Drain field repair and replacement quotes

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Signs the drain field is in trouble

The EPA lists these common signs of a failing septic system:

• Water and sewage backing up into toilets, drains and sinks
• Bathtubs, showers and sinks draining very slowly, and gurgling in the plumbing
• Standing water or damp spots near or over the tank or drain field
• Sewage odors around the tank or drain field
• Bright green, spongy grass over the tank or drain field, even in dry weather

Angi adds that needing to pump the tank more often than you used to can point to a failing drain field. Angi notes the same signs can also mean clogs or cracked pipes, and a clogged filter ($200 to $300) or a baffle ($300 to $900) costs far less to fix than a field, so make sure the company diagnoses the problem before quoting a new one.

Why drain fields fail

• Solids reaching the field. The EPA says that when routine maintenance is skipped, solids in the tank can move into the drain field and clog it.
• Too much water. NC State Extension calls overloading a common cause: leaking toilets or faucets, more people in the house, or a sump pump, roof drain or runoff from paved areas sent onto the field.
• Driving, paving or building on it. NC State Extension says this can crush pipes and compact the soil. The EPA says to plant only grass over the system, because tree and shrub roots can clog and damage the field.
• The site itself. The EPA says some fields were installed in inadequate soils, on steep slopes or where groundwater is high, which can lead to hydraulic failure.

Local soils can make it harder

Two soil series the USDA describes in this part of Tennessee and Georgia show why soil matters for a drain field:

• Talbott: clayey soil weathered from limestone, with moderately slow permeability and bedrock 20 to 40 inches down. The USDA says it is widespread in the Ridge and Valley of Tennessee and northern Georgia.
• Collegedale: clay or silty clay from limestone and shale, also with moderately slow permeability. Its reference site is near Collegedale in Hamilton County, and the USDA notes that a fairly large area of it in the county has been developed.

Slow-draining clay or shallow rock leaves less room for a field to work, and a replacement may need a different design. Your own lot can be different, so a soil evaluation or perc test decides what's allowed. Hamilton County's Groundwater Protection office can require a soils map for work on an existing system.

Repair, rehabilitate, replace or connect to sewer?

• Fix the cause first. Washington State's health department says a field that is just saturated from too much water can sometimes be dried out and rehabilitated.
• Repair part of the field or the lines and distribution box, if the rest is sound.
• Replace the field, or the tank and field, when it has reached the end of its life. Angi says a field can last up to 50 years but averages about 20.
• Connect to sewer where a line is available. WWTA says it can require a connection when sewer is available. Ask before you pay for a new field.

What drain field work costs

Why quotes vary so widely, and why to get 2 or 3

Even Angi's own guides disagree on a "typical" field repair ($1,000 to $3,000 in one, $2,000 to $15,000 in another). Quotes for the same yard can differ for real reasons:

• Different diagnoses. One company may see a repair; another may quote a new field.
• Different designs. Poor soil or shallow rock can push the job from a conventional field to a more expensive system such as a mound.
• What's included. Permit, perc test, pumping, hauling, and putting the yard back are sometimes in the price and sometimes extra.

Get two or three written quotes. Ask each company what it found, what it will do, which permit it will pull, and what's not included. The Tennessee Department of Commerce & Insurance also advises getting several bids, checking licenses at verify.tn.gov, and not paying in full before the work is done.

Permits

Hamilton County, TN: repairs need a $40 repair permit from Groundwater Protection (423-209-7876). Adding field lines or bedrooms is a $440 modification permit. See our septic permits and rules page. Catoosa and Walker counties, GA: repairs go through the county Environmental Health office.

Related: septic repair · inspection · cost guide