Slope Stability - lindsays

APPENDIX G - SOME GUIDELINES FOR HILLSIDE CONSTRUCTION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

pipes.
‘Where structural distress is evident see advice.
Tf seepage observed, determine cases or seek advice on consequences.

 

GOOD ENGINEERING PRACTICE POOR ENGINEERING PRACTICE
ADVICE
GEOTECHNICAL Obtain advice from a qualified, experienced geotechmical practitioner at early | Prepare detailed plan and start stte works before
ASSESSMENT stage of planning and before site works. geotechnical advice.
PLANNING = >
SITEPLANNING | Having obtained geotechnical advice. plan the development with the risk | Plan development without regard for the Risk.
arising from the identified hazards and consequences in nund.
DESIGN AND CONSTRUCTION ¥
Use fiewle structures which incorporate properly designed brickwork, timber | Floor plans which require extensive cutting and
HOUSE DESIGN or steel frames, timber or panel cladding. filling.
" Consider use of spiit levels. Movement intolerant structures.
Use decks for recreational areas where appropriate.
SITE CLEARING Retain natural vegetation wherever practicable Indiscrmunately clear the site.
ACCESS & Satisfy requirements below for cuts, ills, retaining walls and drainage Excavate and fill for site access before
DRIVEWAYS Council specifications for grades may need to be modified. geotechnical advice
Driveways and parking areas may nead to be fully supported on piers.
EARTHWORKS Retain natural contours wherever possible. Indiscrmmatory bulk earthworks.
Minimise depeh Large scale cuts and benching.
Cuts. Support with engineered retaining walls or batter to appropriate slope. ‘Unsupported cuts.
Provide drainaze measures and erosion control Ignore drainage requirements
Minumse height. Loose or poorly compacted fill, which if it fas,
Strip vegetation and topsoil and key into natural slopes prior to filling. may flow a considerable distance including
Use clean fill nvterials and compact to engineering standards. onto propery below.
Fars Barter to appropriate slope or support with engineered retaimine wall Block natural drainage lines
Provide surtace drainage and appropriate subsurface dramage. Fill over existing vegetation and topsoil.
Include stumps, trees, vegetation, topsoil.
boulders, building mbble etc in fill
Rock Ourcrors | Remove or stabilise boulders which may have unacceptable risk. Dist) or undercut Getachad Blocks or
& Bowers Support rock faces where necessary. boulders.
Engineer design to resist applied soi! and water forces. Construct a structurally inadequate wall such as
RETADING Found on rock where practicable sandstone flaggme, brick or umreinforced
WALLS Provide subsurface drainage within wall backfill and surface drainage on slope | blockwork.
above Lack of subsurface drains and weepholes.
Construct wall a3 900 as possible after cut fill operation.
Found within rock where pracncable Found on topsoil, loose 17. detached boulders
FOOTINGS ‘Use rows of piers or stp footmgs oriented up and down slope. orundercut cliffs.
‘Design for lateral creep pressures if necessary.
Backfill footing excavations to exclude ingress of surface water.
Engineer desimed
Support on piers to rock where practicable.
SWIMMING POOLS | Provide with under-dramage and gravity drain outlet where practicable
Design for high soil pressures which may develop on uphill side whilst there
may be little or no lateral support on downhill side
DRAINAGE
Provide at tops of cut and fill slopes. Discharge at top of fils and cuts.
Discharge to street drainaze or narural water courses. Allow water to pond on bench areas.
SURFACE Provide general fails to prevent blockage by siltation and incorporate silt traps.
Line to minimise infiltration and make fexible where possible
Special structures to dissipate energy at chanzes of slope and/or direction.
Provide filter around subsurface drain Discharge roof moéf into absorption trenches.
Suneuasate Provide drain behind retaining walls.
- ‘Use flenible pipelines with access for maintenance.
Prevent inflow of surface water.
— ‘Usually requires pump-out or mains sewer systems, absorpoon tmenches may | Discharge sullage directly onto and ito slopes.
State be possible m some areas if risk is acceptable. Use absorption trenches without consideration
Storage tanks should be water-tight and adequately founded. of landslide risk.
EROSION Control erosion as this may lead to instability. Failure to observe earthworks and drainage
CONTROL & Revegatate cleared area. recommendations when landscaping.
LANDSCAPING
DRAWINGS AND SITE VISITS DURING CONSTRUCTION
DRAWINGS Building Applicanon drawings should be viewed by geotechnical consultant
SITE VISITS Site Visits by consultant may be appropnate dunng construction’
INSPECTION AND MAINTENANCE BY OWNER
OWNER'S Clean dramage systems; repair broken joints in drams and aks m supply
RESPONSIBILITY