14 CAR § 21-701. Absorption trenches

(a) A standard onsite wastewater system consists of a field of perforated pipe: (1) Surrounded by gravel or other conventional trench media product authorized by the Department of Health; and (2) Installed in such a manner that the clarified effluent from the septic tank or pretreatment unit will be distributed with reasonable uniformity into the natural soil. (b) The individual absorption trench should not be more than one hundred feet (100’) without mechanical dosing, and the trench bottom and perforated pipe or gravel substitute should be installed at a grade of zero to two inches (0” – 2”) per one hundred feet (100’). (c) In all cases, line length shall not exceed one hundred fifty feet (150’). (d) In order to ensure even distribution of the effluent, all onsite wastewater systems utilizing a distribution box shall have absorption trenches of the same length. (e) Onsite wastewater systems utilizing serial distribution of the effluent shall be provided with an authorized diversion device to allow drying of the most used absorption trenches. (f) The most used absorption trench should be allowed to drain and dry out during the summer months. (g) A minimum of two (2) absorption trenches is required to ensure that the absorption area will function even if one (1) absorption trench is disturbed.