 snake" to remove the obstruction. If the blockage is too far down the pipe to feel, or if the obstruction seems to be at the union of the drain field supply pipe and the distribution system, dig up the junction, disconnect the supply pipe from the perforated pipe, and inspect the perforated pipe for roots or other material. Root out the blockage with the "sewer snake." If roots are the problem, treat the drain field with copper sulfate as described in the System Renovation section. If no blockage can be found, chances are that the drain field is "clogged." If this is the case, you must either restore the clogged drain field (a temporary measure) or replace it. LIQUID PONDED OVER DRAIN FIELD Ponded liquids mean that the soil is not accepting the amount of liquid flowing into it, and has become saturated all the way to the surface. Before you panic and replace or restore the drain field, assess the situation. Is the drain field in an area that collects runoff ONSITE WASTEWATER DISPOSAL or drainage from the foundation? If so, you could fill in the depres- sion or redirect the foundation drainage. Has there been an unusual rainfall or snow melt? Has there been an unusually large amount of water used in the house? Is the drain field wet over its whole area or only part? If only part, the problem could be poor distribution due to a blockage or to a high spot in a distribution pipe. Would it be feasible to reduce household water use by 20% or SO and see if the problem goes away? Another important factor is the age of the drain field. If a new drain field (on the order of three years old or less) fails, you should suspect a problem in design, construction, or installation. Was the drain field sized correctly? Check the chapter on drain fields and compare. Was it installed in wet weather SO that the trench sides were smeared? If so, replacement may be necessary. Get a shovel and expose the end of a trench. Is there enough gravel? Expose the top of the distribution pipe at the junction with the supply pipe and at the end 