Specifications for the construction of Soil-Bentonite slurry walls have been developing for over 30 years. In this paper, the elements of good specifications and recommended parameters are discussed. Recent new provisions in specifications and their potential contributions to the cost and/or quality of the finished product are evaluated. Examples include requirements for low slurry sand content, undisturbed backfill sampling, cleaning the backfill, and other recent additions to “standard” specifications. Recommendations are made as to the best methods for field sampling of the slurry trench backfill and testing for permeability in the field and laboratory.