Night-time generator noise, dust and silt discharge next to a hospital
You are the environment coordinator for a 2.5-acre commercial project. The site boundary is 12 m from a residential colony and 300 m from a 200-bed hospital. Work runs in two shifts, and a 125 kVA diesel generator runs until 23:30 because grid power is unreliable. Recent readings: 78 dB(A) at the residential boundary at 22:00; PM10 260 µg/m³ at the site gate; the batching plant's wash water and silt from the excavation are discharged into the municipal storm drain; cut branches and packing waste are burnt behind the site shed; and excavated spoil is dumped on the road shoulder. Residents have complained to the municipal corporation, and an inspector is expected. The project has a Consent to Establish but no Consent to Operate yet, and the DG set has no acoustic enclosure.
1. List the violations in this scenario with the applicable standards and the measured exceedances.
Read the worked answer
- Noise: the area is residential (the hospital at 300 m is outside the 100 m silence-zone radius, so silence-zone limits do not apply). The residential night limit is 45 dB(A); 78 dB(A) exceeds it by 33 dB, which is a large exceedance, not a marginal one. DG sets also require an acoustic enclosure and must meet the prescribed noise limit at 1 m.
- Dust: PM10 of 260 µg/m³ at the gate exceeds the 24-hour NAAQS of 100 µg/m³ for residential areas.
- Water pollution: silt-laden wash water and excavation water discharged to the municipal storm drain without treatment or consent violates the Water Act, 1974; the drain ultimately reaches a nala.
- Open burning of branches and packing waste is prohibited and is an air-pollution offence.
- C&D waste dumped on the road shoulder violates the C&D Waste Management Rules, 2016; spoil must go to an authorised facility.
- No Consent to Operate from the State Pollution Control Board - the project is operating on a CTE only.
2. Rank the corrective actions and show whether a noise barrier alone can solve the 78 dB(A) problem.
Read the worked answer
Ranking: stop open burning immediately (direct health hazard, easiest to prove); stop night-time DG operation; contain and treat silt water; clear the road-shoulder spoil; then address dust and documentation.
Noise arithmetic: the shortfall is 78 − 45 = 33 dB. A well-built site barrier typically gives 10–15 dB insertion loss, and less if it is not close to the source or is bypassed by openings. Even 15 dB leaves 63 dB(A), still 18 dB above the night limit. A barrier alone cannot comply.
Required package:
- Acoustic enclosure on the 125 kVA DG and a proper exhaust silencer; relocate the set away from the boundary.
- Shut the DG down by 22:00, or run it only in emergencies; arrange reliable grid supply or a quieter rented set.
- Fit barriers/masks around noisy activities (cutting, batching) and schedule them in daytime.
- Log boundary noise at night and keep the readings for the SPCB inspection.
3. What regulatory route and records should you put in place before the inspector arrives?
Read the worked answer
Approvals: apply to the State Pollution Control Board for Consent to Operate under the Water Act, 1974 and the Air Act, 1981, referencing the existing CTE and the actual plant and DG details. Obtain groundwater permission from the Central Ground Water Authority if a borewell is used, and register the DG set as required locally.
Records to assemble:
- CTE and CTO applications with诚 supporting documents and fee receipts.
- Noise and PM10 monitoring reports from a recognised laboratory, with locations and times.
- Water and silt management plan: settling tank, silt fencing, no discharge without consent.
- C&D waste plan with authorised transporter and disposal receipts.
- DG log book, enclosure specification and maintenance records.
- Complaint register and the action taken on the residents' complaint.
Do not wait for the inspection to start correction; begin with the burning and night DG, because those are visible violations that an inspector will record immediately.