Soil always interested Randy Miles, who grew up on a farm in central western Indiana. It was a diverse farm. “We grew a wide variety of crops, and what we grew sustained the various animals we raised, and it all sustained our family,” Miles recalls.
Living on the land that his family farmed, he became attuned to what soils had to say to him. The experience led him to study agronomy, which is the management of crops and soils. Over the years, he came to appreciate soil not just for its ability to grow food but for its capacity to accept and treat our wastewater.
He now dedicates much of his time to advancing the onsite profession by conveying to industry professionals the importance of soil to the proper design and functioning of onsite treatment systems.
“Soil is not dirt, but dirt is soil,” Miles says. “4-H kids learn that early on, and so do those that constantly work with earth’s thin skin.” Miles has bachelor and master’s degrees in agronomy, and a doctorate in soil science, all from Texas A&M University.
He is now a soil scientist and associate professor of soil science at the University of Missouri, School of Natural Resources, in Columbia, Mo. His areas of interest, and his influence, go far beyond the campus and even beyond state lines. His participation in the Consortium of Institutes for Decentralized Wastewater Treatment brings him into contact with onsite educators from across the nation and around the world.
More than roots
While it may seem a long stride from agronomy to onsite systems, Miles says that’s not really the case. “The same soil characteristics that affect crop growth — texture, structure, composition and permeability — also affect the way effluent released from onsite systems will interact with the soil environment,” he says.
In the late 1980s, with a research grant to fund his work, he went to the Lake of the Ozarks in Missouri to study zones of saturation and the movement of water on and in the soil. “While we were there, we saw a large number of small lots where the onsite systems were malfunctioning,” he recalls.
Those observations led him to a hypothesis that the way the soil responded to water from natural sources would be mimicked by the manner in which it responded to effluent generated by people. “Sure enough, the soil did not care where the water was coming from, it reacted the same way,” he says. “To the soil, water is water.”
Miles views that project as a turning point in his career. Since that study, his work and interests have been directed to onsite systems and the soil that sustains them. Miles believes there are three reasons that academia is interested in onsite systems.
In the field
First, the field (people’s yards) provides an opportunity for the real-world application of the lessons learned through scientific study. The process of taking research results out to the community is, in large part, the heritage and role of land grant institutions like MU, and Miles feels comfortable with and connected to that tradition.
Second, “the opportunity to first fix problems and then, on undeveloped sites, to avoid duplicating those same problems, appeals to me and to many in academia,” Miles says. The roles of troubleshooter and problem avoider are rooted in the research findings. “It is the process of fixing systems one by one that is a kind of laboratory for refining field techniques that, when validated, can also become part of every installer’s tool kit,” Miles predicts.
Third, the linkage and, to some extent, the redirection of soil science to onsite treatment opens new horizons for those in the profession. Typically, it was the engineers who designed the perc test and determined appropriate vertical isolation distances and square footage requirements for absorption areas. But soil scientists are now being called upon to apply their skills to issues from regulation writing to site evaluation, design review and approval.
“With more fields of specialty ready for the agronomist’s auger, it is becoming easier to recruit candidates to the soil science curriculum,” Miles says. “In some measure, job creation is dependent on a vibrant new crop of candidates each year.”
A popular accessory
Miles sees soil science as an ever-more-attractive “accessory pursuit for students in planning, engineering, architecture, and similar curriculums. It adds a desirable depth of knowledge to supplement these other interests.” He sees that supportive role as good for the profession, as well.
Research brings one set of practical challenges. Incorporating the results into practical application entails an entirely different set of challenges. “Researchers must be skilled in reading and understanding a second and somewhat ephemeral landscape — the political landscape,” Miles says.
For Miles, the first step into this brave new world was to introduce the concepts of soil science to onsite regulators in the Missouri Depart-ment of Health and Senior Services. One clear result was that regulators saw a need to rewrite the rules to bring more soil science into play.
Miles chaired an 18-member Onsite Sewage Taskforce that included installers, builders, Realtors and others with interests in all aspects of onsite management. The committee, formed in 1992, took four years to get its first set of regulations adopted.
Starting at the end
The group focused on the receiving environment (the soil) to determine how much pretreatment would be needed for specific sites. “Some folks thought we were starting the discussion at the wrong end of the system,” Miles chuckles. “But we wanted to base our standards on a soil’s structure, texture, permeability and redoximorphic characteristics. Other influences were the site’s slope and its position on the landscape.
“We wanted to assure that the soil could adequately complete the renovation process and that the system was sized so that whatever volume of liquid was released could indeed be received by and dispersed into the soil.”
Still working “backwards,” the committee created sizing tables that set forth the minimum square footage for various soils to accommodate various daily flows. Next, they set minimum isolation distances (also called vertical separation distances) for various soil absorption technologies.
While mounds can be permitted, site conditions are such that they are not seen in all areas. For mounds, the regulations specify minimum material depths and minimum soil depths. Drip irrigation lines are constrained by a maximum 6 to 8 inches below the surface and a minimum of 12-inch separation above restrictive soil layers or adverse features. Traditional subsurface gravel bed or trench bottoms must be at least two feet above these features, while the max-imum excavation depth is 30 inches.
The drip parameters emerged from the second round of the National Onsite Demonstration Project (NODP II). “Also emerging from that study is the hypothesis that more frequent dosing helps to keep drip lines from freezing during the cold winters of the heartland,” Miles says.
Listening to the site
Miles enjoys putting his skills to work in the field. “When I get to a development, I like to walk around and listen to the site,” he says. “There is much to learn by listening to and reading the site. It’s all in front of you, if you just listen and look.
“Asking some basic questions helps get the conversation started. Where is the water moving? Where are the high and low spots? What is the three-dimensional geometry telling you? What vegetation clues are there? These are just the beginning.”
Most homeowners looking at a lot will first pick the building site. Miles prefers to pick the site most appropriate for the absorption area. After protecting its upslope and downslope areas, he works with what is left for the house, drive, and any outbuildings.
“A great site can be instantly ruined when construction activities commence during too-wet soil conditions,” he says. “Installers need to accept and work with nature. Postponing construction until a site dries out can avoid one or more call-backs, and may even save the entire absorption area.”
He advises installers to first, divert upslope surface water, then keep as much ground cover intact as possible. He cautions against compacting upslope and downslope areas — and especially the absorption area itself.
To test soil moisture, Miles advises using a shovel to dig a small hole and look for soil smearing. If smearing is present, it’s necessary to wait a day or two, then test the site again. “Do not guess the soil moisture level — check it!” Miles says. Among his other basic soil-protective recommendations:
• Select the materials stockpile sites and the spoil storage sites carefully.
• Segregate excavated material into distinct piles — vegetative layer material, topsoil, subsoil.
• Use the best soil for the final cover and the least desirable for noncritical uses.
• Always plan the equipment travel routes to protect the site’s most critical areas. Avoid needless equipment movements, as irreversible soil compaction occurs quickly.
“Eighty percent of the final compaction occurs the first three times a machine traverses the same travel route,” Miles says. And he can show you research to prove it.
In it together
“Soil science is becoming an ever-more accepted partner on the onsite team,” Miles observes. “Site evaluation, system design and installation are not separate tasks done by disconnected professionals.
In Miles’ view, the more we learn about the natural environment, the more we realize that everything is connected to everything else. Finding a site for an onsite system, then designing, installing and successfully operating it, must be a collaborative effort. Soil scientists are expanding the horizons of regulators, designers, installers and homeowners, and that is good for all involved.
“Soil scientists have been invited to the dance, and we want all our partners to shine,” Miles says. “We are all in this together.”
