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Inspecting Difficult Septic System Sites: steep, lakeside, rocky InspectAPedia®  -     Where to look outside for evidence of septic failure, difficult sites, steep or rocky sites What other site clues indicate a probable septic problem? How to perform a septic loading & dye test, step by step

This document describes how to look for visual evidence of septic failure without or before testing a septic system and also difficult site conditions that may require special measures to install a working septic system. Our page top photo shows a fresh pile of rock and soil pushed over the edge of a steep rocky embankment near where we understood a septic tank to be located. Even before beginning our inspection we were concerned about what we might find since this was a difficult septic site.

A later page, FAILURE SPOTS, which is part of our STEP BY STEP SEPTIC TEST procedure, describes where you're likely to see actual evidence of septic failure during a loading and dye test. Looking for these conditions can give key information about the condition of the septic system before (and perhaps without) performing a septic loading and dye test and also before (and perhaps without) invasive septic system inspection measures such as excavation.

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How to Inspect DIFFICULT SEPTIC SITES - Indicators of Difficult Septic Installation Sites

Septic System Near a Stream exposed to flooding: at homes along Wappingers Creek in Dutchess County, NY, many septic tanks and drainfields are close to the waterway. Seasonal flooding such as shown in this photo make drainfield floods likely. Even when flood conditions are not present, some drainfields may be too close to the creek to comply with state building and health codes, and worse, the high water table near the creek may prevent such systems from adequately treating septic effluent before it is discharged into the environment. Up-slope drainfields with effluent pumps or other special measures may be needed.

Dye tests of septic systems close to a lake or stream like this will sometimes discover that a property owner having a failing septic system succumbed to the temptation to simply run an effluent discharge line right from the end of a bad drainfield into the stream. Remember to look both above and below the water line for unexplained pipes in the area.

• Steep Slope or Steep Site Septic Systems: If the building site is steep then special measures may have been needed to provide a working drainfield, or septic tank and field components may not be located near the building they serve and a pumping system may have been needed. Be on special alert for evidence of septic effluent breakout down-slope and at the bottom of steep slopes if septic components are nearby. See STEEP SLOPE SEPTIC DESIGNS for details of how septic system need to be installed on steep or sloping sites in order to provide a working and durable drainfield.
  
  
• Rocky Site Septic Systems: if there is insufficient depth of soil, proper treatment of septic effluent may be impossible using a conventional septic tank and drainfield. At some sites including the one shown in our page top photo, there may be so little topsoil over bedrock that there is not depth for a conventional septic tank to be buried. At such sites an installer may provide a "low boy" septic tank - one that obtains its volume by spreading over a larger footprint but with a shallow septic tank.
  
  Shallow septic tanks may need special or more frequent pumping, and should be taken as an alert to inspect the D-box and drainfield carefully. A drainfield or soil absorption system needs (typically) about 2 ft. of soil below the bottom of the drainfield and the top of any nearby rock or high ground water. So a drainfield installed in just a couple of feet of soil over bedrock is not going to perform well and may not be approved by local health officials.
  
  

Flat septic site near a lake: The land shown in this photo was a new home site which not only had standing water, but had only a few feet of elevation between the yard top grade and the top of the nearby lake also shown in the photo. The pipe shown was a footing drain emptying at the edge of a nearby lake. The septic tank and drainfield were buried in this area. I couldn't imagine how a conventional septic tank and drain field would work in this location.

Here is a photo of the septic tank being installed at this property. That downspout you see spilling by the foundation needs to be extended away from the home, but not where the roof drainage will simply enter the septic tank and flood the leach field. Here is a photo of the end of the home footing drain, higher than where the bottom of a leach field trench needs to go, and spilling into the lake.

Here is a photo of the contractor's "repair" of the exposed footing drain and minimal soil depth at the property. I can't inform readers of what the building department ultimately had to say about this installation.

Vehicle areas near Septic Tanks or Fields: Is there evidence of driving or parking on the leachfield or over a tank? (Risks damaging the system or dangerous collapse.) At the property shown in this photo, the truck is parked over a "low boy" septic tank which was installed over bedrock. The rock pile shown at the top of this page was behind this truck and pushed over the embankment to cover a failed seepage pit - there was no working drainfield at this site.

Soil conditions before septic test start: What are soil and site conditions before start of the test: are there wet areas, evidence of surface discharge of effluent or sewage, green grassy or soft, suspect areas? Odors? It is important to be able to record these conditions and their extent before and after testing.

• Mound systems vs. original site: Has the mound system been constructed over a natural surface drainage path or stream? Are trees and stumps sticking out of the mound (meaning it was used to bury site debris not to make a proper absorption field)?

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SEPTIC SYSTEMS HOME
SEPTIC SYSTEMS ONLINE BOOK
SEPTIC DYE TEST PROCEDURE
HOW TO PERFORM A SEPTIC DYE TEST
WHAT TO DO FIRST
OUTSIDE SEPTIC INSPECTION
  IMMEDIATE FAILURE EVIDENCE
  LOOK FOR COMPONENTS
  DIFFICULT SEPTIC SITES
  RECENT SEPTIC WORK
  SEPTIC SAFETY
STEP BY STEP SEPTIC TEST
  INSIDE SEPTIC TEST STEPS
  WATCH FOR INSIDE
  OUTSIDE SEPTIC TEST STEPS
  SEPTIC FAILURE SPOTS
  SPOTTING SEPTIC BREAKOUTS
SEPTIC TEST VOLUMES & DYE AMOUNTS
  SEPTIC TEST WATER & DYE TABLE
  SEPTIC TEST FIXTURE FLOW RATE
  HOW TO SET THE SEPTIC TEST VOLUME
REPORTING SEPTIC TEST RESULTS
PUMP THE SEPTIC TANK
SEPTIC DYE TEST WARNINGS

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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More Information on Building Diagnostic Inspections and Repairs

• Return to the septic system textbook: Inspecting, Testing, & Maintaining Residential Septic Systems
• The Septic Information Website
  
  
• Safety Warnings to Septic System Inspectors
• Testing Water for Real Estate Transactions - Water Test Cheating Warnings for Home Buyers and Home Inspectors.
• Home & Outdoor Living Water Requirements
• Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow calculating septic tank volume and septic tank size required
• How Big Should the Leach Field Be? - table of soil percolation rate vs. field size
• The Home Buyer's Guide to Septic Systems
• Material Safety Data Sheet MSDS for Red Septic Dye from Tramfloc.
• MSDS for Septic Dye Tablets from Tramfloc.
• MSDS for Septic Dye Liquid from Tramfloc.
• Septic Dye Technical Data Bulletin from Tramfloc.
• Tramfloc, Inc. source of septic system testing tracer dyes
• Bright Dyes Inc. source of septic system testing tracer dyes
• Pollard Water source of septic system testing tracer dyes

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