Research Soil Composition & Waste Water Treatment Systems Before You Buy Rural Land

First United Realty Spring 2017


Owning land in a quiet rural setting is the goal of many, but understanding ahead of time some of the practical challenges that must be faced, will help you avoid costly mistakes. How to dispose of your wastewater is one of those challenges. Knowing ahead of time what the cost will be to install a county approved waste water system is critical to deciding what land to buy. A wide range of soil conditions determine which systems can be used and which ones can’t.  Modern highly engineered systems, which can be mandated by local health departments, can cost in excess of $20,000 to install, while traditional septic tanks average under $8,000 for a two bedroom two bath home.


Start by Getting a Percolation Test

County health departments require proof of soil absorption rates as a condition of receiving a waste water disposal certificate. If the property that you a planning to buy has heavy clay soils or is extremely rocky, you may not be able to use a conventional septic tank and leach field system which is by far the least expensive method. A percolation test will be required by your local authorities to demonstrate the absorption rate of the soil. This test is performed by digging three holes on the property. Two in the area of the proposed disposal field and one in the proposed reserve disposal field. Each test hole is dug to the County required depth. Once the holes are completed, a county representative will visit the property for a site and soils evaluation. During this inspection, an engineer will use a variety of testing methods to determine the rate at which the soil is able to absorb water that is introduced. The result will be used to help design the complexity of the disposal field that will be required to receive the effluent water from the waste water system once it is installed. Once the final plans for the system are approved by the County, an approval to construct will be issued. Installation may now proceed.

Standard Septic Tank and Leach Field System

This is by far the most simple as well as least expensive method to dispose of wastewater. The concept and installation is simple and time proven to be effective at eliminating wastewater. Septic tanks are large underground chambers designed to receive the wastewater. The heavier solids settle to the bottom of the chamber and are eventually eliminated by natural bacteria and bacteria introduced by products specifically formulated for that purpose. The lighter water based liquids are channeled out of the main chamber by a series of perforated pipes that transmit the liquids directly into the soil where they are leached into the ground. This area is known as the leach field. A leach field contains a series of pipes (usually 20 to 40 feet long) that extend out from the main tank.  Septic tanks require that a prescribed amount of area be dedicated for both the tank and leach field, so understanding the limitations of the lot size that you are considering buying is critical to your buying decision. If the lot is too small to handle both the home and the septic system, step away and look for another more suitable property.

Aerobic Treatment System

An aerobic treatment system or ATS is a small scale sewage system similar to a septic tank system, but which uses an aerobic process for digestion rather than just the anaerobic process used in septic systems. These systems are commonly found in rural areas where public sewers are not available, and may be used for a single residence or for a small group of homes.

Unlike the traditional septic system, the aerobic treatment system produces a high quality secondary effluent, which can be sterilized and used for surface irrigation. This allows much greater flexibility in the placement of the leach field, as well as cutting the required size of the leach field by as much as half.

Engineered Systems

If the land will not percolate at the required rate and qualify for a standard septic tank installation, then a much more costly engineered system will have to be specifically designed to do the job. The cost of the various engineered systems varies and can easily exceed $20,000. In addition to the high expense and ongoing maintenance requirements, engineered systems typically require the land owner to set aside a large portion of his property to build the system on. Not only will the taking of land limit the usability of the property (for nothing can be constructed upon it), it can also require the removal of precious trees and native plants that inspired the purchase of the land in the first place. Here are two of the most widely used engineered waste water systems:

A mound system is an alternative to the traditional rural septic system drain field. The mound system is an engineered drain field used in areas where septic systems are more prone to failure due to having extremely permeable or impermeable soils, soil with shallow cover over porous bedrock, and soils that have a high seasonal water table.

The primary waste liquids cleaning and purification action in a drain field is performed by a biofilm in the loose fill surrounding the perforated drain tile. If the soil permeability is too low, liquid is not absorbed fast enough, resulting in surface ponding of unsanitary liquids. If the soil permeability is too high, or is exposed to fractured bedrock, the wastewater quickly penetrates down to the water table before the biofilm has time to purify the water leading to contamination of the aquifer. In either situation, the mound system provides an ideal habitat for the biofilm and has the correct permeability to assure slow absorption of effluent into the mound before exiting as purified water into the surrounding environment.

EcocyclET systems

Most plants use photosynthesis and evapotranspiration (ET). EcocyclET is a closed-loop operation that employs lined beds of sand, crushed stone and gravels and specified plantings. Effluent from tanks, greywater, composting toilets leachate or urine from separating toilets, is recirculated through the bed. There, naturally occurring micro-organisms convert the chemical constituents of the wastewater into nutrients for plants growth. The impervious bed liner ensures that no effluent can enter the subsurface environment or nearby receiving waters. All the wastewater will be ultimately transpirated as un-transpirated effluent is drained back into a recycle tank, stored and pumped back to the bed when the conditions for evapotranspiration are optimal. The system can also be used as a greywater reuse planter to be installed where soils are too poor to be considered for a soil absorption system.