Alternative Septic Systems: Options for When a Conventional System Won’t Suffice –
Septic systems are fairly common in rural Northern New Jersey and Eastern Pennsylvania in municipalities where sewage systems don’t exist. When a new septic system design is required for new construction or for the replacement of a failed system on an existing improved property (known as an alteration), a conventional system consisting of a buried septic tank and a leach field can usually be used. Conventional septic systems aren’t suitable for every property, however, in which case an alternative septic system design may be necessary.
There are various reasons why a plot of land might require an alternative septic system. Perhaps the soil didn’t pass its perc test, or there’s shallow bedrock, or the water table is too high. In other instances, the property may be in an environmentally-sensitive area, on a steep slope, or doesn’t otherwise meet regulations. Here are some of the more commonly-used alternative septic systems used in our area.
Mound septic systems are often used where the soil is too dense or shallow, groundwater is too high, or bedrock is too close to the surface. In a mound system, wastewater flows from the septic tank to a dosing chamber that pumps prescribed doses to a raised leach field constructed of sand and gravel and covered in topsoil.
Like the mound system, a pressurized dosing system uses a dosing chamber installed after the septic tank to pump wastewater to the leach field in controlled amounts. This helps prevent overloading and improves system performance. Pressurized dosing can be used in combination with various types of septic systems.
Aerobic Treatment Unit (ATU)
An ATU functions much like a small-scale municipal sewage plant in that oxygen is injected into the treatment tank to increase the growth of aerobic bacteria (as opposed to the anaerobic bacteria found in a conventional septic system) and help break down organic matter more quickly. Aerobic systems are often selected when a water table is too high, soil is of poor quality, on small lots, or when a sensitive body of water is nearby. ATUs can be fairly expensive and require substantial maintenance.
Drip Distribution System
Drip distribution systems employ a long, winding length of flexible tubing that disperses timed doses of wastewater over a large area. These systems require a large dosing chamber, a timer, and oftentimes a filtering device. Also known as drip irrigation, it can be used to water
lawns and non-edible plants. They are a good selection for clay soil, shallow soil, and on steep slopes. Because drip distribution systems require electric and are susceptible to freezing, they require substantial monitoring and maintenance.
Alternative septic system design requires the services of a licensed professional engineer to perform a site evaluation determine system requirements, and to conduct all necessary site inspections, soil testing, system design, and handling of system certifications. Finelli Consulting Engineers, Inc. is expert in alternative septic system selection, design, inspection, and troubleshooting. For more information, please call us at (908) 835-9000
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