account for than nonpoint source reductions
– can be used to offset nonpoint source load reductions
• Example: Clay County Utility Authority– credits for construction of 2 advanced wastewater treatment
plants & efficient operation of 2 other secondary treatment facilities that produce treated effluent below the TMDL target concentrations for domestic wastewater facilities
– transfers up to 49,579 lb/year of TN in water quality credits from the Authority to offset the County’s required nonpoint source load reduction of 48,159 lb/year of TN
Water Quality Trading• Credits valued at $186.25 per pound of TN
removed:– $45,160,233 cost of Authority projects / 242,467 lb TN
removed by the projects per year– credit price is adjusted annually to cover the cost to Authority
of carrying the debt– total value of credits: $8,083,250 (43,400 lb/yr TN x $186.25)
• Win-Win-Win:– Authority: approx. 20% of wastewater improvements funded
by County’s stormwater program– County: cost-effective & achievable load reductions– State: restored water quality
Sustainable Water Resource Management
Comprehensively managing water across diverse watersheds:
• respecting the “uniqueness of place”
Molecular structure of a diamond
Winter Haven: conditions driving wq & biological response
Proposed interim water quality targets & restoration project types for WHCL based on EPA’s Numeric Nutrient Criteria
Science & Engineering
Analyze Design ConstructObserve
Need sound science to have sound engineering and planning
