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TMDL Purgatory: Stuck Between Compliance and Futility

City of Winston-Salem Stormwater/Erosion Control Division

APWA Stormwater Conference September 15, 2014

01 Salem Creek TMDL Background

02 Case Study on Structural BMPs

03 Hurdles to Implementation

04 Final Thoughts

01

Salem Creek TMDL Background

303d listed stream for biological impaired TMDL approved in September 2006 by EPA 11.7 stream miles of Salem Creek Watershed land use Dry and wet weather exceedences of 400 cfu/100 mL instantaneous standard

The ‘Purity’ of Salem Creek

Forested, 30%

Residential (1/3 to 1/4 acre), 13%

Industrial, 11%

Open Space, 10%

Commercial , 7%

Salem Creek Watershed Land Use, Year 2011

Source: City of Winston-Salem Watershed Masterplan

MS4 Waste Load Allocation

WLA NPDES WLA MS4 LA MOS TOTAL

Existing Load (cfu/day) 4.54x1011 4.22x1012 1.07x1012 NA 5.74x1012

Load Allocation (cfu/day)

4.54x1011

2.95x1011 7.37x1010 9.14x1010 9.14x1011

Percent Reduction 0% 93.0% 93.1% NA 84.1%

Load Reduction (cfu/day) - 3.93x1012 9.96x1011 - 4.83x1012

Wildlife – most prevalent isolate source within watershed

Pets – 1 pet (dog or cat) per every 2 people in US

Sources: ASPCA and U.S. Census Bureau, 2012

Human – a dominant source during baseflow conditions

Source: NCDWQ, 2006

Livestock – greater contributor during high flow conditions

Source: NCDWQ, 2006

Fecal Coliform Sources

Numerical ‘Sins’ of the Past

Locate and prioritize fecal coliform pollutant ‘hot spots’

Expand current pollutant reduction strategies

Explore innovative methods of nonstructural BMP measures to actual WLA reduction

Document and track pollutant reductions

Hierarchy of appropriate BMPs for implementation

‘TIP’ to Salvation

Site-specific,

structural BMPs

Additional or expanded BMPs (nonstructural or

structural)

Broad, appropriate nonstructural BMPs

02

Case Study on Structural BMPs

Short Term o Fecal coliform impairment o Prioritize water quality capital projects and opportunities o Evolve existing water quality modeling (XP-SWMM) and

field efforts (BMP retrofit reconnaissance) Long Term o Impairments for other emerging urban pollutants o Address source controls or non-structural BMPs o Tool for tracking existing controls and load reductions

Water Quality Modeling Needs

• Populated with GIS and spatial data • Based on EPA SWMM and other

accepted water quality simulations • More intuitive BMP parameterization • Integrated cost-efficiency optimization tool

Why we selected EPA SUSTAIN model?

Source: EPA SUSTAIN Training Documentation, Tetra Tech 2009

Explicit, Relative Approach o Structural BMP opportunities screened to

analysis subset • 45 opportunities > 11 feasible site

o Goal to identify most cost effective structural BMPs

o Optimize size per site by 75-125%

A Twist on SUSTAIN

SUSTAIN Model

Optimized BMP Configuration

Data

BMP Placement, Types, Number, and Configurations

BMP/LID Optimization

Specifics of our Approach o Detention or infiltration BMP o Designed per State BMP guidance o Simulated average annual hydrologic

conditions o Modeled 12 constituents o Set cost indices for

• Excavated volume • Filter media

How we used SUSTAIN

Source: EPA SUSTAIN Training Documentation, Tetra Tech 2009

Load Reduction Cost Effectiveness o Structural BMPs as engineer specified o Structural BMPs optimized by SUSTAIN

Anticipated Results

Source: Introductory Webcast on SUSTAIN, EPA 2010

Salem Creek Results

2.4

2.5

2.6

2.7

2.8

$7,000,000 $7,500,000 $8,000,000 $8,500,000 $9,000,000 $9,500,000

Perc

ent R

educ

tion

(%)

BMP Construction Cost

Total Cost($) 273_FC_AAL_1 BIORETENTION WETPOND 136_Length 275_Length 127_Length

8400087.01 97.3 2162560.505 6237526.5 214 208 424

Prioritized Water Quality Capital Improvements

Watershed/Site Characteristics

o 135 acres o 34.5% impervious o 1.1 x 1013 cfu/year o < 1 acre wetland footprint

Benefits

o Repurposing of lightly used park o Flood control o Water quality improvement

Evolution of an Opportunity

Structural BMPs may have a limited role as a cost-effective solution o 11 structural BMPs produced 1.9% reduction at a cost of $7-8 million

Model simulations validate early processes and engineering judgment o Screening process was effective at identifying appropriate scale and location for BMPs

Wet ponds (detention) were more cost effective than bioretention (infiltration) o Despite higher efficiency for bioretention, wet ponds

were aided by lower start-up costs and ability to handle more volume

Conclusions from the Winston-Salem Case Study

03

Hurdles to Implementation

More emphasis to be placed source control and behavioral changes

Structural BMPs - Most Measurable, But Likely Cost-Prohibitive For Implementation

ID

Proposed BMP Performance

Approximate Size (acres)

Removal Efficiency (%)

Load Removed (cfu/day) Cost ($)

BR-03 0.7 79.7 3.3E+09 $317,036

BR-05 3.2 72.4 4.1E+10 $1,732,271

97.2 97.2 97.3 97.3 97.4 97.4 97.5 97.5 97.6 97.6 97.7

$6,500,000 $7,000,000 $7,500,000 $8,000,000 $8,500,000 $9,000,000 $9,500,000

o Aspects of Frameworks • Create credits for multi-objective benefits • Individual (innovating) measures versus universally accepted practices • Confidence rating (ease level and detail of monitoring)

» Applicability » Data scope and depth » Data quality » Study factors

• Review Committees and Expert Panels (Chesapeake Bay Urban Nutrient Management Expert Panel)

• Technology and Information Exchanges (Environmental Information Exchange Network, International Stormwater BMP Database)

How To Determine Effectiveness Of Measures

Source: Chesapeake Bay Urban Nutrient Management Expert Panel

Require shift to integrated planning with stormwater and wastewater entities

Success For Bacteria & Nutrient TMDL Implementation

Develop monitoring strategy to answer questions more so than hope for trends

Random Monitoring Produces Random Results And Is Not Cost Effective

Frequency Occurrence from Antibiotic Resistance Analysis

Strategic Planning – Holistic Methodology for Appropriate BMPs

Source Percentage (%)

Wildlife 35

Pets 32

Human 18

Livestock 15

04

Final Thoughts

Thank you!

Contact information o Andy Allen, City of Winston-Salem, andrewa@cityofws.org o Patrick Blandford, HDR, patrick.blandford@hdrinc.com

Questions