UIDANCE FOR NDERGROUND TORAGE ANK …

1 1 FINAL August 16: This document is intended to provide basic information and is not intended to be a complete guidance document. All suggestions may not necessarily be applicable to every station or situation and therefore may not be required. Consult your company operating manuals and/or your state UST management requirements for complete requirements in your area. GUIDANCE FOR UNDERGROUND STORAGE TANK MANAGEMENT AT ULSD DISPENSING FACILITIES INTRODUCTION If a fuel storage facility is not properly maintained, bacteria and fungi can grow in the fuel water interface, causing filter problems and deactivating the water monitoring system.

2 With the exception of fuel with inadequate low temperature fluidity ( , wax formation in diesel tanks at cold temperatures), most problems can normally be avoided by keeping the fuel storage system clean and as water free as possible. Water in the storage system can accelerate fuel degradation which should be avoided in order to assure vehicle performance and because it can increase sludge accumulation in the bottom of tanks. Contaminants such as salts in the water may cause the fuel chemical structure to degrade into components that may be detrimental to storage system components.

3 These contaminants may also cause fuel additives necessary for maintaining the quality of the fuel distribution system to leave the fuel and enter the water. Not only is water a problem in itself, but it is also the environment for biological growth within the fuel. Less than inches of water is more than sufficient to promote microbial growth. Microorganisms live at the fuel water interface and feed on the fuel. The presence of microorganisms can lead to filter plugging, pump and injector problems, deactivation of the water monitor and buildup within the tank that is costly to remove.

4 IDENTIFICATION OF SYMPTOMS When dispenser flow slows to about half its normal rate (at gas stations from 10 12 gpm to around 5 gpm or at truckstops from 30 or more gpm to about 15 gpm), it is an indication that the dispenser filter requires attention and needs to be replaced. However, reduced dispenser flows along with frequent filter replacement, constant system maintenance or customer complaints may indicate that a more systemic problem exists as opposed to routine maintenance. Signs of fuel or fuel system issues include plugged fuel lines, erratic gauge readings, a rotten egg odor (of the fuel or filter), and frequent replacement of other components such as valves, rubber seals and hoses.

5 Figure 1 Plugged Dispenser Filter vs. new Issues contributing to the problem can sometimes be found by cutting open a clogged fuel filter and examining its contents. This can be done onsite or at an experienced laboratory. Solid or semi solid 2 contaminants, microorganisms, water, or fuel quality problems ( , high paraffin content, fuel degradation, etc.) are the most likely causes of filter blockages. Solid and Semi Solid Contaminants Solid contaminants, such as scaly, gritty deposits, consisting of reddish orange metal, may be indication of corrosion and/or silt introduction into the tank.

6 Black, brown, or other semi solid particulates/deposits may indicate fuel product degradation. Microbial Contamination The presence of a foul (rotten egg) odor in the fuel or on a filter usually indicates the presence of microbial contamination. The presence of an inversion rag layer ( ) from a tank bottom sample is a significant indication of microbial activity. Corrosion of interior metal filter parts may also indicate the presence of microbial activity. A non uniform covering of a fuel filter (Fig. 3) or leopard spotting (Fig.)

7 4) of a water coalescing filter is indicative of the presence of microorganisms. Since microorganisms need water to grow, microbial growth is always a direct indication of the fuel being in long term contact with a water layer in a storage tank. MANAGING FUEL SYSTEMS AND FUEL DELIVERIES It is recommended that facility owners/operators implement a simple and routine set of management and housekeeping practices to monitor and minimize fuel quality and fuel system issues. It is also recommended that facilities install a nominal 5 micron filter on the dispenser to ensure that fuel being dispensed to a vehicle is free of suspended particulate matter.

8 If a fuel storage tank has chronic water accumulation problems, then a 5 micron water absorbing filter in an equivalent pore size may be required. Owners/operators should make sure tanks and piping systems containing different grades or types of products are isolated as independent systems. Implementing routine management practices leads to reduced fuel quality and fuel system issues. For example: At Open and Close of Business: (1) Read all totalizing meters; (2) Gauge all tanks (either electronically or manually); (3) Check all tanks for water.

9 If possible, remove any water greater than or equal to 1 inch; and, (4) Reconcile meter and tank readings by product system on a daily basis. Photos courtesy of Fuel Quality Services, 2 Fig. 3 Fig. 4 3 Before and After a Fuel Delivery: (1) Gauge all tanks immediately prior to delivery and after delivery; (2) Remove standing water, ice/snow, and other debris from around the tank fill cover before allowing a fuel delivery into the tank; (3) After removing the tank fill cover, remove any and all water from inside the spill containment bucket; (4) All tanks should be checked for water before and after delivery.

10 And, (5) All fill and gauge caps should be reinstalled, making sure that caps and gaskets are in good condition. After Delivery: (1) Calculate the amount of product received and compare with the amount shown on the invoice; (2) Make inventory adjustments for transactions during delivery; (3) Make sure fill and gauge caps are tight and locked. Consider sticking the tank a second time after receipt for water detection. The tank needs some time to settle out, allowing any suspended water to separate and migrate to the tank bottom; and, (4) Make a special note and inventory adjustments for increase in water level.