Overview

Mound systems are prohibited on sites that have shallow soils. In most cases, ground cover with a depth of 2 feet is enough for a mound system. However, impermeable rock strata require a depth of 5 feet. Mound systems are not allowed in flood plains or filled areas. Additionally, mound systems cannot be installed in compacted soil or over a failing conventional system.

Perk tests for mound systems must be conducted at a depth of 20 to 24 inches from existing grade. If a slowly permeable horizon exists at less than 20 to 24 inches, the perk test must be conducted within that horizon. An acceptable perk rate for a mound system is set at a rate of more than 60 minutes per inch and less than, or equal to, 120 minutes per inch.

When shallow permeable soils are encountered over bedrock, a perk test must be conducted at a depth of 12 to 18 inches below existing grade. If a slowly permeable horizon is found within 12 to 18 inches, the perk test must be conducted within that horizon. A mound system in this type of situation is allowed a perk rate between 3 minutes per inch and 60 minutes per inch.

High ground water in permeable soils requires a perk test at 20 to 24 inches. When a slowly permeable horizon is found at less than 20 to 24 inches, a perk test is required in that horizon. Mound systems for this type of site must have...