A hands-off approach
Managing product collected from separate phase product recovery systems can be a formidable task. Law Engineering and Environmental Services, Inc. (LAW), Kennesaw, Ga., designed and constructed a practical trailer-mounted tank and pump system to assist in free product management. Though it appears to be only a simple tank and pump, the system saves time while improving the health and safety of project workers.
LAW is currently working on a site where years of leaks in underground storage tanks and pipeline systems have resulted in the accumulation of light hydrocarbon-free product in several separate areas. In addition to investigation and regulatory support, the company provides day-to-day operation and maintenance of free product recovery systems.
The recovery systems include an air operated (pneumatic) groundwater depression pump and a separate pneumatically operated skimmer pump for removal of free product. The initial project included operation of two recovery systems, and has recently expanded to include the design and installation of nine additional recovery systems.
Each of these recovery systems has a dedicated 55-gallon drum for collection of free product pumped from the wells. Drum contents required disposal approximately twice per week. The operator disposes of the free product by moving the product from the well locations to an on-site collection tank, where it is temporarily held for off-site disposal.
Finding a better way
"We were operating the original recovery systems by one of two ways," said Alison Levinson, project coordinator. "Either the 55-gallon drum was removed from the recovery system and transported to the collection tank, or the drum contents were manually pumped into 5-gallon buckets and carried to the collection tank. The manual pump wasn't too bad so long as you only had to pump 20 to 30 gallons. This method was manageable for a limited system. However, with nine additional recovery systems coming on-line, we knew that we had to come up with a better method.
"The team brainstormed all sorts of ideas, from motorized carts to installing pipeline systems. The approach selected involved constructing a small, 5-foot-by-8-foot utility trailer with a tank and dedicated pump to transport the free product. We found an off-the-shelf, 120-gallon tank from Hoover Containment, Inc. that fit our needs. It was a double wall steel tank and was small enough to fit on the utility trailer," said Levinson.
A unique feature of the trailer system is its all-pneumatic operation. A facility-wide air system was already used to supply air to the recovery systems. Taking advantage of this fact, a pneumatically operated double diaphragm pump was chosen to move the product. Double diaphragm pumps provide adequate suction head to pull the product out of the drum and pump it into the trailer-mounted tank. Special valving designs allow the same pump to be used for emptying the tank.
"The team even found a pneumatically operated high level cut off system for the tank," said Levinson.
The air supply hose and product hose are kept neatly in hose reels mounted on the trailer. A truck tool box was also mounted on the trailer for additional storage.
A project scientist built the trailer system. After purchasing the utility trailer at a local trailer supply store, he built the system in his garage at home. After the tank was lifted onto the trailer, it was bolted to the trailer floor. The pump and hose reels were obtained from a local equipment supplier and also bolted to the trailer floor. To make the piping system easy to install, standard copper pipe and valves were chosen from a local builders' supply store. Total construction time was only two weeks.
This innovative, yet simple tank system is easy to operate. The trailer is pulled to the recovery system drum location and the air line is connected to the local air source. The product line is connected to the 55-gallon drum using a quick disconnect type fitting to a drop tube in the 55-gallon drum. The trailer mounted pump is used to pump the contents from the drum to the 120-gallon trailer mounted tank. Once the tank is full, the trailer is moved to the central collection tank and the trailer tank is emptied.
"What's really interesting is the versatility of the trailer," said Brad Malone, the project's field technician. "We found that the trailer could be used to recover free product from the 2-inch monitoring wells. We bail a number of wells containing free product and a few of the wells produce 5 to 6 gallons of product each week. We found that the pump has enough suction to pull the product right out of the well. It also works great pumping out accumulated rainwater."
The trailer-mounted tank and pump system has saved a considerable amount of time in the field. Previous operations required approximately one hour per drum location. Using the trailer, each drum can be pumped in about 15 minutes. The additional recovery systems would have made them almost impossible to maintain by manually moving the free product to the collection tank.
An equally important benefit is the improved health and safety conditions. "Since we no longer have to move 55-gallon drums around, or are not carrying 5-gallon buckets of free product, we have much less contact with the product. The trailer-mounted tank system has saved a great deal of time and effort for this project, as well as improved health and safety," said Levinson.
This article originally appeared in the 03/01/1999 issue of Environmental Protection.