The material requirements in §733-20 Underdrain Filter Material was revised to include an acceptable material substitution. Specifically, crushed glass will be allowed as a substitution for the crushed stone, sand, gravel, or screened gravel typically used to process Underdrain Filter, TYPE_s 1 or 2.
Glass aggregate and blends thereof are strong, safe, and economical. The main source of crushed glass utilized in the construction industry is via glass cullet. Glass cullet is comprised of the mixed colored glass fragments resulting from the breakage of colored glass containers, typically collected at Municipal Recovery Facilities (MRFs). Glass cullet, if properly sized and processed, can exhibit characteristics similar to that of gravel or sand.
In 1991, Executive Order #142 directed all State Agencies to make maximum use of recycled materials. In 1994, the Department issued EB 94-039 allowing crushed glass to be recycled on construction projects as a substitute for natural aggregates as part of a blended product. Subbase material may be a blend of Blast Furnace Slag, Stone, Sand, and Gravel, with not more than 30% by weight of glass. In addition, glass may be incorporated into embankments if it is thoroughly mixed with other suitable material so that glass constitutes no more than 30% by weight anywhere in the embankment.
