Differences

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--- oil_and_grease_control [2022/05/11 09:22] – admin
+++ oil_and_grease_control [2023/06/15 14:29] (current) – admin
@@ Line 1: / Line 1: @@
 ====== Oil and Grease Control ======
-For commercial or industrial development with greater than 40 parking stalls or where the potential for pollution by oil and/or grease exists, the first half inch of runoff must be treated using the best technology available.  This requirement may be waived by the plan reviewer only when the applicant can demonstrate that installation of such practices is unnecessary.
+For development with greater than 40 parking stalls or where the potential for pollution by oil and/or grease exists, the first half inch of runoff must be treated using the best technology available.  This requirement may be waived by the plan reviewer only when the applicant can demonstrate that installation of such practices is unnecessary.
-======Approved Practices======
+=====Approved Practices=====
-=====Bioretention=====
+====Bioretention====
-Please see the [[Bioretention Basin]] page for information on this practice.
+Please see the [[Bioretention Device]] page for information on this practice.
-=====Sorbent Inlet Filters=====
+====Sorbent Inlet Filters====
 Permanent inlet filters designed to trap oil and grease have sorbent media either as part of the filter bag, as a boom around the rim of the frame, or as a pouch that sits in the bag. The frames must be made of a durable material, typically stainless steel, that will not require frequent replacement.
@@ Line 25: / Line 25: @@
 Installation and maintenance of these inlet filters should should follow all manufacturers’ specifications. The frames, filter, and media should be inspected regularly to ensure that the practice is functioning properly and parts replaced when they become ineffective.
-=====Media Filtration=====
+====Media Filtration====
 Filtering devices are designed to remove oil, grease, sediments, trash, and other debris from stormwater by passing them through a filtering device. Oil and grease filters are most often used at gas stations, industrial sites, parking lots, loading areas, and anywhere hydrocarbons are likely to be present in large quantities. Because they generally operate underground, they are often used in retrofit applications where other management practices are not practical. In high flow situations, the volume of water may exceed the capacity of the filter chamber and stormwater may bypass the device without treatment.
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 Installation and maintenance of these devices should should follow all manufacturers’ specifications. They must be inspected regularly to ensure that the device is functioning properly and filters replaced when they become ineffective.
-=====Rock Trench=====
+====Rock Trench====
 Stone or rock trenches are designed to trap oil and grease pollution on the surface and pores of limestone. These trenches will typically line the edges of parking areas to act as the first line of treatment, before the oil and grease is emulsified downstream.
@@ Line 58: / Line 58: @@
   *Replacement of rock may be difficult
-The trench needs to have the volume to treat the first half inch of runoff, either through total void space or through hydrologic modeling. The trench must also have a way to draw down between storms, typically with an underdrain. Because this trench does not have pretreatment, it is assumed to be clogged and may not take credit for infiltration.
+The trench needs to have the volume to treat the first half inch of runoff, either through total void space or through hydrologic modeling. The trench must also have a way to draw down between storms, typically with an underdrain, and be lined with geotextile fabric to prevent soil migration. Because this trench does not have pretreatment, it is assumed to be clogged and may not take credit for infiltration.
-The trench must be inspected regularly to ensure that the device is functioning properly and rock replaced when it becomes ineffective. The rock will become blacker and less effective as it gets coated with oil and grease.
+The trench must be inspected regularly to ensure that it's functioning properly. Replace the rock when it becomes coated with oil or grease (i.e. black-colored) or if it becomes filled with sediment.