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Off-Site BMP Implementation Program


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The overall goal of this project was to develop an implementation framework for an offsite BMP program
to maximize the environmental and economic effectiveness with which the City of Wichita meets its
NPDES stormwater permitting requirements to ultimately improve water quality in the Little Ark and
Arkansas Rivers. This program aims to integrate watershed stakholders across sociopolitical bounds and
provide a sustainable funding mechanism to implement and maintain water quality practices in the rural
landscape, a critical need as watershed managers struggle to meet water quality targets (e.g., TMDLs).
Based on dialogue between stakeholders representing the watershed’s agricultural (represented by the
Little Ark Watershed Restoration And Protection Strategy program, or WRAPS) and urban (represented by
the City of Wichita’s Stormwater Advisory Board and City officials) communities and the Kansas
Department of Health and Environment (KDHE), which administers TMDLs and water quality permits, the
program works to optimize the placement of BMPs within the watershed for maximum water quality
benefit of the integrated system. Rural management practices tend to be less costly, thereby enabling
greater pollutant load reduction per dollar spent on BMPs in rural versus urban areas. For this reason, net
costs to urban developments participating in the offsite program should be significantly less than if
traditional urban water quality control practices were installed and maintained. A program framework was
developed in which a “sediment credit” fee is paid annually by urban developments participating in the
program to finance implementation and maintenance of offsite BMPs as facilitated through the Little
Arkansas WRAPS program. Adoption of this offsite program is anticipated to lead to greater reductions in
sediment (and other pollutant) loads leaving the watershed than could be achieved through conventional
implementation of BMPs within urban bounds to meet MS4 permit requirements. The program is currently
in its first year of implementation.

Published in: Environment
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Off-Site BMP Implementation Program

  1. 1. Wichita MS4 Program: “Unifying watershed management through an Off-site BMP Implementation Program” Ron Graber & Trisha Moore Kansas State University Spring Stormwater Symposium March 8, 2017
  2. 2. Storm Water Advisory Board formed November 2011  Greg Allison, PE (Appointed by: City Manager)  Richard Basore - Ex-Officio KDHE Member  Chris Bohm, PE (Appointed by: Wichita Area Builders Assoc.)  Don Kirkland (Appointed by: Wichita Chapter KS Society of Professional Engineers)  Hoyt Hillman (Appointed by: Sierra Club/WRAPS)  David Leyh (Appointed by: Wichita Area Assoc. of Realtors)  Mitch Mitchell (Appointed by: Sedgwick County Stormwater Advisory Board)  Gary Oborny (Appointed by: Kansas CCIM)  Joe Pajor, (Appointed by: City of Wichita Public Works & Utilities)  Jim Weber, PE (Appointed by: Sedgwick County Public Works)
  3. 3. Storm Water Advisory Board Purpose and Duties  Advise City Council and staff on storm water management policy  Review proposed changes to manuals  Comment on matters forwarded by the Director of Public Works  To frame our actions in conformance with the MS4 permit and EPA
  4. 4. Current Onsite BMP Program  Stormwater discharge from City of Wichita, KS regulated by MS4 permit (MS4 = Municipal Separated Storm Sewer)  Permit includes requirement to address TMDLs within MS4 area  Development and redevelopment required to meet water quality treatment (> 1 acre)
  5. 5. TMDLs in Wichita’s MS4 permit • Many TMDL streams influenced by land use upstream of City • Current TMDL regulated pollutants include Sediment, nutrients & bacteria
  6. 6. How its done Currently Current Onsite BMP Program
  7. 7. Storm Water Advisory Board  Substantial onsite expense involved  What if the SWAB could find a cheaper method?
  8. 8. WRAPS
  9. 9. Targeted WRAPS
  10. 10. Little Arkansas Watershed Agricultural watershed  913,430 acres  78% cropland  19% grazingland  237 registered CAFO’s TMDLs set for the watershed  52% of stream segments required TMDLs  Water quality concerns include bacteria, nutrients, sediments, pesticides Drinking water source for city of Wichita and numerous smaller cities and towns  205 public water supplies  7400 groundwater wells
  11. 11. WRAPS Implementation Goals  Atrazine from Cropland  Sediment from Cropland  Nutrients from Cropland and Livestock  Fecal Coliform Bacteria from Livestock  Sediment and Nutrients from Streambank and Riparian Areas
  12. 12. Targeted Areas for Sediment Load Reduction Needed – 6,571 tons/yr (40 years) Priority 1 Priority 2
  13. 13. Cost effectiveness: “Rural” BMPs Little Ark Watershed Cropland BMP Effectiveness Best Management Practice Cost Per Treated Acre Erosion Reduction Efficiency Total Reduction* Over lifetime $/Ton No-Till $40 75% 14.0 $2.87 Conservation Tillage $20 38% 7.0 $2.87 Grassed Waterways $160 40% 18.6 $8.60 Vegetative Buffers $67 50% 9.3 $7.17 Nutrient Management $57 25% 11.6 $4.88 Terraces $102 30% 5.6 $18.28 Intensive Crop Rotations $20 25% 4.7 $4.30 Cover Crops $60 25% 1.4 $43.01 Water Retention Structures $125 50% 9.3 $13.44 Permanent Vegetation $500 95% 17.7 $28.30 Streambank stabilization $91/ft 85% 60 $2.30 *Assumes an erosion rate of 1.86 tons/acre/year, with the exception of streambank stabilization (2.8 tons/ft/yr)
  14. 14. Cost effectiveness: “Urban” BMPs Urban BMP Lifecycle Costs/ton sediment removed Best Management Practice Cost Per Acre treated Erosion Reduction Efficiency Sediment Reduction* Over lifetime (tons) $/Ton sediment removed Hydrodynamic separator $28,750 50% 5.3 $5,425 Pervious pavement $179,840 88% 9.4 $19,130 Extended detention basin $18,465 80% 8.7 $2,120 Bioretention $35,500 75% 8 $4,440 Vegetative Buffers $4,500 90% 9.5 $475 Grass filter strip $9,600 95% 10.3 $930 *Assumes an Erosion Rate of 0.43 tons/acre/year for Medium Density Residential or Parking Lot 25-year lifetime assumed for all urban BMPs
  15. 15. Evolution of offsite program • Clear: offsite program more effective economically and, potentially, environmentally • But how to operationalize? City of Wichita Stormwater Advisory Board City should administer the program WRAPS should administer the program Desired to own ground or easements Did not believe ownership was necessary Desired to operate/maintain offsite practices WRAPS should oversee maintenance of offsite practices City should provide reporting WRAPS annual report could meet reporting requirements
  16. 16. MS4 Permit ision for offsite BMP program in current MS4 permit (2
  17. 17. Program Framework  Sediment credit ratio – Ratio serves as “factor of safety” given uncertainty in actual sediment delivery from offsite sediment sources to downstream aquatic systems – 2:1 selected to meet expectations of regulatory community (KDHE) 1 ton TSS2 tons TSS
  18. 18. Program framework  Allowable offsite BMPs – City’s comfort level with “non-permanent” (e.g., no-till) BMPs was initially low – We accommodated by assuming that sediment credits provided by non-permanent BMPs would be replaced. The sediment credit fee reflects this assumption.
  19. 19. Program framework  Sediment credit payment rate – Developed spreadsheet tool to assist City in setting payment rate in a transparent manner. Payment rate based on: • Cost to producer to adopt AND maintain practice (selected no-till as a representative and “most-likely” offsite BMP) • Cost to replace offsite BMPs should be discontinued • Administrative costs to enroll and track offsite BMPs
  20. 20. Program Framework  Sediment credit fee should (1) cover life-cycle costs of offsite BMPs while (2) providing some incentive for program participation. To illustrate: McCann Scenario 1 Onsite BMP for 40-ac development Scenario 2 Onsite BMP for 1-ac development Scenario 3 Offsite BMP for any developmen Marginal Cost for WQv Excavation $46,464 Outlet Structure $8,000 Total Capital $54,464 Biannual inspection $500 Marginal Cost, hydro. sep Hydrodynamic Separator cost $15,000 Installation $7,500 Total Capital $22,500 Biannual inspection $500 $37.60 per acre development per year
  21. 21. Program framework  Opting to pay an annual, sediment credit fee to the offsite program is more economic than traditional onsite measures. Onsite BMP: pond for 40-acre residential Onsite BMP: Hydrodynamic sep. for 1- acre commercial Offsite BMP: $37.60 per acre per year
  22. 22. MS4 NPDES Permit Requirements  July 2014: MS4 permit issued for the City of Wichita now requires the City to manage post-construction stormwater runoff quality  Permitted Post-construction stormwater management options include: – On-site stormwater quality BMPs (traditional approach) – Off-site stormwater program  KDHE continues to emphasize the MS4 Permittee should develop a Stormwater Management Program which works for their location and circumstances MS4: Municipal Separated Storm Sewer System NPDES: Non-Point Discharge Elimination System BMP: Best Management Practice
  23. 23. Where we are now  City Council supports program – June 17  Authorize start up funds - $60,000  Amend ordinance  Execute contract with program administration –August 9  Enrollment as of Jan. 17 - 108 acres urban, 115 acres rural Onsite developers City WRAPS Producers KDHE, EPA $ $ $ Report TSS reductions
  24. 24. Timeline  Nov. 2011 – SWAB formed  April 2012 – Ideas brought forward  Feb. 2013 – Brainstorm/ KDHE supportive  Nov. 2013 – WRAPS  June 2014 – RFP  Sept. 2014 – KSU contracted  June 2015 - Final Report  July 2015 – Public outreach  May 2016 – City council meetings  June 2016 – City council approval  Aug. 2016 – Approval to execute contract  Jan. 2017 – First payment to operator
  25. 25. What does it take?  Stakeholder buy-in (education) – KDHE, City of Wichita, Sedgwick County, development community  Watershed “champion” – WRAPS – prioritize watershed efforts, landowner/producer relationships  Monitoring – Assess changes in eco service provision & adapt as necessary
  26. 26. Ron Graber Watershed Specialist Trisha Moore Bio & Ag Engineering