pf_03193 - Laserfiche WebLink

Home

Principle No. 10: Parking Lot Runoff , Table 10.2: Perceived Impediments to Parking lot Stormwater Management (Continued) Perception Facts, Case Studies, and Challenges 5. Snow removal may be FACT: Bioretention areas, filter strips and surface sand filters can be used for more difficult. snow storage in the winter months (Caraco and Claytor, 1997). 6. Quantity control 1S FACT: Some jurisdictions do allow temporary ponding of storm water in parking difficult to achieve (lot) bays when detention and space limitations are a primary with bioretention consideration (Bell, 1998). areas, sand filters, FACT: By providing storm water management at the source, these facilities can filter strips, and open channels. reduce downstream stormwater management requirements. CHALLENGE: Bioretention areas, sand filters, filter strip, and open channels. are not specifically designed to provide quantity control. Effectiveness Because most of the storm water management technology for parking lots is relatively new, only a limited amount of effectiveness data is available to evaluate the long-term performance. However, preliminary monitoring results suggest that these practices can significantly reduce sediment, nutrient, hydrocarbon, and metal loads (PGDER, 1997; Brown and Schueler, 1997). Table 10.3: Pollutant Removal Effectiveness of Stormwater Management Practices for Parking lots , Stormwater Management Pollutant Removal Effectiveness Practices Total Suspended, Total ' ,Total, Nitrogen Metals SOlids Phosphorus Bioretention facilities! Assumed comparable to the dry swale. Dry swalesz 91 % 67 % 92 % metals: 80 - 90% Sand filters!'z 85% 55 % 35 % lead 60 % Zlnc 68 % Filter strips! 70 % 10 % 30 % metals 40 - 50 % ! Claytor and Schueler, 1996; Z Brown and Schueler, 1997 Expense The major expenses for parking lot stormwater management are land acquisition, construction, and maintenance. land acquisition is particularly a concern because many parking lots are associated with commercial development. Commercial land is typically more costly than other land uses. Limiting storm water management,facilities to already required landscaped areas and setbacks could significantly reduce land acquisition costs. The real challenge is that onsite storm water management is often more costly than offsite management. However, construction costs for onsite stormwater management may be partially offset by reduced storm - 89 -