Absorption Beds

Absorption Beds. Absorption beds may be constructed using large diameter aggregate replacement filter wrap pipe: 1. Absorption beds and trenches should be located a minimum of 10 feet from any trees. 2. The amount of linear footage required shall be the same as for trench configurations. The bottom of the bed should have a relatively level grade; the grade within the bed shall not exceed the grade allowed for trench installations. 3. Lines for distributing effluent shall be spaced from 3 to 6 feet apart with the first and last pipe placed next to the sidewall of the bed. The number of lines will depend on the linear feet of aggregate replacement line [Table 4] and width of the bed to be constructed. 4. Care should be taken to prevent heavy machinery from damaging the bed during backfilling. 5. The effluent must be equally distributed to the bed by means of a distribution box or with a pipe manifold. 6. When a change in elevation of the disposal trench is required, a 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 replacement pipe in the preceding trench so that an undisturbed block of earth will remain in place for the full depth of the pipe. Crossover lines shall be laid on undisturbed earth. The invert of the crossover must be at least four inches lower than the invert effluent line of the septic tank, aerobic treatment plant or vessel supplying effluent to the pipe. [See Figure 13.]