Polyacrylamides are a broad family of polymers that possess a wide range of physical and chemical properties. One formulation, granular, linear anionic polyacrylamide (LA-PAM), has recently been used for water conservation purposes. When applied to an unlined water delivery canal, LA-PAM flocculates suspended sediment and settles to the bottom of the canal forming a layer that can reduce seepage. This document provides guidelines for applying LA-PAM to unlined water delivery canals in a manner that reduces the risks associated with treatment, while still providing seepage reduction benefits.
These guidelines manage environmental health risks by requiring the use of LA-PAM certified to have a low concentration of the residual acrylamide monomer (AMD), a known animal and suspected human carcinogen. In addition, the quantity of LA-PAM applied is limited to only those canal reaches known to have significant seepage rates and by limiting the rate of LA-PAM applied to no more than 10 lbs/canal acre per treatment and no more than 20 lbs/canal acre per year. The application rate of LA-PAM should be further reduced when optimum suspended sediment concentrations are not available. Although the human health risk from LA-PAM is small, common-sense safety procedures are required to minimize both direct contact and the accidental creation of secondary health hazards, such as slip hazards. As the canal water can transport LA-PAM beyond the treatment reach, downstream stakeholders and the potential for unintended consequences must also be considered before application commences.
These guidelines describe application techniques that can maximize seepage reduction effects. Techniques include applying LA-PAM only when there is sufficient suspended sediment to react with all the LA-PAM added, and applying LA-PAM upstream of the desired treatment reach to account for the time that LA-PAM needs to hydrate before it becomes reactive.
Download full document: 41239_PAM_Application_Guidelines.pdf
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