Boat Washing in Rhode Island

This guidance was developed based on collaboration with, and feedback from, the Rhode Island Marine Trades Association. Several specific questions were raised about regulatory compliance as related to pressure washing activities during the development of this document. In an effort to more fully explain RIDEM policy, we have developed the following guidance on pressure washing at RI marinas and formatted the guidance to address the concerns raised during the discussions that occurred during the drafting process:

  • Wastewater from boat bottom pressure washing activities should be contained, collected, and handled as a process wastewater. Process wastewater discharges are not covered by the General Permit for the Discharge of Stormwater Associated with Industrial Activity (Industrial Stormwater General Permit).
  • Wastewater should not accumulate or pond to create a discharge to the ground or surface water or escape the boundaries of the property.
  • Maintain equipment, including hoses, to prevent discharges. Leaks of non-potable water from hoses and equipment are considered process wastewater and discharges are prohibited.
  • Set the pressure at which water is dispensed, from the pressure washing gun, to the minimum required to remove biological organisms from the bottom of a boat.
  • Pressure washing guns should be operated as intended. Prevent excessive use or discharge of water away from the boat bottom surface while performing boat bottom pressure washing.
  • Direct discharge to the ground through an underground tank, (e.g. Underground Injection Chamber) is prohibited.
  • Pressure washing of vessels shall only be trained employees or persons under the supervision of trained employees.

Containment Pad Guidance

  • Management practices for operation and maintenance of wash containment pads (pad), and the discharge of stormwater from a pad should be identified in the Stormwater Pollution Prevention Plan (SWPPP) as required by the General Permit for the Discharge of Stormwater Associated with Industrial Activity (Industrial Stormwater General Permit). Practices that should be clearly described in a SWPPP include documents and forms to be used for weekly inspections, identification and management of activities performed on the pad, staff training, stormwater monitoring including sample location and procedures, and all other requirements of the Industrial Stormwater General Permit.
  • All power washing should be conducted on the designated pad.
  • Pads should be constructed of an impervious material (e.g. asphalt or concrete coated with a sealant). The design and construction of the pad should prevent or minimize stormwater from entering onto the pad, other then direct rain fall.. Concrete pads should be constructed with at least a 1% slope to the collection point and a 1 - 2% slope for asphalt surfaces.
  • Pads constructed to allow stormwater to overflow, when process activities are not being conducted on the pad, are considered a point source and subject to the conditions of the Industrial Stormwater General Permit.
  • The integrity of the pad should be inspected as part of the bi-annual stormwater Comprehensive Site Compliance Evaluation (CSCE) as required by the Industrial Stormwater General Permit. Any leak, crack, fissure, or damage to the impermeable surfaces and coatings should be repaired immediately.
  • Plumbing or pumps associated with the diversion of stormwater from the pad should be equipped with a lockable valve, a watertight cover or plug, or a dedicated power source equipped with either a lock or the ability to be secured.
  • Prior to initiating any process activities on the pad, verify that the pad's stormwater conveyance valve, watertight cover or plug, or pump power source is closed or deactivated, watertight, and locked or secured. When a system is in use, all drains, plugs and/or vales should be closed to prevent discharges.
  • Prior to opening or activating the stormwater diversion conveyance the pad should be cleaned of all debris, chemical waste, paint waste, sludge, and other solids. The pad should then be rinsed using a potable water source and all wastewater and debris collected and handled as process waste.
  • Process wastewater should not overflow or run off the pad at any time.
  • Wastewater generated from fresh water flushing of vessel systems, bilge wastewater after oil absorption, and engine cooling wastewater may be drained onto the pad for collection and off-site waste disposal or, discharge to the sanitary sewer in accordance with the local waste water treatment plant approval.
  • Stormwater that commingles with process wastewater should be handled as a process wastewater.
  • Process water discharges that result from a bypass of collection, storage, or treatment are considered a violation and may result in enforcement action and penalties.

Removal of solids from recycling systems and tanks:

  • Solids and sludge from recycling systems must be properly characterized prior to disposal. A representative sample must be taken and analyzed to determine if the solids meet criteria for disposal as a solid waste to be eligible for disposal in a dumpster.
  • Testing may cease after one season of solids accumulation is shown to meet solid waste criteria.

In-water boat bottom maintenance:

In-water cleaning, modification, surface preparation, or coating of any portion of a painted hull, below the water line is not a recommended practice. These activities may unnecessarily release toxic materials to the environment, impair water quality, and contaminate dredge material.

Underground and aboveground boat bottom pressure washing collection tanks:

DEM policy is to not regulate underground or aboveground holding tanks unless they contain a hazardous substance or a petroleum product. DEM does not consider power washing discharge from boat bottoms a hazardous substance or containing a petroleum product and therefore will not require compliance with the Underground Storage Tank or Above Ground Storage Tank rules and regulations.


This document is meant as guidance from RI marina operators, based on current regulations and technology. As technology and industry practices change, either party may request a review of this guidance document for further consideration.