Distribution of Effluent

Distribution of Effluent. 1. When a change in elevation of the disposal trench is required, a distribution box, connecting lateral or crossover must be used. At the point where a crossover line leaves a lateral, the trench for the crossover line shall be dug no deeper than the top of the aggregate in the preceding trench so that an undisturbed block of earth will remain in place for the full depth of the aggregate. The distribution box shall be level and supply all lines equally. Field lines must be equal lengths when served by one distribution box. 2. Distribution boxes may be used to connect the effluent line to the effluent distribution lines. Non-perforated rigid pipe shall exit the distribution box for a minimum of five feet at level grade before the effluent distribution line (perforations) begins. [See Figure 12.] 3. Crossover lines shall be laid on undisturbed earth. The invert of the crossover must be at least four inches lower than the invert of the septic tank outlet line: a. Crossovers shall be constructed as shown in Figure 10. Source: Miss. Code Ann. § 41-67-3. TABLE 1 - SETBACK REQUIREMENTS FROM SENSITIVE WATER (Aggregate Systems) Minimum Distance from the Water Edge Soil Textural Class Slope of Less Than 8 Percent Slope of More Than 8 Percent Gravel NOT APPLICABLE Coarse Sand 50 feet 50 feet Medium Sand 50 feet 50 feet Fine Sand 50 feet 50 feet Loamy Sand 50 feet 50 feet Sandy Loam 50 feet 50 feet Light Loam 50 feet 50 feet Heavy Loam 50 feet 50 feet Silt Loam 50 feet 50 feet Sandy Clay Loam 50 feet 50 feet Light Clay Loam 50 feet 50 feet Heavy Clay Loam 50 feet 50 feet Light Silty Clay Loam 50 feet 50 feet Heavy Silty Clay Loam 50 feet 50 feet Sandy Clay 50 feet 50 feet Silty Clay 50 feet 50 feet Clay 50 feet 50 feet The effluent disposal setback is based on the soil texture of the horizon in which the absorption trench or bed is to be placed. These setbacks are to be used on all individual on-site wastewater disposal systems except spray irrigation disposal and overland discharge. Source: Miss. Code Ann. § 41-67-3. TABLE 2 - SIZING: AGGREGATE (Gravel, Crushed Stone, Tire Chips, or other approved media) Results of the Soil and Site Evaluation Soil Textural Class Ribbon Lengths (Inches) EPA Manual Application Rate GPD/ Ft2 Absorption Area Per Bedroom (3’ Trench)* Additional Absorption Area Over 2 Persons Per Bedroom Ft2 Lf Ft2 Lf Gravel - - NOT SUITABLE Coarse Sand - 1.2 Medium Sand - 1.2 Fine Sand - 0.8 Loamy Sand - 0.8 Sandy Loam <.5 0.6 Light Loam <.5 0.6 Heavy Loam .5 – 1 0.45 Silt Loam <1 0.45 Sandy Clay Loam 1 – 2 0.45 Light Clay Loam 1 – 1.5 0.30 Heavy Clay Loam 1.5 – 2.0 0.20 Light Silty Clay Loam 1 – 1.5 0.30 Heavy Silty Clay Loam 1.5 – 2.0 0.20 Sandy Clay >2.0 - NOT SUITABLE Silty Clay >2.0 - NOT SUITABLE Clay >2.0 - NOT SUITABLE *Bedroom is equivalent to 130 GPD. Source: Miss. Code Ann. § 41-67-3. FIGURE 6 – Conventional Subsurface Absorption Source: Miss. Code Ann. § 41-67-3. FIGURE 7 – Ultra Shallow Absorption Field Source: Miss. Code Ann. § 41-67-3. FIGURE 8 – Conventional Absorption Bed Source: Miss. Code Ann. § 41-67-3. FIGURE 9 – Effluent Distribution for Absorption Beds Source: Miss. Code Ann. § 41-67-3. FIGURE 10 – Connection Lateral (Spillovers) Source: Miss. Code Ann. § 41-67-3 FIGURE 11 – Conventional Absorption Bed Source: Miss. Code Ann. § 41-67-3. FIGURE 12 – Distribution Box