Changes

[[File:Gravel diaphragm.png|thumb|Note the fall from the impervious surface to the gravel surface]]

[[File:Gravel diaphragm.png|thumb|Note the fall from the impervious surface to the gravel surface]]

Gravel diaphragms are simply gravel filled trenches which act as inlet structures by redistributing concentrated flow to sheet flow: reducing the erosive power of the water and promoting infiltration. They also act as a pretreatment by settling out sediment particles before they reach any downstream structure or practice.  

Gravel diaphragms are simply gravel filled trenches which act as [[inlet]] structures by redistributing concentrated flow to sheet flow: reducing the erosive power of the water and promoting [[infiltration]]. They also act as a [[pretreatment]] by settling out sediment particles before they reach any downstream structure or practice.  

If the contributing drainage area is solely turf (e.g., sports field), then the gravel diaphragms may be eliminated from the treatment train.

If the contributing drainage area is solely turf (e.g., sports field), then the gravel diaphragms may be eliminated from the treatment train.

==Materials==

==Materials==

<h4>Gravel</h4>

===Gravel===

{{:Pea gravel}}

{{:Pea gravel}}

===[[Geotextiles]]===

===[[Geotextiles]]===

*[http://vwrrc.vt.edu/swc/april_22_2010_update/DCR_BMP_Spec_No_2_SHEET_FLOW_Final_Draft_v1-8_04132010.htm VIRGINIA DCR STORMWATER DESIGN SPECIFICATION No. 2]

*[http://vwrrc.vt.edu/swc/april_22_2010_update/DCR_BMP_Spec_No_2_SHEET_FLOW_Final_Draft_v1-8_04132010.htm VIRGINIA DCR STORMWATER DESIGN SPECIFICATION No. 2]

*[https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17751.wba National Engineering Handbook Part 628 Dams Chapter 45 Filter Diaphragms]

*[https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17751.wba National Engineering Handbook Part 628 Dams Chapter 45 Filter Diaphragms]

 

[[category: pretreatment]]

[[category: pretreatment]]