Using Model Ordinances and LID Design Guidance Manuals to Overcome Implementation Obstacles

Chris Conway, CPSWQLynn Orphan, P.E.

Kennedy/Jenks ConsutlantsTerri Svetich, P.E.

Truckee Meadows Storm Water Program Coordinator

Central Coast RWQCB WorkshopSan Luis Obispo - November 18, 2005

Outline

I. LID Principles & Practices

II. Recommended Policies & Procedures

III. Tools to Promote LID

IV. LID Design Considerations

V. Monitoring Program Success

What is LID?

Design features and practices distributed throughout urban development that:

Disconnect Impervious Surfaces

Mimic Natural Hydrologic Processes

Reduce Runoff Rates & Volumes

Reduce Pollutant Loads

Pioneered in Maryland 1985 to address economic and environmental issues

Applied to western communities such as:

Denver, Boise, Phoenix, Los Angeles, San Diego, San Francisco, Portland, and Seattle

Evolution of Low Impact

Development

Boise, ID

Portland, OR

Reno, NV

Carson City, NV

Porous Pavement at Lake Tahoe

Cluster Development & Open Space Preservation

How Do We Implement LID?

The Truckee River Watershed

Lake Tahoe to Pyramid Lake

Pollutants of Concern

Fine Sediment & Lake Clarity

TSS, N, P, TDS, Temp, & Turbidity

The Truckee Meadows

Reno, Sparks, Washoe Co.

Rapid Urban Development

TMDLs: N, P, TDS

Non Point Source Control

LID & Public Outreach

Reno Whitewater Park

Professional Advisory Group (PAG)

Formed in 2004 to develop recommended policies & procedures for implementing treatment controls and LID

PAG Members (Stakeholders):

Developers and Engineers

Builders, Contractors & Landscaping Associations

Community Development, Public Works & Maintenance

Regional Water Planning Commissioners

Environmental Interests

Recommended Policies & Procedures

1. Plan Review & Permitting

2. Construction Inspection

3. Tracking & Maintenance Notification

4. Long-term Operation & Maintenance

5. Inspection & Enforcement

6. Training & Public Outreach

Plan Review and Permitting

All projects that will disturb one acre or more:

Require storm water quality and soils information in drainage, hydrology and geotechnical reports

Display treatment controls and LID practices on proposed private and public development site plans

Enforce existing policies to preserve natural drainage ways and groundwater recharge zones

Require standard design criteria

If infiltration proposed, testing required

Apply existing building permit and/or environmental control permit process to storm water BMPs

Construction Inspection Inspections by environmental control, other agency

staff, or the engineer of record during construction

Provide GPS coordinates of completed facilities to the appropriate jurisdiction

Tracking and Maintenance Notification

Cities and County:

Track the type, location and ownership of treatment controls and LID practices using a GIS

Notify BMP owners maintenance required

Link BMP GIS to County Assessors database

Operation and Maintenance

Require O&M plans that include maps of facilities, define O&M requirements, and responsible parties

O&M Responsibility & Funding

Property owners of industrial, commercial and civic (i.e. churches & schools) land uses

City or County for public facilities and residential developments (Not HOAs!)

Maintenance easements and funding mechanisms (i.e. Drainage Districts, Storm Water Utilities, etc.)

O&M by agency staff or maintenance contractor

Inspection and Enforcement

Cities and County:

Apply existing legal mechanisms and agency inspection and enforcement procedures

Apply industrial storm water discharge permit classifications to determine inspection frequencies

Adopt City of Reno construction inspection procedure ($100 re-inspection fee)

Training

Develop annual training sessions:

1. Design training for engineers, planners, landscape architects and agency staff

2. O&M training for property BMP owners, operators and agency inspection and maintenance staff

Low cost training developed through NWEA and UNCE

Certificate of completion

Nonpoint Source Education for Municipal Officials (NEMO)

LID Seminars & Workshops

Water Watch by Storm Center

Public Education & Outreach

Additional Tools to Promote LID

1. Design examples and standard details

2. Streamline plan review & permitting

3. Egineering tools & financial incentives

4. LID demonstration projects

NRCS Soils Maps

1. Water Quality Volume (WQV) - Landscape Detention Basin Storage

a) Percent of Watershed Impervious Area = I I = 85 %

b) Drainage Area = A (ft2) A = 14,000 ft2

c) Watershed Runoff Coefficient = Rv (unitless) Rv = 0.82

d) 90th Percentile Precipitation Depth = P (inches) P = 0.60 inches

e) Water Quality Volume = WQV (ft3) WQV = 571 ft3

2. Landscape Detention Basin Dimensions

a) Ponding Depth = DWQV (6-inch minimum, 12-inch maximum) DW QV = 12.0 inches

b) Surface Area (SA) of basin = WQV/DWQV SA = 571 ft2

Standard Design Forms

Blue cells: Designer enters site specific data

Yellow cells: Write protected formulas produce design data

LID vs. Conventional Storm Drainage for a 2 acre Parking Lot

1. Conventional Storm Drain System (catch basins and storm drain pipes)

2. Landscape Detention with Underdrains (poorly drain soils, e.g. clayey soils)

3. Landscape Detention without Underdrains (well drained soils, e.g. sandy soils)

200’

420’

10

’

60’

20

’Conventional Storm Drain SystemConcrete pipe & mounded landscaping

3 catch basins, 1 manhole, 200’ of 12” RCP, 75’ of 18” RCP

Catch BasinManhole

18

” R

CP

12” RCP

Increased flow rate, volume and pollutant loadingIncreased flow rate, volume and pollutant loading

Landscape Detention (Bioretention)

Physical, Chemical & Biological Physical, Chemical & Biological Processes Reduce PollutantsProcesses Reduce Pollutants

Source: Center for Watershed Protection

Landscape Detention (Bioretention)

200’

420’

10

’

60’

20

’Landscape Detention with 5 Underdrains1 catch basin, 1 manhole, 75’ of 12” RCP, 670’ of 4” PVC

5 bioretention basins, all with underdrain systems

(167 CY engineered soil, 75 CY Type 2 aggregate)

Bioretention & Underdrain

4” PVC

12

” R

CP

4” P

VC

SwaleSwale

Inflow & Overflow via curb cuts

Overflow to SD system

Inflow via curb cuts

200’

420’

10

’

60’

20

’Landscape Detention with 3 Underdrains1 catch basin, 1 manhole, 75’ of 12” RCP, 410’ of 4” RCP

5 bioretention basins, 3 with underdrain systems

(167 CY engineered soil, 75 CY Type 2 aggregate)

4” PVC

12

” R

CP

Bioretention & Underdrain

Inflow & Overflow via curb cuts

SwaleSwale

Overflow to SD system

Inflow via curb cuts

200’

420’

10

’

60’

20

’Landscape Detention without Underdrains

5 infiltration tests, 1 catch basin, 25’ of 12” RCP

5 bioretention basins with no underdrain system

(167 CY eng soil, 74 CY Type 2 aggregate)

SwaleSwale

Bioretention & Infiltration

Inflow & Overflow via curb cuts

Overflow to SD system

Inflow via curb cuts

LID Cost Comparison

Landscape detention scenarios reduce pollutant loads by 80 – 90% and retain approximately 4,000 ft3

of storm water runoff onsite = 100% of 5-yr storm

1. Conventional Storm Drain System approx. $31,000

2. Landscape Detention with Underdrain approx. $29,000 to $36,100

3. Landscape Detention without Underdrain approx. $15,000

LID Design ConsiderationsPrevent groundwater contamination

Proper siting of infiltration systems essential

Infiltration rates 0.5 to 2.4 in/hr (120 to 25 min/in)

150 ft or more from drinking water wells

Pretreatment recommended

Keep storm water out of crawl spaces Proper grading

Good ventilation

Foundation Drains

Prevent mosquito breeding No standing water 7 days or more (May - October)

Proper design and maintenance required

Monitoring Monitoring Program SuccessProgram Success

Codes & Ordinances Adopted and EnforcedCodes & Ordinances Adopted and Enforced Standard Design Forms UtilizedStandard Design Forms Utilized LID Demonstration Projects ImplementedLID Demonstration Projects Implemented Professional Training EstablishedProfessional Training Established Public Awareness IncreasedPublic Awareness Increased

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