Water

Constructed wetland

I live in a small, developing village in northeast Missouri. We practice and demonstrate environmental and ecological sustainability. I am in the early stages of building a general store and restaurant with a bed and breakfast. What is the possibility of using a constructed wetland to treat our graywater? The business will have a composting toilet so there will be no blackwater. I project the outflow to be around 60,000 gallons per year. The Department of Natural Resources is accustomed to dealing with businesses with outflows of 10,000 gallons per day. Can you help me out with some guidance as to how to approach the DNR? Can I get special permits or variances or something?

From your description, it sounds like your project could be very adaptable to the use of a constructed wetland. Typically, such systems consist of a septic tank to catch any solids, followed by a constructed wetland to clean the liquid portion of the wastewater before it is returned to the environment. Even with graywater, there are enough solids suspended in the liquid that a septic tank will still be needed. Owners of constructed wetlands must be prepared to do some gardening of the water-loving plants that grow in the rock-filled, watertight "tray" built of concrete or rubber-lined soil. It usually takes two years before the plants mature enough to provide consistently good treatment of the wastewater. So you may have to have an interim plan to deal with the wastewater to satisfy the Department of Natural Resources and assure them there will be no discharge from your property. In many cases, the plants use all the wastewater for growth, so there is no discharge. It will be helpful in working with the DNR if you can identify all the sources and estimated volumes of waste from your project, and how you intend to deal with them. Have these answers in hand when you visit with DNR, and even consider inviting them to the site so they can see how the project will work.

Bob Schultheis
Natural Resource Engineering Specialist

Lagoon at wedding site

I am in the process of putting in plumbing at a wedding site on my land in southwest Missouri. The area is down in a valley where two creeks merge. I want to build a lagoon about 40 to 50 feet from the creeks. Am I in jeopardy of contaminating them? There is at most one wedding a week.

Whether the lagoon will fit the site will depend on whether it can meet the minimum setback distances required by your county sewage ordinances, and whether the soils are suited for lagoon construction. The county Health Department can tell you what ordinances will apply to your site. See a list of onsite soils evaluators who can help determine if your soils are suited for lagoon construction.

In general, the minimum setback distance for the lagoon would be 50 feet from the creek if the creek maintains permanent flow. If your site is prone to flooding when the creeks are swollen with stormwater, a lagoon would not be a good choice at that location, due to uncontrolled discharge or structural failure.

Assuming the setbacks can be met, the lagoon overflow pipe must discharge at least 100 feet back from the property line, and the effluent must stay on your property. The lagoon would need to be constructed under moist soil conditions and well-compacted to prevent leakage through the bottom or banks. If there is a high percentage of rock fragments, a rubber liner may be necessary to prevent leakage that could contaminate the creek.

For more information on general lagoon construction procedures, see WQ402, Residential Sewage Lagoon Systems: A Homeowner's Guide to Installation and Maintenance.

Bob Schultheis
Natural Resource Engineering Specialist

Pond water testing

I recently purchase 45 acres in Howard County. I don't plan to drink water from the pond, but want to know if it's safe to swim in and eat fish from the pond. How can I have the water tested?

MU Soil Testing and Plant Diagnostic Services analyzes water for domestic, irrigation, livestock and poultry suitability. However, we do not test for toxic chemicals or E. coli bacteria. Since you would like to know whether this water is suitable for swimming, I would think the most appropriate water test package we offer would be for domestic suitability. But based on this test, we won't be able to say whether it is safe to eat fish from this pond. The best place to check for that test is the Missouri Department of Health lab at Jefferson City.

Manjula Nathan
Director
Soil Testing and Plant Diagnostic Services

Sand septic filtration system

I am a realtor helping with the sale of a house. You mentioned a sand septic filtration system in your article, but I have been told sand systems are no longer code even though this is only an 18-year-old house. The house is on rock at the top of a hill and the ground would not perk so the builder put in a sand system now I want to make sure the system is proper and want to know what to do to be up to code? Where the discharge pipe comes out the water does not have an odor and never has but I have been told discharge above ground is not proper. Is this correct and what do you recommend?

Septic system soil selection matrix Since each Missouri county can be different in how its ordinances govern on-site sewage systems, I suggest you contact county health department. They can tell you whether they or another local authority has jurisdiction over the on-site sewage systems in your county, and whether restrictions on sand-based systems apply. If a sewage pipe discharges on top of the ground, that certainly would not meet sewage ordinance requirements in any Missouri county today, except for use of aerobic sewage lagoons on properties large enough to accommodate them. The soils at the site dictate what sewage system might be appropriate, and the Missouri Department of Health and Senior Services soils evaluators could assist with this determination. If the site is all rock with no soil, the system choices will be limited and more expensive than if soil is present. The septic system soil selection matrix chart at right shows the suitability of some of the common systems based on the site.

Bob Schultheis
Natural Resource Engineering Specialist

Duckweed in lagoon

My sewer system lagoon has a lot of duckweed. I have been told to remove it so the sun can shine on the water and to leave it because it is removing harmful items from the lagoon. What should I do?

First, confirm whether you are dealing with algae or with duckweed and watermeal. See the Missouri Conservation Department's Common Nuisance Water Plants in Missouri Ponds and Lakes for comparison. If it is algae, the lagoon is operating normally and you don't want to get rid of the algae.

If it is duckweed and watermeal, a little can actually be beneficial to treating the wastewater. However, if it covers the whole water surface, it can interfere with growth of the necessary algae. Duckweed and watermeal can be treated chemically with a herbicide such as Weedtrine-D, Reward, Sonar or Avast. If you prefer a non-chemical option, you can periodically rake it from the lagoon water surface using a garden rake attached to a length of PVC pipe. However, during warm weather, it reproduces prolifically, so raking may become a weekly chore. The duckweed you remove can be composted or tilled into the soil as fertilizer.

Bob Schultheis
Natural Resource Engineering Specialist