Aggregate

Aggregate shall be required for all soil absorption systems, unless otherwise approved in writing by the Department in accordance with 310 CMR 15.280 through 15.288, according to the following specifications: (a) Base aggregate for leaching structures shall be provided from below the elevation of the crown of the distribution line(s) to the bottom elevation of the soil absorption system and shall consist of double washed stone ranging from ¾ to 1½ inches in diameter and shall be free of iron particles, fines and dust in place; (b) A minimum of a two-inch layer of double washed stone ranging from c to ½ inch diameter and free of iron particles, fines and dust in place shall cover the base aggregate to prevent intrusion of fine textured soils to the system. Geotextile fabric may be substituted for the minimum two-inch layer of double washed stone.