Main Break, Eleven PSI, and a Nursing Home
At 02:40 on a Sunday a 12-inch unlined cast-iron main (installed 1954) fails under a state highway in front of a 120-bed nursing home. The crew isolates it at 03:30 using two gate valves; the valve that would have confined the outage to four blocks is stuck open. A pressure logger in the affected zone records 11 psi from 03:30 to 06:15, recovering to 58 psi. Two hydrants on the dead-end side run muddy water when flushed. The repair is complete at 13:50; the main is chlorinated, flushed, and returned to service at 17:20. Normal free chlorine in the zone is 0.8 mg/L; it reads 0.35 mg/L at the nursing home tap after flushing. There are 140 service connections and one school, closed on Sunday.
1. Do you issue a boiled water notice? Defend the call, including who you notify and when.
Read the worked answer
Yes. Issue it, and issue it early.
The reasoning is pressure, not turbidity. Eleven psi held for nearly three hours is below the 20 psi threshold at which the system is presumed to have lost the barrier that keeps contaminants out. Joints, service line connections, and any leaking packing can admit groundwater and soil when the gradient reverses. The muddy hydrants confirm that sediment and quite possibly groundwater moved into the main.
Mechanics:
- Notify NJDEP as soon as the pressure loss is known - same day, and no later than the 24-hour mark. NJDEP approves the notice language and the affected area; coordinate the boundary with them rather than guessing.
- Also notify the county health department and the local office of emergency management.
- Deliver door-to-door in the affected blocks, post it, and push it to local media. The school needs it before Monday opening even though it was closed Sunday.
- Hand-deliver to the nursing home and arrange bottled water. A 120-bed facility with immunocompromised residents cannot be served by a door hanger.
- Document every notification time.
The burden of proof runs against the utility. Keep the notice up until the sampling says otherwise - lifting it early to avoid inconvenience is the mistake that turns a precaution into an outbreak.
2. What must be done and documented before the notice can be lifted?
Read the worked answer
All of the following, with records:
- Repair disinfection - the new pipe and fittings disinfected and the main chlorinated after the repair, following standard practice for main disinfection.
- Flushing - until turbidity clears at the hydrants and dead ends and the residual is restored. A 0.35 mg/L reading at the nursing home tap against a normal 0.8 mg/L says the zone is not fully recovered or not fully flushed. Find out which before you sample.
- Two rounds of coliform samples, 24 hours apart, all absent, covering the affected area and its extremities - the dead-end side, the nursing home, the school, and the blocks near the repair. A single clean round is not enough.
- Residual confirmed and held throughout the zone at a stable, normal level - not just at the plant.
- Cross-connection check - confirm that any temporary bypass or connection used during the repair has been removed.
- Valve status - the stuck valve repaired or at least exercised and logged, and all valves returned to normal position. The next break in this zone will be worse if that valve stays stuck.
- NJDEP concurrence on lifting the notice.
The 11 psi event, the low post-flush residual, and the stuck valve should all appear in the after-action record, not just the sample results.
3. To free the stuck valve, a worker must enter a 5-foot-deep valve vault on the highway shoulder. What has to be in place?
Read the worked answer
A permit-required confined space entry. Depth is not the criterion - a 5-foot vault is a confined space if it has limited entry and is not designed for continuous occupancy, and wet vaults routinely go oxygen-deficient or accumulate hydrogen sulfide. Treat it as permit-required unless it has been positively demonstrated otherwise.
Required:
- Pre-entry and continuous atmospheric testing: oxygen 19.5–23.5%, flammable gas below 10% LEL, H2S and CO within limits.
- Forced-air ventilation before and during entry.
- A written entry permit, an attendant stationed outside for the entire entry, and a retrieval system - harness, tripod, lifeline.
- Communication with the entrant and a rescue plan that does not depend on the entrant self-rescuing.
Also on this site:
- Traffic control per the MUTCD: signs, cones, high-visibility apparel, and a buffer between the work zone and live lanes. Struck-by is a bigger risk here than the vault.
- Excavation protection for the 8-foot-deep repair excavation: shoring or sloping, spoils and equipment kept back from the edge, and a competent person inspecting.
- Valve operation hazard: a stuck valve stores energy in the stem. Use the correct operator, stand clear of the stem line, and expect it to release suddenly when it breaks free.
If the crew leader says it is only five feet, that is the moment to stop the job and read the permit.