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27 Cards in this Set

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Proper site design for fire fighting

1. Direct, easily perceived all weather vehicular access to each building and hydrant and/or to each surface water impoundment where applicable

2. Control massing of development with firebreaks or walls to reduce risk of conflagration

3. site layout allowing hoses to be run to all sides of each building

4. At least two hydrants within 500-600 ft of every building

Sources of potable water

1. public water supply

2. On-site wells or cisterns

3. surface reservoirs and ponds

Surface catchments for potable water

Must have a treatment system to clean the water and be able to store 1 years worth of water from the upstream catchment

High-yield wells

May be needed for new towns, require specialized expertise to plan and build. Good sites may include coarse outwash plains, ice channel fillings along valleys, river terraces, kame fields, and similar surficial deposits.

High yield wells often require a protected buffer zone in which other land uses are prohibited. These may be several hundred feet wide.

Should consider proximity to and possible contamination by seawater, organic deposits in marshes, urban land, and industrial waste.

Wells in seacoast environments

Water table must not fall below sea level or brackish water may enter potable water supply

Wells near organic deposits

Draw down cone may cause oxygenated water to come into contact with anaerobic organic deposits, releasing metallic sulfides into the water supply. Resting the well and allowing water table to rise can reverse these effects over time.

Wells in or near urban or industrial development

Recharge cone should not include developed areas or potentially contaminated sites unless analysis indicates no contamination risk exists.

What type of effluent disposal can be used with a septic tank?

All septic systems are limited to subsurface effluent disposal because of the odor inherent to septic effluent.

Which is more expensive: individual on-site sewage disposal or a cluster system?

A cluster system is more expensive, often by a ratio of 10:1 due to the need for pipelines, pumping stations, and manholes. Also higher operation cost.

For what dwelling density is on-site sewage disposal appropriate

5 DU/Acre for single family residences and 12 du/Acre for 3 story apartment buildings

What site conditions must be met for on-site sewage disposal

Adequate depth to groundwater and soil permeability

Subsurface leaching system layout

Aerobic digester with surface infiltration bed

Aerobic digester with evapotransporation system

Unaerated lagoon for sewage disposal

Aerated lagoon for sewage disposal

Most effective, economical, and environmentally safe method for disposing of waterwater

Slow filtration of wastewater through soil. Can be accommodated only if adequate space, permeability and depth to groundwater exist

Septic system

least-expensive small system

least-expensive small system

Package plants

aerobic systems for sewage disposal that can be employed if space or site conditions are constrained. Minature versions of municipal treatment plants, designed to settle out dissolved sewage and contaminants. Typically require periodic pumping


How much unsaturated soil must there be between a septic leaching field and the water table?

Typically about 1m. Can be achieved via mounding if underlying soil is permeable

Septic tank maintenance

1. Infrequent pumping to remove nondegradeable solids

2. Resting of the leaching facility

How long can a septic tank function before it should be rested?

20 years. Site layout should leave space for two septic leaching fields even though often only one is built initially.

What determines the infiltration rate of effluent?

The permeability of the bacterial slime generated by the effluent itself, which is often much less permeable than the soil.

Disadvantage of unaerated lagoon for sewage treatment in cold climates?

In cold climates sewage lagoons will turn over twice a year, which has a strong odor. Aerating the lagoon year-round can mitigate that effect

Can evapotranspiration systems be used with effluent from septic systems?

No, effluent must be aerobic to be taken up by plants.

What uses are compatible with an evapotranspiration system for sewage disposal

Typically none while field is active. When inactive compatible uses may include crops not used for human food, game habitat and hunting grounds, forest products, and forage crops for horses.