87.25.6. Installation conditions: An above-ground leaching field built with borrowed sand may be installed in the following conditions:(a) the grade of the disposal site is less than 10%;
(b) the leaching field meets the siting standards in section 7.2; and
(c) the disposal site is composed of high permeability soil and the level of bedrock, underground water or any layer of impermeable soil, low permeability or permeable soil is less than 60 cm but more than 30 cm.