Seasonal high water tables are among the toughest challenges onsite installers face. The challenge is to ensure ade-quate separation between the bottom of the infiltrative surface for septic tank effluent and the saturated soil. Separation is necessary to provide for unsaturated flow from the trench and to enable oxygen exchange, which results in effective treatment of the effluent. Our preferred solution is to install an at-grade or mound treatment system to avoid the water problems. However, we are always asked about using artificial drainage as a way to solve the problem, and in some instances this can be a preferred
