Title
The Board of Water Commissioners for the City of Detroit, Water and Sewerage Department authorizes a fee-in-lieu rate of $8.00 per gallon managed for Developers who choose the alternative compliance option under the Post Construction Stormwater Management Ordinance.
Body
Agenda of June 5, 2019
Item No. 19-00171
TO: The Honorable
Board of Water Commissioners
City of Detroit, Michigan
FROM: Gary Brown, Director
Water and Sewerage Department
RE: Fee In Lieu - Post Construction Stormwater Management Ordinance
MOTION
Upon recommendation of Palencia Mobley, Deputy Director and Chief Engineer, the Board of Water Commissioners for the City of Detroit, Water and Sewerage Department authorizes a fee-in-lieu rate of $8.00 per gallon managed for Developers who choose the alternative compliance option under the Post Construction Stormwater Management Ordinance.
BACKGROUND
The purpose of this memorandum is to provide a summary of the proposed in-lieu fee for development projects that have been approved for an alternative compliance method to comply with the post-construction stormwater management ordinance.
The Stormwater Management Group (SMG) has three sets of cost data to evaluate: 1) conceptual cost data from drainage charge credit engineering analysis; 2) construction contract amounts for green stormwater infrastructure projects that have been installed by DWSD for permit compliance and 3) cost data for other fee-in-lieu programs across the country. Due to the fact that data set 1) is conceptual in nature, we opted to exclude this information from our analysis of cost information for the proposed fee-in-lieu of ordinance compliance on-site.
Detroit Water and Sewerage Green Stormwater Infrastructure Projects
As of the date of this memorandum, DWSD has completed construction, or has achieved substantial completion of thirteen sites that include twelve individual bioretention gardens, and four permeable pavement projects. Construction costs for each of the thirteen sites along with volume managed is summarized in the table below.
Costs shown in the table do not include design and engineering, land acquisition, or long term operation and maintenance costs.
Cost Data for Fee-in-Lieu Programs Across the Country
A review of research regarding the development of payment in lieu programs across the country found that fees varied greatly. Factors that go into the development of costs for stormwater management fee in lieu data include, but are not limited to, the following:
• Redevelopment versus new development
• Engineering complexity
• Site constraints
• Native soil conditions
West Virginia
A study performed in West Virginia to develop in-lieu fees summarized cost data for bioretention practices from recent sources and is excerpted from the report below.
The study data considered costs for construction, design, land acquisition, and 20 years operation and maintenance. Excluding an outlier at Beckley #3 site which was noted to be a highly-urban, small project with concrete retaining walls, the study found that a plausible range for a fee would be between $25 and $60 per cubic foot treated ($3.34 to $8.02 per gallon treated) with the present value of 20 years of operation and maintenance costs included.
California
Another study performed by the California Stormwater Quality Association summarized implementation costs for bioretention that included planning/design, construction, and 20-year operation and maintenance. The suggested fee-in-lieu was $45 per cubic foot ($6 per gallon).
Detroit
A study performed by HR&A as part of the alternative compliance evaluation for the City of Detroit published general descriptions of selected green infrastructure treatments costs as well. The study included five different green infrastructure techniques, which are summarized in the table below.
Other
Another study evaluated four communities across the country and summarized the rate structure for the fee-in-lieu programs. The four communities evaluated were Washington DC, Aspen, CO, Park Ridge, IL, and San Antonio, TX. The in-lieu fees ranged from $3.57 per gallon retained to $10.22 per gallon detained. One community developed the fee-in-lieu rate based on a cost per square foot of impervious surface ($0.15 to $0.25 per sf).
Based on the green stormwater infrastructure projects that DWSD has already constructed, and supported by the studies referenced above, it is recommended that the fee-in-lieu cost for developers who choose this alternative compliance option be $8 per gallon managed. This is based on DWSD’s average cost per gallon treated of $5.65 plus 40% for design and engineering and operation and maintenance. The proposed fee-in-lieu cost is comparable to the fee used in many communities across the country.
Center for Watershed Protection, 2012. Guidance for Developing an Off-Site Stormwater Compliance Program in West Virginia. Prepared for West Virginia Department of Environmental Protection by Center for Watershed Protection, Inc. December 2012.