ROADSIDE DRAINAGE DITCHES IN THE DOG RIVER WATERSHED
Tracy A. McClure, Department of Earth Sciences, University of South Alabama, Mobile,
AL 36688. Email: tracyamcclure@yahoo.com.
Roadside drainage ditch networks (RDDNs) play a significant role in the water
quality of the Dog River Watershed (DRW). They must be maintained, however, through the
implementation of a regularly administered routine maintenance plan. Unfortunately, a
municipality can fall so far behind in RDDN maintenance, that it is unclear how to proceed.
The focus of this project is to determine whether a volunteer force can assist their area by
performing an occasional inventory of the RDDN in the DRW that establishes a baseline for
mapping and identifying problems, which urgently need to be addressed. I counted,
cataloged and classified the entire RDDN in my study area. I traversed the length of each
roadside drainage ditch, photographed areas of interest, then reported problems via a
dedicated Facebook page, which had been established for this project. This information was
then used to make maps using GIS technology. We learned that the RDDN in the study area
was interspersed with the Storm Sewer System (SSS) and that the worst documented
problems were found at the confluences between the two. We concluded that it would be
prudent to incorporate the SSS into the RDDN inventory when this project is performed
throughout the entire DRW. It was necessary to provide volunteers with some minor
training, but it became clear that the use of volunteers to inventory and evaluate the
conditions of the RDDN/ SSS was a viable method for collecting data on a cyclical basis.
Keywords: ditch maintenance, drainage ditch, storm drains
Introduction
The roads throughout Mobile Alabama’s Dog River Watershed (DRW) are lined
with a copious network of roadside drainage ditches. The roadside drainage ditch network
(RDDN) in the DRW plays an important role in the overall health of this watershed because
it directly affects water quality. Ditches, as part of the RDDN, are designed to protect road
integrity by catching runoff and conveying it to the water bodies downstream. Runoff,
however, is frequently laden with harmful contaminants from sources such as automobiles,
agriculture and the atmosphere. Within the RDDN, water quality and quantity form “a
complex system of temporal and spatial interactions between land use and management,
climactic conditions and landscape factors” (Kimberly Falbo 2013). Roadside drainage
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ditches modify the slope of the landscape and alter watershed hydrology “by re-routing and
concentrating landscape-derived runoff and by lowering water table depths downslope of
roads” (Brian Buchanan, Modeling the hydraulic effects of roadside ditch networks on
receiving waters 2013). Poorly maintained roadside drainage ditches are prone to erosion
and will carry the resulting turbid, contaminated water into the DRW’s surface streams.
Conversely, properly constructed and maintained RDDNs have a positive effect on
the watershed. Well-functioning roadside drainage ditches, for example, often do a better job
at protecting water quality than the Storm Sewer System (SSS). Storm sewers simply
transport the water into pipes that lead directly into the streams, but vegetation in roadside
drainage ditches slows the water down, causing “a portion of it to infiltrate into the soil
allowing some of the debris and pollutants to settle out” (University of Minnesota Sea Grant
Program and the Natural Resources Research Institute 2014). Dr. Rebecca Schneider of
Cornell University, a leading expert on roadside drainage ditches, concludes, “if we rethink
how we manage these ditches, we can (actually) reduce flooding and pollution, recharge
groundwater, and buffer our communities from the impacts of climate change” (Schneider,
Cornell Climate Change 2013).
To ensure higher water quality in the watershed, RDDNs must be kept in optimal
working condition through the performance of regularly scheduled, routine maintenance and
by making repairs as necessary. Routine maintenance can be as simple as mowing the
ditches, properly disposing of ditch spoils (such as grass clippings), correcting sediment
buildup and sowing grass seed. The performance of routine maintenance presents an ideal
opportunity to identify and correct problems in the roadside drainage ditches, such as damaged
culverts or erosion related issues (University of Minnesota Sea Grant Program and the
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Natural Resources Research Institute 2014). Preparation of a good routine maintenance plan
involves establishing a care plan for hundreds of miles of roadside drainage ditches. The
overall task of keeping track of the location and condition of every ditch in the RDDN (in
addition to planning and enacting a regular, routine maintenance schedule) can potentially
take up considerable time and resources. As a result, routine RDDN maintenance can be
assigned a low priority.
The ideal RDDN maintenance plan takes into consideration routine maintenance,
dredging and repairs. It also establishes Best Management Practices (BMPs) for RDDNs.
The Environmental Protection Agency (EPA) defines BMPs as “a term used to describe a
type of water pollution control” (Choctawatchee, PEA and Yellow Rivers Watershed
Management Authority 2000). A good routine maintenance plan also pinpoints ideal
construction styles and compositional shapes for roadside drainage ditches in the area.
Before that plan is written, however, a full inventory must be made of the RDDN so that
ditches can be categorized and mapped in order that the planning commission will know
exactly what they are working with.
Research Questions
Cataloging and classifying every mile of RDDN in the DRW is a process that can be
both time consuming and costly for the City of Mobile/Mobile County. I want to help to ease
the burden of this undertaking by answering the following questions:
(1) Can a volunteer force effectively make this inventory, perhaps making use of social
media to document and report issues?
(2) What is the best method for inventorying the RDDN that volunteers can duplicate?
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Methods
I began by researching RDDN maintenance methods across the United States
(Alabama Soil and Water Conservation Committee 2009) (City of Chickasaw 2014)
(Schneider, Cornell Local Roads Program 2010) (Ohio Department of Transportation 2015)
(Smith 2006). These resources provided me with a firm understanding of accepted BMPs for
roadside drainage ditches as well as the prevailing ditch maintenance practices nationwide. I
created a Facebook page for volunteers to use when reporting problem areas, making
comments and sharing other pertinent information. Afterward, I turned my attention to the
subject of volunteers. It was necessary to establish a few tenets regarding a volunteer work
force, which, ultimately, defined the size of the study areas in addition to the dates and times
I would take these volunteers into the field. First: safety dictated that they should work in a
minimum of two-volunteer groups. Second: acknowledge that volunteers (most likely), will
be unwilling to work in the cold or rain. This was not a major issue because the needs of the
project were best served by observing the physical condition of the ditch (e.g. erosion). The
solution was to take into account the local climate and the forecasted weather when
scheduling volunteer fieldwork. Third: it is unreasonable to expect volunteers to work in
excess of 5 hours in a day. This axiom suggested that the study areas needed to be of an
appropriate size to allow a two-person team to complete their study area/s within two days.
This was a pilot survey that included two study areas, which are situated on opposite
sides of the watershed. They include ditches in both commercial and residential zones,
provide examples of both old and new construction methods for roadside drainage ditches
and serve as a cross section of the entire RDDN in the DRW.
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Study Area 1 (Fig 1):– a 2 square mile area located in West Mobile near the headwaters of
Second Creek, bounded by: (A) Hitt Rd./Schillinger Rd. S., (B) Hitt Rd./Cody Rd., (C) Cody
Rd./Cottage Hill Rd., (D) Cottage Hill Rd./Schillinger Rd. S.
Study Area 2 (Fig.1) – a 1 ½ square mile area situated near the mouth of Dog River,
bounded by: (A) Dog River, (B) Dauphin Island Pkwy. (C) Clubhouse Rd.
Walking on foot or observing from the car, my volunteer crew and I performed a physical
inventory of every roadside drainage ditch within the study area. We sketched and annotated
anything that seemed important. Problems that we encountered, such as erosion, culvert
damage or sites in need of dredging were photographed and uploaded to the Facebook page.
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Finally, volunteers with GIS skills mapped our findings, so that we could share our data with
the city.
Results
We learned very quickly that volunteers require some minor training in order to ensure
consistent results. They needed a basic understanding of what constituted a good ditch versus
a problem ditch and clear instructions on how to report their findings. Despite initial
uncertainty as to how long it would take to assess the study areas, we learned that volunteers
working in a two-person team could inventory the designated study areas in one day. We
observed that the storm sewers system (SSS) was intertwined with the RDDN. The most
urgent problems that we discovered, in fact, were at the confluences between the two
systems. Identifying these types of problems is the cornerstone of this project. The site found
in (Fig.2) was not visible from the road and it is unlikely that routine-maintenance crews
would ever see the structural damage unless it was reported to them. We took photos of these
and similar problems with digital cameras and smartphones. In both cases, we uploaded the
images to the dedicated Facebook page (Fig. 3), tagging the pictures with the location of the
problem and other pertinent data. Many smartphones are capable of adding latitude and
longitude coordinates which can be posted together with the photo, which was quite useful
for GIS mapping. By default, we identified the location of the storm sewers in our study
areas during this inventory. We determined that it was reasonable to map both the RDDN
and SSS simultaneously. Using GIS, we made a shape file for the various categories of water
run-off mechanisms that we found in Study Area One (Fig.4) which the City of Mobile should find
helpful when making maps and planning maintenance.
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Discussion
In the event that this project is implemented throughout the DRW, it would be
reasonable to incorporate the storm sewer system into the study. While tagging the
photographs with latitude/longitude when uploading them to Facebook is helpful, it is not an
absolute necessity. It is important to recognize that volunteers will come to the project with
varying types of technology and it is unreasonable to require them to obtain new, unfamiliar
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applications. The Facebook page is an acceptable platform for this project. It gives the
volunteer the opportunity to tag the picture and make important comments about what they
have found. This type of social media is expandable, allowing other types of information to
be shared, such as announcements and training materials.
For a complete inventory of the RDDNs and the SSS in the Dog River Watershed, the
watershed can easily be broken down into approximately 20 areas of manageable sizes. This
should be done prior to beginning the project and maps should be made of each study area.
Because the volunteers will be working in groups of at least two persons, it follows that
approximately 40-60 volunteers will be needed. There needs to be some level of organized
activity, perhaps a short meeting, where the volunteers are shown a short presentation that
explains how roadside drainage ditches and storm sewers affect water quality, how the
negative impacts can be reduced and what they can do, as volunteers, to help with that
process. They should also be provided with an illustrated field guide that includes the field
maps of the 20 study areas in the DRW, examples of ditch problems and pages for making
sketches and notes. This will be crucial for receiving consistent assessments from the
volunteers in the field. The field guide should also be uploaded to the dedicated Facebook
page to act as a back-up resource. At the meeting, the volunteers should be assigned partners
and study areas, be provided with their illustrated field guides and given a realistic deadline
to complete the work. Once all of the photos and field guides have been turned in to the
coordinator, the data can be mapped. GIS is the recommended platform for this task because
its format makes it easier to share the information.
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Conclusion
Use of volunteers to inventory and evaluate the conditions of the RDDN is a viable
method for collecting this data. The most crucial factors in making a project such as this
work are the training, field guide and social media site for the volunteers. This project has
the potential to serve as a quality resource for the planners in the DRW (City of Mobile).
Our maps will generate an up-to-date assessment of the physical conditions of the RDDN
and pinpoint the locations where maintenance/repair efforts should be focused first. This
project can be expanded, if necessary. Once the basic inventory has been performed, future
re-assessments can be tailored toward to meet the needs and concerns of the citizens as well
as the city.
References
Alabama Soil and Water Conservation Committee. 2009. "Volume 2 Installation,
Maintenance, and Inspection of Best Management Practices." Alabama Handbook
for Erosion Control, Sediment Control and Stormwater Management on
Construction Sites and Urban Areas. Montgomery: Alabama Soil and Water
Conservation Committee, March.
Brian Buchanan, Zachary M. Easton, Rebecca L. Schneider, M. Todd Walter. 2013.
"Modeling the hydraulic effects of roadside ditch networks on receiving waters."
Journal of Hydrology 293-305.
Choctawatchee, PEA and Yellow Rivers Watershed Management Authority. 2000.
"Recommended Practices Manual A Guideline for Maintenance and Service of
Unpaved Roads." Environmental Protection Agency, February.
City of Chickasaw. 2014. National Pollutant Discharge Elimination System Municipal
Separate Storm Sewer System Storm Water Management Program. Implementation
of EPA "Waters of the United States" ruling, Mobile: Volkert, Inc.
Kimberly Falbo, Rebecca L. Schneider, Daniel H. Buckley, M. Todd Walter, Peter W.
Bergholtz, Brian P. Buchanan. 2013. "Roadside ditches as conduits of fecal indicator
organisms and sediment: Implications for water quality management." Journal if
Environmental Management 1050-1059.
Ohio Department of Transportation. 2015. "ODOT Post Construction Storm Water Best
Management Practices Maintenance "Do's and Dont's"." Location and Design
Manual Volume Two Drainage Design. Columbus: ODOT Office of Hydraulic
Engineering, Jan 16.
Schneider, Rebecca. 2013. Cornell Climate Change. Accessed 02 13, 2015.
http://climatechange.cornell.edu/re-plumbing-our-watersheds/.
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—. 2010. "Cornell Local Roads Program." Roadside Ditches, Best Management Practices to
Reduce Floods, Droughts, and Water Pollution.
http://www.clrp.cornell.edu/tip_sheets/pdf/others/roadsideditches.pdf.
Smith, Duane E. 2006. "Local Roads Maintenance Workers' Manual." Ames: Iowa
Department of Transportation, Center for Transportation Research and Education,
June .
University of Minnesota Sea Grant Program and the Natural Resources Research Institute,
University of Minnesota Duluth. 2014. "Protecting Lakes and Streams through
Proper Ditch Maintenance." Field Guide for Maintaining Rural Roadside Ditches.
Duluth: Regents of the University of Minnesota.
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