product must be specifically labeled for use in sewers to control tree roots. The foaming herbicide must be such that the foam is delivered and deposited evenly and uniformly throughout the treated sections of sanitary sewer line. When properly used in foaming generating equipment, the foam generating equipment must produce a minimum 400:1 expansion ratio (air and water:concentrate). FOAMING HERBICIDE: Shall be composed of two non-systemic herbicides for controlling roots in sewer lines. It shall be a water dispersible, surfacing-active formulation of Sodium Methyldithiocarbamate (anhydrous) and Dichlobenil plus a foaming surfactant system. REGISTRATION: The product must be currently registered by the US EPA for root control use in sanitary sewer lines. PRODUCT COMPONENTS: The root control product shall be formulated containing no less than 24.25% by weight of Metam-Sodium (Sodium Methyldithiocarbamate,anhydrous) and no less than 1.95% by weight of Dichlobenil (2,6- Dichlorobenzonitrile 50W (wettable) type; i.e., 50% dichlobenil and 50% bentonite clay, including the foaming surfactants. The Dichlobenil 50W powder must have a particle size of not less than 95% through an ASTM 325 mesh (44 micron) screen to assure adequate suspension and low abrasion in the foaming equipment. The foaming herbicide shall contain no heavy metals in any of its components. The proper amount of foaming agent shall be provided to produce a stable and effective foam.
