Posted By Stuart Nagle Dot. Entry should be avoided if reasonably practicable other methods of doing this work are available (CS Regs 97). I propose that they are available, and include; 1) Employing lifting tackle to a fixed chain attached to the pump(s) to raise and lower in/out of the chamber. 2) Employment of a sludgetanker to empty and 'jet' down the wet well/pump sump, thus avoiding entry. However, the methane problem could pevent these 'other' methods if not tackled, and if not dealt with could lead to an explosion, so be very carefull.... The costs involved in the above tasks, employing these types of equipment, would, I am sure be regarded as 'reasonably practicable' given the circumstances (i.e. high levels of methane in the space) and should ensure that your safe system of work complies with the regulations. Is this a temporary site or a permenet fixture? As under the CDM Regs (in conjunction with the CS Regs 97) there is duty, where practicable, to improve/modify confined spaces to prevent entry or improve entry if it is unavoidable. This duty will fall on the owner/operator of the facility (I take it you are a contractor) and shouldbe brought to their attention !! The UEL and LEL (Upper and Lower Explosive limits for methane are between 5% and 14%. You need to be aware of the fact that introducing forced air ventilation could, in essence, take a mixture that is 'too rich' to ignite/explode into this danger area (5% to 14%) and actually create a flammable/explosive risk !! The only method that may work, if entry/work is unavoidable or the means may give rise to risk of explosion, is the inert gassing of the space (with a denser/heavier gas to force the methane out - usually carbon dioxide, and then forced air ventilation with air from a clean source to permit entry, but BA should still be employed - perhaps escape sets but check duration of escape routes as only 10 to 15 minute supply at 40 litres per minute and less if heart/lung rate is higher) This needs to done by professional persons who know what they are doing and should not be attempted by inexperienced/untrained personnel. I suggest that you seek competent help/assistance in this and bring that competent assistance to the site to survey the problems first. Please be carefull... confined spaces kill !! Hope this helps. Stuart Nagle

Posted By Dot Tadman Thanks to Stuart and John for your help. The site is permanant and the pump (which is a sump pump)has fallen off its skid unit and so has not been able to control level of sewage in chamber. There is no valve chamber further up line and the only means of blocking ingress of liquid is by blanking off within chamber. Although our engineers are fully trained in confined space work and in the use of breathing apparatus, I was not keen in them doing this job with such high risks; and so on the information gathered from yourselves and another H&S professional I have recommended that the job is passed onto a more specialised contractor. Thanks once again. Dot

Posted By Ian Waldram I don't disagree with anything said before, but here are some other things to think about: 1) Are you quite sure the atmosphere is that high in methane? Most simple gas testers are calibrated on % Lower Explosive Limit, not % of the actual gas in air. If the % Methane figure IS correct, I agree that it's the area just outside the entry point which is very hazardous - where the methane is mixing with air and will be in the flammable range. However if your readings are actually % LEL, it's a VERY different situation, and the hazard is much lower; 2) Did you feed the air from the mover in via trunking to the bottom of the pit? Of course, if the readings ARE Methane, as described above, it would be VERY dangerous to introduce air and thus create an explosice atmosphere inside the pit as well as at the entry point. However if the readings are %LEL, that's the best way to 'sweep' the pit clear of the relative small amount of flammable gas - it's also easier to sample the exit flow and watch the % reading fall to zero (pure air); 3) Who designed this for you? Why wasn't this hazard of maintenance entry picked up during the Hazop? If it was, what did the Hazop team conclude? - their report should include this. Have you ensured this lesson is passed back to them, so they think harder about ventilation for safe entry in future? If there wasn't a Hazop at the design stage, it sounds like your Project procedures need an upgrade. Hope these additional thoughts help you, and possibly others.