Method Statement – Hydraulics
Quantifying and understanding the hydraulic performance of water and sewerage infrastructure
are fundamental to successful water utility projects. Hydraulic constraints can often shape an
entire project and can greatly influence investment requirements.
Significant savings can be made in the whole life cost of pumped systems by considering the
hydraulic characteristics of the entire system. Appropriate selection of pipe sizes, materials,
pump duties and control characteristics is crucial in providing the most cost effective and
environmentally sustainable solution.
Flow capacity of existing installations is a common limitation on the refurbishment or upgrade of
hydraulic systems. Hydraulic constraints due to poor design of pipelines and treatment plant
may cause serious operational problems such as failure to meet consents or maintain adequate
water supplies.
MWH’s experience on AMP3 shows that optimisation of existing assets to give improved
hydraulic performance is more economic than new build solutions.
MWH’s approach
The importance of hydraulics in all water and sewerage utility designs is understood by MWH.
The wastewater and water networks group currently comprises over two hundred fully qualified
engineers and technicians, based in twelve offices throughout the UK, who have extensive
experience in all aspects of hydraulic modelling.
Supported by an active global knowledge community, local teams can build on the best
hydraulic capability developed globally, to ensure that innovation and lessons learned can be
applied locally. This has allowed MWH to develop our staff to meet the challenges of an
expanding programme of work. A hydraulics knowledge base addresses design issues and
provides links to specialists working in other areas, including water and wastewater networks,
water and wastewater treatment, pipeline engineering, dams and hydropower.
We are recognised industry specialists in software development and data management and
have utilised these skills in developing systems for a number of clients. Our engineers have
access to both in-house and commercially available software such as HADES, ModAsset DM,
H2ONet and H2O Surge, complemented by other industry standard software for sewer
modelling, integrated catchment modelling, water network modelling and transient analysis.
Industry leading analysis capabilities includes the use of computational fluid dynamics, scale
modelling and project-specific MatLab control models.
1
Method Statement – Hydraulics
Benefits
Specialist solutions
Our nationwide virtual team of hydraulic experts ensures that project delivery incorporates
appropriate recognition of hydraulic issues, provides project start-up advice to clients and
engages in troubleshooting. Specialist services that we provide include river modelling,
groundwater modelling, transient modelling (surge), control modelling, physical modelling, CFD
modelling as well as general advice backed up by extensive industry experience.
Treatment plant hydraulics
MWH’s wastewater and water treatment groups are responsible for the hydraulic design of any
new build or refurbishment at treatment plants. Our hydraulic specialists work closely with
process engineering staff to provide our civil engineers with the necessary tools for the design
of treatment plant structures and ancillaries. The hydraulics knowledge base governs the
technical quality of treatment plant projects through involvement of nominated specialists and
periodic discipline reviews.
Experience
Selected examples of benefits realised in AMP3 through MWH’s hydraulics expertise are given
below.
Treatment plant optimisation:
Hydraulic investigations at one utility company’s 570Ml/d water treatment plant enabled
upgrading of the inlet plant to provide an additional 8% gravity throughput.
Treatment plant cost savings:
MWH’s detailed hydraulic modelling for a 400Ml/d wastewater treatment plant demonstrated
that construction of a storm return pumping station could be avoided through sophisticated
actuation of control penstocks. Construction savings estimated at £800,000, plus operating
costs, were generated.
Physical modelling:
2
Method Statement – Hydraulics
Physical models have been employed to solve process problems at wastewater treatment plants
and storm tanks. Recent studies include modelling of vortex separators, flumes and backwash
distribution facilities at a 350 Ml/d secondary wastewater treatment plant as part of a solution
to overcome persistent operational and process problems.
Computational fluid dynamics:
We employed computational fluid dynamics to solve stagnant water and short circuiting
problems for a 62Ml water service reservoir chlorine booster retrofit.
Surge analysis:
We carried out detailed surge analysis to ensure safe operating conditions at a 12m 3/second
storm outfall pumping station, overcoming unacceptable structural loading at this prominent,
beachfront site.
Standardised CSO design:
MWH has developed solutions for approximately nine hundred UIDs using our CSO design tools.
Summary
Hydraulic engineering can be the key to success for water and wastewater projects. Through
our hydraulics knowledge community and with access to global specialists and tools, MWH
ensures the successful performance of new build and retrofit asset solutions.
“A very good job … the team has met the challenge of producing a very flexible design.”
(Client quote from United Utilities’ Sandon Dock wastewater treatment plant).
3