Current through December 26, 2024
Section 250-RICR-150-10-6.17 - Additional Site TestingA. Determination of depth to bedrock and the presence of storm deposited sand in the backdune environment or human transported material, as required in §§ 6.17(B) and (C) of this Part, shall be made by a Class II or III Licensed Designer or a Soil Evaluator on forms approved by the Director.B. Determination of Depth to Bedrock 1. Bedrock test holes, conducted in accordance with § 6.17(B)(2) of this Part, shall be required when any of the following occur: a. Bedrock is encountered within eight feet (8') of original ground surface in the excavation of any of the test holes for the soil evaluation;b. Bedrock outcrops are visible in the surrounding area; orc. Landscape conditions warrant bedrock test holes.2. Bedrock test holes a. Bedrock test holes shall be excavated to a depth of ten feet (10') in the center and four (4) corners of the proposed leachfield. Additional test holes or probe tests shall be required within twenty-five feet (25') of the proposed leachfield, the number and location depending on the site. Bedrock depth shall be determined on all sides of the proposed leachfield. In order for DEM approval, testing must demonstrate that: (1) Bedrock is at least five feet (5') below the bottom elevation of the stone in the leachfield in the area of the proposed leachfield and within twenty-five feet (25') of the proposed leachfield. The five foot (5') vertical separation requirement may be waived on the up-gradient side as long as bedrock is no higher than the bottom of the stone in the leachfield within twenty-five feet (25') of the proposed leachfield (§ 6.59 of this Part, Figure 1); and(2) Depth to Bedrock from original ground surface must be a minimum of four feet (4') within twenty-five feet (25') on all sides of the leachfield, including the up-gradient side.b. A bedrock test hole shall be witnessed by the Director unless the Director waives this requirement.c. If during the bedrock exploration work the Director determines that additional bedrock test holes or probe tests are not warranted, then the Director may waive such additional testing.C. Human Transported Material and Storm Deposited Sand - If human transported material or storm deposited sand in the backdune environment is encountered in the excavation of any test hole or is evident within twenty-five feet (25') of any test hole, an adequate number of additional test holes shall be excavated to a sufficient depth to determine the lateral and vertical extent of this material within twenty-five feet (25') of the leachfield. Limitations for OWTS design regarding depth to groundwater and depth to bedrock shall be determined from original ground surface. The Director may require that this material existing in the area of the proposed leachfield be removed. Test holes in human transported material or storm deposited sand in the backdune environment shall be witnessed by the Director unless the Director waives this requirement.250 R.I. Code R. 250-RICR-150-10-6.17
Amended effective 11/25/2018
Amended effective 12/28/2021
Amended effective 7/1/2022