Putting the “LID”on Water Pollution
New Water Quality
Requirements for Land Use
County of Orange Mary Anne Skorpanich
Richard Boon
Overview
1. Introduction
2. Key Terms
3. Regulatory Framework
4. WQMP Process
5. Schedule
6. Questions
Urban Runoff Effects
There are four interrelated but separable effects of land-use changes on the hydrology of an area:
• changes in peak flow characteristics,
• changes in total runoff,
• changes in quality of water,
• and changes in the hydrologic amenities.
--Luna Leopold, 1968
Low Impact Development: LID
The low-impact development “functional landscape” emulates the predevelopment temporary storage (detention) and infiltration (retention) functions of the site.
This functional landscape is designed to mimic the predevelopment hydrologic conditions through runoff volume control, peak runoff rate control, flow frequency/duration control, and water quality control.
--Low Impact Development Hydrologic Analysis, The Prince George’s County DER, 1999. p.11
Water Quality Management Plan
• A project submittal that describes the Best Management Practices that will be implemented and maintained throughout the life of a project.
• Conceptual and/or Preliminary WQMPs
• Final Project WQMPs
Municipal Stormwater Permits
• Require County, OCFCD and cities to:
• Effectively prohibit non-stormwater discharges into the municipal drainage system
• Implement controls on stormwater pollution to the maximum extent practicable
• Prescribes a management program
• Drainage Area Management Plan
• Section 7.0 - Land Development
• Renewed in 1990, 1996, 2002, 2009
2009 Stormwater Permits: Land Development
Santa Ana Region San Diego Region
LID: On- or off-site 85th percentile storm volume capture for LID and water quality
LID: On-site 85th percentile storm volume capture for LID and water quality
Hydromodification: 2 year storm volume capture for discharges to susceptible channels
Hydromodification: (0.1)2 year-10 year storm volume hydrograph matching
Land Development Program Revamp2003 Stormwater Permits
Priority Projects must treat the design storm runoff volume
2009 Stormwater PermitsPriority Projects must retain the design storm runoff volume using LID
and/or participate in alternative compliance mechanisms
Priority Projects must address hydromodification
Consultation Process
• Permittee Advisory Group, PAG
• Technical Advisory Group, TAG
• Building industry representatives, OCBC
• Engineering, geotechnical, and landscape architecture professional associations
• Water and wastewater agencies
• OC Coastkeeper, Natural Resources Defense Council
• Federal and state regulators
• Meetings held October 2009 - 2011
Priority Projects (I)
• New development projects that create 10,000 ft2 or more of impervious surface
• Automotive repair shops
• Restaurants where the land area of development is 5,000 ft2 or more, including parking area
• Hillside developments of 5,000 ft2 or more
• Parking lots of 5,000 ft2 or more
Priority Projects (II)
• Impervious surface of 2,500 ft2 or more located within, directly adjacent to, or discharging directly into receiving waters within Environmentally Sensitive Areas
• Streets, roads, highways, and freeways
• All significant redevelopment projects: the addition or replacement of 5,000 ft2 or more of impervious surface on an already developed site
• Retail Gasoline Outlets
WQMP Process, North Orange County
LID Hierarchy
1. On-site Infiltration
2. On-site Evapotranspiration
3. On-site Harvest and Reuse
4. On-site Bio-treatment
5. Off-site LID
6. In-lieu fee
Developing a Project WQMP
Infiltration
Evapotranspiration, Harvest & Use, Bio-Treatment
Regional Retention
Resources
Schedule
• Submit Proposed Model WQMP and Technical Guidance Document to Santa Ana Regional Board (March 22, 2011)
• Board Approval of Model WQMP (April 22, 2011)
• Model WQMP implementation (August, 2011)
• Submit Updated Model WQMP (SUSMP) to San Diego Regional Board (December, 2011)
Questions
www.ocwatersheds.com
office: 714 955 0670
24-hour hotline: 877 89 SPILL
