Posted By Ken Urquhart PS. You should consider the British Standard Code of Practice for Earthworks or its current equivilant. I do not have the up to date details to hand but you can access the BSI Web site. Question? Why are you pre-drilling through what you describe as a temporary stockpile? I know land space in HK is difficult. However, has anyone thought of the added drill time, drill lengths,labour, fuel and plant costs asociated with drilling through an additional 5m of surcharge which as I interpret your description will not form any part of the works that will ultimatly be built on that area or on top of your boreholes? Also have you considered the Environmental Impact in relation to HK Environment Ordinances, particularly as regards Plant Noise and Neighbourhood Noise and the monthly Noise/Plant emissions predictions? As you are in Hong Kong this is also an issue for the projects Authorised Person and the Registerd Structural Engineer. There should be a Safety Supervision Plan for this work and the appropriate number of TCP's, with of course the appropriate qualifications, training and competences. These members of the Construction team all have project safety responsibilities and they must contribute to what you are trying to do. In general terms, your stockpile should be compacted. This should have been done in layers to ensure its general stability. The slope edges should be batterd or cut to a Safe angle of repose.The slopes should also be protected from rain and water scour and run-off/washout. Check with the RSE. Take account of the weather conditions. We are not yet quite out of the Rain/Typhoon season so heavy rainfall and water scour/washout could also pose problems. As regards any fence that you erect around the edge: Dont just stick up any old barrier the general Hong Kong way as it will be right on the edge and will probably collapse if any significat weight or fall or knock impact pressures against it. The fence or barriers should be fixed and securely anchored at least 1 metre back from the edge of the stockpile. They should be capable of taking an impact and staying fixed and in place in such circumstances. Also be mindful of any site vehicles , plant or machines that might be driven on, up around or over the stockpile. Make sure that there are anchored stop blocks at least 1 metre away from all edges big enough to stop the wheels of the vehicles and make sure that the drivers do not take them over the edge. Keep crawler plant, excavators, cranes etc well back from any slope edge. The crawler tracks spread the machines load into the ground. Position the machine too near the edge and you could find the machine or crane toppling down the collpsing edge of the stockpile with all the attendant injuries and loss, damage and waste etc. You might have to construct and place spreader mats for your rigs or machines to stand on to help spread the load. Presumably you have Contractors and or tiers of sub and sub sub contractors involved in this operation. Have you had there Risk Assessment. Have they produced a Safety Plan and a Method Statement? Have you and your Technical and Construction Managers reviewed and agreed these documents and procedures with the tiers of parties involved. Have they (The parties involved, actually doing the work) identified, recognisd and addressed risks? In regard to your pre-drilling water. The drilling contractors are notorious for not managing the recirculating water. You, must get them to do this. Collect it in temporary holding tanks as it comes back up out of the drill hole and don't let them just let it run off all over your work area or stockpile. This will simply cause scour and wash out and weaknesses which will led to slope/stockpile collapse. Then you will have drill rigs and people falling/buried in slurry slopes. Lack of water management will also create puddles and ponds of unknown depth and they may become boggy, trapping workers and supervision on foot, like quicksand. Such conditions will also bog down vehicles or plant with all the attendant hazards of recovery and there potential for injury and damage. Poor or no water management also makes the conditions unsafe for the operative personnel who have to work the rigs and for other pedestrian personnel who may have works to do on, at or around the stockpile. Just observe somedays the piling and predrilling workers that you see in HK, paddling and dragging their rubber booted feet about in 300mm of slurry trying to do their work comfortably. This muddy, slurry mess is a regular cause of handling, slip, trip and ground level fall type accidents and it also is extremely tiring for the operatives involved. It also creates a place where tools, particularly hand tools and components once dropped in the slurry become lost. Thatis a waste and a cost to the project. If dropped hand tools are recovered and then used they invariably contibute to minor handling and use hand injuries because thy are contaminated with mud/slurry. The operative loses grip and or control of the task and suffers as a consequence. Be mindful also of the EPD / Environmental reuirements. What are your drilling contractors doing to ensure that there is no muddy or slurry water washing out into drains and nullahs causing silting and Mud that will attract EPD prosecution etc. If they are discharging surplus water, is it cleaned, desilted and do they have an EPD discharge permit? I hope some of this helps. I am also based currently in Hong Kong, so, contact me on kenurquhart@pccw.com if you want to discuss any more. Regards. Ken Urquhart