Aging drainage systems require creative engineering solutions

Since 1965, county surveyors have been tasked with the job of maintaining the regulated drains in their counties. At the time the Indiana Drainage Code (IC 36-9-27) was passed into law, land use in Indiana was largely agricultural with the state’s population of 4.9 million concentrated in its larger cities and towns. In the decades since, Indiana’s population has grown to almost 6.7 million, and areas once used primarily for agriculture have given way to suburbs and other types of development. The development of Indiana’s landscape has introduced pressures on county drainage systems that they were never designed or intended to support. Rapid urbanization combined with aging systems has created the perfect storm – one which requires new engineering solutions to meet current drainage needs and future growth.

Dave Eichelberger, Director of Regulatory Services for Christopher Burke Engineering (CBBEL), said most counties are struggling with aging systems – clay drainage tiles that were installed decades ago to drain agricultural fields.  “Today, many of these drains are in disrepair or don’t have the capacity to handle the amount of water coming into them,” he said.

Eichelberger explained that the purpose of regulated drains – often called “legal” drains – is to carry excess water drained from farm fields through agricultural field tiles to a nearby stream. Some legal drains are open ditches while others might be clay tiles like the agricultural tiles that drain into them. He said the stresses on these systems differ depending on the nature of the land use in a given county, “Surveyors in Indiana’s highly urbanized counties and those where the population is growing face a different set of challenges than those in our more agricultural counties.”

Smarter Farming Introduces New Challenges

Eichelberger said that one of the challenges with agricultural drains is that farmers are becoming more savvy when it comes to drainage. “With the more modern equipment and technology farmers have available, they can more closely pinpoint their drainage problems, note the location of reduced crop yields, and now know where to put their tiles to achieve better drainage.” He said that while incremental drainage improvements are helpful, the cumulative effect of more efficient drainage can overwhelm the regulated drains that receive that water.

Calvin Lesley Drain in Tippecanoe County, Indiana is a good example. In 2012, The Tippecanoe County Drainage Board hired CBBEL to engineer a way to reduce flooding and crop damage in the watershed. Previous investigations by the Tippecanoe County Surveyor’s office revealed that although the existing trunk line tile for the drain was functional, it was consistently overloaded by the private lateral tiles feeding into it.

CBBEL investigated a number of reconstruction alternatives, developed the probable construction costs, and assisted with the corresponding estimated reconstruction assessments. When the county selected the approach it wanted to use, CBBEL completed the final construction plans and assisted the county with developing the contracts necessary to hire the companies that would complete the reconstruction.

CBBEL’s solution was to install a parallel drain tile adjacent to, and northwest of, the existing tile to intercept lateral drains from the northwest. This approach required approximately 10,000 feet of new 18-inch and 24-inch perforated tile and related work including the installation of breathers, blind-tap laterals and a new headwall. Once complete, the project reduced the load to the existing trunk line tile by one-half, allowing the existing tile to more effectively drain the southeast half of the watershed and the northwest half of the watershed to drain to the new parallel tile.

Another example is in Morgan County, Indiana where the E.R. Robards Regulated Drain (commonly known as Lake Ditch) drains more than 40 square miles of primarily rural agricultural land. Over the years, log jams, severe erosion, and field runoff had partially filled the ditch with sediment, reducing capacity in the system and blocking the field tiles it was intended to drain.

In 2011, the county hired CBBEL to design a better system and to help navigate the permitting for the project.  CBBEL engineered a solution that included restoration of 10.6 miles of stream to its original bed elevation, log jam removal and bank stabilization in five locations to help reduce future erosion. CBBEL also engineered temporary crossings for many of the tributaries feeding into the regulated drain. Permitting can be complex with a project of this scale. So, CBBEL also worked with both the county’s surveyor and its stormwater coordinator to seek a design and related documentation so the project would meet state and federal regulatory requirements.

Suburban Development Stresses Aging Systems

At times, communities have allowed increased residential development without fully addressing the need for surface water drainage systems. Eichelberger said residential and other types of development in a traditionally agricultural area will put more stress on existing systems. With more roofs, roads and parking lots, storm runoff often has nowhere to go but into the existing agricultural drainage system.

He said, “There usually aren’t any stormwater systems in place in these areas, so when a storm hits, it’s all going into that 100-year-old tile – an agricultural tile that was never meant to carry water under these conditions.”

Indiana’s communities continue to grow, sometimes relying on decades-old drain tiles incapable of conveying this increased runoff. Residents are usually unaware of the cumulative impact of development and the limitations of these antiquated systems until the agricultural drain that serves their neighborhood stops functioning properly and water begins backing up on their properties.

Engineering Firms Can Help

Whether a county is mostly agricultural, a mix of agriculture and urban, or highly urbanized, aging drainage systems are feeling the pressure, and county surveyors are, too. The number of staff to deal with drainage problems varies widely throughout Indiana. While more urbanized counties may have a staff of half a dozen or more, some counties have only one or two people to maintain all the drains in the county.

According to Eichelberger, hiring an engineering firm to handle the bigger problems that require more complex solutions can help take the pressure off local surveyors, allowing them to focus their attention on other drainage issues that can be completed in-house and in less time.

Good Coordination and Communication is Key

Good coordination is key to a successful drainage project said Eichelberger. And, the more stakeholders involved, the more important good communication becomes. He cited the Kirkpatrick Regulated Drain Reconstruction – another project in Tippecanoe County – as an example.

Eichelberger said the Kirkpatrick Regulated Drain was one of the most complex projects of his 26-year career with CBBEL. “We started back in the ‘90s, with a reconstruction to turn an old tile drain into a ditch drain,” he said. He explained that the work on the Kirkpatrick Drain was completed in phases, following the new development on the south side of Lafayette. “We engineered the first two miles of the ditch, then another two miles a few years later, and this fall, we just finished another three-quarters of a mile.”

The Kirkpatrick project is not unlike others in areas experiencing rapid growth. In addition to working with the drainage board, county surveyors might have to collaborate with city/town officials, utilities, developers, and state highway officials as well as state and federal permit program managers. To ensure the project’s success, Eichelberger and the CBBEL team coordinated often with all the stakeholders involved during each phase.

Expertise Helps, Too

In addition to drainage projects that require complex engineering, Eichelberger said, CBBEL is often tapped for its experience in permitting. “We tend to get involved on the larger projects that have more in-depth permitting challenges.” He added that this is where an engineering firm can really help move things along.

Eichelberger said that permitting can be a “daunting issue” that can make a project more difficult to get done. “We have an environmental staff with extensive experience in getting environmental permits through the permitting agency,” he said, “and that expertise helps.” Knowing the specific concerns of these agencies along with the goals of a drainage project and of the surveyor are critical to success.

Upgrading Aging Drainage Systems Can Have Enormous Benefits

The restoration of regulated drains can have far-reaching impacts for a county. It not only improves crop production for agricultural producers in the county but can also lead to increased economic development.

Eichelberger again cited the Kirkpatrick Regulated Drain Reconstruction as an example, pointing to the large General Electric (GE) Aviation manufacturing facility and the Nanshan America Company, a 435,000 square-foot aluminum extrusion manufacturing facility that have been built on the south side of Lafayette.  He said, “Here are two huge plants, significant community investments, that Lafayette secured. If the drainage in that area had never been upgraded to handle new development, they may not have chosen Lafayette.”

“Just think of all the new jobs those plants have brought to that community,” Eichelberger said, adding, “When you drive through an area where new development was allowed to occur because of the drainage work you’ve done there, it’s incredibly satisfying.”