Percolation Testing

(1) The standard percolation test is intended to give an approximate measure of the soil's percolating capacity. Unsaturated hydraulic conductivities vary dramatically from the saturated hydraulic conductivity with changes in soil characteristics and moisture content. Percolation testing may be conducted at any time of the year and the data obtained in accordance with the procedures specified by 310 CMR 15.000 may be deemed valid for an indefinite period provided the soils within the site evaluated remain undisturbed and unaltered. All percolation testing shall be performed in the presence of the Approving Authority. (2) A percolation test shall provide data necessary to assess the suitability of the soil to transmit water from the soil absorption system and to a depth of four feet below this elevation. Where the soil varies with depth as indicated by the results of the deep observation hole testing performed pursuant to 310 CMR 15.102, percolation tests shall be conducted in the soil which is identified to be the most restrictive by the Soil Evaluator with the concurrence of the Approving Authority. (3) Percolation tests shall be performed by a Massachusetts Registered Professional Engineer, Massachusetts Registered Sanitarian, a Soil Evaluator, or a person who: (a) in the opinion of the Approving Authority is qualified to perform such tests; (b) has one year of documented experience in satisfactorily performing such tests; and (c) has used or gained skills that demonstrate sufficient competence to perform such tests. (4) At least one percolation test shall be performed at every proposed disposal area, one in the primary area in which the soil absorption system is to be located and one in the proposed reserve area. Additional tests shall be required where soil conditions vary or as determined by the Approving Authority or where system design exceeds 2,000 gpd. In such instances, a minimum of three percolation tests, spaced uniformly over the proposed soil absorption area, shall be performed in addition to the test in the proposed reserve area. (5) Where 310 CMR 15.104(4) or the Approving Authority requires multiple percolation tests, the results of the test providing the slowest rate shall be used for system design. Averaging of percolation test rates across the site is prohibited. (6) Percolation tests may be performed at any time of the year provided the soil to be tested is below the frozen soil layer. (7) Percolation tests shall not be performed in holes that have remained open to the atmosphere for more than three consecutive days. (8) Percolation tests shall not be performed in filled or disturbed ground.