Presentación Algas

491 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
491
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
8
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Presentación Algas

  1. 1. Nutrient Offsets in Virginia: Update and Alternatives Analysis Kurt Stephenson Dept Ag & Applied Economics, Virginia Tech Virginia Rural Water Association Conference March 18, 2008
  2. 2. Virginia Nutrient Trading Design and Sequencing In general, the Virginia nutrient trading program establishes a sequencing logic that prioritizes compliance options to achieve stringent mass load caps. This applies to both existing and new/expanding point sources.
  3. 3. Existing Point Source Compliance 1.Devise plan to meet wasteload allocation (WLA) 2.If discharge > WLA, purchase credits from another point source 3.If no PS credits available, secure equivalent NPS credit by paying into Virginia Water Quality Program.
  4. 4. New/Expanding Point Source Compliance 1A) Meet limit of technology concentration standard for N and P, and 1B) Acquire WLA to offset new discharge: • Buy WLA from point source • Acquire NPS credit from “best management practices” at 2:1 rate • If none above, “other means” • If none above, payments into WQIF
  5. 5. Nonpoint Source Credit, Offsets Nonpoint source credits are reductions in nutrient load beyond a baseline. Defined in statute as: “achieve reductions beyond those already required by or funded under federal and state law” §62.1-44.19:15.B.1b
  6. 6. Nonpoint Source Offsets New/expanding sources must permanently offset new load Any nonpoint source offsets must be included within the point source’s individual VPDES permit.
  7. 7. Alternatives Analysis
  8. 8. Alternatives Analysis Ask the Question: What are the activities and costs of offset alternatives needed to offset total nitrogen load from a 1 mgd WWTP expansion (or about 10,000 lbs/yr)? (1 mgd operating at 3 to 3.5 mg/l TN)
  9. 9. Alternatives Analysis Virginia trading program requires 2 pounds of reductions per 1 pound of nonpoint source offset. Thus, 20,000 pounds of TN reduction needed for 10,000 pound offset Assume no long term point source WLA (offset) available
  10. 10. Classes of Offset Alternatives 1) Agricultural Offsets (DEQ approved) 2) Urban Offset Options 3) Nutrient Assimilation Offsets
  11. 11. 1. Agricultural Offsets DEQ published BMP offset guidelines January 2008.
  12. 12. Agricultural BMP Baselines Before any offset is granted, agricultural sources must meet baseline (reductions not available as offsets)
  13. 13. Agricultural BMP Baselines 1. Soil Conservation – implement soil conservation plan to achieve specific soil loss tolerance value 2. Nutrient Management – certify & implement nutrient management plan 3.Cover Crops - Cover crops to meet the required standard planting date 4. Riparian Buffer –maintain minimum 35 ft vegetative buffer 5.Livestock Exclusion – fence out, alternative watering, and minimum 35ft buffer
  14. 14. Ag BMPs available for Credit 1. Early Cover Crops – vegetative cover crops by early planting dates. 2. 15% N Reduction on Corn – Nitrogen application rates at 85% of recommended rates in nutrient management plan 3.Continuous No-Till – implement and maintain continuous no till for minimum 5 yrs 4. Land Conversion – converting agricultural and to less nutrient intensive use
  15. 15. Example: Ag offsets in Shenandoah 15% N Reduction + Continuous No-Till Total Nitrogen Reduced: 4.01 lbs/ac Total Number of Acres: 4,988 acres (20,000 lbs / 4.01 lbs/ac)
  16. 16. Example: Ag offsets in Shenandoah 15% N Reduction + Continuous No-Till Cost to Implement ??? Technical Feasibility: • # producers at baseline thought to be small • Only 77,000 acres of corn grown in the entire S. Valley in 2006 (many counties less than 5,000 acres).
  17. 17. Example: Ag offsets in Shenandoah Land Conversion: Crop to Forest Total Nitrogen Reduced: 10.91 lbs/ac Total Number of Acres: 1,833 acres (20,000 lbs / 10.91 lbs/ac)
  18. 18. Example: Ag offsets in Shenandoah Land Conversion: Crop to Forest Cost to Implement: $86/lbs TN annually (land costs $10,000/ac, conversion costs $867/ac, annualized 20 years @ 7%) Technical Feasibility: Yes, if land available
  19. 19. N Offset Alternatives Summary Offset Option Action Approved Cost/lb Feasible 15% less N + No-till 5,000 ac ? ? Crop to forest conversion 1,833 ac $86/lb ?
  20. 20. 2. Urban Offsets DEQ has discussed offsets from urban nonpoint source reduction. Options might include: • Stormwater management practices (wet ponds, bioretention areas, sand filters) • Septic retirement
  21. 21. 2. Example: Wet ponds Assume wet pond draining 75 acres, residential development, estimated TN load into pond 165 lbs/yr, 30% removal efficiency Wet pond reduces 50 lbs/yr # ponds needed: 400 Cost per lb approximately $600/lb
  22. 22. 2. Example: Other stormwater Bioretention areas: $75 - $1,300/lb Sand filters: $3,000/lb
  23. 23. 2. Septic Retirement EPA has allowed nutrient offsets in other areas of country for septic retirement At 18/lb household, 1,111 existing individual septic systems would need to be connected to central sewer Low ball cost: $30/lb* * Assume connecting 300 home existing development, piping costs only annualized over 20 years at 7%.
  24. 24. N Offset Alternatives Summary Offset Option Action Approved Cost/lb Feasible 15% less N + No-till 5,000 ac ? ? Crop to forest conversion 1,833 ac $86/lb ? Wet ponds 400 ponds TBD $600/lb Septic retirement 1,111 homes TBD Min $30/lb ?
  25. 25. 3. Nutrient Assimilation Credits Enhancing the nutrient assimilative capacity of the ecosystem to remove nutrients from Bay system is another way to remove nutrients beyond source reduction.
  26. 26. 3. Examples • Oyster Aquaculture • Algal Biomass Harvest • Wetland Restoration
  27. 27. Illustration: Nutrient Assimilation Offsets from Oyster Aquaculture “It is the oyster's eating habits that make it so important to its environment: it is a voracious filter feeder that performs several vital functions in the Bay's ecosystem”
  28. 28. Example: Nutrient Assimilation Offsets from Oyster Aquaculture While wild restoration has been difficult, oyster aquaculture can successfully grow native Chesapeake Bay oysters. Expansion, however, is limited by finances. N and P removal from: • Oyster harvest (biomass harvest) • Nutrient conversion of oyster biodeposits (nitrification & denitrifcation)
  29. 29. Example: Nutrient Assimilation Offsets from Oyster Aquaculture 2006 Chesapeake Bay Targeted Watershed Grant Project: “Nutrient Assimilation Credits: Opportunities for Enhanced Oyster Production” http://oyster.agecon.vt.edu/ Nutrient removal credits from mussel aquaculture in Sweden Nutrient removal projects from oyster aquaculture in Buzzards Bay MA, and ribbed mussels in NY, NY
  30. 30. Example: Nutrient Assimilation Offsets from Oyster Aquaculture Previous research estimates between 700 and 5,500 lbs of TN removed annually per 1,000,000 oysters (3” oyster) 3.6 to 28.5 million oysters needed as an offset At current stocking densities, less than 100 acres leased private bottoms needed. Cost/lb: ?
  31. 31. Example: Nutrient Assimilation Offsets from Algal Harvest Algal harvest facilities rapidly grow algae in order to remove nutrients from ambient water or from treated effluent discharge. Nutrients removed when algae is harvested
  32. 32. Example: Nutrient Assimilation Offsets from Algal Harvest Algal Turf Scrubber (left) N and P removal rates can be directly quantified with high levels of certainty Projects underway in FL & NY http://www.algalturfscrubber.com/
  33. 33. Example: Nutrient Assimilation Offsets from Algal Harvest Algal Turf Scrubber Assume: 12 g dry weight m2/day & 3% TN (but these are based on systems managed for P) 16 acre facility needed to produce 20,000 lbs of TN of reduction Cost/lb of TN? ($15-$25 per pound of P in FL)
  34. 34. Illustration: Nutrient Assimilation Offsets from Wetland Restoration “Forested riparian (or streamside) wetlands remove about 80 percent of the phosphorus and 90 percent of the nitrogen from water, which act as water contaminants and may result in unhealthy algae blooms.”
  35. 35. Example: Nutrient Assimilation Offsets from Wetland Restoration Invested in 1,300 acre wetland restoration project to demonstrate nutrient removal in IL. WI claims restored wetlands can remove 275 pounds of TN/ac/yr 73 acres wetland restoration needed http://www.wetlands-initiative.org/NutrientFarming.html
  36. 36. N Offset Alternatives Summary Offset Option Action Approved Cost/lb Feasible 15% less N + No-till 5,000 ac ? ? Crop to forest conversion 1,833 ac $86/lb ? Wet ponds 400 ponds TBD $600/lb Septic retirement 1,111 homes TBD Min $30/lb ? Oysters 3.5-28.5m oysters TBD ? ? (< 100 acres) Algal Harvest < 16 acres TBD ? ? Wetland Restoration 73 acres ? TBD ? ?
  37. 37. Comments or Questions? Kurt Stephenson Department of Ag & Applied Economics Virginia Tech Kurts@vt.edu (540) 231-5381

×