Landscape Architect Articles

LCN February 2008 Maintenance Issues01-29-08 | News

Chemical Storage

Adapted from Treatment, Storage, and Disposal of Hazardous Waste, www.epa.gov/epaoswer/osw/tsds.htm

Chemical containment structures come in single-door units like these, suitable for landscape contractors and other licensed pesticide applicators. The self-contained units are made of heavy-gauge steel with a chemical-resistant epoxy coating. Photo courtesy of U.S. Chemical Storage

The EPA, OSHA, state and local agencies don?????t mess around when it comes to chemical storage. It makes sense to be in compliance when your local inspector says hello. The EPA has compiled information relating to containment buildings (below), but much of these instructions apply to smaller structures suitable for contractors.

Standards for chemical containment buildings (or structures) include requirements for structural soundness and measures to prevent waste spilling into the adjacent environment. Because of the importance of such standards, before use, a professional engineer must certify that the unit is satisfactorily designed according to federal specifications.

The information in this document is not by any means a complete representation of EPA?????s regulations or policies, but is an introduction to the topic used for training purposes.

A view of the building interior shows shelves, lighting and part of the ventilation system. Photo courtesy of Safety Storage, Inc.

Federal Standards

The containment structure must be completely enclosed with walls, a floor and a roof. The floor, walls and roof must be constructed of manmade materials possessing sufficient structural strength to withstand movement of wastes, personnel and heavy equipment within the unit. Doors and windows need not meet these standards, but the building must be strategically designed with interior walls and partitions to ensure that wastes do not come into contact with them. Dust control devices, such as air-lock doors or negative air pressure systems (which pull air into the containment building), must be used as necessary to prevent fugitive dust from escaping through these building?????s exits.

All surfaces in the containment building that come into contact with waste during treatment or storage must be chemically compatible with that waste. Incompatible wastes (strong acids, etc??????) that could cause unit failure cannot be placed in containment buildings. The remaining containment building design standards establish a system of barriers between hazardous wastes in the unit and the surrounding environment.

Modern chemical containment buildings like this Safety Storage product include the security of steel, EPA-mandated signage and space for forklift trucks to lift and move the structures. Photo courtesy of Safety Storage, Inc.

Floors: Key Features

The floor of the containment structure is considered the unit?????s primary barrier, since it is the first measure used to prevent wastes from being released into the ground beneath the building. Construction materials vary with the type of wastes to be managed in the containment building, but concrete floors are typical.

The floor should be sloped toward a sump, trough or other liquid collection device to minimize standing liquids in the containment building and to facilitate liquid removal. A leak-detection system must be constructed immediately beneath the unit?????s floor to indicate any failure in the integrity of the floor and subsequent release of waste at the earliest practicable time. A secondary barrier such as a liner must be constructed around the unit to contain and to allow for rapid removal of any wastes escaping the primary barrier before such wastes reach adjacent soils, surface water or groundwater.

As with the unit floor, the secondary barrier must be structurally sound and chemically resistant to wastes and liquids managed in the containment building. In buildings where only certain areas are delineated for management of liquid-containing wastes, these secondary containment standards are mandatory only for wet areas, provided waste liquids cannot migrate to the dry areas of the containment building.

Containment buildings and structures are an important part of pesticide use, but federal and state rules also mandate an impermeable base for mixing and loading of chemicals. This site at the University of California?????s test facility near Irvine includes a concrete slab with a drainage system that collects spilled liquids. Photo by Erik Skindrud

Owner Requirements

As a matter of good housekeeping, the owner and operator of the unit must maintain the floor so that it is free of significant cracks, corrosion or deterioration. Surface coatings or liners that are subject to wear from movement of waste, personnel or equipment must be replaced by the owner and operator as often as needed.

EPA placed certain limitations on how high hazardous waste may be piled within containment buildings to ensure that no releases will occur should wastes slide under their own weight. If the outer walls of the containment building are used to support the piles of waste, hazardous waste cannot be piled higher than the portion of the wall that meets the required design standards

A decontamination area must be constructed within a dedicated containment building, and site-specific decontamination procedures must be followed as necessary to prevent waste from being tracked out of the unit on personnel or equipment.

Maintenance Details

100: Feet, the minimum recommended distance from surface water that chemical storage facilities should be located. In addition, these facilities should be located downslope from wells.

40 to 90: Degrees, Fahrenheit, the ideal temperature range inside the storage facility when storing pesticides. Humidity should be kept low to prevent lumping or degradation of powder formulations and to reduce corrosion of metal containers.

Source: Environmental Protection Agency, OSHA