A. Absorption systems shall be set back as specified in § 13.20.170. Distribution shall be made in accordance with all applicable requirements of Article VII of this chapter;

B. Absorption systems shall not be placed in floodplains. Absorption systems should not be placed in areas subject to excessive runoff. All absorption systems located on slopes greater than 1% must have a diversion constructed immediately upslope from the system to intercept and direct runoff;

C. The absorption area of trenches and seepage beds shall be in original soils. The bottom and sides of the absorption system to the top of the distribution medium shall be excavated in such a manner as to expose the original soil structure in an unsmeared and uncompacted condition;

D. Excavation equipment or other vehicles must not be driven on the excavated trench or absorption bed bottom. Once the trench or absorption bed is excavated, it shall not be exposed to rainfall prior to placement of the final backfill;

E. A vertical inspection pipe at least 1-1/2 inches in diameter shall be installed and secured in the distribution medium of every trench or absorption bed. The inspection pipe must be located at an end opposite from where the sewage tank effluent enters the medium. The inspection pipe must have 3/8-inch or larger perforations, spaced vertically no more than 6 inches apart. At least 2 perforations must be located in the distribution medium. No perforations shall be located above the geotextile fabric or untreated building paper. The inspection pipe must extend to the bottom of the distribution medium, and must be capped flush with or above finished grade;

F. A finder wire of Number 14, solid strand, insulated copper wire shall be installed for all new and upgraded onsite wastewater system installations. The finder wire shall be accessible at the clean out, and run to and around the septic tank access hole, and through the trenches or around the bed;

G. A geotextile fabric, or untreated building paper, or a 4 to 8 inch thickness of hay or straw, shall be used to cover distribution rock medium. The fabric must be of sufficient strength to undergo installation without rupture. In addition, the fabric must permit passage of water without passage of overlying soil material into the rock medium. When fabric or untreated building paper is used, the:

H. The minimum depth of cover over the distribution medium shall be at least 6 inches. The trenches or absorption beds shall be backfilled and crowned above finished grade to allow for settling. The top 6 inches of soil shall have the same texture as the adjacent soil; and

I. A vegetative cover shall be established over the absorption system. The absorption system shall be protected until a vegetative cover is established. The vegetative cover established shall not interfere with the hydraulic performance of the system, and shall provide adequate frost and erosion protection.