Septic Systems
Design options are determined by circumstances which include specific site characteristics including favorable soil depths, available area to meet set backs and site topography or slope. Other criteria are client preference or installation/maintenance costs. These various septic systems are generalities that are site specific.

Gravity

Consists of a septic tank which flows effluent by gravity to a distribution box (D-box). One or more connections of this D-box drain into 3 foot wide trenches or 3 feet to 10 foot wide beds typically filled with washed gravel. Only a small part of the drainfield is used at any one time. Requires a minimum of 42 inches of permeable soil, depending on topography, above a restrictive layer to be used on new construction. Least amount of maintenance required of any system type but requires the greatest soil depth in order to provide adequate treatment of the effluent.


Gravity with Pump

Gravity with the addition of a pump tank. Allows the drainfield to be located upslope from the septic tank. In addition, the drainfield is dosed which permits intermittent resting of the drainfield between doses. A dosing system provides for the periodic discharge of a determined amount of effluent to the drainfield.  Dosing uses the principle of wetting and resting, which provides multiple daily dosings of effluent to a subsurface soil absorption system with a period of resting and re-aeration between doses.  This resting period is important in maintaining the aerobic condition of the soil absorption system in and around the distribution trench or bed, and thus slowing the development of a clog of soil interfaces and subsequent failure that naturally occurs over time.  Additional maintenance to the pump tank and float switches are necessary.


Pressure Distribution 

Consists of a septic tank and pump tank with pressurized lines leading to individual trenches or beds. This allows dosing of the drainfield and use of the entire drainfield at once. Requires at least 30-42 inches of permeable soil above a restrictive layer to be used on new construction. A dosing system provides for the periodic discharge of a determined volume of effluent to a drainfield.  Dosing uses the principle of wetting and resting, which provides multiple daily dosings of effluent to a subsurface soil absorption system with a period of resting and re-aeration between doses.  This resting period is important in maintaining the aerobic condition of the soil absorption system in and around the distribution trench or bed, and thus slowing the development of a clog of soil interfaces and subsequent failure that naturally occurs over time. Maintenance required to assure the orifices do not plug over time.


Mound

A treatment-based system consisting of pressurized lines lying in a sand bed mounded above the original soil surface. Requires at least 18 inches of permeable soil above a restrictive layer to be used on new construction. This system type has allowed construction on sites previously thought unsuitable due to lack of soil depth. Mound systems are used primarily in shallow soils overlying a restrictive layer or elevated groundwater table.  The shallower the soil the more attention must be paid to transporting the treated effluent away from the point of application. Mounds are an excellent treatment and dispersal choice on appropriate sites, but they are not very forgiving.  Special attention must be given to siting, design, pre-construction planning, site preparation, filter media selection, construction and maintenance of these systems.  Quality control throughout the process cannot be overemphasized. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.

Sand Lined Bed or Trench

A system consisting of pressurized lines lying in a sand bed or trench buried into the ground. Used in situations where the soil is deep but very porous thus lacking treatment capability. This occurs in areas where soils are very gravelly or extremely gravelly in nature. Sand lined beds/trenches provide biodegradation or decomposition of wastewater constituents by bringing the wastewater into close contact with a well developed aerobic biological community attached to the surfaces of the filter media.  This process requires unsaturated downward flow of the effluent through the filter media.  The media may be coarse mineral sand or equivalently sized crushed glass.  As a departure from the intermittent sand filter, the media is not contained in a watertight vessel.  Instead, the media is placed in trenches or beds in the native soil.  Proper function requires that influent to the sand filter be distributed over the media in controlled, uniform doses.  In order to achieve accurate dosing, these systems require timed dosing with associated pump chambers, electrical components, and distribution network, with a minimum of 4 to 18 doses per day spread evenly over a 24 hour period.  The effluent is absorbed into the native soil at the bottom of the sand lined beds/trenches, which accomplishes dispersal into the subsoil environment and some further treatment.  A sand lined bed/trench is a combined treatment component and soil dispersal component. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.


Intermittent sand filters
A system that provides biodegradation or decomposition of effluent by bringing the wastewater into close contact with a well developed aerobic biological community attached to the surfaces of the filter media.  This process requires unsaturated downward flow of the effluent through the filter media.  The filter media may be mineral sand or equivalently sized crushed glass.  The media is contained in a watertight vessel either below the surface of the ground or wholly or partially elevated in a containment vessel.  Proper function requires that influent to the filter be distributed over the media in controlled, uniform doses.  In order to achieve accurate dosing, these systems require timed dosing with associated pump chambers, electrical components, and distribution network, with a minimum of 4 to 18 doses per day spread evenly over a 24 hour period.  The effluent is collected in the bottom of the filter and discharged either by gravity or pressure to a soil dispersal component, usually a conventional sub-surface drainfield. This technology is used on sites with shallow soil conditions where treatment must be accomplished before the effluent is discharged into the soil.  Sand filter effluent may be discharged to a soil profile containing as little as 12 inches of vertical separation.  Intermittent sand filters are also used as part of a mitigation strategy when horizontal separations are reduced.

Bottomless Sand Filters
A bottomless sand filter is a special case of sand lined drainfield  trench which is quite similar operationally to an intermittent sand filter that is not lined on the bottom.  It may be selected to utilize more suitable soils high in the soil profile for dispersal and treatment. The containment vessel must be designed by and/or approved by a qualified professional engineer and have a support foundation to prevent vertical and horizontal movement of the vessel.

Upflow Sand Filter (Glendon Biofilter)

All these units are upflow media filters and are based upon the same patented principles, which involve the biological treatment of septic tank effluent as it flows upward through sequential layers filter media within a containment vessel that may be partially buried or set on grade depending on the model, and then out of the vessel through matric and gravitational forces.  No separate drainfield is required as final treatment. Effluent dispersal occurs in the native soil surrounding the vessel. The effluent from the vessel is conveyed from the vessel to the prepared native soil through the cover sand material.  This cover sand is the top layer of sand, which continues over the rim and out over the native soil at the perimeter of the containment vessel. This system can be used in situations where a lot has only 12 to18 inches of soil. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.


Aerobic Treatment Unit (ATU)

Consists of a watertight tank with an aeration chamber where sewage and microorganisms come in contact with each other in the presence of dissolved oxygen. Blowers, compressors or air pumps supply the air. To meet the highest treatment standards a disinfection unit must be part of the device to reduce the bacteriological counts. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.


ATU - Mound

Consists of a watertight tank with an aeration chamber where sewage and microorganisms come in contact with each other in the presence of dissolved oxygen. Blowers, compressors or air pumps supply the air. The treated effluent is then pumped into a mound system for final treatment and disposal. This system works well in combination as the ATU lowers waste strength but still produces high bacteriological counts, which are eliminated in the mound. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.


ATU - Pressure Distribution

Consists of a watertight tank with an aeration chamber where sewage and microorganisms come in contact with each other in the presence of dissolved oxygen. Blowers, compressors or air pumps supply the air. The treated effluent is then pumped into a pressure distribution system for final treatment and disposal. To meet the highest treatment standards a disinfection unit must be part of the device to reduce the bacteriological counts. With disinfection the system may be used with as little as 18 inches of soil. Without disinfection the system requires no less than 30 inches of soil. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.


Composting Toilet 

A composting toilet is a system designed to store and compost (primarily by unsaturated, aerobic microbial digestion) human excrement (human urine and feces), ideally to a stable soil-like material called “humus.” These systems are commonly designed to accommodate fecal and urinary wastes (human excrement), toilet paper and small amounts of organic carbonaceous material added to assist their function. The owner/operator of a composting toilet system should be aware that the successful operation of these systems requires a consistent diligence to the details of the composting process.  Only individuals, private organizations or government agencies who are willing to accept the responsibility of composting human excrement should be involved.  If composting toilet systems are not routinely monitored and maintained as required, or improperly operated, they will fail and the owner will be faced with disposing of unprocessed human excrement. Owners/operators of composting toilet systems should also be fully aware of how the final composted product may either be used for beneficial purposes or disposed according to federal and state sludge/biosolids laws and regulations.

Holding Tank

Self-contained watertight wastewater tank with a high water alarm. Must be routinely pumped to prevent overflows or back-ups into the house. Most commonly used as a temporary measure to allow continued occupancy of a house until a more permanent fix can be arranged. Requires posting a bond for potential spills and being on contract with an approved sludge hauler. Management oversight is needed to prevent sewage overflows.

Subsurface Drip System

A subsurface drip system (SDS) is an efficient pressurized wastewater distribution system that can deliver small, precise doses of effluent to shallow subsurface dispersal/reuse fields.  SDS distribution piping is small diameter, flexible polyethylene tubing (dripline) with small in-line emitters (orifices that can discharge effluent at slow, controlled rates, usually specified in gallons per hour).  Driplines can be trenched (by hand or with a trenching machine) into narrow, shallow trenches or plowed (with a vibratory plow or other insertion tool) directly into the soil and backfilled without gravel or geotextile.  Typical installation depth is between 6 and 10 inches.