Groundwater control is a specialist process, which when measured in cost or manpower terms, is often only a tiny part of the overall construction project - a study by Roberts and Deed (1994) showed that the direct cost of construction dewatering systems was typically less than 1 per cent of total costs on a large civil engineering project. Despite this, ground- water (and its inadequate or inappropriate control) has historically been the cause of many construction disputes. Suitable contractual arrangements are an important part of managing dewatering works for positive results. This section discusses the background to contractual issues and outlines some arrangements used in practice.

The Need for Contracts

As has been described throughout this book, groundwater control is highly dependent on the ground conditions, over which the designer has no control. It follows that groundwater control must run a greater risk of poor performance than, say, reinforced concrete construction (where the designer can specify and control the materials used). The dewatering designer must gain his design information from the results of the site investigation (see Chapter 11). Sadly, it is still the case that not all investigations attain the standards that designers would aspire to - see Inadequate Site Investigation (Institution of Civil Engineers, 1991) and Without Investigation Ground is a Hazard (Site Investigation Steering Group, 1993).

Because groundwater control works are often carried out at the very start of a construction project (e.g. for construction of foundations), any problems or delays at that stage can have serious knock-on effects for the rest of the project. A review of cost overruns on groundwater lowering projects is given in Roberts and Deed (1994).

The specialized and perceived ‘risky’ nature of groundwater lowering works has led many clients and main contractors to view dewatering as a ‘black art’ best left to the cognoscenti. Apart from on the very largest projects, many contractors prefer to sub-contract dewatering works to specialist organizations that provide the expertise, experience and equipment to carry out such work. It is important that an appropriate contract exists between the various parties, and that the rights and responsibilities of each are clearly identified.

Traditional Contract Arrangements

In the United Kingdom, the traditional form of construction contract involved the client appointing a client’s representative (called the Engineer under some forms of contract) to administer and supervise the works. Traditionally, the client’s representative would also design the permanent works but not the temporary works, which were the remit of the contractor. The client’s representative would, via a bidding or negotiation process of some sort, arrange for a contractor to undertake the works. The contractor would be employed directly by the client under a form of contract such as one of the editions of the Institution of Civil Engineers conditions of contract (known as the ICE conditions).

Groundwater control works are almost always classed as temporary works and are the main contractor’s responsibility. These works are commonly sub-contracted, and the contractor would employ a dewatering sub-contractor. The sub-contract between the dewatering company and the main contractor would typically be ‘back to back’, meaning that the rights and responsibilities of each party apply to the other. In essence, this means that the dewatering sub-contractor is effectively acting on behalf of the contractor and takes over their responsibilities relevant to the dewatering. It also means that in the event of any changes or problems, the dewatering sub-contractor has the same rights as the contractor to apply for additional time or money via the clauses in the contract.

One of the most common types of serious disputes in traditional dewatering contracts occurs when the groundwater lowering system does not achieve the target lowering of groundwater levels, and it is believed that the ground conditions may not be as represented in the site investigation data provided at tender stage. The ICE conditions contain clause 12 (commonly known as the ‘unforeseen ground conditions’ clause), which allows the subcontractor and contractor to apply to the client’s representative for additional time or payment. The ‘claims’ process is often protracted, whereby the contractors have to demonstrate that the physical conditions or artificial obstructions encountered could not reasonably have been foreseen by an experienced contractor. This process can sometimes distract from the real problem of trying to finish the project and to deal with the conditions actually present in the ground. Some claims cannot be quickly resolved, may go to court and are only finally resolved (one way or the other) several years after the end of construction.

Alternative Forms of Contract

From the 1990s onwards, in the United Kingdom, there were moves away from traditional contracts, which were viewed as being too adversarial and leading to many costly and time- consuming ‘claims’. When construction problems occur, prompt and open sharing of information can be vital in developing solutions; this did not always happen under traditional contracts. Sometimes, in the past, these contracts were applied in such a way that rather more effort was spent on trying to apportion blame than on solving the problem.

At that time, reports by Latham (1994) and Egan (DETR, 1998) reviewed the then performance of the UK construction industry and recommended specific improvements to planning and execution. They promoted increased efficiency and integration between the different parties involved in projects. With hindsight, the concept of having more integrated planning on projects has often improved the way that groundwater control has been carried out.

Under the old, often adversarial, contractual system, the need to control groundwater was often left as a last-minute temporary works fix for the contractor (after many other aspects of the project had been finalized) - described as a ‘distress purchase’ by Preene (2016) - and was procured on a lowest-cost basis. If the integrated approach of Latham and Egan is followed, it is more likely that key constraints, such as the need to control groundwater, will be identified as risks early during construction planning. This can allow rational assessment, and open discussion between the various parties to construction, of the potential risks and the way they could be managed. This opens up a wide range of options to control ground- water, including, for example, redesign of the permanent works to reduce (or avoid completely) the need for groundwater control. The High Speed 1 rail line (HS1, formerly known as the Channel Tunnel Rail Link), constructed in the United Kingdom from the mid-1990s onwards is a good example of how geotechnical engineering requirements, including the need to control groundwater, were among the key factors considered throughout the design process when assessing options for structures below ground level (O’Riordan, 2003).

In recent years, the nature of contracts has also changed as a result of the increased use of so-called ‘design and build’ contracts. These involve the contractor designing the permanent works as well as the temporary works, changing the nature of the relationships between client, client’s representative and contractor.

Various non-adversarial forms of contract have been developed. A number of different schemes are possible, including:

  • a) ‘Partnering’ - which implies the development of longer-term relationships between the various parties, including client, permanent works designer, contractor and specialist sub-contractors.
  • b) ‘Open book’ contracts - where information is shared, and all parties are kept informed of what is going on and are able to have input into relevant decisions.

These forms of contract can allow the ‘risks’ of unforeseen ground conditions (or other factors) to be shared between the various parties in an open and transparent way. Dispute resolution procedures exist within such contracts to allow problems to be quickly highlighted and examined without the need for claims or other confrontational procedures.

When these forms of contract are used, the aim should be to control risks to the project. Any sub-contractors should be selected on the basis not merely of cost but also in terms of quality, health and safety, environmental management and ability to meet the programme timescale. It is also important that by involving all the parties, expertise and experience can be pooled to solve problems as quickly as possible. The need to overcome problems in a timely manner cannot be over-emphasized - on modern construction projects, many cost overruns result mainly from time delays rather than changes in methods. The control of geotechnical risks in construction is discussed by Clayton (2001).

Dewatering Costs

Because of the varied nature of groundwater lowering works and the wide variety of ground and groundwater conditions, the development of generic costs is not easy. It is not possible to estimate dewatering costs, even on an approximate basis, from the quantity of water pumped, the volume of soil dewatered or the depth of drawdown. Dewatering costs are more commonly broken down on an ‘activity schedule’ basis. Some of the activities will be costed on a unit basis (e.g. per well, per metre of header pipe), while the costs during the pumping period - pump hire, fuel, supervision, etc. - will be time-related charges (e.g. per day or per week).


As described in Section 21.2, in relation to construction works, groundwater is viewed primarily as a problem; hence the need for groundwater control. In other contexts, groundwater is a resource, used for public and private drinking water and for industrial use. Furthermore, in many locations, natural groundwater flows play an important role in supporting rivers, lakes, wetlands and other ecosystems. In many countries, environmental regulations or laws exist to help safeguard groundwater resources (Charalambous, 2011). This section describes the environmental regulatory regime applicable in England and the implications for the planning of groundwater control works.

Similar regulations apply elsewhere in the United Kingdom and in other locations internationally. In addition to national regulations, there may be additional legal requirements at state/prov- ince level and at city/municipal level. An example of local regulation is given in Section 25.4.6.

Because the pumping and discharge or disposal of groundwater are regulated by law, the person or organization responsible for the groundwater control has certain legal obligations to ensure that consents and permissions are obtained from the regulators. Under the normal forms of contract, the party responsible is either the contractor or the client. The dewatering sub-contractor or pump hirer is not normally responsible for the consents, but they should satisfy themselves, before work commences, that the necessary consents and permissions have been obtained.

There are two main facets to the legal requirements. The first deals with pumping of groundwater (termed abstraction) and is intended to make sure that the regulators can control groundwater abstraction to ensure that groundwater lowering systems do not cause nearby groundwater users to lose their supplies. The second deals with disposal of ground- water (termed discharge) and is intended to ensure that the pumped water does not itself cause pollution or other impacts.

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