Pennsylvania Farm-A-Syst: Worksheet 3: Household Wastewater Treatment System

Nearly one-third of Pennsylvania residents rely on private household waste treatment systems. Maintenance of these systems is the responsibility of the homeowner.
Pennsylvania Farm-A-Syst: Worksheet 3: Household Wastewater Treatment System - Articles

Updated: December 13, 2017

Pennsylvania Farm-A-Syst: Worksheet 3: Household Wastewater Treatment System

Why Be Concerned?

Nearly one-third of Pennsylvania residents rely on private household waste treatment systems. Maintenance of these systems is the responsibility of the home owner. Up to 50% of the solids retained in a septic system decompose while the remainder accumulate in the tank. Septic tanks need to be pumped every 3 to 5 years to prevent the solids from escaping the tank and clogging drain-fields. The frequency of the pumping depends on the size of the septic tank and the number of people it serves.

Septic system regulations enacted in 1966 set uniform standards for construction and repair of septic systems. Systems installed before this date may be prone to drainfield malfunctions. Systems that have been in place for more than 20 years and have not been inspected may be leaking disease-causing organisms and nutrients into groundwater or surface water.

Nutrients such as nitrate-nitrogen can contaminate the ground-water supply. Phosphorus from detergents can excessively enrich surface water. Excess nutrients in surface water can cause overgrowth of vegetation, which harms (smothers) aquatic life.

The goal of Pennsylvania Farm-A-Syst is to help you protect groundwater and surface water, shared resources which are important to everyone.

How to Rank Groundwater and Surface Water Protection Using This Worksheet

  • You can select from a wide range of household wastewater management conditions and practices that are related to potential groundwater or surface water contamination.
  • You can rank your household waste management practices according to how they might affect groundwater or surface water.
  • Based on your overall ratings, you can determine which of your conditions or practices are reasonably safe and effective, and which might require modification to better protect groundwater and surface water.

How to Complete the Worksheet

Download the Household Wastewater Treatment worksheet and follow the directions. It should take 15 to 30 minutes to complete the evaluation and determine your ranking. Evaluate each household wastewater treatment system on your farmstead for its effect on groundwater and surface water. Space is provided to rank up to 3 sites on your farmstead. If you have more than 3 sites, please use another worksheet. Directions for determining your ranking are on the last page of the worksheet. If you are unfamiliar with any of the terms used, refer to the glossary provided with this worksheet.

How to use The Rankings

Step 1. Now that each feature has been ranked, add all these rankings together and put that value in the “Total” box at the end of the worksheet. Transfer that number to the box below.

Step 2. Divide the value in the “Total” box by the number of features ranked.

Step 3. Repeat for each additional site. Calculate the average ranking for all sites combined.

Step 4. Evaluate the overall management practices and site conditions.

  • 3.6-4.0 = best management
  • 2.6-3.5 = good management
  • 1.6-2.5 = fair management
  • 1.0-1.5 = poor management

This ranking indicates how household waste treatment practices as a whole might affect groundwater and surface-water quality. This ranking should serve only as a general guide, not a precise diagnosis. Since it represents an average of many individual rankings, it can mask any individual rankings (such as 1’s and 2’s) that should be of concern.

Step 5. Look over the rankings for individual features of each site:

  • Best (4’s): best management according to current guidelines
  • Good (3’s): provides reasonable groundwater and surface water protection
  • Fair (2’s): inadequate protection in many situations
  • Poor (1’s): poses a high risk of polluting groundwater or surface water

Regardless of the overall ranking, any individual rankings of “1” should receive immediate attention. Some problems can be taken care of right away; others could be major or costly projects, requiring careful planning before action is taken.

Step 6. Consider how farmstead management practices or site conditions could be modified to better protect groundwater and surface water. Contact the township or municipality Sewage Enforcement Officer, Conservation District, Penn State Extension office, or the USDA Natural Resources Conservation Service for ideas, suggestions, or guidance.

Calculations for Septic Tanks, Absorption Fields and Sand Mounds

Septic Tank Sizing

  1. The minimum liquid capacity of a septic tank for any system should be 900 gallons.
  2. For single-family dwellings not served by a community system, a minimum flow of 400 gallons per day should be used to determine adequate septic tank capacity. Increase the minimum 400 gallons per day flow rate by 100 gallons for each additional bedroom over three.
  3. The minimum capacity of any septic tank for most situations can be calculated from the following table, using estimated daily sewage flows.
Design Flow (gallons per day)Tank capacity (gallons)
0-500(3.5 x flow exceeding 400 gpd) + 900
500-5000(1.5 x flow exceeding 500 gpd) + 1250

Absorption Field Sizing For All Systems and Sand Mounds

Calculations for appropriately sized absorption areas and sand mounds can be found in the Pennsylvania Chapter 73 regulations. The soil’s percolation rate, in minutes per inch, must be considered when sizing an absorption area. For a regular septic system, not requiring a sand mound, a general rule can be used.

(1.19) x (total flow per day) = square feet of absorption area

There are exceptions to this rule, so refer to Chapter 73 or see your local Sewage Enforcement Officer (SEO) for details. For very fast (less than 5 minutes per inch) and very slow (greater than 91 minutes per inch) percolation rates, an absorption area is unsuitable, and therefore a private septic system cannot be installed.

To estimate the size for an elevated sand mound, the following general rule can be used.

(1.50) x (total flow per day) = square feet of absorption area

There are exceptions to this rule, so refer to Chapter 73 or your local SEO. For percolation rates of less than 3 minutes per inch and greater than 121 minutes per inch, an elevated sand mound is not appropriate.

Source: Pennsylvania Code, Title 25. Environmental Resources Chapter 73. Standards for Sewage Disposal Facilities.

Minimum Separation Distances

Treatment Tanks

These are the distances required between any treatment tanks and the following features:

FeaturesMinimum Distance
Property line, easement, or right-of-way10 feet
Occupied buildings, swimming pools, driveways10 feet
An individual water supply or water supply system suction line50 feet
Water supply line under pressure10 feet
Streams, lakes, or other surface waters25 feet

Absorption Areas

These are the distances required between any absorption areas and the following features:

FeaturesMinimum Distance
Property line, easement, or right-of-way10 feet
Occupied buildings, swimming pools, driveways10 feet
An individual water supply or water supply system suction line100 feet
Water supply line under pressure10 feet
Streams, lakes, or other surface waters50 feet
Other active on-lot systems20 feet
Surface drainageways10 feet
Mine subsidence areas, bore holes, or sinkholes100 feet
Rock outcrop or identified shallow pinnacle10 feet
Natural or constructed slope greater than 25%10 feet

Source: Pennsylvania Code, Title 25. Environmental Resources Chapter 73. Standards for Sewage Disposal Facilities

Glossary

Approved disposal site: A site for land application of wastewater or tank pumpage that meets state standards and is approved by the state regulatory agency.

Cesspool: Covered excavation in the ground that receives sewage directly from the building’s sanitary drainage system. It is designed to retain the organic matter and solids and allow liquid to seep into soil cavities. A cesspool is an antiquated treatment system that predates current standards and does not adequately protect the public health.

Clear water infiltration: Entry of water that does not need treatment into a septic system through unsealed joints, access ports, and cracks, such as rainfall or tile drainage water or any water not generated from inside the house.

Design capacity: The maximum volume of liquid that can be treated in a particular wastewater treatment system. For systems that include subsurface wastewater disposal and distribution, capacity is also based on the soil’s ability to accept and treat sewage effluent.

Effluent: Liquid discharged from a septic tank or other treatment tank.

Groundwater: Water beneath the earth’s surface that supplies wells and springs.

Household chemicals: Items such as detergents, solvents, bleaches, cleaners, and pesticides, etc.

Off-site disposal: Disposal of wastewater or sludge at an off-farm site, such as a municipal treatment plant or approved disposal site.

Packaged aerobic system: Similar in design to a septic tank system except that the septic tank is replaced by an “aerobic” (aeration) tank. Air is stirred or bubbled into the wastes, which breaks down the material and results in a reasonably clear liquid and sludge. The liquid is discharged to the leaching bed and the sludge must be periodically pumped from the “aerobic” tank.

Pretreatment: The first step in treating wastewater to make it suitable for further treatment or disposal. For example, the septic tank retains most of the sludge from the wastewater, making further treatment in the leaching bed more effective.

Seepage pit (dry well): Underground receptacle constructed to permit disposal of septic tank effluent, treated wastes, or clear wastes by soil absorption through its bottom and walls.

Septic tank system: Consists of a separate tank to settle the solids out of the wastewater, followed by an underground leaching bed in which the wastewater is treated and dispersed in the soil.

Treatment: Eliminating the components of wastewater or reducing their concentration, so that they are not harmful to human health or the environment.

Wastewater: Waste of domestic origin, including waterborne waste from kitchen, laundry, and bathrooms (toilet,shower, and tub).

Acknowledgments

Material for the Pennsylvania Farm-A-Syst package was developed by revising Farm-A-Syst material from the University of Wisconsin Cooperative Extension Service, University of Minnesota Extension Service, and the National Farmstead Assessment System Program. The format and style for the Pennsylvania package was based on the Ontario Environmental Farm Plan published by Ontario Farm Environmental Coalition, Ontario, Canada.

Partial funding for the development of the Pennsylvania Farm-A-Syst package was provided by the Pennsylvania Association of Conservation Districts through the Chesapeake Bay Program from the U.S. Environmental Protection Agency and the Pennsylvania Department of Environmental Protection.

Preparation: Shelly Ogline, Project Assistant, Penn State Extension; Les Lanyon, Associate Professor of Soil Fertility, Penn State, Department of Agronomy.

Project Coordinators: Barry Frantz, Pennsylvania Association of Conservation Districts; Les Lanyon, Associate Professor of Soil Fertility, Penn State, Department of Agronomy; Jerry Martin, Penn State Extension.

Advisory Committee: Larry Martick, District Manager, Adams County Conservation District; Lamonte Garber, Agricultural Specialist, Chesapeake Bay Foundation; Lori Sandman, Project Leader, Dairy Network Partnership; Amanda Ritchey, Ridge and Valley Coordinator, Pennsylvania Association for Sustainable Agriculture; Tom McCarty, Multi-county Water Quality Agent, Penn State Extension; Susan Fox, Extension Agent, Penn State Extension, Bedford County.

Technical Review: Gary Obleski, Program Specialist, Pennsylvania Bureau of Water Quality Management; Khatija Swaroop, Pennsylvania Bureau of Land Recycling and Waste Management; Patricia Pingel, Pennsylvania Bureau of Land and Water Conservation; Daniel Fritton, Professor of Soil Science, Penn State; John Miele, Parks Manager, Pennsylvania Bureau of State Parks.

Pennsylvania Farm-A-Syst is a cooperative effort among Penn State Extension, Pennsylvania Association of Conservation Districts, Pennsylvania Department of Agriculture, Pennsylvania Department of Environmental Protection, and USDA Natural Resources Conservation Service.