Section 62-03.1-03-12 - Alternative systems1.Mounds. Mounds may be constructed on soils having a percolation rate faster than one hundred twenty minutes per inch [2.54 centimeters]. For soils slower than one hundred twenty minutes per inch [2.54 centimeters], either the system must be moved to more amenable soil or see subsection 2 on lagoons. a. Location. Mounds may not be located on sites of greater than twelve percent slope. For moderately permeable soils, the administrative authority may approve construction on slopes over six percent. Mounds may not be built in areas where water may pond. b. Design. The basal sand area of the mound must be sized on the basis of eighty-three hundredths gallons [3.12 liters] per square foot [0.09 square meter] per day. The basal sand may be twelve inches to twenty-four inches [30.48 centimeters to 60.96 centimeters] deep and must extend at least five feet [1.52 meters] beyond the rock filter material in all directions. The rock layer may be twelve inches to twenty-four inches [30.48 centimeters to 60.96 centimeters] deep and may not exceed ten feet [3.05 meters] in width. Only pressure distribution may be used in the mound, so piping shall be one and one-half-inch to two-inch [38.10-millimeter to 50.80-millimeter] diameter rigid ABS or PVC. A one and one-fourth inch [31.75 millimeters] hole must be drilled every thirty-six inches [91.44 centimeters] and the ends of the lateral must be capped. A one-fourth inch [6.35 millimeters] hole shall be drilled in the top of the cap to serve as a siphon break. Laterals shall be spaced no further than forty inches [101.60 centimeters] on center and no further than twenty inches [50.80 centimeters] from the edge of the filter rock. Surface water must be diverted by a berm located uphill from the base of the mound. c. Specifications. Sand must be uniformly graded, with no more than fifteen percent fines. Filter rock must be one inch to three inches [25.40 millimeters to 76.20 millimeters] in diameter, washed or screened to less than ten percent fines. A jar test should be used to determine sand suitability. In a one quart [.95 liters] jar, place two inches [50.8 millimeters] of the sand. Add water to three-fourths level, cap, shake, and set aside to settle. If a layer of silt is present on top which is more than one-eighth inch [3.18 millimeters] thick, the sand is not suitable for mound construction.
d. Construction. (1) Scarify the area with backhoe teeth or a cultivator. Do not remove topsoil. Bring outlet pipe from pump up into the center of the mound area. (2) Lay sand on scarified area. Do not compact the soil with machinery tires. Level sand to desired depth. (3) Lay filter rock down the center of the sand layer. Level. (4) Connect piping to manifold and lay pipe on rock. Cover pipe with rock and level by hand. Holes must be on bottom of the pipe. (5) Lay sand up to the top of the rock on all sides, sloping sand away at a three-to-one or four-to-one slope. (6) Cover rock with red rosin paper, hay, or filter fabric. (7) Backfill entire mound to a three-to-one or four-to-one grade. Downhill side of mound on slopes must be backfilled at a four-to-one or longer grade. Cover mound with topsoil. (8) Seed grass over mound. Trees and shrubs may be planted on the toe and up the sides of the mound, but do not plant shrubs or trees on top. If vegetation is not established before winter, cover mound with hay or straw to prevent freezing. 2.Lagoons - Total containment. In areas where normal septic systems will not function, and where the administrative authority finds that a nuisance will not be presented, a lagoon may be used for onsite sewage disposal. a. Design. Depth may not exceed five feet [1.52 meters], and side berms shall be graded to three-to-one for proper aeration. The site must be fenced, and the berms must be seeded. The berms must be at least one foot [0.30 meter] higher than the liquid level at design capacity. Inlet pipes must discharge onto a splash pad to minimize erosion. Outlet pipes may not be installed without the approval of the administrative authority. b. Maintenance. Weeds must be controlled in the lagoon and on the berms to maximize aeration. c. Prohibitions. Lagoons may not be constructed on sand, gravel, or light loamy soils. No lagoon may be discharged into receiving waters or onto the ground without the approval of the state department of health. 3.Alternative design. Alternate designs for construction of sewage treatment systems complying with the intent of this code may be submitted to the administrative authority for approval. N.D. Admin Code 62-03.1-03-12
General Authority: NDCC 43-18-09
Law Implemented: NDCC 43-18-09