On December 1, 2009, the US Environmental Protection Agency (EPA) finalized and published a rule in the Federal Register establishing, for the first time, numeric effluent limitation guidelines (ELGs). The numeric ELGs include turbidity limits and sampling requirements for stormwater discharges from construction sites. The original rule requires that sites that disturb 20 or more acres of land at one time are required to comply with a turbidity limit of 280 NTUs. In August 2010, EPA agreed to defer implementation of the rule and conduct additional analysis after being challenged in court by a number of parties. It is likely a new turbidity limit will be developed that will still be numeric but somewhat higher than the original requirement.
These new requirements will place a special burden on DOTs and other entities, whose construction projects are linear in nature. Sampling of runoff on an active highway construction site can be technically difficult because of safety, access, and the number of potential discharge locations. In addition, the constantly changing conditions on the site will make the installation of permanent sampling sites infeasible.
There are two primary objectives of this research. The first is to develop guidance for linear construction projects to help DOTs meet the impending numeric discharge limits. Construction projects pass through a number of discrete phases beginning with clearing and grubbing through final stabilization. The numeric standard must be met during each of these. Consequently, appropriate BMPs and guidance on their use must be developed for each phase of construction. Recent research on polymers has focused on sediment control, but additional work is needed on erosion control in early phases of construction before final grade is established.
The second objective is to develop monitoring protocols that DOTs can present to their state regulators. Each state is allowed to adopt its own monitoring requirements and it is critical that those requirements recognize the special difficulties of monitoring on highway construction sites. Questions that need to be addressed include the following:
- Must all discharge locations be monitored?
- Can representative locations be designated that are typical for the project?
- What is the appropriate frequency of sample collection?
- How should samples be collected (grab or automated samples)?
- What should the requirements be for sampling outside of normal work hours?
- How should access and safety impact sampling requirements?
STATUS UPDATE: October 2011: The Project 10-90 Panel is holding the issuance of the RFP for this project pending publication of final EPA Effluent Limitation Guidelines.
April 2012: The project panel will convene in July-August 2012 to discuss future course of action.
August 2012: The project panel reviewed the final report for NCHRP 25-25/Task 74 and decided to hold the project pending publication of final EPA Effluent Limitation Guidelines. The panel will teleconference in May 2013 to discuss further course of action.
May 2013: The project panel decided to hold the project until February 2014.
February 2014: The project panel decided to hold the project for 6 more months. A panel teleconference is scheduled for July 2014.