S.C. Code Regs. § § 61-56.204

Current through Register Vol. 48, No. 10, October 25, 2024

Section 61-56.204 - Evaluation of Alternative Infiltration Trench Products

The Department shall be responsible for the evaluation and approval of alternative infiltration trench products prior to their use in the state, unless otherwise regulated by statute. This evaluation shall include a review of available research data; a review of parameters relating to structure, geometry, and volume; and the establishment of required equivalency values for comparing the product to a conventional wastewater infiltration trench.

204.1. Application.

(1) All requests for approval of alternative infiltration trench products must be submitted in writing to the Department and must include the following:

(a) Complete description of the product and its intended use.

(b) Complete listing of materials used in the construction of the product, including specifications.

(c) Copies of all available literature pertaining to the product and a listing of all appropriate reference materials.

(d) Copies of any and all available research, testing, and monitoring data, to include records of performance and/or prior experience in actual field conditions.

(2) The Department will review the application and may seek other information, including additional evaluations.

204.2. Equivalency Value for Infiltrative Surface.

(1) The total infiltrative surface area surrounding the sides and bottom of a conventional wastewater infiltration trench (i.e., 5.33 sq.ft./lin.ft.) shall serve as the basis for all geometric comparisons to alternative infiltration trench products.

(2) The effective infiltrative surface area of a conventional trench shall include the total of both rectangular sidewalls, beginning at the top of the aggregate and extending to the trench bottom, in addition to the width of the trench bottom. Similarly, the effective infiltrative surface area of a product shall include the total of both immediately adjacent, rectangular sidewalls, beginning at the top of louvers, slits, holes or similar orifices, in addition to the rectangular width of the trench immediately beneath the product.

(3) The equivalency value (E) for any given product is determined by comparing the total effective surface area of the product, as defined above, with that of a conventional wastewater infiltration trench as follows:

(a) Total Infiltrative Surface Area for One (1) Foot of Conventional Trench:

Trench Sidewalls = 2 x (1.16ft.H x 1.0 ft.L) = 2.33 sq.ft./lin.ft.

Trench Bottom = 1 x (3ft.W x 1ft.L) = 3.0 sq.ft./lin.ft.

Total Infiltrative Surface Area = 5.33 sq.ft./lin.ft.

(b) Equivalency Value (E) Shall Be Computed As Follows:

E = 5.33 sq.ft./ft ÷ Sum of Three Rectangular Interfaces Immediately Adjacent to Product (sq.ft./ft.)

(c) The Required Total Length of the Product Shall Be Calculated As Follows:

Length of Product (L) = E x Length of Conventional 36 in. Wide Trenches Required by DHEC Regulations and Standards

204.3. Other parameters to be evaluated for alternative infiltration trench products may include the following:

(1) Structural Integrity - Products must be of sound construction and able to adequately withstand the normal pressures and stresses associated with installation and use.

(2) Inertness - No product can be approved unless it will remain relatively unaffected for extended periods of time while in contact with typical domestic wastewater.

(3) Storage Volume - The effluent storage capacity of a product must closely approximate or exceed that of a comparable conventional system.

(4) Maintenance of Permeable Interfaces - A product shall have a direct interface with the effective infiltrative surface (undisturbed natural soil) or, if backfill is required, backfill material shall not create a permeability barrier and shall not hinder the downward or horizontal flow of effluent into the undisturbed natural soil.

(5) The unique characteristics of a given product may warrant the evaluation of other parameters not specifically mentioned in this section of the regulation.

(6) The design, construction, or installation methods used with any product shall not conflict nor violate any other requirements established by the Department.

204.4. Approval for General Use.

If warranted, the Department will issue a letter of approval for general use of the alternative infiltration trench product in accordance with equivalency values and other requirements determined herein. At least nine (9) inches of soil cover is required.

S.C. Code Regs. § 61-56.204

Amended by State Register Volume 40, Issue No. 05, eff. 5/27/2016; State Register Volume 45, Issue No. 05, eff. 5/28/2021.