Guam EPA presents new on‑site wastewater rules requiring NSF‑certified 'type 4' systems, operating permits

Guam Environmental Protection Agency staff presented draft amendments to the agency's on‑site wastewater disposal regulations Thursday that would require higher‑performance treatment systems in specified areas and add ongoing operating permits and construction standards.

The draft rule package, developed over several years and presented by Brian (former Guam EPA staff, presenter), implements amendments to 22 GCA chapter 12 and the toilet facilities and sewer connection law (10 GCA chapter 48) and carries out provisions of Public Law 37‑105 and Public Law 38‑7, the presenter said. The rules would require NSF‑certified ‘‘type 4’’ nitrogen‑reducing systems in some locations, mandate site soil (percolation) tests for all on‑site systems, require watertight septic‑tank construction, and add operating permits for certain system types.

The amendments would require type 4 systems — third‑party certified under the NSF program cited in the presentation — to achieve a minimum 50% reduction in nitrogen loading to the aquifer and would require operating permits renewed every two years for type 4 systems and mound systems and annually for holding tanks. The proposal also adds standards for cast‑in‑place (monolithic) concrete septic tanks or equivalent certified units and requires water‑tightness testing, the presenter said.

Why it matters: Guam relies on on‑site systems across the island. Guam EPA emphasized the rules are intended to limit nitrogen contamination of the island's aquifer and to modernize regulations that have not been substantially revised since the 1980s.

Key elements presented

- Type 4 systems: Package treatment units that provide aeration and timed cycles to nitrify then denitrify wastewater; the draft requires NSF certification for systems used where type 4 is mandated (presenter’s description). The presenter said certified systems should guarantee at least 50% nitrogen reduction when operated and maintained per manufacturer specifications.

- Operating permits and O&M contracts: Type 4 and mound systems would require a two‑year operating permit and a manufacturer‑authorized operation and maintenance (O&M) contract from an approved provider; holding tanks would require a one‑year permit and a registered hauler pumping contract. O&M providers must hold or contract a Guam EPA Class 1 wastewater operator or higher or equivalent, the draft says.

- Percolation tests and construction standards: The draft makes mandatory percolation (site soil) tests and requires septic tanks be cast concrete built to specified monolithic‑pour standards, or equivalent certified precast/plastic tanks meeting adopted code sections. The International Private Sewage Disposal Code sections were cited as the construction/design reference the agency proposes to adopt in part.

- Holding tanks and mounds: Holding tanks would be narrowly allowed (single‑family dwellings, government facilities or written administrator approval for specific commercial uses) and owners must provide realistic, documented long‑term pumping cost estimates; Guam EPA staff warned holding tanks can cost hundreds to thousands of dollars per month and carry higher risks of illicit discharge if not properly managed. Mound systems were presented as an option for saturated or poor soils (often in southern areas).

Board exchange and next steps

Board members asked about failure modes, storm‑power outage impacts, and long‑term costs. Brian said type 4 systems revert to septic‑tank‑level performance during extended power outages and that a temporary reduction in nitrogen removal should be expected after outages. He noted the proposed requirement of presoaking test pits for 24 hours in percolation testing to reduce seasonal variability.

Guam EPA staff notified the board of a public hearing scheduled for July 30 at 4 p.m. to receive comments on the draft State Implementation Plan and related regulatory proposals; the presenter and staff said they expect to return to the board in August with final rule language and a vote request.

Staff emphasized the package focuses on balancing environmental protection (particularly wellhead protection and aquifer quality) with permitting flexibilities — smaller leaching fields and exemptions in some situations — enabled by the higher‑performance systems.

Ending

No formal board action was taken on the rules at Thursday's meeting. Staff said they will post the proposed regulations, collect public comments at the scheduled hearing, and return with a recommendation for the board at the next meeting.