![]() Water running off these impervious surfaces tends to pick up gasoline, motor oil, heavy metals, trash and other pollutants from roadways and parking lots, as well as fertilizers and pesticides from lawns. Storm water may become contaminated while running down the road or other impervious surface, or from lawn chemical run-off, before entering the sewer. The first flush from urban runoff can be extremely dirty. Storm drains may discharge into man-made excavations known as recharge basins or retention ponds.Įnvironmental impacts Water quality Main article: Urban runoff Storm drains may be interconnected using slotted pipe, to make a larger dry well system. Small storm drains may discharge into individual dry wells. Other than catchbasins, typically there are no treatment facilities in the piping system. Most drains have a single large exit at their point of discharge (often covered by a grating) into a canal, river, lake, reservoir, sea or ocean. Several different materials can also be used, such as brick, concrete, metal and even plastic in some cases. ![]() Pipes can come in many different shapes (rectangular, square, bread loaf shaped, oval and, more commonly, circular) and have many different features (including waterfalls, stairways, balconies and pits for catching rubbish or Gross Pollutant Traps (GPTs). Municipalities typically have large vacuum trucks that perform this task.Ĭatchbasins act as pretreatment for other treatment practices, such as retention basins, by capturing large sediments. The performance of catchbasins at removing sediment and other pollutants depends on the design of the catchbasin (e.g., the size of the sump), and routine maintenance to retain the storage available in the sump to capture sediment. Most catchbasins will contain stagnant water during the drier parts of the year and can be used by mosquitoes for breeding. However in the United Kingdom, where they are called gulley-pots, they are designed as true water-filled traps and do block the egress of gases and rodents. In the United States, unlike the trap, the catchbasin does not necessarily prevent sewer gases such as hydrogen sulfide and methane from escaping. ![]() The catchbasin serves much the same function as the "trap" in household wastewater plumbing in trapping objects. Water from the top of the catchbasin drains into the sewer proper. Many of these small objects are caught by the catchbasin, or sump, which lies immediately below the grating. Consequently, many small objects can fall through. However, their bars are fairly widely spaced so that the flow of water is not impeded. Grated inlets have gratings or grids to prevent large objects and debris from falling into the sewer system. They are usually depressed at the invert of the channel to improve capture capacity. Side inlets are located adjacent to the kerb (curb) and rely on the ability of the opening under the backstone or lintel to capture flow. There are two main types of stormwater drain (sewer) inlets side inlets and grated inlets. 3 Relationship to sanitary sewer systems.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |