Details
Type: Bulletin
Topic or Program: Hydraulics | Water Resources
Final Number: HE24-02(B)
Effective Date: 12/06/2024
Updated Date: 12/06/2024
Signature on File: Paul R. Wirfs, State Hydraulic Engineer
Purpose
This bulletin provides direction to ODOT employees on compliance with the turbidity monitoring and reporting requirements of Clean Water Act (CWA) Section 401 water quality certifications (WQC) for projects covered by federal permits.
NOTE: This bulletin does not address turbidity monitoring requirements of other regulations or permits, such as the National Pollutant Discharge Elimination System Stormwater Discharge Permit 1200-CA or the Oregon Department of State Lands (DSL) removal/fill permit. These or other permits may require monitoring turbidity according to other protocols, in addition to those of the WQC.
Guidance
Contract specifications require compliance with environmental permits. If in any case any of the following guidance is determined to be inconsistent with a contract’s specifications or permit, the terms of the contract or permit take precedence.
Monitoring Protocol
WQCs issued by Oregon Department of Environmental Quality (DEQ) require the permittee to implement best management practices (BMPs) to minimize and monitor turbidity during work in water[1]. This includes:
- Work that occurs within jurisdictional waters of the state below the water surface,and
- Work that would be below the water surface were it not for artificial dewatering of the work area.
Merely having properly functioning isolation BMPs in place does not by itself constitute “work in water.”
The WQC prescribes the required turbidity monitoring protocol including the monitoring method, frequency, sampling location, “stop work” thresholds, and recording procedure. Construction contract special provision SP00290.30(a)(8) requires contractors to conduct turbidity monitoring as described in the WQC issued for the project and report the results on the ODOT Turbidity Monitoring Report (Form# 734-2755).
The WQC requires all turbidity monitoring reports to be available for inspection by DEQ and other regulators upon request. After project completion, the reports should be filed with the other project documents and retained according to ODOT’s record retention schedules for construction and permit compliance records. Even while work is not being performed in water, if routine observations indicate that isolation BMPs are not adequately preventing turbidity in the non-isolated water body, the BMPs must be repaired or upgraded.
Turbidity Control During Construction
The WQC and contract provisions require BMPs to be implemented, repaired, upgraded, and documented as needed to meet turbidity criteria, and require work in water to cease if turbidity exceeds the specified stop-work threshold (typically 50 nephelometric turbidity units, or NTU, above background conditions).
Definitions
- Best management practices (BMPs)
- Structures and actions intended to prevent or reduce the generation or release of turbidity into surface waters.
- Clean Water Act (CWA) Section 401 water quality certification (WQC)
- A written certification by DEQ that the action authorized by a federal permit (such as a U.S. Army Corps of Engineers dredge/fill Section 404 permit) will comply with the federal CWA and state water quality standards if conducted according to the limits and conditions contained in the certification.
- Nephelometric turbidity units (NTU)
- The unit of measurement of turbidity used by ODOT, its contractors, and its regulators.
- Turbidity
- The extent to which sediment and other particles suspended in water scatter and absorb light. When caused by sediment, turbid water appears cloudy and dark.
- Turbidity monitoring report
- A report that documents compliance with turbidity criteria by recording the results of turbidity monitoring and actions taken to address elevated turbidity.
- Work in water
- Work that occurs within jurisdictional waters of the state below the water surface, or which would be below the water surface were it not for artificial dewatering of the work area. “Work in water” does not include merely having properly functioning isolation BMPs in place.
Background/Reference
A CWA Section 404 permit is often required for work in waters of the United States, and the 404 permit in turn requires a WQC from DEQ. Generally, an individual WQC must be obtained for any project that requires either a standard individual 404 permit or a nationwide 404 permit with a preconstruction notification requirement.
WQCs contain conditions intended to ensure state water quality standards are met, including turbidity control and monitoring, and specific actions to take if turbidity limits are exceeded. In Oregon, DEQ issues the WQC for all 404 permits except for projects on certain Indian lands.
The ODOT Turbidity Monitoring Report (Form# 734-2755) is designed to include all reporting requirements of the WQC. Included in the form is information on monitoring/sampling locations, monitoring intervals, turbidity thresholds, and required responses. The form should suffice for most turbidity monitoring performed under WQCs but may be modified for project-specific requirements.
Responsibilities
Water resources program coordinator within the Hydraulic Engineering Section of the Engineering and Technical Services Branch shall:
- Provide training, support, and guidance to construction inspectors, consultants, contractors and regional staff on turbidity monitoring requirements.
- Maintain special provisions, operational notices, bulletins, and other guidance documents relating to turbidity monitoring.
Project Delivery team shall:
- Add special provision SP00290.30(a)(8) to project contracts according to the instructions to staff found in the boilerplate special provision document. Consult with water resources program coordinator as needed regarding BMP implementation, monitoring requirements, and turbidity exceedances.
- Partner with and provide feedback to the water resources program coordinator as needed to make program-level changes to improve compliance with the turbidity control and monitoring requirements.
- Obtain 404 permits and WQCs from regulators, as well as permit modifications when requested by resident engineers during construction.
- Ensure that the contractor has physical and legal access to upstream and downstream sites necessary to monitor turbidity.
Construction inspectors[2]:
Read and understand applicable permits, including when, where, and how contractors are required to monitor turbidity.
- Observe contractor turbidity monitoring and review turbidity monitoring reports.
- Stop or modify work as appropriate when project-caused turbidity levels exceed thresholds indicated in the permits and contract specifications.
Construction resident engineers:
- Ensure monitoring and reporting is done per permit requirements.
- Ensure that construction inspectors are familiar with the requirements of this bulletin.
- Advise regions when permit modifications are required.
Construction contractors:
- Coordinate with resident engineers and construction inspectors as needed.
- Carry out contract specifications, including those relating to turbidity monitoring.
Special Instructions
Failure to monitor turbidity and provide turbidity monitoring reports when requested by the appropriate agencies constitutes a permit violation. This may result in enforcement action by DEQ which may include a civil penalty assessment for each day of violation.
Footnotes
- Nearly every DEQ WQC requires turbidity monitoring “during in-water work.” However, DEQ has clarified that they are using this phrase to mean work within actual water or dewatered areas, and not in the more commonly understood sense that DSL and ODFW use it. To avoid confusion, this bulletin doesn’t use the phrase “in-water work.”
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- Directing the activities of Construction or contractors is outside the scope and authority of this bulletin. The responsibilities of construction inspectors, resident engineers, and contractors described here are intended to provide the general and usual roles of these personnel in turbidity monitoring and is not prescriptive.
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