Construction Stormwater Exceedance and a Contractor's Silence Request
At a 22-acre residential construction site covered by a state construction general permit, the SWPPP requires weekly inspections, a sediment basin sized for the 2-year, 24-hour storm, and a turbidity benchmark of 50 NTU as a daily maximum at Outfall 001. After a 1.2-inch rain, your sampling technician reports 210 NTU at the outfall. The technician also notes that the concrete washout pit has no liner and is 15 feet from a roadside ditch. The sediment basin is half full of sediment, and the last inspection form was signed 19 days ago. The general contractor tells you to 'wait for the next rain' before reporting because the discharge was diluted and the project is behind schedule. The permit requires oral notification within 24 hours for a discharge that causes or contributes to a violation of a water quality standard.
1. Determine whether this is a reportable permit violation and explain the basis, including the roles of the benchmark, the 24-hour notification, and the inspector's observations.
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The 210 NTU result exceeds the 50 NTU benchmark, but a benchmark is often a trigger for corrective action and additional monitoring rather than an automatic permit limit; the permit language controls. The stronger violations are SWPPP implementation failures: the last inspection was 19 days ago against a weekly requirement, the sediment basin is half full, and the unlined concrete washout is 15 feet from a ditch. Those are permit conditions. The 24-hour oral notification applies to a discharge that causes or contributes to a water quality standard violation. A 210 NTU discharge with visible sediment escaping toward a roadside ditch is credible evidence of a turbidity or sediment violation, so waiting for the next rain is not defensible. Report orally within 24 hours, follow with the required written report, and include the sample result, visual observations, BMP failures, and corrective actions.
2. List immediate corrective actions and the revised inspection and maintenance schedule.
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Immediately stop discharges from the concrete washout, install a lined or manufactured washout, and berm the ditch to prevent further migration. Clean any sediment that entered the ditch and dewater or clean the sediment basin. Inspect all BMPs, repair or replace silt fence, and stabilize exposed soils. Reinstate weekly inspections and inspections after every 0.5 inch of rain, with signed forms and photographs. Sample again after repairs and during the next discharge. Update the SWPPP to reflect the washout location, a basin maintenance threshold such as 50% capacity, and the inspection schedule. Train the site crew on washout use and spill response. Notify the permit authority and the owner, and keep a log of all corrective actions until the site is stabilized.
3. How do you handle the contractor's instruction not to report?
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I cannot follow the instruction to wait. The permit's 24-hour notification is a legal obligation, and the inspection gaps and BMP failures are documented. Waiting for the next rain would compound the violation and could allow more sediment to reach waters. I would tell the contractor that I am reporting, offer to include the contractor's corrective commitments in the report, and escalate to the owner's project manager and legal counsel. If the contractor interferes, I would document the instruction and report as required. Professional ethics require protecting public health and the environment and complying with the law; schedule pressure is not a defense. I would also document the contractor's instruction in the project file in case the regulator asks about delay.