Stormwater Controls on Construction Sites

Erosion can be caused by both wind and water. It takes place where a naturally stable surface is disturbed. On construction sites, disturbances occur during clearing & grubbing, vegetation removal, spills, trenching, and excavation. Where natural or established man-made drainage patterns are changed resulting in flow concentration and higher velocities soils will erode and enter water courses.

There are three types of controls to put in place:

Drainage Controls: Examples include ponds, basins, berms depressions, pumps in concert with piping, stabilized channels, permanent riprap, and concrete structures….

Erosion Controls: Examples include surface roughing, revegetation, tarping stockpiles, matting, spray sealing (EG: mag chloride), mulching, reverse grade, check dams, equipment slope tracking, temporary riprap lining…

Sediment Controls: Examples include Check dams, detention basins, inlet protection/socks, gutter socks, wattles, silt fence, tracking pads, straw bales, motorized sweeper, pipe outfall basins….

 

Erosion and Sediment Control Principles

Some of the principles often referred to Best Practices, used to manage erosion and sediment from leaving a job site include:

  • Proactively stabilizing areas planned to be left disturbed for 14 days or greater.
  • Managing stockpiles with berms or silt fence on the downhill side, temporary seeding, covering them with tarps or spraying them with sealants to prevent soil loss.
  • Haul Roads designed and maintained to avoid water buildup, establish controlled release points for precipitation, adequate culvert crossings to pass flows, and grading to avoid ponding.
  • Diversion of clean water around job sites with berms, piping, or ditches to reduce the amount of stormwater running onto the site.
  • Filtering site runoff through a temporary detention basin, sediment inlet socks or riprap check before releasing to channels or storm sewer.

 

Preparing for Severe Weather Events

The Five-Step Process to be ready for precipitation from storms includes:

  • Plan the work tasks and identify what controls are needed for each step. Phase the work.
  • Install the controls prior to commencing the work and as the work progresses.
  • Maintain the controls, vigilantly monitor daily the controls in place and revise/add/relocate controls that did not work as expected.
  • Empower employees to be proactive in identifying issues and being able to speak up to address them
  • Finalize the construction as soon as practicable to get the permanent drainage, site controls and revegetation in place as soon as possible.

 

Things to Remember

As participating members of the Colorado Stormwater Excellence Program (CSEP), citizens of our beautiful State, and for our children, it is our responsibility to maintain clean water, clear air, and a sustainable environment for those that come after us.

Have some basic materials on hand to counteract spills and repair erosion & sediment controls when encountered. To include sandbags, spill kit, a roll of silt fence, stakes, sandbags, trash bags, silt socks, wattles, stapler, shovel, and broom.

Always have appropriate spill control materials on job sites and in vehicles close to the work. Clean up and report all spills immediately.

Include Sediment and Erosion Controls as a topic of discussion in the Daily Safely Toolbox Huddle. Take time daily to look at controls in place. Act to address small items before and after storms.

“The earth will not continue to offer its harvest, except with faithful stewardship. We cannot say we love the land and then take steps to destroy it for use by future generations.”

Pope John Paul II, Religious Leader

Summary of changes from 2007 CO CGP to the new 2019 CO CGP:

  • The ordering and numbering format of the SWMP narrative has changed
  • Owners and Day-to-Day Operators (GCs) MUST be on the Permit and are equally liable for compliance/violations (on projects starting after 4/1/19)
  • All Applications and Permit related correspondence (modifications, reassignments, transfers, change of contact, etc.) must be done through their online Colorado Environmental Online Services (CEOS) system
  • Must make changes to the SWMP prior to, or simultaneously with, changes in the field and must document the date and time of all changes to the SWMP.
  • Terminology changes – ‘Control Measures’ instead of just ‘BMP’ (a BMP is a control measure)
  • Initial inspection by the site team must occur within 7 days of any earth disturbance
  • 7 day and 14-day inspection schedule (Choosing the 7 day inspections eliminates the need to perform post-storm event inspections)
  • Inspections must include inspection frequency, weather conditions at the time of the inspection, and the amount of disturbed acreage on the project
  • The SWMP narrative must be completed prior to construction starting (instead of Permit Application submittal)
  • At least one Qualified Stormwater Manager (QSM) must be identified in the SWMP for every project. QSM(s) = any persons responsible for certain aspects of CGP compliance (Super, inspector, BMP Installer, etc). The term “Qualified” is not explicit, but is evaluated based on performance/proficiency at the time of observation
  • Permission given in a written agreement is required when using control measures outside of the permitted area
  • Sediment Ponds/Basins must drain from the top down (skimmer or filtered riser pipe is acceptable) unless infeasible
  • Additional site map requirements – State waters, flow arrows and stream crossings
  • 50′ of vegetation must be preserved along waterways, unless infeasible
  • Disturbed areas of the site (including stockpiles) that are dormant for more than 14 days MUST be stabilized, unless infeasible
  • Corrections for control measure/BMP regular maintenance items must be documented
  • A Finding of non-compliance that cannot be corrected immediately must include an explanation of why and a schedule of when it will be corrected (temporary measures still need to be implemented to mitigate discharge potential) – project is out of compliance until the finding is fully corrected.

Go to this address for all of the CDPHE permit guidance documentation, including how to use their new online system: https://www.colorado.gov/pacific/cdphe/cor400000-stormwater-discharge

 

Please feel free to contact SRM with any questions.

Stormwater Risk Management, LLC www.StormwaterRM.com Call us @ (303) 627-7867

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