ped out because the sewage in the end may not flow through the sand as fast as the pumper can suck it out. If the pumper starts sucking air, then he will either have to wait for the area around the stand pipe to resaturate, or use a pump with smaller capacity. He won't be happy about either. An alternative might be to get the septic tank pumped out (which you have to do once in a while anyway), and rent a small sewage rated pump to move the sewage in the bed back into the septic tank. Removal of 1000 gal of sewage LOW-IMPACT SYSTEMS will lower the water level in the bed by only a couple of inches, SO several pumper trips may be required. And now for a final note. As the sewage evaporates from the surface of the ET bed, the salts dissolved in the sewage are left behind. A white crust of salt may develop on the surface of the bed, since the salt concentration in the bed will rise. Concern has arisen about the effects of this salt buildup on the plants and on the ability of water to evaporate from the surface. More than a decade of expe- rience with ET systems indicates that this is not much of a cause for alarm. The salt crust doesn't seem to inhibit evaporation, and salt- tolerant plants seem to survive for years with proper care. However, should salt buildup ever cause a significant problem, there are cor- rective measures to take. You can remove the top few inches of sand and salt deposits, and you can pump out the bed, flood it with fresh water to wash out the remaining salt, and pump out that wash water. This should completely rejuvenate the bed. HOLDING TANKS Application Holding tanks are sealed vaults which receive liquid wastes and accumulate and store those wastes until they can be pumped out and hauled away. There is no onsite discharge, so, like the ET sys- tem, the holding tank is used where no discharge can be allowed. But although they are very inexpensive to buy and install, and although they cannot pollute if they are constructed and maintained properly, almost no one likes them, and their applicati