Advanced Environmental Interface

1. General Information 2. Regulatory Requirements 3. Cathodic Protection 4. Tank Types 5. Tank Closures 6. Reimbursements

1. Tanks / General Information

Tanks are commonly used for bulk storage of heating fuel, production-related liquids or chemical feedstocks. Tanks can be constructed of several different kinds of materials, can be located under ground or above ground, and can hold a wide variety of fuels or chemicals.

In Connecticut, most industrial or commercial underground storage tanks (USTs) with capacity greater than 2,100 gallons are subject to either state or federal UST regulations or both, unless they hold water or some other innocuous, unregulated substance. USTs that contain flammable liquids (e.g., gasoline, solvents) may also be subject to state and local fire codes, and to various emergency planning requirements (e.g., community right-to-know, EPA risk management planning, OSHA chemical process safety). In Connecticut, most above ground tanks are not regulated by environmental rules (except for the requirement for a spill prevention, control and countermeasure plan for petroleum products). However, most of them are subject to fire code and safety rules if they contain flammable materials.

These pages deal mainly with USTs holding fuels or hazardous materials. The regulations discussed are the EPA rules at 40 CFR 280 (Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks), and the DEP rules at 22a-449(d)-1 (Control of Nonresidential Underground Storage and Handling of Oil and Petroleum Liquids). There's a lot of information about USTs and regulations on the EPA website, and some on the DEP website. That information is extensive, and is not duplicated here -- these pages deal mainly with the most common questions we get, and the most common compliance problems we see, out in the field.

2. Tanks / UST Regulatory Requirements

This page summarizes regulatory requirements for underground storage tanks (USTs), and provides information helpful to diagnosing and preventing problems. At commercial or industrial sites (aside from gas stations), the most common USTs are for storage of heating fuel, solvents, other production-related liquids or chemical feedstocks.

Historically, the problem with USTs has been that leakage wasn't detected because it occurred underground and was not visible. Loss of significant volumes can occur through even small corrosion holes in tanks, or through piping connections worked loose by traffic vibration or frost action. In the early 1980's this became a widely recognized environmental problem, in Connecticut as well as many other states.

In May 1986, DEP promulgated state rules (RCSA 22a-449(d)-1); in December 1988, EPA promulgated federal rules (40 CFR 280). DEP subsequently amended its rules in July 1994 (RCSA 22a-449(d)-101 et seq) to incorporate the federal, but retained the earlier section to cover tanks not regulated at all by the federal rules.

Both state and federal rules set standards for new tanks, and allowed facilities time to come into compliance, either by:

removing the tank;
replacing the tank with a new one meeting the standards; or
upgrading an existing tank to meet the standards.

The two sets of rules had somewhat different approaches, but converged on the same objective (better protection against leaks). At present, most USTs at commercial or industrial sites have to be in compliance, or face potential penalties. (Residential USTs currently are not regulated by state or federal rules, although several towns in Connecticut have local ordinances). With a few exceptions, USTs in place today at commercial or industrial sites in Connecticut must meet the following regulatory requirements:

Performance standards must be met. New and upgraded USTs must be:

Constructed of non-corrodable material, or if steel coated and cathodically protected (including piping).
Protected against spills (that can occur when the tanker truck's fill hose is disconnected -- this usually takes the form of a small sump around the fill pipe).
Prevented from overfilling (this can be done a number of ways, from an alarm that goes off when the liquid gets near the top of the tank, to a simple valve that automatically shuts off the fill line or creates a backpressure condition that prevents continued filling when the level approaches the top).
Certified as to proper installation by a qualified person.

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Notification must be made to DEP when a UST is installed, removed or modified. This is done on the DEP's EPHM-6 form. (You need Adobe Acrobat Reader v3.0 or later enabled on your browser as a helper to view this form. To return to this page after viewing the form, just click the browser back button. If you don't already have this free software, we suggest you download Acrobat Reader). Depending on your browser and platform, to print a paper copy of this DEP form, you may need to first Save As a .pdf file on your hard drive. Don't use this for official purposes!!! Call DEP for a blank multipage form with instructions.
Specific operating requirements must be met. USTs must be:

Monitored during filling for spills and overfills.
Checked monthly or annually to verify the cathodic protection system is functional.
Prevented from taking delivery of materials incompatible with the tank.
Repaired promptly if neede.
Reported as leaking to DEP if there is a confirmed loss to the environment.

Some form of release detection must be provided. This may be:

Double-walled tank and piping construction with sensors in the interstice between the walls.
Keeping an inventory control system for recording and reconciling tank deliveries and outputs (see the example inventory form and its instructions). (In order to view these documents, you must have Adobe Acrobat Reader v3.0 or later enabled on your browser as a helper. To return to this page after viewing, click the browser back button. If you don't already have this free software, we suggest you download Acrobat Reader). Depending on your browser and platform, to print a paper copy of the inventory form or instructions, you may need to first Save As a .pdf file on your hard drive.
An automatic gauge that detects changes not related to usage (such as the Veeder-Root TLS-350 system used on many gas stations).
Monitoring in the ground outside the tank for vapors in the soil.
Monitoring the groundwater in the vicinity of the tank for indication of a product loss.
Any other method capable of detecting a 0.2 gal/hr leak rate with a probability of detection of 95% or better and a probability of a false alarm of 5% or lower.

Actual and suspected releases to the environment must be reported to DEP, including spills and overfills as well as subsurface leaks.
Confirmed releases to the environment must be investigated and cleaned up appropriately (see the pages on Site Investigation and Site Remediation).
UST owners/operators must be covered by insurance or some other form of financial responsibility (this is automatically provided by the Connecticut Leaking Underground Storage Tank Trust Fund, popularly known as the "Lust Trust").

USTs containing only heating oil for use in an adjacent building do not need to have leak detection monitoring, spill protection or overfill prevention (although for a new installation these additions are relatively inexpensive and a good idea). If larger than 2,100 gallons, such USTs are still subject to the original DEP rules for making a life expectancy determination, conducting tank tightness testing several years prior to the end of life expectancy, and removing the tank at the end of its life expectancy.

If you want to review your tank status, see the list of key questions to ask yourself on tanks. (In order to view this pdf document, you must have Adobe Acrobat Reader v3.0 or later enabled on your browser as a helper. To return to this page after viewing the list, just click the browser back button. If you don't already have this free software, we suggest you download Acrobat Reader).

These questions are the most common starting questions for environmental auditing of underground storage tanks at facilities in Connecticut. Depending on your browser and platform, to print a paper copy you may need to first Save As a .pdf file on your hard drive.

3. Tanks / Cathodic Protection

Unprotected steel structures placed in the ground tend to corrode (rust) in many soils because the steel acts as one half of a galvanic cell, similar to a battery. Steel tanks and lines can be protected by coating them, but if the coating is incomplete (holidays), or is damaged, the uncoated areas can be subject to high rates of corrosion.

There are two common methods to protect against this:

An anode made out of a more electrically active metal (magnesium or zinc) can be attached to steel tanks and lines. This metal corrodes in preference to the steel, thus the term "sacrificial anode". These are sometimes called "passive systems", and they are similar in concept to a battery.
A rectifier can be used to maintain a slight charge on the tank and lines. This keeps the steel at an electrical potential where it won't corrode. These are sometimes called "active systems", and are similar in concept to a battery charger -- they plug into an electrical ac outlet, and produce a low-voltage dc output to the tank and lines.

Given the nature of modern tank coating materials and technology, cathodic protection is mainly insurance against small exposed areas of steel (from installation damage or mistakes in the coating process). Neither method is intended to protect big expanses of bare steel. The standard voltage stated in the DEP regulations to protect steel tanks is -0.85 vdc (from the tank to a copper/copper sulfate reference cell in contact with the soil). More negative than that (i.e., -0.86 and up) is good), less negative than that (i.e., between 0 and -0.84 vdc) is bad.

Typical problems that can cause a sacrificial anode on a tank to not maintain the proper voltage are:

Overly rapid consumption of the anode in highly corrosive soil.
An electrical conduction pathway developing between the tank and a large area of bare metal exposed to the soil:

the piping is not coated, and/or electrical isolation between the tank and lines has been breached;
the piping is coated, but is not electrically isolated from other metal in the ground (i.e., the boiler plumbing or water supply line or facility electrical grounding system);
there is a conductive pathway (short circuit) of some kind that is letting current from the anode bleed off at an excessive rate into the soil.

Installation problems, such as:

removal of electrical isolation bushings at the tank;
failure to wrap and seal across isolation bushings, particularly in a highly conductive soil (e.g., brackish water by the shore);
not removing the plastic shipment cover off the sacrificial anode, or not wetting down the anode bag when installed.

Similar conditions can occur with rectifier systems, but unlike an anode which has a fixed electrical potential, the rectifier can sometimes be up-sized to maintain the required voltage.

Here's a couple of fairly typical problems, the first an installation problem, the second a problem that developed after installation:

With either cathodic protection method, problems with insufficient voltage need to be remedied to stay in compliance with state and federal UST regulations. This could mean replacing or adding anodes, or excavating and replacing or re-wrapping piping, or exploring conduction pathways to determine what the problem is. See the before/after diagrams of a typical upgrade below.

Also, sacrificial anode systems need to be checked once per year, and rectifier systems once per month, with records kept, in order to stay in compliance with UST regulations.A fair percentage of tank owners forget to do this. Not being in compliance could cut down on the money reimbursed by the LUST Trust for cleanup expenses, particularly if a corrosion hole was the source of a leak.

4. Tank Types

Underground Storage Tanks

State-of-the-art USTs manufactured today are highly protected against leakage. Construction may be either single-walled or double-walled. Double-walled tanks have an interstice (space) between the two walls for detecting leaks, and thus offer built-in secondary containment in the event of a leak in the primary (inner) tank. Steel tanks are highly protected against corrosion, with dense coatings, sacrificial anodes and electrical isolation bushings.

Shapes of USTs are generally horizontal cylinders, with capacities ranging from 300 gal to 40,000 gal, in several combinations of diameter and length. Coatings may be polyurethane, fiberglass, high density polyethylene or other material that is non-corrodable, not electrically conductive (i.e., dielectric), chemically resistant to the material(s) to be stored in the tank, and hard enough to resist incidental nicks and scratches during installation.

Sizes of older tanks are not as well standardized, but they also approximate this chart. It's sometimes necessary to verify the configuration of an old heating oil tank for which there is little documentation. This can be done by sticking the tank to determine the depth of the bottom of the tank, then hooking the bottom of the fill pipe (unless it's a submerged fill) with a tape measure to determine the depth of the top of the tank. The depth to bottom minus the depth to top gives the tank diameter. If the volume is known (it usually is, for delivery purposes), then the length is very close to one of those shown on the chart.

Above Ground Storage Tanks

Above ground tanks (AGTs) are reasonable alternatives to USTs in certain circumstances (enough room, local fire codes allow them, more convenient). Many AGTs are fitted with secondary containment, or are double-walled, or are installed in a secondary containment. They are also generally protected from accidental damage, either by their inherent design or by thoughtful placement on the site.

Unlike USTs, AGTs have many different shapes in addition to horizontal cylinders: they may be tall vertical cylinders, short stubby vertical cylinders, or rectangular. Frequently, they are manufactured with (or fitted in the field with) rain guards to prevent water accumulation in the secondary containment.

The materials, coatings and types of construction are generally the same as for USTs. Steel AGTs typically don't have cathodic protection, since they're not in contact with the soil.

(Pictures courtesy of Highland Tank)

5. Tank Closures and Reporting of Leaks

Leaks can occur from holes (usually caused by corrosion) in a tank, or from piping fittings that have worked loose due to vibration from traffic, frost action, improper installation or some other cause.

Even the best leak detection methods and tightness tests cannot detect leak rates of less than about 0.05 gal/hr. A continuous leak at this rate could lose about 438 gallons to the ground in a year. Depending on the substance lost, the nature of the soils and the water table elevation, this amount of loss could cause a substantial contamination problem in the groundwater. Subsurface leaks to the groundwater are of particular concern where there are public or private drinking water wells that may entrain contaminated groundwater.

Sometimes a leak is discovered on tank closure (i.e., excavating the tank to remove or replace it). There is a sequence of actions spelled out in the DEP UST regulations:

Notify DEP of intent to close (no format specified) 30 days or more before beginning closure [22a-449(d)-107(b)(1)].
Notify DEP of abandoned or removed tanks (on form EPHM-6) within 30 days of abandonment or removal [22a-449(d)-1(d)(4)].
Assess tank excavation zone at closure [22a-449(d)-107(c(1)].
If find free product, contaminated soils or contaminated groundwater, begin corrective actions [22a-449(d)-107(c)(2)].
Compile all information on items 1 through 4 above, and retain for 5 years minimum in files of owner/operator who closed the tank, and in files of property owner of the site (no format specified) [22a-449(d)-107(e)]. No specific requirement for sending any kind of report to DEP, if there was no release from the tank.
If a release from the tank is confirmed, take corrective actions [22a-449(d)-106(b), (c), (d) (e) and (f)].
Report initial abatement steps [22a-449(d)-106(d)(2)] within 20 days after confirming a release (no format specified) and report all information on corrective actions taken [22a-449(d)-106(e)(2)], within 45 days after confirming a release (no format specified).
Investigate possible contamination of soil and groundwater [22a-449(d)-106(g)(1)].
Report information on items 6 and 7 above to DEP (no format specified) [22a-449(d)-106(g)(2)]. A report is required by this section when: (a) free product is found; (b) contaminated soil is in contact with groundwater; (c) drinking water wells are affected; or (d) DEP requires it. Note that the intent here is more of a contamination assessment report than a tank closure report.

In general terms, DEP wants a report when the spill reporting statute [CGS 22a-450] is triggered. This happens when there is a spillage or loss "which poses a potential threat to human health or the environment". The statute doesn't further define this concept, but a reasonable interpretation is that soil or groundwater contamination above the remediation standards would constitute a threat to the environment. Therefore, if investigative actions at closure detected contaminants above these standards, this would trigger a spill report under 22a-450, which would then require a report under item 8 above.

DEP can also "require a report" under specific administrative vehicles, such as their advisory memo of May 28, 1996 re Sampling and Analytical Methods for UST Closure. This document indicates DEP must be notified (no format specified) if contaminated soil, contaminated groundwater, or free product as a liquid or vapor is observed, or detected by lab analysis.

Various public safety statutes [e.g., CGS 29-322b] require some sort of disclosure of substantial and imminent hazards. Six types of specific environmental imminent hazards are reportable under Public Act 98-134 if discovered in the course of any environmental investigation, including tank closure.

The bottom line is that any evidence of leaks from a tank needs to be evaluated carefully and investigated appropriately.

6. Tanks / Reimbursements from the LUST Trust

To cover the financial responsibility requirements of state and federal regulations, Connecticut has set up a Leaking Underground Storage Tank Trust Fund (popularly known as the LUST Trust Fund). This fund may reimburse (after a $10,000 deductible) some or all of the costs for an owner/operator to investigate and clean up a tank leak (up to a cap of $1,000,000). It doesn't cover unregulated tanks (such as residential). The fund gets its money from a 1-cent/gal tax on oil and gasoline.

The funds are disbursed by a Board (appointed by the Governor), and the entire process is administered by the DEP. UST owners/operators seeking reimbursement for expenses incurred during investigation and cleanup must file an application. Usually, owners/operators find the application complicated enough to get outside help from attorneys and/or environmental consultants.

An application to the Fund requires an evaluation of compliance with UST regulations. The fund's payout is reduced in proportion to the number of non-compliance items. In particular, if non-compliance is the proximate cause of a release, there may be a very substantial reduction in the payout awarded by the Board. The DEP reviews each application in detail, and makes recommendations to the Board. See the list of questions for the compliance review. (You need Adobe Acrobat Reader v3.0 or later enabled on your browser as a helper to view this list. To return to this page after viewing the list, just click the browser back button. If you don't have this free software, we suggest you download Acrobat Reader). Depending on your browser and platform, to print a paper copy of these questions you may need to first Save As a .pdf file on your hard drive.

It is rare for any owner/operator to be able to demonstrate 100% compliance. Most applicants to the Fund get between 60% and 90% of their costs back. Accurate and extensive documentation of incurred costs is required in the Fund application, because DEP evaluates each line item against rigorous standards to determine if the cost of each item is allowable. Good bookkeeping is essential.