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SEPTIC SYSTEM INSPECT DIAGNOSE REPAIR
SEPTIC CARE INSTRUCTIONS
SEPTIC D-BOX INSPECTION
SEPTIC DRAINFIELD FAILURE DIAGNOSIS
SEPTIC DYE TEST PROCEDURE
SEPTIC FAILURE SIGNS
SEPTIC INSPECTION & TEST GUIDE
SEPTIC LIFE EXPECTANCY
SEPTIC SUPPLIES & PARTS
SEPTIC SYSTEM DESIGN ALTERNATIVES
SEPTIC SYSTEM DESIGN BASICS
SEPTIC SYSTEMS, HOME BUYERS GUIDE to
SEPTIC SYSTEM SAFETY WARNINGS
SEPTIC TREATMENTS & CHEMICALS
SEWAGE BACKUP PREVENTION
SEWAGE EJECTOR / GRINDER PUMPS
SEWER GAS ODORS
SEWER LINE REPLACEMENT
SINKHOLES, WARNING SIGNS
SOAKAWAY BED FAILURE DIAGNOSIS
SULPHUR & SEWER GAS SMELL SOURCES
TOILETS, INSPECT, INSTALL, REPAIR
TRAPS on PLUMBING FIXTURES
TREATMENTS & CHEMICALS, SEPTIC
VIDEO GUIDES: Septic Videos
WATER CONSERVATION MEASURES
WATER SOFTENERS & CONDITIONERS
WATER SUPPLY & DRAIN PIPING
WATER, WELLS, WATER TANKS: TESTING GUIDE
WASHING MACHINES & SEPTIC SYSTEMS
WASTEWATER TREATMENT BASICS
WINTERIZE A BUILDING
This document describes how to inspect the condition of a septic tank, providing special considerations for inspecting concrete septic tanks. Inspecting concrete septic tanks is a key component in onsite wastewater disposal systems. Also see SEPTIC TANK BAFFLES & SEPTIC TANK TEES and SEPTIC TANK PUMPING PROCEDURE.
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The photo shows a round concrete septic tank cover being removed to prepare for pumping a concrete septic tank. This is a safe cover and is rated thick enough to be driven-over by a car - but we do not recommend that practice.
Of course the area is quite unsafe while the septic tank cover is off - we would not leave the tank cover off and the area unattended.
Concrete septic tanks at an existing septic installation are usually viable, but might have damaged baffles or cracks that permit seepage of groundwater in or septic effluent out around the tank.
Occasionally we've seen tanks made of poor-quality concrete (insufficient portland cement) which eroded badly. If the tank outlet or absorption system have been blocked, examination of the tank interior may show that effluent is or has been above the top of the baffles (see "baffles" below) thus indicating a system failure.
Types of Damage Found at Concrete Septic Tanks
One of the most common problems found on concrete (and some other) septic tanks is tank flooding due to either a drainfield backup or due to surface runoff or groundwater entering the septic tank.
How do we know if the septic tank is flooded? See SEPTIC TANK LEVELS of SEWAGE.
Concrete tanks can crack or sections may separate causing leaks with the result of not only improper disposal of effluent (wrong location) but also subverting an attempt at a septic loading and dye test since when the system is un-used the tank liquid levels drop abnormally.
The inspector may detect this condition only if there is a tank inspection port which is readily and safely accessible for before, during, and after inspection when running a loading and dye test.
Repairs to concrete septic tanks
Repairing damaged or lost concrete septic tank baffles
On occasion we find that the baffles at inlet or outlet ends of a septic tank have deteriorated, usually due to poor original concrete mix, and occasionally due to mechanical damage. A lost or damaged baffle at a septic tank is asking for sewage backup into the building or the passage of solids into the drainfield - substantially shortening its life.
Repairing leaks into a concrete septic tank
Besides leaks due to a crack in a concrete septic tank, we find leaks into the tank due to improperly algined or placed entry or exit piping or missing, damaged gaskets at those locations. To repair septic tank leaks see SEPTIC TANK LEAKS.
In addition to sealing openings at tank piping and cracks or holes (described below) if your septic tank is being flooded from local groundwater or surface runoff, the flooded tank will also flood the drainfield or may cause a sewage back-up into the building. Some readers have suggested sealing the septic tank covers and access ports - but these need to be removable for service or repair, and really you may be treating the symptom, not the problem.
We agree that faced with a high cost of site drainage corrections, sealing the septic tank lid may be an appealing solution. First make sure that the flooded septic tank is due to surface runoff or groundwater, not a backing-up or failed drainfield, or you're simply fixing the wrong problem.
It makes sense to direct surface runoff away from the septic tank, or if necessary, install an intercept drain to keep ground water and surface water away from the tank.
Reparing cracks & holes in a concrete septic tank
It is possible to repair a crack or hole in a concete septic tank using concrete patching compounds and some foundation repair compounds, epoxies, and crack sealers. Key considerations are
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