Wichita MS4 Program: “Unifying watershed management through an Off-site BMP Implementation

Program”

Ron Graber & Trisha Moore Kansas State University

Spring Stormwater SymposiumMarch 8, 2017

Storm Water Advisory Boardformed 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)

Storm Water Advisory BoardPurpose 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

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)

TMDLs in Wichita’s MS4 permit

• Many TMDL streams influenced by land use upstream of City

• Current TMDL regulated pollutants include Sediment, nutrients & bacteria

How its done Currently

Current Onsite BMP Program

Storm Water Advisory Board

Substantial onsite expense involved What if the SWAB could find a cheaper

method?

WRAPS

Targeted WRAPS

Little Arkansas WatershedAgricultural 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

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

Targeted Areas for Sediment

Load Reduction Needed – 6,571 tons/yr

(40 years)

Priority 1 Priority 2

Cost effectiveness: “Rural” BMPsLittle 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 $2.87Conservation Tillage $20 38% 7.0 $2.87Grassed Waterways $160 40% 18.6 $8.60Vegetative Buffers $67 50% 9.3 $7.17Nutrient Management $57 25% 11.6 $4.88Terraces $102 30% 5.6 $18.28Intensive Crop Rotations $20 25% 4.7 $4.30Cover Crops $60 25% 1.4 $43.01Water Retention Structures $125 50% 9.3 $13.44Permanent Vegetation $500 95% 17.7 $28.30Streambank 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)

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 $5,425Pervious pavement $179,840 88% 9.4 $19,130Extended detention basin $18,465 80% 8.7 $2,120Bioretention $35,500 75% 8 $4,440

Vegetative Buffers $4,500 90% 9.5 $475Grass 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

Evolution of offsite program• Clear: offsite program more effective

economically and, potentially, environmentally• But how to operationalize?

City of Wichita Stormwater Advisory BoardCity 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

MS4 Permit

Provision for offsite BMP program in current MS4 permit (2014)

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

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.

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

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 1Onsite BMP for 40-ac development

Scenario 2Onsite BMP for 1-ac development

Scenario 3Offsite BMP for any development

Marginal Cost for WQv

Excavation $46,464 Outlet Structure $8,000 Total Capital $54,464 Biannual inspection $500

Marginal Cost, hydro. sepHydrodynamic Separator cost $15,000Installation $7,500Total Capital $22,500Biannual inspection $500

$37.60 per acre

development per year

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 residentialOnsite BMP: Hydrodynamic sep. for 1-acre commercialOffsite BMP: $37.60 per acre per year

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 SystemNPDES: Non-Point Discharge Elimination SystemBMP: Best Management Practice

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$

$

$

Pollutant reduction credits

Report TSS reductions

Report TSS

reductions

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

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

Ron Graber Watershed Specialist

rgraber@ksu.edu

Trisha Moore Bio & Ag Engineering tlcmoore@ksu.edu