[Owtsinfo] Attention OWTS Professionals - OWTS Design and Installation Reminders

Mon Jul 24 09:21:37 EDT 2023

Attention OWTS Professionals:

The RIDEM OWTS program recently met with the RI Builders Association Environmental Committee which represents OWTS soil evaluators, designers, and installers. The purpose of the meeting was to discuss potential avenues to improve the OWTS permitting process and to solicit general feedback in both directions. During the meeting several items were highlighted as areas where designers and installers need to pay particular attention as they carry out their work. These areas are summarized below:

  1.  OWTS Rule 6.47 – OWTS Installation establishes the responsibilities of licensed installers and designers during the construction process. We would like to remind designers that 6.47.H requires the designer to collect specific information that can be used to verify that the installation of the OWTS was performed as specified. The licensed designer shall keep this information on file for a minimum of ten (10) years from the date of the Certificate of Construction. At the RIDEM’s request, the licensed designer shall make this information available for review.

Please make sure that if you are a licensed designer that you are performing the required inspections and that you are maintaining the required records as outlined in OWTS Rule 6.47.H. An excerpt of this Rule is provided below. A link to the OWTS Rules is also provided here: https://rules.sos.ri.gov/regulations/part/250-150-10-6

6.47.H. Installation Verification – The Licensed Designer shall collect the information in §§ 6.47(H)(1) through (4) of this Part that can be used to verify that the installation of the OWTS was performed as specified. The Licensed Designer shall keep this information on file for a minimum of ten (10) years from the date of the Certificate of Construction in § 6.48 of this Part. At the Department's request, the Licensed Designer shall make this information available for review.

1.Daily inspection report (weather conditions, individuals onsite, work accomplished, and other information customarily included in inspection reports);

2.A minimum of two (2) photographs of the OWTS being installed, which must include the bottom bed and the completed system prior to covering;

3.List of all materials used, their source, and the dates delivered to the site; and

4.Product specification sheets, if different from those specified in the approved design.

  1.  OWTS Rule 6.33.K – Stone: requires stone used in leachfields to consist of clean, washed stone free of fines, soils, stone dust or debris. Please seek out material suppliers that can meet these specifications and inspect the materials being delivered to the site prior to installation.

6.33.K. Stone – The stone used in the leachfield shall consist of clean, washed stone ranging from three quarter inch (¾”) to not more than two inches (2”) in size and free of fines, soils, stone dust or debris. The stone shall be covered with a layer of synthetic filter fabric that meets the requirements of § 6.33(L) of this Part.

  1.  OWTS Rule 6.37.C.2.e – Bottomless Sand Filter (BSF) cover stone:  allows for the use of screened or crushed stone as long as it meets all of the other specifications of this Rule. OWTS Rule 6.37.C.2.e is provided below:

6.37C.2e.BSF cover stone: A three eighths to one half inch (3/8” – 1/2") round or sub-rounded, screened or crushed, uniform in size so that no more than five percent (5%) of the sample is greater than one half inch (1/2”) and no more than five percent (5%) shall pass a three eighths inch (3/8”) sieve, non-shale or other soft stone, double washed, containing little or no fines shall be used for cover stone on the BSF. Total depth of the stone shall be eight to nine inches (8” – 9”), depending on the size of the lateral (see § 6.79 of this Part, Figure 21 and installation procedures).

  1.  Per OWTS Rule 6.33.Q – Adjacent Side Slope and 6.37.C.1.d Fill perimeter: when designing any leachfield regardless of the length of the fill perimeter required (10ft or 5ft ) the fill perimeter shall be maintained and land surface regrading adjoining the fill perimeter must maintain a minimum of 3:1 (run:rise) slope down gradient. Wherever possible, utilize an additional property line setback safety factor when siting a leachfield adjacent to a property line to allow for unforeseen installation conditions and to eliminate the potential for grading within five feet of the subject property line. OWTS Rules 6.33.Q and 6.37.C.1.d are provided below:

6.33Q. Adjacent Side Slope – A minimum ten foot (10’) horizontal separation distance shall be provided between the outer edge of the stone in the outer dispersal trench and any ground surface elevation less than the elevation of the invert of the distribution line. The adjacent side slope shall not be steeper than 3:1 (horizontal: vertical) for a twenty-five foot (25’) minimum distance from the edge of the stone in the dispersal trench or until the toe of the slope returns to the elevation of the original grade. The toe of the 3:1 slope shall be a minimum of five feet (5’) from any property line.

6.37.C.1.d. Fill perimeter: The land surface elevation two feet (2’) below the cover stone-sand media interface shall be maintained for a distance of at least five feet (5’) from the edge of the BSF. Land surface re-grading adjoining this five-foot (5') perimeter must maintain a minimum of 3:1 (run:rise) slope down gradient (See § 6.76 of this Part, Figure 18).

Thank you for your attention to these requirements and for working with us to accomplish our mission to protect human health and the environment.

[cid:image001.jpg at 01D9BAF5.CB1316C0]

Rhode Island Department of Environmental Management

Office of Water Resources – Onsite Wastewater Treatment Systems (OWTS) Program

235 Promenade Street, Providence RI 02908

Website Address: www.dem.ri.gov/septic<http://www.dem.ri.gov/septic>;

OWTS Phone Line: 401.222.3961;

OWTS General Information Email Address: DEM.OWTS at dem.ri.gov<mailto:DEM.OWTS at dem.ri.gov>

[cid:image002.jpg at 01D9BAF5.CB1316C0]<http://www.dem.ri.gov/septicsmart>

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