TYPE OF GEOTECHNICAL INVESTIGATION CATEGORY 1. SMALL/SIMPLE STRUCTURES LIGHTLY LOADED GROUND CONDITIONS KNOWN FROM EXPERIENCE STABILITY AND SETTLEMENT CALCULATION NOT CONSIDERED NECESSARY CATEGORY 2. MEDIUM SIZE STRUCTURES BRIDGES…RETAINING WALLS…..EMBANKMENTS CATEGORY 3. LARGE STRUCTURES POTENTIALLY DIFFICULT GROUND CONDITIONS
PREFERRED TYPE OF SAMPLING REQUIRED Disturbed or Undisturbed Class 1: Disturbed Strata identification only Class 2: Disturbed Soil Classification tests only Class 3: Disturbed Soil Classification & water content Class 4: Disturbed or Undisturbed Soil Classification, water content,density Class 5 : Undisturbed Soil Classification, water content, density, shear strength, consolidation tests
TYPE OF GEOTECHNICAL INVESTIGATION REQUIRED CATEGORY 1. SHALLOW INVESTIGATIONS TEST PITS- GENERALLY UP TO 3.0 METERS …… MAX 5.0 METRES DUE TO LIMITATIONS OF EXCAVATORS EQUIPMENT ALSO GOVERNED BY THE SUBSURFACE MATERIAL HAND AUGERS MACHINE AUGERS DIRECT PUSH PROBING EQUIPMENT CLASS OF SAMPLE Class 1,2,3, & 4. SIZE OF SAMPLE VARIES ….5KGS FOR P.I.& P.S.D…………UP TO 20KGS FOR MMDD & CBR
TYPE OF GEOTECHNICAL INVESTIGATION REQUIRED CATEGORY 2, & 3 DEEPER INVESTIGATIONS MACHINE AUGERS DIRECT PUSH PROBE (DPP) & SPT HQ3 DIAMOND CORE & SPT ELECTRIC FRICTION CONE PENETROMETER (CPT) TYPE OF SAMPLE DISTURBED CONTINUOUS UNDISTURBED
OPTIMAL DRILLING SOLUTIONS GEOTECHNICAL DIRECT PUSH PROBE ( DPP) CLASS 1 & 2. (Shallow Investigations) Soil & Soft Rock < 20 Mpa DPP can add SPT or CPT CLASS 3 & 4. ( DEEPER Depths) DPP with SPT or CPT (Soil & Soft Rock) Hollow flight auger with SPT (Soil & Soft Rock) Diamond Drilling with SPT ( Soft Rock & Hard Rock) continuous sample for UCS tests CLASS 5. Diamond core with SPT ( Soft Rock & Hard Rock) continuous sample for UCS tests
Geotechnical /Environmental overlap SHALLOW INVESTIGATIONS < 5.0 METRES SMALL SAMPLES REQUIRED FOR BOTH DPP IDEAL GEOTECHNICAL ENVIRONMENTAL
COST EFFECTIVE APPROACH Geotechnical & Environmental Combine Information from Desk Top Study AND P.S.I HSE issues identified Acid Sulphate Soils (ASS) addressed CAN OFTEN Use DPP for both Geotechnical & Environmental investigation and sampling 1 mob/demob charge Extend DPP depths and use SPT & CPT for extra Geotechnical design parameters. Outcome from DPP limited by hardness of rock and need for continuous rock coring
BENEFITS OF Direct Push Probe (DPP) CAN BE USED IN BOTH GEOTECHNICAL & ENVIRONMENTAL INVESTIGATIONS SAVE ON MOB/DEMOB $$ EXTEND THE DEPTH DO MORE LOCATIONS INCLUDE SPT OR CPT ONE SIZE DOES NOT FIT ALL BUT YOU WILL GET A MORE COST EFFECTIVE RESULT IF YOU CAN PLAN THE GEOTECHNICAL & ENVIRONMENTAL INVESTIGATIONS & SHARE THE SITE TIME.
SELECTING DRILLING METHODS FOR THE BEST OUTCOME ENVIRONMENTAL PRACTIONER’S PERSPECTIVE & REQUIREMENTS
INVESTIGATION PERCEPTIONS There is a perception that the Geotechnical Investigation is more important than the Environmental Investigation? Why is that ? They both carry equal importance to understanding the site conditions.They both carry equal importance to understanding the site conditions. Is Geotechnical data seen to be more commercially viable than environmental data?Is Geotechnical data seen to be more commercially viable than environmental data? This leaves the site developer the following scenario Investigating the site twice which includes:Investigating the site twice which includes: Two mobilisation costs. and Two investigations within the same soil space.
WHAT IF ? What if both investigations were undertaken at the same time? Would this impede both investigations? Could the drill methods be adapted to accommodate both investigation requirements? Would there be a conflict of interest - two consultancies wanting the same soil sample at the same depth?
BACKGROUND DATA UP FRONT If there was one thing we could change it would be to get clients to carry out Preliminary Site Investigation (PSI) at the planning stage up front. Why is this ? Benefits the Environmental Scientist and Geotechnical Engineer.Benefits the Environmental Scientist and Geotechnical Engineer. Provides the data to develop a Detail Site Investigation (DSI).Provides the data to develop a Detail Site Investigation (DSI). Environmental impacts can be assessed and targeted.Environmental impacts can be assessed and targeted. Develops a Conceptual Site Model (CSM) for the site.Develops a Conceptual Site Model (CSM) for the site. This information at an early stage can be beneficial to geo- technical engineers and all future site investigations including the environmental scientist.
PSI INFORMATION IS GOOD INFORMATION The PSI will provide: Historic Land Ownership Historic Maps and Aerial Photos. Land use history – landfills, soil import / export Potential contamination from land use – harmful / toxic Dangerous goods history Acid Sulfate Soils (ASS) risks Geological conditions Hydrogeological conditions - Groundwater depths and local users All of this information helps makes informed decisions about how the site should be investigated and potential control measures required.
DEVELOPING A SCOPE OF WORKS TOGETHER Achieving synchronised investigations in an ideal world: Environmental practioners and geotechnical engineers to collaborate and form partnerships.Environmental practioners and geotechnical engineers to collaborate and form partnerships. Joint development of a site investigation to collect data for both parties.Joint development of a site investigation to collect data for both parties. Reduce any risks to site workers and visitors.Reduce any risks to site workers and visitors. Minimise risk to the environment.Minimise risk to the environment. SAVE client time and money in duplicated works.SAVE client time and money in duplicated works. All before the ground is broken on the site!
HOW DEEP IS TOO DEEP? Typically environmental investigations are concerned with the upper few metres of the soil profile. Is this enough for the geotechnical engineer? Would drilling depths have to be deeper to accommodate geotechnical requirements? Could the geotechnical engineer sample the soils left? Would soil volumes be sufficient to sample? Does the geotechnical engineer want the same sample depth? Would collaboration at the beginning of the project allow both parties to achieve respective project requirements?
ENVIRONMENTAL DRILLING Environmental drilling for sampling purposes is usually undertaken via push probe methodology. This sampling method is selected for: Clean environmental drilling (no drill fluids).Clean environmental drilling (no drill fluids). Soil cores which detail individual soil horizons.Soil cores which detail individual soil horizons. Allows installation of environmental monitoring wells.Allows installation of environmental monitoring wells. Efficient.Efficient. The size of the rig allows access onto most sites.The size of the rig allows access onto most sites.
PROS If the Environmental Scientist and Geotechnical Engineer investigated together? Reduced uncertainty in tendering and quoting.Reduced uncertainty in tendering and quoting. Identify potential site hazards early.Identify potential site hazards early. Identify spatial irregularities about site.Identify spatial irregularities about site. Reduce need to remobilise.Reduce need to remobilise. Identify opportunities to reduce duplication.Identify opportunities to reduce duplication. Enhanced focus on chemical properties of upper soil profile.Enhanced focus on chemical properties of upper soil profile.
CONS Conflict of issues in methodologyConflict of issues in methodology Sampling depth requirements (Environmental vs Geotechnical)Sampling depth requirements (Environmental vs Geotechnical) Potential contamination of samples (drilling method)Potential contamination of samples (drilling method) Lost billing opportunity: real or perceptiveLost billing opportunity: real or perceptive Who determines objectivesWho determines objectives LiabilityLiability Perceptions about experience and qualificationsPerceptions about experience and qualifications
SUMMARY Site investigations require the site history, characterisation of physical properties of underlying lithology and vertical profiling of the upper soil profile. Typically this has been achieved via a piece meal process rather than an integrated process. Data from any investigation can serve multiple functions provided the requirements of each function are met. No one method will meet all needs but an integrated approach via early incorporation of a PSI has the potential to save time and money.
SELECTING DRILLING METHODS FOR THE BEST OUTCOME FOR GEOTECHNICAL OR ENVIRONMENTAL DRILLING Specialist Geo- Environmental Drillers
GEOTECHNICAL DRILLING METHODS METHOD DIAMOND DRILLING/TRIPLE TUBE DIAMOND DIAMOND DRILLING/TRIPLE TUBE DIAMOND MUD ROTARY/SONIC MUD ROTARY/SONIC RAB/AIRCORE/RC RAB/AIRCORE/RC DIRECT PUSH/HOLLOW STEM AUGER/CONTINUOUS FLIGHT AUGER DIRECT PUSH/HOLLOW STEM AUGER/CONTINUOUS FLIGHT AUGER DRILLING ADDITIVES WATER/BENTONITE/POLYMERS/LUBR ICANTS/LOST CIRCULATION MATERIAL WATER/BENTONITE/POLYMERS/LUBR ICANTS/LOST CIRCULATION MATERIAL AIR /MUDS/POLYMERS/ LOST CIRCULATION MATERIAL/CONTAINS HYDROCARBONS AIR /MUDS/POLYMERS/ LOST CIRCULATION MATERIAL/CONTAINS HYDROCARBONS MUDS/WATER MUDS/WATER Specialist Geo- Environmental Drillers
ENVIRONMENTAL DRILLING METHODS COMMON METHODS DIRECT PUSH DIRECT PUSH HOLLOW STEM AUGER/CONTINUOUS FLIGHT AUGER HOLLOW STEM AUGER/CONTINUOUS FLIGHT AUGER SONIC SONIC DRILLING ADDITIVES WATER WATER WATER/MUDS/POLYMERS WATER/MUDS/POLYMERS Specialist Geo- Environmental Drillers
DESIRED OUTCOMES SOIL SAMPLE FOR TESTING SOIL SAMPLE FOR TESTING BULK – STRENGTH, MOISTURE ETC BULK – STRENGTH, MOISTURE ETC ASS - ANALYSIS ASS - ANALYSIS INSITU PARAMETERS INSITU PARAMETERS SPT, VANE SHEAR, CPT, SIESMIC, ETC SPT, VANE SHEAR, CPT, SIESMIC, ETC ADDITIONAL EQUIPMENT DATA LOGGERS ADDITIONAL EQUIPMENT DATA LOGGERS STAND PIPES STAND PIPES GROUND WATER LEVELS, PORE PRESSURES, WATER QUALITY GROUND WATER LEVELS, PORE PRESSURES, WATER QUALITY GEOTECHNICAL Specialist Geo- Environmental Drillers
DESIRED OUTCOMES ENVIRONMENTAL SOIL SAMPLE FOR TESTING SOIL SAMPLE FOR TESTING CONTAMINATION, ASS, CONTAMINATION, ASS, WATER WELLS – QUALITY, CONTAMINATION, LEVEL WATER WELLS – QUALITY, CONTAMINATION, LEVEL DATA LOGGERS DATA LOGGERS SOIL VAPOUR READING/WELLS SOIL VAPOUR READING/WELLS DIRECT IMAGE – MIP, HPT, EC, ETC DIRECT IMAGE – MIP, HPT, EC, ETC Specialist Geo- Environmental Drillers
ONLY WATER WILL DO SOME BENTONITE BASED MUDS AND DRILLING FLUIDS CAN CONTAIN SRB. SOME BENTONITE BASED MUDS AND DRILLING FLUIDS CAN CONTAIN SRB. SRB – SULPHUR REDUCING BACTERIA SRB – SULPHUR REDUCING BACTERIA CORROSIVE TO IRON – WELL HEADS AND DOWN HOLE INFRASTRUCTURE CORROSIVE TO IRON – WELL HEADS AND DOWN HOLE INFRASTRUCTURE DRILL STRINGS DRILL STRINGS CAN INTERFERE WITH ASS RESULTS CAN INTERFERE WITH ASS RESULTS PRODUCES H2S PRODUCES H2S WATER WELLS REQUIRE DECONTAMINATION AFTER DRILLING WATER WELLS REQUIRE DECONTAMINATION AFTER DRILLING ALTERS THE CHEMISTRY OF THE WATER ALTERS THE CHEMISTRY OF THE WATER AIR – CONTAINS HYDROCARBONS, SPREADS CONTAMINATION (ASBESTOS, BIOLOGICAL HAZARDS) AIR – CONTAINS HYDROCARBONS, SPREADS CONTAMINATION (ASBESTOS, BIOLOGICAL HAZARDS) OXIDISES AND VOLATILISES OXIDISES AND VOLATILISES POROUS FORMATIONS WILL ABSORB AIR AND DISCHARGE FOR HOURS SOMETIMES DAYS AFTER DRILLING HAS CEASED POROUS FORMATIONS WILL ABSORB AIR AND DISCHARGE FOR HOURS SOMETIMES DAYS AFTER DRILLING HAS CEASED TOOL JOINTS USUALLY LUBRICATED WITH EP GREASE CONTAINING A VARIETY OF ADDITIVES TOOL JOINTS USUALLY LUBRICATED WITH EP GREASE CONTAINING A VARIETY OF ADDITIVES Specialist Geo- Environmental Drillers
JOINT GEOTECH & ENVIRO DRILLING METHODS DIRECT PUSH VARIETY OF DIAMETER SAMPLES - 32MM UP TO 70MM (IDEAL FOR ASS, GEOTECH AND CONTAM SAMPLING) VARIETY OF DIAMETER SAMPLES - 32MM UP TO 70MM (IDEAL FOR ASS, GEOTECH AND CONTAM SAMPLING) CAN DO SPT/CPT, VANE SHEAR, DIRECT PUSH, WELL INSTALLATION, HOLLOW STEM AUGER – SAVING TIME AND EXPENSE ON MOBILISING MULTIPLE RIGS CAN DO SPT/CPT, VANE SHEAR, DIRECT PUSH, WELL INSTALLATION, HOLLOW STEM AUGER – SAVING TIME AND EXPENSE ON MOBILISING MULTIPLE RIGS VARIETY OF DIRECT IMAGING APPLICATIONS VARIETY OF DIRECT IMAGING APPLICATIONS ONLY WATER USED IN DRILLING OPERATION – AND THEN ONLY ONCE THE WATER TABLE HAS BEEN REACHED ONLY WATER USED IN DRILLING OPERATION – AND THEN ONLY ONCE THE WATER TABLE HAS BEEN REACHED ALL DIRECT PUSH SAMPLES ARE CONTAINED IN EITHER SPLIT SPOON OR SAMPLE TUBES ALL DIRECT PUSH SAMPLES ARE CONTAINED IN EITHER SPLIT SPOON OR SAMPLE TUBES RIGS ARE COMPACT AND HIGHLY MOBILE RIGS ARE COMPACT AND HIGHLY MOBILE Specialist Geo- Environmental Drillers
SPT DIRECT PUSH RIG SPT/VIBRATING WIRE PIEZO INSTALLATION/OFF SHORE WORK Specialist Geo- Environmental Drillers Geotechnical Drilling Methods
CPT DIRECT PUSH RIG DIFFICULT SITE ACCESS Specialist Geo- Environmental Drillers Joint
CONCLUSION Specialist Geo- Environmental Drillers BOTH GEOTECHNICAL AND ENVIRONMENTAL INVESTIGATIONS HAVE THERE OWN STAND ALONE REQUIREMENTS THAT DEMAND THE USE OF SPECIALIST EQUIPMENT. BUT THERE IS THE COMMON GROUND THAT CAN SAVE TIME AND EXPENSE BY COMBINING PARTS OF INVESTIGATIONS WITH THE EFFICIENT USE OF SOME DUAL PURPOSE DRILLING RIGS