Born of the necessity to clean up coastal waters and rivers, and to maintain drinking water quality, while containing operating costs, Massachusetts Water Resources Authority’s (MWRA) tunnel programme features subsea work, hard-rock and soft-ground tunnelling, microtunnelling, directional drilling and pipeline rehabilitation.
Michael McBride, MWRA deputy director of capital construction, outlined the many current projects instigated by the authority which is headquartered in Boston. Although the Metrowest water supply project, the tunnelling for which is nearing completion, is probably the best known project, MWRA is promoting many others in a major effort to catch up with earlier years of neglect and an expanding population.
The reasons for using underground construction have been many and varied. For example, said McBride, a second water supply pipeline on the Metrowest route had never been built due to the low availability of labour during the second world war. Subsequently Boston’s urban sprawl made the construction of a pipeline problematical and a tunnel was chosen instead. Despite the extra cost, a tunnel also provides a more efficient delivery system.
The other major tunnelling projects have been part of the campaign to clean up Boston harbour and associated coastal waters, the benefits of which are already being felt. These include the 8.9km (5.5mile) inter-island tunnel and 15.3km (9.5mile) outfall tunnel. The first is operational but, although tunnelling on the latter has been completed, it will not be operational until next summer.
A fatal diving accident last year resulted in work stoppage for investigations, and recovery of the diffuser is just commencing. Also associated with Boston Harbour environmental improvements is the Braintree & Weymouth tunnel which will collect sewage from communities to the south of the harbour, removing storm capacity problems at Braintree and will also connect a new sludge processing facility to eliminate barging to dumps.
The next major tunnelling work in the programme will be for the North Rochester combined sewer overflow (CSO) elimination, which involves soft-ground bores. Other planned tunnelling includes microtunnelling under Chelsea Creek for a sewer force main, and the East Boston Interceptor sewer to serve communities around Logan Airport.
MWRA was originally set up by the legislature of the Commonwealth of Massachusetts in 1985 mainly to reduce pollution of the Boston Harbour area and to provide an integrated, improved, water supply. As the primary objectives are achieved, McBride explained that the subsequent work would be chiefly to eliminate combined sewer overflows (cso’s) to reduce local coastal and river pollution. Previously water and sewerage services were mainly the responsibility of individual city and county authorities that were difficult to co-ordinate on an ad hoc basis.
MWRA’s current annual capital budget plan is $410M. McBride said that spending is set to continue at this level for the next three years after which the budget is expected to drop to around $100M a year for the next decade. Thus the programme to meet delayed needs is now approaching its end, but heightened government environmental standards, public expectations, or increased capacity requirements could increase spending in the future.
Such a capital spending and engineering programme would stretch the resources of most organisations, even one with a dedicated set-up to specific objectives, like MWRA. Consequently, MWRA supplements its own with those from leading engineering practices, organised into core project groups. Thus RCF Kaiser is integrated into the Boston Harbour team, Stone & Webster for the Metrowest project and ICF Kaiser on Walnut Hill water storage scheme.
Skilled and professional staff are in great demand in the Boston area, particularly for civil engineering work. Apart from MWRA’s projects there is the dominant Central Artery/Tunnel highway project, the Silverlink (Transitway) bus-route link and development of Logan international airport and the surrounding east Boston area, as well as all the smaller projects associated with a booming metropolitan area.
As the economic climate of the area warms up, there is a danger of cost overrun on major projects, but MWRA has been successful in keeping rate demand increases below 5% in recent years. An important element in preventing capital expenditure escalation is careful, realistic project planning, including structuring of contracts.
“In deciding how to structure contracts for each project,” said McBride, “we combine MWRA’s vast experience with observations on the practices of other agencies. We adopt contract clauses to solve problems. We’ve had billions of dollars of construction experience leading to the most appropriate contract terms and conditions.”
On project planning McBride echoes the themes of many speakers at the recent North American Tunnelling Conference, organised in Boston by the American Underground Construction Association (AUA).
“We do a lot of work to find the risks in a job, and try to plan for them. This includes risks to and from third parties, such as neighbourhoods, and other authorities, such as fire departments. We investigate solutions and deal with situations positively, in advance. For example,” he says “the Metrowest project is working with five different communities, all with their own different boards for the police, health, etc; six agencies in each town, making thirty overall.
“There is a lot of work before a contract bid to achieve agreements of construction practices and measurable effects on third parties. These are indicated in the contract documents themselves, and endorsements are required to be signed by the principal contractor on the project to abide by the terms of the third party agreements. In turn, contractors are involved early in subsequent community meetings.
“Such agreements have achieved some remarkable project efficiencies” he adds. “On the Metrowest project we have been able, with the agreement of the relevant community, to set up a batching plant adjacent to a residential area. This has reduced the number of truck trips with consequent environmental and efficiency benefits.”
Another initiative to reduce trucking was to retain as much spoil on site as backfill for later development areas even though it had a commercial value.
Another trend in American contracting is the need to reduce contractors’ up-front costs, giving the benefit to the client/owner of speedier mobilisation. Unlike some US clients, MWRA does not believe in purchasing large items such as TBMs themselves.
“We do not pre-purchase most items, apart from those used in the finished structure,” explains McBride, “but we do agree to pay for invoiced machines when they arrive and are set up on site. Contractors have a free choice of equipment to suit their own assessment of project needs, except that major items must be suitable for the expected conditions.”
The concept of “partnering” is often seen as a solution to contractual problems, and there is an emerging movement to import European practice to America. “The Authority has not adopted formal partnering”, says McBride, “but we do keep open lines of communications. In tricky relationships I can lay my concerns on the table, and so can the contractor.”
Neither does the MWRA adopt a strict shared “pain or gain” approach to contract progress. “We operate a standard low bid with unit prices approach to contracts.” explains McBride. “Payment does not include bonuses or other incentives, but we do go for liquidated damages if jobs run too long. This is to cover client management and engineering teams, etc.”
MWRA has recently taken up the trend to “design-and-build”with an $89M covered water storage scheme. “It’s a refreshing way to do business, with the team concept and the contractor involved in design, but it needed special state legislation.”
Questioned about whether the design-and-build concept allows late design changes to delay projects, McBride states that major design changes are only usually allowed up to design stages. “We have modified original contract packages,” he says. “For example, we split one Metrowest contract into tunnel and shaft, therefore limiting our exposure on tunnelling by breaking up the package. One activity is then not so dependent on the other.
Further possibilities for modification are provided by value engineering clauses included in all contracts. “If the contractor gives a better suggestion, we can agree to use it during construction and share the savings made.”
Summarising the principles of contractor involvement in project teams McBride comments: “Certainly it can be very successful for both if each recognises the goals and objectives of each other, and keeps that in mind in the set-up of a job, and the execution of it. Integrity is a very important thing. There must be a development of trust and the ability to shake hands on the deal.”
However, asked whether the adoption of more inclusive approaches to project management has eliminated unnecessary change-of-conditions claims by contractors to make money, McBride comments: “I’ve never known a contractor admit to a claim being unnecessary – as he drives away in his Mercedes!”
