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Criterion Details

PD-08 Stormwater Quality and Flow Control

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Project Development Scorecard

  • Rural Basic
  • Urban Basic
  • Rural Extended
  • Urban Extended

Goal

Improve stormwater quality from the impacts of the project and control flow to minimize their erosive effects on receiving water bodies and related water resources, using management methods and practices that reduce the impacts associated with development and redevelopment.

Sustainability Linkage

Triple Bottom Line

Implementing more sustainable stormwater management practices supports the environmental principle by improving water quality, managing runoff, and using technology that mimics natural hydrology.

Background & Scoring Requirements

Background

See PD-24: Low Impact Development for scoring of BMPs used on the project.

Scoring Requirements

To calculate the total number of points achieved for this criterion, follow the directions in each of the scoring sections below for Water Quality, Flow Control, and Low-Impact Development (LID), and add the points achieved in each of the three areas up to a maximum of six points total.

Requirement PD-08.1

1-3 points. Water Quality Treatment

Treat target pollutants from at least 80 percent of the total annual runoff volume. To calculate the points earned for this scoring requirement, follow Steps 1 through 4 below:

Step 1    Calculate the Amount of Runoff Treated (as a percentage of annual volume).

Step 2    Determine which target pollutants the project’s water quality treatment system is designed to treat (sediments or sediments, metals and other basin-specific pollutants).

Step 3    Calculate the Target Impervious Surface Area Treated as a percentage of added impervious surface area). For retrofit projects, use Table PD-08.1.A on the next page to calculate the equivalent value to use for Target Impervious Surface Area.

TABLE PD-08.1.A. RETROFIT PROJECTS – CALCULATING EQUIVALENT TARGET IMPERVIOUS SURFACE AREA

Step 4    Use the Amount of Runoff Treated from Step 1, the Target Pollutants from Step 2, and the Target Impervious Surface Area Treated from Step 3 in Table PD-08.1.B to calculate the points earned for water quality treatment.

TABLE PD-08.1.B. POINTS EARNED FOR WATER QUALITY TREATMENT

Requirement PD-08.2

1-3 points. Flow Control

Manage the flow from at least 80 percent of the total annual runoff volume. To calculate the points earned for this scoring requirement, follow Steps 5 through 8 below (the steps for this scoring requirement start at 5 to avoid confusion with scoring requirement PD-08.1).

Step 5    Calculate the Amount of Runoff Managed through flow control (as a percentage of total volume).

Step 6    Determine if the flow control standard used is based on peak rates or flow durations.

Step 7    Calculate the Target Impervious Surface Area Managed (as a percent of Added Impervious Surface Area). For retrofit projects, use Table PD-08.2.A to calculate the equivalent value to use for Target Impervious Surface Area.

TABLE PD-08.2.A. RETROFIT PROJECTS – CALCULATING EQUIVALENT TARGET IMPERVIOUS SURFACE AREA

Step 8    Use the Amount of Runoff Managed from Step 5, the Flow Control Standard Used from Step 6, and the Target Impervious Surface Area Treated from Step 7 in Table PD-08.2.B to calculate the points earned for flow control management.

TABLE PD-08.2.B. POINTS EARNED FOR FLOW CONTROL MANAGED

Resources

None referenced.

Case Studies & Criterion Examples

George V. Voinovich Bridge: INVEST helped ODOT improve the sustainability of the largest project in ODOT history, the replacement of the Cleveland Innerbelt Bridge on I‐90, now called the George V. Voinovich Bridge. The project has two phases – the first was construction of the westbound bridge, completed in 2013; the second phase, design and construction of the eastbound bridge, began in 2014. ODOT used the pilot version of INVEST to score the first phase to see if the project was meeting its goals. ODOT found the process so valuable, that for the second phase of the project, the agency stipulated in its request for proposals that the contractor use INVEST to demonstrate sustainability. The George V. Voinovich Bridge project provides an example of scoring and documenting the INVEST stormwater management criterion.

TxDOT - Embedding INVEST in Contracting for the Corpus Christi Harbor Bridge: The Texas Department of Transportation (TxDOT) used INVEST during the procurement process for the Harbor Bridge Project in Corpus Christi. TxDOT’s request for proposals (RFP) required that bidders describe how their proposal would meet a “Platinum” rating on the INVEST PD module and a “Silver” rating on the INVEST OM module. The sustainability score, along with price and other factors, was part of the total score for selecting among the four bidders. This provided a strong incentive for bidders to achieve high sustainability at low cost. The winning bidder committed to a range of sustainability practices that will bring tangible benefits to the community.

Arizona DOT - Using INVEST to Integrate Sustainability: The Arizona Department of Transportation (ADOT) decided to use all three modules of INVEST – System Planning, Project Development, and Operations and Maintenance – to help the agency meet its sustainability goals across the transportation life cycle.  ADOT used INVEST to integrate and advance existing sustainability efforts and to push forward new efforts.  INVEST’s comprehensive sustainability framework and criteria helped ADOT institutionalize sustainability across the agency and with local partners through inclusion in manuals, trainings, and awards.  This case study focuses on ADOT’s use of the Project Development module.

Scoring Sources

The project is considered to have met this criterion if the requirements above can be reasonably substantiated through the existence of one or more of the following documentation sources (or equal where not available):

  1. Project Drainage Report or other relevant calculations and studies.
  2. Project Contract Documents.