Sewers surface drainage

No gas detector should be located where it would be constantly affected by ambient conditions such as surface drainage runoff, sand, ice, or snow accumulation. Special consideration should be given near open sewer grates and oily water drain funnels were frequent alarms may appear due to vapor emissions. 

When water suppression systems are provided, due concern should be made for the disposal of the released water. Of primary importance are the capacity and location of surface drainage systems. Fire water usage usually places greater demands on a facility gravity sewer system than rainfall or incidental petroleum spillage effects. 

Characterization of the natural setting is usually a major portion of the field investigation. At most sites, permeability of the local soil and rock types, the depth of the water table, and the direction of groundwater flow will strongly influence movement of contaminants from the point of disposal. The anomalies which occur naturally within the geohydrologic section must be taken into consideration. Surface drainage, sewers, and buried utilities can affect surface and groundwater flow around a hazardous waste site. 

Wash water collected in these surface-drainage areas should be collected in the acid sewer. Where possible, however, storm-water surface drainage should not be run into the acid sewers, if avoidable. 

The storm-water sewer should be designed to collect the maximum surface drainage. This is to include the rainfall in one hour, wash water not of a contaminated nature and cooling water when not returned in return headers to the cooling water facilities. 

Flap Valve. Storage areas which are curbed or diked should be provided with sufficient catch basins to accommodate the surface drainage. Sewer... 

Paved or unpaved areas in outlying locations not adjacent to process equipment or buildings should be divided into surface drainage areas. These areas will most likely be free from contamination and may be channeled into the storm-water sewer. 

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 surface drainage areas, having been divided according to slope and drop in elevation, must now be segregated and run to the proper sewer classification. 

Catch basins (see Figure 8-5) should be used as a junction for changes of direction of sewer branch lines. The location of branch sewer junctions may so coincide that a catch basin may be substituted for a sewer box, which would normally be provided for surface drainage. A catch basin should... 

Manholes with open tops covered with grating may be used to collect surface drainage as explained for catch basins. The grating cover for sealed manholes requiring vent connections should be filled with concrete and sealed or bolted down tightly to prevent the escape of sewer gases. 

Most runoff from TA-V flows west onto TA-III as overland flow and in natural and manmade surface drainage features. The remainder flows into two storm sewers in the northern portion of TA-V. Both storm sewers discharge to open channels within, and just north of, TA-III. Drainage from TA-III is to the west onto undeveloped portions of KAFB and then into playas on undeveloped state land. At present there is no requirement for monitoring runoff from TA-V because the runoff flovwng from that area is not discharged to Waters of the United States (SNL 1998c). 

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. 

There are several drainage mechanisms are employed at petroleum and related facilities - surface runoff or grading, spill containment (diking), gravity sewers (oily water and sanitary) and pressurized sewer mains, and lift station collection sumps. 

An adequate drainage system should be provided for all locations where a large amount of hydrocarbon liquids has the possibility of release and may accumulate within the terms of the risk analysis frequency levels. Normal practice is to ensure adequate drainage capability exists at all pumps, tanks, vessels, columns, etc., supplemented by area surface runoff or general area catch basins. Sewer systems are normally gravity flow for either sanitary requirements or oily surface water disposal. Where insufficient elevation is available for the main header, lift stations are installed with a forced pressure outlet header to a disposal or treatment system. 

The die produces a column of clay with the desired form and a steel wire cuts it in individual parts. Products made by an extruder bricks (both perforated and not), hollow bricks, large building blocks, drainage pipes, sewer pipes, riven slabs, tiles and roof tiles. The extruder requires the use of a plastic clay. The baked product is characterized by its square shape and smooth surface. 

Groundwater contamination is most likely where stormwater is discharged into soakaways (e.g. pits filled with rubble to speed transfer to groundwater) or infiltration areas, and where the aquifer is vulnerable. However, in many cases, stormwater is collected in the drainage system, which may discharge into sewers. Stormwater or (when sewer capacity is exceeded) a combination of stormwater and diluted raw sewage may be discharged into surface waters, Box 6,3 summarizes the main risk factors associated with urban runoff,... 

Chemical warehouses should be constructed with provisions for spill containment and drainage to provide protection to the surrounding property, ground water, surface water and public sewers in the event of an accidental chemical release or discharge of sprinkler water. This protection should be commensurate with the toxicity of the stored materials and the risk and consequence of exposures. 

On paved and unpaved surface areas adjacent to tanks, towers, exchangers, pumps and compressors where process waste spillage is likely to be considerable, drainage sho d be divirted to the oily-water sewer. Wash water heavily contaminated with hydrocarbons during turnaround or maintenance operations should be drained to the oily-water sewer. 

Concrete, metal or plastic pipes are conventionally used in stormwater sewers for urban surface runoff drainage. A stormwater sewer pipeline is laid parallel to the ground surface with a cover of more than 0.9 m. Scrap tire pipes may be used as the construction material of storm drainage systems in small towns if the pipes can provide required flow capacity. 

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