Putting the “LID” on Water Pollution New Water Quality Requirements for Land Use County of Orange Mary Anne Skorpanich Richard Boon.

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