Who needs a SWPPP in Hawaii?
Any construction project that disturbs one acre or more — or is part of a larger common plan of development reaching one acre — needs a SWPPP under Hawaii permit HAR 11-55 Appendix C.
Hawaii runs its own delegated stormwater program. Operators obtain coverage from Hawaii Department of Health (DOH), Clean Water Branch under NPDES General Permit Authorizing Discharges of Storm Water Associated with Construction Activity (HAR 11-55, Appendix C) (HAR 11-55 Appendix C), not directly from the EPA. A small subdivision, a solar pad, and a road-widening project all clear the same one-acre line.
Hawaii adds requirements worth flagging early: Submit the NOI through the DOH e-Permitting portal no later than 30 days before construction starts, with the SWPPP prepared first and its nature-of-construction, sequence, and site map information included in the NOI (Sections 11.1–11.4, 7.1); Notify DOH of the construction start date through e-Permitting within 7 calendar days before construction starts (Section 12.2); Prepare a monthly compliance report (including noncompliance and corrective actions), keep it on site, and provide it by the end of the next business day on request (Section 13.1); Submit a Notice of Cessation within 7 calendar days after the end of the month in which all construction activities cease (Section 13.2); Obtain written approval from the owner of any separate storm water drainage system before discharging into it (Section 2.1.4); discharges using polymers, flocculants, or other treatment chemicals are not covered (Section 2.1.2); Keep a corrective action log: condition within 24 hours of discovery, follow-up within 7 calendar days, each entry certified and signed (Section 10.4); Discharges are controlled as necessary to meet the applicable water quality standards specified in HAR section 11-54-4 (Section 6.1), and the director may require any permittee authorized by this general permit to apply for and obtain an individual permit (Section 2.3; HAR sections 11-55-34.05 and 11-55-34.11).
What the plan must contain
A Hawaii SWPPPis the site's compliance binder — the document an inspector opens first. It documents:
- 1Site & project descriptionTotal and disturbed acreage, soils, slopes, and the sequence of construction.
- 2Receiving waters & discharge pointsWhere stormwater leaves the site and the waterbodies it reaches.
- 3Erosion & sediment control BMPsSilt fence, stabilized entrances, inlet protection, and stabilization measures.
- 4Inspection schedule & recordsDated, signed inspection logs and the corrective actions taken.
- 5Operator certificationThe SWPPP is signed by the legally responsible party before work begins.
Required and conditional BMPs
| Best management practice | Category | Status |
|---|---|---|
| Perimeter silt fence / sediment barrier | Sediment control | Required |
| Stabilized construction entrance | Tracking control | Required |
| Storm drain inlet protection | Sediment control | Required |
| Soil stabilization (seeding, mulch, blankets) | Erosion control | Required |
| Concrete washout containment | Good housekeeping | Required |
| Sediment basin or trap | Sediment control | Conditional |
| Dewatering / turbidity controls | Pollution prevention | Conditional |
Filing your Notice of Intent
Submit the Notice of Intent through the DOH Clean Water Branch e-Permitting portal at least 30 days before construction begins; DOH issues a Notice of General Permit Coverage (NGPC) with a file number to cite on all submittals.
A Notice of Termination closes coverage once the site reaches final stabilization. Keeping the SWPPP and its inspection records on site is what keeps a project clear of stop-work orders.
Inspection requirements
The permit allows 2 inspection schedules; the operator follows one and records the choice in this plan: (a) 7-day schedule — inspect at least once every 7 calendar days (inspections are only required during the project’s normal working hours) (HAR 11-55 Appendix C Section 9.1.2.a); or (b) 14-day schedule with storm inspections — inspect at least once every 14 calendar days and within 24 hours of the occurrence of a storm producing 0.25 inch of rain or more within a 24-hour period (also once the discharge of snowmelt from a storm producing 3.25 inches or more of snow accumulation within a 24-hour period occurs; smaller storms that together produce 0.25 inch or more in 24 hours count; for a multi-day storm producing 0.25 inch or more each day, inspect within 24 hours of the first day and within 24 hours after the last such day; inspections are only required during the project’s normal working hours) (HAR 11-55 Appendix C Sections 9.1.2.b, 9.1.2.1.1, and 9.1.2.1.2). The SWPPP must specify which schedule will be followed (HAR 11-55 Appendix C Section 9.1.2). Every inspection is dated and signed, and any failed control is corrected before the next storm.
| Trigger | Requirement |
|---|---|
| Routine — 7-day schedule | At least once every 7 calendar days (inspections are only required during the project’s normal working hours) |
| Routine — 14-day schedule with storm inspections | At least once every 14 calendar days and within 24 hours of the occurrence of a storm producing 0.25 inch of rain or more within a 24-hour period (also once the discharge of snowmelt from a storm producing 3.25 inches or more of snow accumulation within a 24-hour period occurs; smaller storms that together produce 0.25 inch or more in 24 hours count; for a multi-day storm producing 0.25 inch or more each day, inspect within 24 hours of the first day and within 24 hours after the last such day; inspections are only required during the project’s normal working hours) |
How Hawaii differs from the federal permit
| Hawaii | Federal (EPA) | |
|---|---|---|
| Authority | Hawaii Department of Health (DOH), Clean Water Branch | U.S. EPA |
| Permit | HAR 11-55 Appendix C | EPA CGP |
| Disturbance threshold | 1 acre | 1 acre |
| Plan name | SWPPP | SWPPP |
Because Hawaii administers its own program, the federal EPA Construction General Permit does not apply directly here — the state permit governs. Sites inside a regulated municipal storm sewer system may carry additional local ordinance requirements on top of the state permit.
Frequently asked questions
Does Hawaii require an engineer to prepare the SWPPP?+–
No. Hawaii does not require a licensed PE stamp on a construction SWPPP statewide. The operator certifies the plan; engineer review is optional for complex sites.
What is the disturbance threshold in Hawaii?+–
One acre — including sites under an acre that are part of a larger common plan of development totaling one acre or more.
How often must inspections happen in Hawaii?+–
The permit allows 2 inspection schedules; the operator follows one and records the choice in this plan: (a) 7-day schedule — inspect at least once every 7 calendar days (inspections are only required during the project’s normal working hours) (HAR 11-55 Appendix C Section 9.1.2.a); or (b) 14-day schedule with storm inspections — inspect at least once every 14 calendar days and within 24 hours of the occurrence of a storm producing 0.25 inch of rain or more within a 24-hour period (also once the discharge of snowmelt from a storm producing 3.25 inches or more of snow accumulation within a 24-hour period occurs; smaller storms that together produce 0.25 inch or more in 24 hours count; for a multi-day storm producing 0.25 inch or more each day, inspect within 24 hours of the first day and within 24 hours after the last such day; inspections are only required during the project’s normal working hours) (HAR 11-55 Appendix C Sections 9.1.2.b, 9.1.2.1.1, and 9.1.2.1.2). The SWPPP must specify which schedule will be followed (HAR 11-55 Appendix C Section 9.1.2).
Hawaii-ready in minutes
Siltworks fills in your site data automatically, applies the Hawaii requirements, and hands you an inspection-ready SWPPP — at 70–90% less than a consultant.
Requirements summarized from the publicly available NPDES General Permit Authorizing Discharges of Storm Water Associated with Construction Activity (HAR 11-55, Appendix C) (HAR 11-55 Appendix C) for planning purposes. The operator must review and certify every SWPPP before use.