Transloading, terminal facilities present environmental risks that must be addressed
Apr 1, 2002 12:00 PM
LOADING and unloading of liquid and dry bulk cargoes presents some of the biggest environmental challenges for shippers, carriers, and consignees. This is where product spills are most likely to happen.
Sites used for product transfer may cover only a few acres, but even the smallest accidental releases can have a profound impact on surrounding areas, according to Merrill Bishop, president of TransEnvironmental Services Inc. The impact may not be visible for years, but state and federal environmental agency officials have the tools to trace pollution back to the source.
Loading racks, storage terminals, rail transloading facilities, and other product transfer points need to be designed with product containment in mind. Factors, such as rainwater runoff, that can spread contaminants also must be considered.
Bishop lists seven key points to keep in mind when performing an environmental risk assessment on an existing or proposed product transfer facility. “The objective here is to avoid overly complex and costly systems,” he says. “Good results can be achieved with common sense, inexpensive strategies.”
- Divert pass-through surface water
A company has enough tainted rainwater disposal problems without adding runoff from neighboring properties to a detention pond. Often, disposal of this tainted rainwater can cost more than a dollar per gallon, according to Bishop.
When possible, concrete culvert piping should be used to move this off-site runoff across the property. If this can't be done, diversionary ditches and dikes should be used to route this surface water away from product transfer areas.
- Direct collected rainwater away from transloading areas
Facility planners usually take into account the amount of the heaviest rain in 10 years on the facility, but they sometimes miss the fact that a large share of the surface water is received and often collected on parking lots and product storage areas.
Roof drain spouts can be connected directly to an underground storm sewer to prevent the pure rainwater from becoming tainted with surface runoff. “Generally, the EPA (Environmental Protection Agency) cannot consider contaminated rainwater that lands on a building roof,” Bishop says. “Product transfer areas should have their own direct surface water storm drains going into a designated detention pond.”
- Build canopies over transloading areas
Because of the higher statistical possibilities of accidental releases in these areas, they should be isolated from receiving rainwater or having surface runoff wash across the product handling area.
Canopies are expensive because of safety and fire requirements. Since railroad safety standards require that roof supports must be at least 23 feet above top of rail, a canopy over a loading rack must have heavy wind bracing. If sidewalls are added, the local fire marshal often will require a dry-pipe sprinkler system for fire suppression.
- Use dry-disconnect hoses and overfill alarms
Closed-loop loading and unloading provides one of the best means of preventing inadvertent product spills. However, the challenge with dry disconnects is that some commodities are difficult to handle through hoses with these types of fitting. These products are viscous or congeal at ambient temperatures, creating more problems than they solve.
Overfill alarms should be used because automatic shutoff controllers — and even trusted employees — are sometimes slow to react. Bishop recommends spill pans as a further backup to prevent product from reaching the ground in the event all other safety systems fail.
- Build detention ponds with poly liners
This should prevent contaminated surface waters from seeping through the pond floor and reaching the ground water level. Containment ponds should be able to hold at least the contents of a tankcar or overflow from storage tank dikes resulting from fire response operations.
- Isolate tainted rainwater sources
Tainted rainwater disposal is expensive. The disposal cost is directly related to the amount and type of impurity in the water. Most city sewer plants require certified laboratory analysis of tainted rainwater prior to release into their treatment system. Depending on the level of analysis, it can cost around $1,000 per sample, according to Bishop.
An oil/water separator may be required if oils or petroleum products are handled at the facility. Activated carbon filtration may be required to remove chlorinated compounds. These options are easier to implement if each spill source has its own retention basin or moat.
- Avoid collecting rainwater in the first place
By using spill pans at the source of possible accidental releases, the whole problem of tainted rainwater can be simplified. A variety of spill pans are available: center and outboard pans for tankcar transloading, portable tank trailer pans, and foldable chemical-resistant fabric hammocks. Some spill containment systems are designed into a rail transfer facility, while other products are designed for retrofit applications. Annual rainfall levels provide a useful guideline for determining total containment capacity requirements.
Retrofit-type spill pans for rail use hold approximately 500 gallons in center and side compartments. Portable spill pans for tank trailers typically will contain 40 to 50 gallons. The emergency containment Haz-Hammock from TransEnvironmental Systems holds approximately 50 gallons and works with tankcars and tank trailers.
Bishop cautions that rainwater collected in open spill pans at transloading facilities and loading racks must be dealt with in accordance with federal and state environmental regulations. He adds that spill pans with rain covers may be the best choice for many operations.
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