According to the Indiana Department of Environmental Management’s “Indiana Storm Water Quality Manual”, sediment is the number one water quality pollutant by volume in Indiana. As erosion causes off-site sedimentation, it can lead to damage in numerous ways. Sediment deposition in storm sewers can reduce their efficiency and capacity, thereby causing flooding. As sediment is deposited in stream channels, it decreases the channel’s capacity. This can also lead to flooding, as well as increase the possibility of erosion and scour on the banks of the stream. Sediment caused by soil erosion can also accumulate in lakes, resulting in a decrease in lake depth. This negatively affects the recreational value of a lake, the aesthetic value of a lake, and degrades water quality and can lead to algae growth as shown in the photos below. Sediment accumulation can also adversely affect fish and wildlife habitat.

Reduced pond depth due to sedimentation     Degradation of water quality due to sedimentation
                Reduced Pond Depth                                    Degradation of Water Quality
               Due to Sedimentation                                        Due to Sedimentation

Due to the nature of land development, it is a leading cause of off-site sedimentation. As vegetative cover is removed from a site during construction activities, erosion and sedimentation can take place if the construction activities are not managed properly. In order to attempt to reduce these erosion and sedimentation problems, regulations that require storm water pollution prevention plans have been established by the State of Indiana. These plans are mandated by applicable sections of 327 IAC 15-5 and 327 IAC 15-13, which can be found by following this link.

As a result of the regulations stated in 327 IAC 15-5 and 15-13, Vanderburgh County was required to develop local ordinances that necessitate the preparation of erosion control plans for construction sites. Section 13.05 of the Vanderburgh County Code provides these erosion control plan requirements. This ordinance establishes the procedures for preparing, reviewing, and implementing erosion control plans for construction sites. These regulations have established the Vanderburgh County Engineering Department as the review agency for sites requiring these erosion control plans. When these plans are reviewed, they are compared to this erosion control plan review checklist.  Any questions regarding the plan review and approval process should be directed to Mike Wathen at 812-435-5773 or MWathen@Vanderburghgov.org.

The preparation of a storm water pollution prevention plan also requires filing a Notice of Intent (NOI) with the Indiana Department of Environmental Management. Once a project has been completed, a Notice of Termination (NOT) must also be filed with IDEM. The NOI and NOT forms can be found under the “Storm Water and Wetlands” heading after following this link.


Erosion Control Plan Implementation

Proper implementation and maintenance of the erosion control measures called for in erosion control plans can reduce the chances that sedimentation will cause any flooding and/or water quality problems near a construction site. However, installing and maintaining erosion control measures can also reduce construction costs by preventing both on-site and off-site damage during construction. Examples of sites requiring reconstruction work due to failed, inadequate, or omitted erosion control measures are shown in the following photos.

Lack of erosion control measures will require additional work to a swale that had been constructed properly
The grass lined drainage swale behind these houses was properly constructed and was in a stable condition. However, due to the lack of erosion control measures, the swale will require additional grading and seeding work in order to remove the sediment that accumulated on the swale.

Sedimentation     Sedimentation
Due to sediment that accumulated as a result of inadequate erosion control measures, this basin had to be drained in order to remove the sediment that had significantly reduced the depth of the retention basin.

Failed ECM     Failed ECM
Due to inadequate and/or failed erosion control measures, re-grading of the construction site was required, as well as a significant amount of off-site cleanup.

Failed ECM
Failed erosion control measures, plus a failure
to establish stable grass cover resulted in the
need to re-grade this drainage swale.

Failed ECM
Failed erosion control measures resulted in
the need to clean the street and storm sewer system.

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Last updated: 12/9/2011 2:31:31 PM
http://www.vanderburghgov.org/index.aspx?page=2551