Diked area drain

If uncontaminated rainwater from diked areas drains into a storm drain or open watercourse the following procedures will be implemented at the facility [ 112.8(c)(3) and 112.12(c)(3)] Bypass valve is normally sealed closed Retained rainwater is inspected to ensure that its presence will not cause a discharge to navigable waters or adjoining shorelines B3 ass valve is opened and resealed under responsible supervision Adequate records of drainage are kept ... 

A diked area drain is shown in Exhibit 13-45. Because dikes are designed to hold the contents of a storage vessel in the event of a rupture, area drains must be kqx closed at all times. A drain valve operates just outside the dike wall so that plant personnel can see when the contents have been drained and the valve may be redosed. 

Drainage slopes within tank areas should ensure that any spills are drained away from tanks, manifolds or piping. Small fires that can occur in gutters or drains around tanks weaken connections to the storage tank and release the contents of the tank. Any gutter encircling the tank should be located at a safe distance from the tank and drain basins should not be located under tank mixers, major valves or manway entrances to the tank. The diked areas should be provided with an impervious surface that is will collect liquids towards a drainage collection point. 

Diked areas around refinery storage tanks are frequently provided with storm drains discharging into the trunk sewer. An overflow as the result of an overfilled or ruptured tank could discharge large quantities of oil to the refinery sewer and would ultimately overload the separating facilities. To prevent this and to allow recovery of the oil within the diked area, it is common practice to provide some type of valve arrangement to isolate the storm drains in tank fields from the trunk sewer. 

When hazardous materials are handled, these sources of leaks should be located in curbed or diked areas to localize spills. If a permanent curb or drain can not be provided around the leak source, a temporary curb should be provided, using barriers or absorbent materials. 

Spills that pose a high risk to adjacent facilities must be divened to a remote holding area. One method would be to erect a concrete diversion canal see Exhibit 15-15). Drain valves that are located outside the diked area usually would be closed but would be opened in the event of a critical spill. Sump drain lines discharge into the concrete diversion canal and flow downward to a holding basin. 

An impervious barrier was needed between the dike and the limerock to prevent possible draining of the ponds. A slurry trench was used over most of the project to provide the barrier. In one area, along a 100 ft section where the dikes intersected, it was planned to drive sheet piping. After the completion of the slurry walls and the removal of the equipment, when pile driving commenced, it was found that the lower strata of coarse material prevented a satisfactory interface with the limerock. At this point, a grouted cutoff was selected as an alternative. 

SPILLS Sweep or scoop up solid, wosh area with water drained to cotch bosin. Dike solutions... 

Diked or curbed areas at tank farm and storage locations will also require provisions for surface drainage and should be divided into suitable drainage areas. These drains should be run to the oily-water sewer main. 

The storage area shall be graded In a manner to divert possible spills away from buildings or other exposures, or shall be surrounded by a curb or earth dike at least 12 Inches high. When curbs or dikes are used, provisions shall be made for draining off accumulations of ground or rain water, or spills of... 

Drainage—Surface drainage and safe removal of spilled or accumulated liquids is adequately provided and arranged to prevent exposure to the hazard to the process system or critical facihty support systems. Liquids should be immediately removed from an area through surface runoff, drains, area catch basins, sumps, sewers, dikes, curbing, or remote impounding. 

The Dutch have a long history of executing massive engineering projects for the purpose of either flood protection or land reclamation. Flood protection includes the constmction of seawalls, dikes and storm barriers to protect the low lying land along the coast. Reclamation projects involve draining previously submerged areas. 

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