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Wastewater Septic Designs and Repair

Keywords and Definitions

Gravity Septic System - Subsurface Drip Septic Systems - Standard Pressure Distribution Septic Systems
Pretreatment Septic Systems - Mound Septic Systems - Sand Lined Septic Systems - Commercial Septic Systems
Community Septic Systems - Sand Filter Septic Systems - Septic Systems Keywords and Definitions


Contact Leroy Surveyors & Engineers, Septic Design Department By

Calling 253-848-6608 Ext. 103 and/or Emailing Bill Creveling P.G. at bill@lseinc.com for an Estimate

 

Below are Keywords and Definitions of Commonly Used Septic System Terminology.

Gravity
Consists of a septic tank which flows effluent by gravity to a distribution box (D-box); one or more connections to this D-box drain into trenches typically filled with gravel. Only a small part of the drainfield is used at any one time. Requires a minimum of 48 inches of permeable soil 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 up slope from the septic tank. In addition, the drainfield is dosed which permits intermittent resting of the drainfield between doses. 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. This allows dosing of the drainfield and use of the entire drainfield at once. Requires at least 30-36 inches of permeable soil above a restrictive layer to be used on new construction. 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. 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.

Subsurface 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. 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 Filter - Pressure Distribution
Consists of sand placed in a watertight box built into the soil. Effluent is spread evenly over the surface of the sand via a pressurized network. The sand layer treats the effluent and is collected in the bottom of the filter box from which it is then pumped to a drainfield. The drainfield in this case is a pressure distribution system, which finishes the treatment process and then disposes of the wastewater. Requires at least 18 inches of permeable soil above a restrictive layer to be used on new construction. 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 Filter - Gravity
Consists of sand placed in a watertight box built into the soil. Effluent is spread evenly over the surface of the sand via a pressurized network. The sand layer treats the effluent and is collected in the bottom of the filter box from which it then is pumped or gravity fed to a gravity drainfield. Requires at least 24 inches of permeable soil above a restrictive layer to be used on new construction. 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 Filter - Mound
Consists of sand placed in a watertight box built into the soil. Effluent is spread evenly over the surface of the sand via a pressurized network. The sand layer treats the effluent and is collected in the bottom of the filter box from which it then is pumped to a mound. The mound finishes the treatment process and then disposes of the treated wastewater. Used in situations where minimal soil exists, at least 12 inches of soil is required on at least 5 acres. 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 Filter - Subsurface Mound
Consists of sand placed in a watertight box built into the soil. Effluent is spread evenly over the surface of the sand via a pressurized network. The sand layer treats the effluent and is collected in the bottom of the filter box from which it then is pumped to a subsurface mound. The mound finishes the treatment process and then disposes of the treated wastewater. Used in situations where the soil condition does not permit adequate treatment of the wastewater before disposal. The addition of the sand filter may be used to help mitigate other shortcomings of a particular site. 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
A treatment-based system consisting of pressurized lines lying in a sand bed buried into the ground. The sizing of drainfield laterals is equal to a standard system. 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. The system is easier to construct than sand lined trenches but takes up more area than a subsurface mound. It may be the system of choice where there are soil inconsistencies such that a smaller subsurface mound may not have sufficient contact with the more gravelly soil portions of the site. 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 Trench
A treatment-based system consisting of pressurized lines lying in sand filled trenches. The sizing of drainfield laterals is equal to a standard system. 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. Can be used as an alternative to a mound or sand filter system. 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 Filter - Lined Bed
Consists of a sand filter followed by a sand lined bed system. The addition of the sand filter may be used to help mitigate other shortcomings of a particular site. See #10 for more details.

Sand Filter - Lined Trench
Consists of a sand filter followed by a sand lined trench system. The addition of the sand filter may be used to help mitigate other shortcomings of a particular site. See #11 for more details.

Up flow Sand Filter (Glendon Biofilter)
Consists of different layers of sand and gravel placed in a watertight box built into the soil. Effluent is pumped into the bottom of the filter and allowed to wick itself up through the sand and over the rim of the box into the soil. Several boxes or pods may be used to accommodate varying site conditions and number of bedrooms. A splitter along with a timing device is used to assure even flow to all pods. This system can be used in situations where a lot has 18 inches of soil and only12 inches if 5 acres or greater. 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) – Gravity
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 drained into a conventional gravity drainfield. To meet the highest treatment standards a disinfection unit must be part of the device to reduce the bacteriological counts. With disinfection the system could be used on a site with only 24 inches of soil. Without disinfection the system would require at least 4 feet 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.

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.

ATU - Sand Filter
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 sand filter for further treatment. A pressure distribution system would then dispose of the treated wastewater. 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
Consists of a self-contained toilet with a chamber and venting system. The chamber contains sawdust or some other composting media, which when combines with the waste material to form compost over time. There is usually some method to turn the pile to assure an even mixture and complete composting. Once composting is complete the residue is removed manually from the chamber. These systems require a separate grey water discharge and disposal system. Most commonly used where water availability is an issue. The long-term proper operation of composting toilets depends on regular maintenance by the owner.

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. Some schools use this system when sewers are not available and no suitable site exists for an on-site sewage system. Requires posting a bond for potential spills and being on contract with an approved sludge hauler. Management oversight is needed to prevent sewage overflows.

The Keywords Above are per King County's Website, which can be reached by the link below. http://www.kingcounty.gov/healthservices/health/ehs/wastewater/owners/types.aspx


 

Septic Transport Line

Drainfield Distribution Lines


Septic Dig

Excavators Dig Test Pits to Determine Soil Loading and Absorption Rate


Septic Juction Box

Valve Box


Septic Drainfield

Sand and Pressure Bed


Hydrotek Valve


Gravity Septic System Rendering


 

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Leroy Surveyors and Engineers, Inc. 12815 Canyon Road East - Suite F, Puyallup, WA 98373 • (253) 848-6608 or (253) 604-4443 • lyle@lseinc.com

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