Alternate detention options?

[ausue]

Our client is replacing a concrete pad with a building and the City is requiring that a hydro study be produced with 30% reduction in existing flows, applied to the area of redevelopment--just 0.3 acres (and they are not budging on this despite the fact that there is exactly the same amount of impervious area). The existing detention pond area is very wooded, and the remainder of the site is either pavement or buildings. The required decrease in flow is extremely small. Enlarging the pond or changing the outlet structure, or creating more disturbed area, are all undesirable options.

Any suggestions?

 

[gbam]

Have you identified the predeveloped condition versus the developed condition for the entire development not just this parcel? Does the existing basin porovide for the 30% reduction for the entire development including your site? This may be your way out of enlarging the basin for your site. Is there a master drainage plan for the development?

 

[msquared48]

Can you add a rain garden?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[brandonbw]

We had a recent project like this and installed infiltration tanks on the property.

B+W Engineering and Design
Los Angeles Civil Engineer and Structural Engineer

http://bwengr.com

|

http://bwstructuralengineer.com

|

http://bwcivilengineer.com

 

[beej67]

If you're slick about it, you can oversize your storm drain pipes and then take account for their storage in your post development stormwater model. You could also get your reduction out of porous pavement.

Where's the site?

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[CaliDave]

Rainwater harvesting.
Green Roof
Underground retention chambers [URL unfurl="true"]http://www.stormtech.com/[/url]

 

[martin888888]

There are many LID options that might work. Other then that underground pipes would do the trick but are an expensive option

 

[bank]

Some municipalities allow you to use the parking lot for detention. Down here you can include up to nine inches above your inlet grate as part of your detention storage.