Stormwater retrofit goals may include, among other things, the correction of prior design or performance deficiencies, flood mitigation, disconnecting impervious areas, improving recharge and infiltration performance, addressing pollutants of concern, demonstrating new technologies and supporting stream restoration activities.
Retrofits include new installations or upgrades to existing BMPs in developed areas where there is a lack of adequate stormwater treatment.
The public is likely unaware of the permit requirements to upgrade urban infrastructure and this practice is perceived as maintenance to existing facilities.
Difficult. Requires engineering and engagement with U.S. Environmental Protection Agency officials to ensure permit compliance. This work is typically carried out within local departments of public works or similar responsible parties.
Utility fees are the most common form of funding for these upgrades.
Cost Estimates | EPA | Average |
Initial | $26,632 | $26,632 |
Annual | $290 | $290 |
Lifespan (yrs) | 20 | 20 |
Annualized | $1,621.60 | $1,621.60 |
Total Nitrogen removed per acre treated per year
Low 1.67 lbs. |
Medium 2.73 lbs. |
High 4.83 lbs. |
Cost per pound removed = between $336 and $970
Total Phosphorous removed per acre treated per year
Low 0.20 lbs. |
Medium 0.30 lbs. |
High 0.40 lbs. |
Cost per pound removed = between $4,053 and $8,159
Total Suspended Solids removed per acre of practice per year
Low 83 lbs. |
Medium 388 lbs. |
High 573 lbs. |
Cost per pound removed = between $2.83 and $19.48
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