Dikes, retaining

Residue Disposal. The major environmental problem in the Bayer process is disposal of bauxite residue which is effected by marine disposal, lagooning, use of underdrain lakes, or semidry disposal. Marine disposal in oceans or rivers, diluting the alkaline residue by large quantities of water, is environmentally unacceptable. Lagooning behind retaining dikes built around clay-sealed ground is commonly used, but there have been isolated leaks into aquifers. This has motivated installation of underdrains between the residue and clay-sealed, plastic-lined, lake bottom. This design removes the hydraulic head from the lake bottom and improves consoHdation of the residue. 

Spillages resulting from overfilling should be retained in tank dikes (bunds). But very often the drain valves on the dikes—installed so that rainwater can be removed—have been left open, and the spillage is lost to drain (see Section 5.5.2 c). 

Transfer facilities, processors and rerefiners, and burners must also have secondary containment systems to prevent oil from reaching the environment in the event of a spill or leak. Secondary containment consists of an oil-impervious dike, berm, or retaining wall to contain releases, as well as an oil-impervious floor to prevent migration. 

Retaining dikes and berms. Retaining dikes and berms include earthen embankments, earth-filled cellular and double-sheet pile walls, water inflated dams, and so on, which aim to minimize the transport of contaminated sediments. 

Geometric considerations in dike design include the base area configuration, slope of the dike floor, and the height of a retaining wall. Optimal dike design must satisfy two criteria (1) it must provide safe fluid containment, and (2) it must be proportioned for the most economical size. 

In the mitigated case, in which the spilled carbon disulfide is retained by the dike installed around the tank, there is a large reduction in the vaporization rates of carbon disulfide for both sets of meteorological conditions. The primary reason for the differences is that the available surface area for vaporization is significantly reduced. Second, the vaporization rate remains essentially constant for the duration of the incident because the surface area for vaporization is constant. The small variations that do show in these curves are due to small effects of heat transfer into the diked carbon disulfide, as discussed in Chapter 5. 

Most of the flooded oil in the premises remained in the refinery, retained by the dikes there for flood prevention, but part of the oil that came through storm drains into the guard basin flooded out over the sea bypassing the gaps of dampers and drainage pipes.The refinery immediately extended oil-fences to prevent the further extension of the oil spill, and almost all leaked oil was recovered in a week. 

Mud ponds and retention and settling basins are often made by constructing a continuous dike on a relatively impervious formation of a size and shape adequate to retain the desired liquid volume. Such was the case in Delaware, where a dike some 20 ft high was built of fine, granular materials to retain sulfate solutions. 

Several borings were taken from the top of the dike to verify the reported soil formations. pH numbers were determined for each sample recovered. These show very low values below 10 ft, verifying that seepage of the retained acids was occurring. SIROC was selected for this project, and the soil samples were used to check the effects of the low pH on the gel time. 

The dispersive nature of the oil sands extraction process does not affect the settling properties of the coarse solids. These solids segregate from the fines and are used for building the dikes that surround the settling ponds that contain the process recycle water. The fines that are not retained with the beach solids run off into the tailings pond as a thin slurry and consolidate very slowly full consolidation of untreated tailings is estimated to take thousands of years. Large quantities of this suspension... 

In the event of a leak or break in any storage tank or piping the flap valve will prevent the loss of valuable tank contents and allow for the recovery of the tank contents retained within the diked area. It will also prevent any large amounts of hazardous and flammable liquids from entering the sewer system, which would create the possibility of a hazardous fire condition should the tank contents be of a volatile nature. 

This result confirms that the aplite dikes began to retain in-situ produced radiogenic Sr during the Middle Ordovician (lUGS 2002) although they were... 

Secondary containment such as dikes or other retaining structures for process areas, tanks, and vessels containing PSM covered fluids [6] ... 

C) Diked areas. Where protection of adjoining property or waterways is accomplished by retaining the liquid around the tank by means of a dike, the volume of the diked area shall comply with the following requirements ... 

Oil-filled transformers shall not be used underground unless they are located in a fire-resistant enclosure suitably vented to the outside and surrounded by a dike to retain the contents of the transformers in the event of rupture. 

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 floor that covers the entire area within the dike, berm, or retaining walls, or... 

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