Service Strikes and Utility Damage Project Part 2 A case study.

Transcription

1 Service Strikes and Utility Damage Project Part 2 A case study. September 2013 Status: Final Version: Rev 4 Author: Bob Cummins This report was produced by Alternative Safety Limited for and on behalf of CECA Scotland

2 Contents Executive Summary The purpose The study Site visit findings Practice and techniques Utility information Questions asked to gangs on site and their answers Summary of findings Recommendations Page 2 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

3 Executive Summary The purpose of this short study was to review the varying standards of utility drawings supplied to contractors by utility companies, their use and the impact they have when trying to successfully identify and navigate existing services during excavation. The main findings from the study were: 1. Although the utility drawings observed were largely inaccurate, the inaccuracy was not the major cause of service strikes on this project. 2. The greatest likelihood of service damage was when services had been previously laid out of spec by others and when sited within the bituminous road material or they were encased within concrete just below the lower road base. 3. Safe digging was the product of adequate and sufficient experience, resources and time. The study found that, on average, there were six to eight utility drawings that had to be interrogated every time an excavation was to be dug. Those six to eight utility drawings were all of varying quality, scale, type and appearance. The process of reviewing drawings on site prior to excavation is laborious and time consuming due to the amount and variety of information that needs to be assimilated. No drawings could be used to identify the location of services accurately. Drawings were used as an initial reference point but were always taken as indicative by the working gangs. During excavation operations, more than a third of services uncovered were not marked on drawings. Many services that were encountered were at non-standard depths i.e shallower than recommended. However, this did not appear to increase the likelihood of service damage due to the techniques employed by the working gangs. Of the services that were not at the specified depth, some were located within the top or lower base course of the road construction and some were encased in concrete. This dramatically increased the likelihood of service damage during excavation. The review suggests that, for this site and activities within the city centre, utility drawings had minimal bearing on the successful avoidance of services. In other words, the accuracy of the drawing was not found to be making the most difference to successful service avoidance. Successful avoidance of services was, on this site, a product of the following: the working gang s experience of working within city centres; the expectation that, with every shovel of earth taken, services would be present; Page 3 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

4 the allocation of enough time and resources to excavate appropriately and navigate existing services. When spoken to, the gangs firmly believed that it was of the upmost importance to their foreman that they took appropriate and sufficient time to locate and dig around the services when excavating. The gangs stated that they felt that they had enough resources and the appropriate tools to carry out their works properly. The unsafe situation of utilities within hard material was created by others, whom, at the time, worked for the utility company. The main recommendation from this report is that the utility companies should be held responsible for unsafe services that are laid by their contractors. See section 5.0 for full recommendations. 1.0 The purpose The purpose of this study was to gather further evidence of the varying standards of information supplied to contractors by utility companies. It is intended that this will help to facilitate the suggested actions set out in item 4.0 of the Report into Service Strikes and Utility Damages during Construction Activities, published in October It is hoped that this report will allow CECA Scotland to have more detailed discussions with Scottish utility companies, the Scottish Road Works Commisioner, RAUC(S) and the Scottish Government on behalf of its members, regarding the standard of information on drawings and the quality of work often encountered where services have been laid in an unsafe manner by contractors working on behalf of the utility companies. The findings of this study slightly amend previous recommendations within the CECA Report into Service Strikes and Utility Damages during Construction Activities, published in October CECA will also discuss the findings with the Joint Utility Damage Avoidance Forum on which CECA represents the contracting sector. 2.0 The study The study took place over six days, and included four site visits to the Glasgow City Centre water main replacement works that are being carried out by Farrans for Scottish Water. The project started in July 2012 and is valued at 2.5m. The project is within the estimated budget and, at the time of writing, is fourteen weeks ahead of programme. During the project, 3,460 services have been crossed safely. 2,539 of these were charted on utility drawings and 921 were uncharted. Only two services have been damaged during the excavation works. See figure 1 below for further details. Further health and safety performance information is displayed in figure 2. Page 4 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

5 Site visits took place at Bath Street, West George Street and West Nile Street to observe on-going excavation works. A number of visits also took place to the Farrans site office at the Old Pump House. Fig 1 Glasgow City Centre Man-hours Fatalities 0 Major Injuries 0 Dangerous Occurrences 0 Lost Time RIDDOR 0 Lost Time Non-RIDDOR 0 Minor Injuries 3 Improvement Notices 0 Prohibition Notices 0 Convictions 0 Fee For Interventions 2 Service Strikes 2 SSFR (per 10,000 man-hours) 0.26 Page 5 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2 Fig 2

6 3.0 Site visit findings 3.1 Practice and techniques During the visits to site there were, on average, three 5-man gangs whose job it was to excavate and locate the existing water main within the city centre of Glasgow. Once the existing water main was found, a new water main was inserted where possible, or a new main was laid. The following describes the typical process observed. A working gang consisting of a ganger, machine driver, banksman, pipe layer and labourer were in the process of excavating the road in order to access an existing Scottish Water main to allow the insertion of a new main. The gang had been issued with a pack of utility drawings from the contractor (Farrans) s head office. The pack consisted of drawings for Power, Gas, Waste Water, Clean Water, Telecommunications (BT), Cable TV (Virgin), Traffic Signalling (LA), Street Lighting (LA). At each location the ganger would make reference to the pack and attempt to decipher the information that had been provided to him. The area to be excavated was scanned using the CAT and Genny and a permit to dig was completed. The teams would also use other means to identity services e.g. tracks in the road and street furniture. History and experience had shown the gang that they would most likely encounter other services not shown on the drawing. This was indeed the case at this and other locations. History and experience had also taught the gang not to rely on standard depths that the services should be laid to. The gang expected to find services at varying levels as they excavated. Once the area for excavation had been marked up with expected services, a saw cut is made around the perimeter of the excavation. In most cases, a mini digger is then used to break the road surface with the use of a pecker. The surface course and upper base are then removed and the lower base is broken up, again by the pecker. This is then removed by the machine. During this process, a banksman is present and assisted the machine by loading some material into the bucket with a shovel, and also watching for services that may be located within the base layers. In most cases, no services have been uncovered at this initial stage, however, there were examples on this project where services were encapsulated within the lower base and sometimes the upper base layers. Once the lower base is removed, a combination of hand digging and machine digging will take place. It should be noted that, in almost every case, as soon as the pecker or the bucket of the machine breaks the initial surface of the road, it is most probably within 500mm of a service. The process is slow, and the gang tentatively scrape away at the sub-base, again with both machine and shovel. The excavation is periodically scanned as the depth increases. The machine operator and banksman expect to find services with almost every bucket of earth that is removed. There is no further reference made to drawings as the drawings Page 6 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

7 do not assist the gang with the process. When a service is located and uncovered, the banksman clears the surrounding area. Mechanical digging then resumes if possible. In the picture shown below, there is a gas main, power cables, drainage, telecommunications and the water pipe that the gang are looking for. It was not possible from the drawings to predict accurately the position of these services due to the lack of specific detail on the drawings. The poorest drawing for inaccuracy, vagueness and reading difficulty was the telecommunications drawing supplied by BT. The gang cited power and water drawings as being most accurate. 3.2 Utility information In general, the utility drawings were complex, difficult to read and of varying standards. In all cases the gang used the drawings as a prompt for what might be in the ground. There was no practical way of using the drawings to mark up the road accurately prior to excavation as the line on the drawing was, in most cases, purely indicative and could not be accurately referenced to any on-site landmarks. Drawing packs are put together by a dedicated resource in the contractor s main office. Information is gathered from a number of sources and using various methods. Information from Virgin is accessed through their online system. This is also the case for Scottish Power. SGN supply utility drawings on a CD every 3 months. Access to Scottish Water information is through offline access to GIS and is restricted to high level information. It should be noted that this information is not as detailed as that which Scottish Water s own employees or work teams can access. The pre-start information issued by the client contained no information that was of use to the site team regarding service locations. There were general statements regarding services but no detailed information regarding location or contacts. Drawings lack detail and clarity and mostly have no information about depths of services or warnings of shallow services, with the exception of some large power cables noted to be at shallow depth in one area. Drawings are all of different scales, differing accuracies and quality, and different appearances; a lot is left to the individual s interpretation of the information. The ganger and worker have to reference at least six to eight drawings for every location that has to be excavated. Page 7 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

8 3.3 Questions asked to gangs on site and their answers. Would a more accurate drawing make a difference to you? Perhaps, but we have learnt to expect to find anything when we dig in a city centre. Can you stick to the 500mm rule and not use mechanical means when digging? No, not in all cases in the city, as soon as we break ground/tar we are likely to be within 500mm of a service. Have you hit a service because it was not marked on the drawing properly? No, they are all not marked on the drawing properly and we have hit hardly any. What makes it more likely that you would hit a service? Well, the ones we have hit are when they have been really shallow and within the tar. Things like power cables to traffic lights, but also cable TV; sometimes they are really shallow and encased in concrete, you then have no chance. Water, power and gas are usually OK, but with gas it is the cap ended spurs that they have used for bypasses or old connections, they tend to stick up and are sometimes encased within the lower base of the road construction. Again, it s hard not to damage these. If the service is really shallow and within the road surface, what do you do for reinstatement? It s difficult, we contact the utility company and ask them if they can lower it before we reinstate it but they often say no or we hear nothing. What do you do then? We try to protect it as best we can using either split ducts, sand, plates etc so that the next contractor will have a better chance of missing it. Is there a way of recording services that are shallow or encased in concrete with the utility company so that they can then mark up the drawing? No, we can record internally but there is no mechanism for recording existing services that we uncover and feeding back to other utility companies. We do asbuilts for the service we are laying and give them back to Scottish Water. Page 8 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

9 On the occasions where you damaged a service, when the service was shallow, what happened when the utility company repaired them; did they attempt to lower them? No, in some instances, they actually made it worse; the repair made it even shallower. We came across a signal cable for a traffic signal which was 30-40mm deep, encased in the top course of tar. The contractor repaired it and the joint was even higher, they could have lowered it easily but didn t. We re not sure how we will reinstate it safely. On another occasion we uncovered a power cable. It wasn t damaged but we couldn t reinstate it safely, so we called out the Utility owner. They said that there was nothing they could do and that if we hadn t have uncovered it no one would be any the wiser, as if it was our fault for uncovering it. The main problem we face is when services are installed dangerously. We are very good at finding and digging around services that are below the tar, we never damage any of those. It s the services that are installed dangerously that are an issue for us. Would it help if these were marked on drawings? Well, I don t think those who installed them would admit to them being installed at such a depth and in such a way. And even then, it is more about the fact that they are surrounded by stuff we have to break out, or that the blade of the saw goes through it. If they were installed correctly we wouldn t hit them. Page 9 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

10 What makes you safe, what allows you to avoid the services? It s all about the skill and experience of the team and knowing that you have enough time to do the job properly. It takes time to dig the hole, to work around the services. You have to expect that every time you put the bucket in the ground you are digging next to a service. 4.0 Summary of findings Drawings provided by utility companies were difficult to read, of varying quality and of limited use to those engaged on this project. The study and data reviewed shows that although drawings provided by utility companies were not accurate, service damages on this project did not appear to be attributable to the inaccuracy of these drawings. Service damage was most likely when existing services were present within the bituminous makeup of the road or were surrounded by concrete. The unsafe situation of utilities within hard material was created by others, whom, at the time, worked for the utility company. On this project, there appears to be little interest from the utility companies when unsafe services are discovered. There is no easy mechanism to feed details back to utility companies regarding the position and depth of unsafe services as they are unearthed, so they can update utility drawings for the future. There is no form of checks or regulation by utility companies to ascertain whether construction companies are laying services correctly and not encasing them within the road surface. There is no recourse to penalise companies who have laid services in an unsafe manner when these services are discovered by others. The no mechanical dig within 500mm rule is not practicable on this site. Safe digging was achieved on this project by having gangs who had appropriate experience, were allocated sufficient resource and were allowed the appropriate time to complete the job safely. 5.0 Recommendations It is recommended that the utility companies are held responsible for services that are laid by their contractors. It is recommended that utility companies pay for repairs to services if the service is found to be laid outwith the specification for depth and is deemed unsafe. Page 10 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2

11 It is recommended that there is a process of recording and feeding back to utility companies the details of services that have been laid within the road surface and or concrete. It is recommended that such information showing very shallow and encased services is specifically recorded and displayed on utility drawings. Page 11 of 11 Rev 4 Bob Cummins CECA report, Service Damage, Part 2