1. Shawn Tracy
Restoration Specialist
Metro Conservation Districts (MCD)
MCD SWCD’s
Anoka – Carver – Chisago – Hennepin – Isanti – Ramsey –
Scott – Sherburne – Washington - Wright

2. Anoka
Ecological
Wright Restoration Carver
MCD
Washington Chisago
Subwatershed
Stormwater
Assessment
MCD Stormwater
BMP Design
Sherburne LRP Hennepin
Scott Isanti
Education
Ramsey

4. Dan Anderson: http://www.flickr.com/photos/stonebridgedapper/
Urban
Google Earth
Sub-WS
Restoration
Rural/Ag

5. What it is It is not
Urban stormwater retrofitting …a hydraulic or storm sewer
Identification of the highest analysis/planning tool
value stormwater BMP retrofit …primarily used for street-
practices by location (e.g., $/LB- scaping or park development
TP/YR) (secondary benefit)
A Water Quality planning tool …an elaborate excuse just to get
Supplement to existing analyses in more raingardens
One (major) consideration in
Capitol Improvement planning
A Precise and relative model
Labor investment and
quantity/quality of geospatial
and W.Q. data affects accuracy

6. Why an SRA?
Massive effort needed to affect
change in WQ
Disproportionate (insufficient)
funding resources
Disproportionate (insufficient)
labor resources
TMDL implementation guidance
Assurance of “bang-for-buck”
Challenges
Little-to-no outfall and source-
area field data
Limited time and budgets
25 SRA’s completed in 2.5 years by SWCD’s with
at least 5 more currently being worked on

7. The Plus Side
>30 years of pollutant
accumulation, behavior and
washoff data available
>20 years of BMP performance
data with more recent, state-of-
science research (bench and field)
Midwest city data (loading)
Several water quality models
based on this research
If outfall data exists, can be
calibrated to improve accuracy
Can easily be modified (build-
scenarios)
Repeatable (precise) 25 SRA’s completed in 2.5 years by SWCD’s with
at least 5 more currently being worked on
Multiple-year to-do-list based on
value (lbs/$/yr)

8. 1-Selection of Subwatershed
2-Ananlysis of SW’s Catchments
3-Analysis of BMP’s by site

9. Scoping and Remote Data collection
Desktop Analysis
Field Reconnaissance
Treatment modeling and cost analysis
Report

10. Scoping
Water body needs
LGU needs
Existing data review (quality and needs)
Budgets and timeframes
Stakeholder consensus
Desktop Analysis
Field Reconnaissance
Treatment modeling and cost analysis
Report

11. Scoping and Remote Data collection
Desktop Analysis
Catchment and/or pipeshed delineation
Delineate and classify land uses
Delineate and classify permeable surface soils
Analyze existing WQ treatment / base load model
First-tier elimination of catchments for retrofitting
First-tier determination of WQ potential treatments
Field Reconnaissance
Treatment modeling and cost analysis
Report

12. Scoping and Remote Data collection
Desktop Analysis
Field Reconnaissance
Visit existing BMPs
Confirm/modify land-use and storm sewer data
Confirm/modify initial BMP-family selection
Selection of 1° and 2° BMP sites (parcels)
Site-specific data collection
Treatment modeling and cost analysis
Report

13. Scoping and Remote Data collection
Desktop Analysis
Field Reconnaissance
Treatment modeling and cost analysis
Development and optimization of BMP design
Iterations of “train” and/or level of treatment by
BMP quantity – load reduction estimates
Estimates of installation and life-cycle costs
Life-Cycle Cost analysis
Report

14. Scoping and Remote Data collection
Desktop Analysis
Field Reconnaissance
Treatment modeling and cost analysis
Report
Summary table – catchments ranked based on
performance ($/lb/LCyr)
Catchment profiles
Analysis methods and data
References

15. Subwatershed Catchment Site
S1
C1 S2
SW #1 C2 S3
C3 S4
C… S5
S…

16. Existing
Stormwater
Ponds
Storage
Above
Public Land
Roadway
Culverts
STORMWATER
BMP
LOCATION Storage
Large
Parking Lots ANALYSIS Below
Outfalls
Within
Storage in
Conveyance
ROW
System

17. Extended
Detention
Existing
Pond Wet Ponds
Modification
Other Wetlands
BMPS
Swales Bioretention
Infiltration Filtration

18. Pleasant Lake Stormwater Retrofit Assessment, 2011

19. Laek McKusick existing stormwater routing diagram, MSCWMO

20. Lily Lake Stormwater Retrofit Assessment, 2009, Middle St. Croix WMO

21. Pleasant Lake Stormwater Retrofit Assessment, 2011

22. Pleasant Lake Stormwater Retrofit Assessment, 2011

23. Pleasant Lake Stormwater Retrofit Assessment, 2011

24. Pleasant Lake Stormwater Retrofit Assessment, 2011

25. Howard Lake Stormwater Retrofit Assessment

27. 34-Acre Medium Density
Residential Area
Pollutant Amt/year
Water Runoff 963,715 ft3
TSS 12,900 lbs
TP 35 lbs
TKN 128 lbs
Copper 0.73 lbs
Lead 1.34 lbs
Zinc 5.80 lbs
First Tier possible BMP
locations
Lindstrom Retrofit
Assessment, 2009,
Chisago SWCD

29. EXISTING
CONDITIONS RETROFIT OPTIONS
Catchment-based
Base Marginal Network Treatment By BMP
Cost/Benefit Analysis Loading
Treatment
Level 1 Level 2 Level 3
Existing BMP performance (%TP) 54% New Net % New Net % New Net %
TP (lb/yr) 25.2 13.7 1.0 58% 1.9 62%
Treatment
TSS (lb/yr) 7887 6698 261 88% 357 89%
Volume (acre-feet/yr) 21.90 0.00 0.00 0% 2.40 11%
Square feet of practice (or, CU FT of Exc. 3 ft below
1500
storage for WP, ED, SW) outlet
Moderately
Extended Not yet
BMP Type Wet Pond Complex
Detention advised
Marginal Costs
Bioretention
Materials/Labor/Design $30,000 $51,000
Unit Promotion & Admin Costs* $250 $254
Total Project Cost** $30,250 $54,803
Annual O&M $0 $1,125
Term Cost/lb/yr (30 yr) $1,008 $1,554
add 6 RG in
Retrofit Scenario: exc 3 ft on P27 19

30. Catchment or Retro Type Qty of TP TP Volume Overall Est. O&M Total Est.
3 1
Pond ID 100 ft Reduction Reduction Reduction Cost Term Term
BMPs (%) (lb/yr) (ac-ft/yr) (years) Cost/lb-
TP/yr
LILY-03 B 12 10 5 4 $19,900 30 $313
LILY-04 B, PS, VS 8 10 3.3 2.9 $14,150 30 $313
LILY-01 B 11 10 4.4 3.6 $17,650 30 $315
LILY-02 B 11 10 4.5 3.7 $18,000 30 $315
LILY-12 B 18 10 3.2 2.5 $12,000 30 $316
LILY-07 B, VS 20 20 7 5.8 $24,000 30 $318
LILY-09 B 11 20 4.3 3.6 $18,450 30 $337
LILY-22 B 14 20 2.5 4.2 $22,320 30 $352
LILY-10 B, PS, F 7 10 2.9 2.4 $15,225 30 $353
LILY-21 B 12 20 2.2 3.6 $19,325 30 $353
2
P13-W PM n/a 50 20 0 $130,000 15 $433
2
P18-W PM n/a 50 30 0 $265,000 15 $589
Lily Lake Stormwater Retrofit Assessment, 2009, Middle St. Croix WMO

32. http://www.metrocd.org/