Evaluation of the multichambered treatment train, a retrofit water-qualitymanagement practice

This study evaluated the water-quality benefits of a new urban best managem ent practice design called the multichambered treatment train (MCTT). The s tudy consisted of collecting flow-weighted water-quality samples at influen t and effluent locations for 15 consecutive storms. Device efficiencies wer e based on load reductions of 68 constituents. Total rainfall amounts for t he 15 storms ranged from 0.45 to 3.48 cm, yielding 1.7 to 8.9 m(3) of water treated by the device. None of these storms surcharged the unit. High redu ction efficiencies were found for all particulate-associated constituents, such as total suspended solids (98%), total phosphorus (88%), and total rec overable zinc (91%). Dissolved fractions had substantial but somewhat lesse r removal rates (dissolved phosphorus, 78%; dissolved zinc, 68%). Total dis solved solids, which originated from road salt storage, yielded 4 times the total suspended solids load. No appreciable shift was seen between influen t and effluent particle size distributions.