The Effectiveness or
Ineffectiveness of
Storm Water BMP's in the Dog River WatershED
William R. Hicks, Department of Adult Interdisciplinary
Studies,
The major pollution problem in
Keyword: Storm Water BMP’s, silt fences
Introduction:
The major pollution problem in
The law requires developers and
contractors to use Best Management Practices, but the majority are either
installed incorrectly or not maintained properly. “Reasons for the high failure rate of
improperly applied and installed silt fences include: improper placement on the
site; allowing excessive drainage area to the silt fence structure; shallow
trenches with little or no soil compaction; inadequate attachment to post;
failure to maintain the silt fence after installation; installing silt fences
along property boundaries producing “concentrated” runoff.” If construction
workers and contractors had a better understanding of BMP’s and where this
uncontained sediment was winding up, they, hopefully, would spend the time and
the minimal amount of extra money to properly install and maintain the BMP’s on
their construction sites. Properly placed silt fences are the most noticeable
BMP’s that are not being implemented. A person can drive two miles in any
direction on most
Silt fences are possibly the least expensive of all BMP’s and if used properly would dramatically reduce the sediment runoff from most sites. “USEPA (1993) reports the following effectiveness ranges for silt fences constructed of filter fabric that are properly installed and well maintained: average total suspended solids removal of 70 percent, sand removal of 80 to 90 percent, silt-loam removal of 50 to 80 percent, and silt-clay-loam removal of 0 to 20 percent. Removal rates are highly dependent on local conditions and installation.” Engineers and planners are trained in the application of these devices. The average construction worker who actually installs them is not required to be trained in their application and in most cases has had no formal instruction on their use or proper installation.
The Alabama Department of Environmental Management Field Operations Division-Water Quality Program Chapter 335-6-12 states: “Construction Best Management Practices Plan means any research, planning considerations, systems, procedures, processes, activities, and practices implemented for the prevention and/or minimization of pollutants in storm water to the maximum extent practicable, and collection, storage, treatment, handling, transport, distribution, land application, or disposal of construction storm water and onsite management of construction waste generated by the construction activity, and to comply with the requirements of this chapter.” By developing a questionnaire for construction workers and determining exactly what is known and not known about BMP’s, a training program and appropriate educational literature could be developed so that the average worker could be easily and economically trained. The survey could provide valuable information if developed in an inoffensive format that would yield honest and accurate replies. Compiling this information would help develop seminars and training sessions to inform the appropriate persons of the importance and benefits of properly installing and maintaining BMP’s on construction sites.
By educating construction workers on the use and maintenance of silt fences and other BMP’s on construction sites the amount of sediment runoff from storm waters could be dramatically reduced. The exact amount of reduction would be hard to prove but would obviously be significant if BMP’s were working the way they were intended. By increasing this group’s awareness of the impact we as workers and individuals have on the watersheds around us, not only could we reduce sedimentation but most likely it would help to reduce runoff from yards and driveways as well.
You could possibly raise money for clean up and restoration of the watershed as well as educating the general public by requiring each construction worker to have an environmental card. This program could be much like the health cards that restaurant employees are required to have in order to work in restaurants. These cards must be updated each year by watching a video at the Health Department for a fee of five dollars. This would increase awareness and raise revenue at the same time. This would be unpopular at first but think of the benefits to the environment. You could possibly combine this with safety training increasing its usefulness.
Research question:
How much do contractors and construction workers know about BMP’s? Are workers ignoring BMP’s or do they simply not know or understand how they work?
Methods:
I developed a survey about silt fences to determine what is known and not known. I used a brief nine question survey (Fig. 3) to survey thirty construction workers’ knowledge and perception of silt fences. Finally, I compiled and interpreted data.
Results:
If silt fences where installed and
maintained properly, it would greatly reduce the amount of storm water runoff
that makes its way into
When asked how often do you install silt fences twenty-one of thirty stated often and nine said sometimes (Fig. 4) . This let me know that silt fences are very much a part of day-to-day routine for construction workers. Seventeen of thirty surveyed reported that their training was very good while the other thirteen stated that their training was good (Fig.5) . “Silt fences shall be inspected immediately after each rainfall and at least daily during prolonged rainfall.” However, when the workers were asked, how often silt fences should be checked and maintained, only sixteen of thirty stated after every rain event, nine said daily, and five said weekly (Fig. 6) . Almost every worker surveyed stated that silt fences should be maintained for one month after construction was completed (Fig.7) . In reality “The silt fence should not be removed until adequate vegetative growth ensures no further erosion of the slopes.” Depending on the time of the year and weather conditions it could take more than a month for conditions to stabilize.
When asked about the importance of silt fences eighteen said very important, ten said somewhat important, and two said important, however, no one answered not very important or un-necessary (Fig. 8) . One worker candidly said we could be fined if we do not do it right. What effect do you feel that silt fences have on the environment? This is my favorite question, fourteen workers said silt fences have some effect on the environment while sixteen said they have a great effect on the environment (Fig.9) .When asked who if any one instructed you in the proper installation and placement of silt fences one third stated no one or that they picked it up along the way. The answer I was looking for was engineer, architect, or supervisor, only a few said supervisors. When asked where do you think run off from ineffective silt fences winds up, the two most popular answers were the street and the ditch. A few said they did not know. One said he never really thought about it, and only two said the storm drains. I found it very interesting that no one stated the creeks or Dog River.
The final question on the survey was most telling it said, “would you be interested or willing to be trained more in the proper installation of silt fences?” Twenty four of the thirty surveyed said no, only six said yes (Fig.10) . apparently the workers feel they do not need more training.
Conclusion:
The construction workers surveyed were very confident in their knowledge, and for the most part were unreceptive to further training. The results of this survey prove that there are definite gaps in the instruction and implementation of silt fences. To decrease the amount of sediment build up in Dog River , programs must be developed to further educate the rank and file construction worker who thinks he knows enough but could definitely know more about silt fences and what happens to uncontained run off. One solution would be more enforcement of regulations that are already in place, but this is a man power issue and that’s another topic.
Bibliography:
Hulcher, Richard. Alabama Department of Environmental
Management, Field Operations Division, Water Quality Program. 23 January 2003
National Pollutant Discharge Elimination System (NPDES). Retrieved
Idaho Department of Environmental Quailty. (August 2001).
Cataloge of Storm Water Best Management Practices. 2nd Ed. Retrieved
on
Natural Resources Conservation Service. (October 2001).
Salix Applied Earthcare. (2003 March 10). Effective Silt
Fence Installation. Retrieved
