Night-Time Sewer Strike and Downstream Drinking-Water Intake
At 22:40, a contractor's excavator strikes a 200 mm gravity sewer. You estimate 12 m³ of raw sewage has entered a storm sewer that outfalls to Mill Creek about 250 m away. The creek flows toward a drinking-water intake 6 km downstream. No basements are affected. Your permit states: any discharge to surface water requires immediate notification to the regulator and the downstream water utility; a public advisory is required if a recreational area is affected; samples must be collected if safe; and a written report is due within five days. The contractor says, “If we push it back into the sewer and don't report it, nobody will know.” Your supervisor is not answering the phone.
1. Decide whether the spill is reportable and list your immediate actions in order, including the contractor's suggestion.
Read the worked answer
Reportable. Sewage has entered a storm sewer and is 250 m from surface water, with a drinking-water intake 6 km downstream. The contractor's suggestion is not an option: failing to report and concealing a discharge is an offence and exposes the water utility and public.
Order: stop/contain the source (plug, bypass, sandbags), protect the public, call the regulator and water utility immediately, notify the internal chain even if the supervisor is unavailable, collect samples if safe, and begin the written report. Do not delay notification to wait for the supervisor.
2. What information must you have ready for the notifications, and what samples and records would you collect?
Read the worked answer
Have ready: location, time discovered, estimated volume (12 m³), duration, source and cause, receiving water and distance (Mill Creek, 250 m), downstream intake (6 km), weather, actions taken, contractor details, and contacts.
Collect upstream/downstream samples, field parameters (pH, temperature, DO, conductivity, H2S), photos, chain-of-custody, flow estimates, and a timeline. Keep the contractor's equipment and notes; record the suggestion and your response.
3. At 01:00 the contractor offers to cover the cost of a “quiet” cleanup if you delay reporting until morning. How do you respond, and what might change if the creek is a designated swimming area?
Read the worked answer
Refuse. Delaying until morning is a concealed discharge and would violate the permit; immediate notification is required regardless of cost or convenience. Document the offer.
If the creek is a designated swimming/recreation area, the public advisory requirement is triggered immediately: post signs, notify the recreation authority, and expand sampling. The five-day written report is still required, but it does not replace the immediate call.