Movable flood-protection weirs are being installed in the UK for the first time in Leeds, after more than 2,000 homes were flooded in 2015.
In response to many drainage systems being overloaded, the impact of climate change and the increased risk of floods, Atkins has created a toolkit that helps identify the locations where sustainable drainage systems (SuDS) can be implemented.
Whether buildings are comprised of commercial, residential or office space, they can be assessed, rated and certified according to their green and sustainable features.
Adding capacity to the over-tasked wastewater system in Mexico City, an alignment through changing ground conditions is a likely candidate for Robbins’ Crossover TBM, Nicole Robinson reports.In the mountains northwest of Mexico City, the soft rock is self-supporting and very consolidated, a dream to mine. "Even the face is self-supporting," says Roberto Gonzalez, Robbins' general manager in Mexico. "You could use a normal backhoe and excavate like that. It's a beautiful ground to bore."But the alignment crosses valleys of tuff, faults and finishes with a stretch of soft ground with low cover. This is the scenario for Túnel Emisor Poniente II (TEP II), or the English translation of West Drainage Tunnel II.Conagua, Mexico's national water commission, is building the 5.9km-long tunnel with a 7m i.d. to reduce flooding in the area, and increase wastewater capacity. Across three municipalities, some 2.1 million people will benefit from the tunnel project.The contractor joint venture of Aldesa, Proacon and Recsa chose an 8.7m diameter, dual-mode type machine capable of "crossing over" between rock and EPB. With the August 2015 tunnel boring machine (TBM) launch on TEP II, manufacturer Robbins has supplied its first Crossover machine in Mexico.End gameRobbins draws comparisons to the Kargi Kizilirmak hydroelectric project in Central Turkey. The design of the TEP II machine was based largely on experience from past projects, and that TBM in particular. While initial reports on the Turkey project showed fractured hard rock, Robbins explains, within 80m of launch the geology became substantially more difficult than expected, consisting of blocky rock, sand, clays and water-bearing zones. The machine required multiple bypass tunnels and major modifications before it could resume excavation.Robbins says these modifications proved instrumental to the design of its Crossover TBMs, including the TEP II machine.In Mexico, the contractor JV expects to convert the machine from hard rock to EPB mode due to changing ground conditions in the last kilometre of the alignment. "Initially the proposal was a hard rock machine but they found they have 800m of water-more EPM conditions-that's the reason we proposed a Crossover," explains Javier Alcala, job site engineer for Robbins on TEP II.The ground conditions at TEP II are complex, from competent to weathered volcanic rock to clay, and sand. The final 800m is also the portion of the alignment with the lowest cover, some 12m, and the most populated. This is one of the reasons for using a Crossover machine. The rest of the drive has between 50-60m of cover on average with some stretches up to 150m."We try not to convert unless it's completely necessary because you stop, you have to drain the screw conveyor inside the machine, and you have to make a lot of changes, for example on the cutterhead," Robbins' Gonzalez explains.As an open mode machine boring in rock, the TBM is equipped in the event of entering running ground, he says. "These closure doors are able to maintain the material in the cutting chamber. They're just a safety." In smaller valleys of tuff there is potentially some water, but it's unknown for now, he explains."For these cases we believe that these closure doors will be held to see what we have to do with the material, if we have to consolidate in the front."Tight fitAldesa's Castillo says one of the biggest accomplishments on the project so far has been organising the logistics in such a small work space-fewer than 10,000 sq m. The JV excavated a 30m deep launch shaft supported by 800mm-thick Milan walls (slurry walls), and used on-site first time assembly, he says, to start excavation as soon as possible.Once assembled by gantry crane, the machine bored 100m before adding back gantries. When completely assembled the machine has nine gantries for a total length of 1,030m.At the time Tunnels & Tunnelling visited the project, the crews were still adjusting to having the full machine in operation, and had only recently started using the continuous conveyors for muck.The TBM was mining through a transition zone between tuffs and dacites, and had excavated 435m by mid November 2015. At the time of publication the TBM has bored 1,417.5m, which equates to 945 rings. The best day has seen an advancement of 42.8m and the best week is 185.1m. Robbins' Mexico office reports the TBM has reached softer geology and is boring very well.Tunnelling is expected to finish within this year and a second lining of reinforced concrete will be installed following excavation to extend the life of the tunnel. "Once we arrive to the final bit, it's a very close curve of 400m radius," Alcala explains.The tunnel alignment ends along the rivers of San Javier and Xochimanga in Atizapan de Zaragoza.
With a burgeoning market for hydropower development, tunnelling work is seeing an uptick in South America’s third largest country. Nicole Robinson looks at two recent projects.The World Bank released a report in 2010 to help the Peruvian government in assessing the potential role of hydropower in the energy sector and the measures that could be taken to encourage its continued development as appropriate. Hydropower has been the major source of electricity in Peru, traditionally supplying more than 80% of requirements, and serving as a source of independent generation for major mines and industries.However, as the report explains, in the early 1990s efforts turned to natural gas and the government began providing incentives for its use in power generation: "This resulted in a virtual moratorium on hydropower development as a result of the very low price of natural gas (below economic cost)."Over the next decade, with the development of export markets for gas and increased attention to the impacts of climate change, the Government returned its attention to hydropower. The Peruvian government completed its National Energy Plan 2014-2025, which calls for electricity to comprise 60% renewable sources by 2025, with 54% coming from hydropower.The International Hydropower Association called Peru a regional leader in small hydropower projects. In its 2015 Hydropower Status report it estimates Peru has hydropower potential of at least 70GW, "of which only 3.8GW have been tapped so far."In 2014 Peru added 199MW, ranking it among the top 20 countries installing capacity at number 17 —Canada comes in at number three and the US at number 16.The market potential for hydro construction in Peru has captivated the likes of Odebrecht, whose subsidiary Empresa de Generación Huallaga (EGH) is developing the 462MW Chaglla power plant, which will be country's third biggest hydropower project upon opening, scheduled for this year.Norwegian company Statkraft opened its ninth hydropower plant in Peru, the Cheves Hydropower Project, this autumn. "The opening of Cheves consolidates Statkraft's position among the largest power producers in Peru," says Statkraft's executive vice president of International Hydropower, Asbjørn Grundt. "It also underlines our ambition to further strengthen our position as a leading international provider of pure energy. Our efforts in South-America play a very important role in this strategy,"Chaglla’s bypassLocated between the districts of Chaglla and Chinchao, some 420m from Lima, the Chaglla Hydroelectric Power Plant has 406MW of installed capacity. The plant is the result of an investment made by Odebrecht Energia of $1.bn, with support from the Brazilian Development Bank, and the Inter-American Development Bank, among others.The project will also feature a small power house, including a power transformer with an output of 6MW. "Chaglla will be one of the largest hydroelectrical power plants in Peru and it will represent almost 8% of the current consumption of energy of this country," says Erlon Arfelli, manager of Odebrecht Energia in Peru.Construction started in May 2011, with Sandvik supplying six DT820-SC tunnelling jumbos for the excavation at Chaglla. Underground construction includes a spillway composed of three tunnels for a total length of 2,838m, 14.5m x 12.6m-high. The 14.7.km-long intake tunnel is horseshoe-shaped with a 7.6m diameter.One of the most important works in the project is bypassing the Huallaga River, which contractors performed through a trunk tunnel of 12.5m diameter, 1,125m long. Odebrecht says the work concluded nine months prior to the scheduled date. The bypass tunnel, a significant step for the project, allowing the dam to be constructed in the former riverbed.Odebrecht says EGH began filling the reservoir on September 1, 2015, and expects the process to last between 45 and 60 days. The project's lenders appointed Mott MacDonald in 2013 as independent engineer to monitor construction.
A selection of current construction work and studies shows hydropower’s wide range, says Patrick Reynolds. Numerous hydropower and pumped storage projects are in construction or planning across the globe, and International Water Power & Dam Construction (IWP&DC) briefly notes progress and developments on a selection in Asia, Europe, North America and South America, and also the Middle East.A major hydropower scheme that is well advanced is the Ulu Jelai project, in Malaysia. Being constructed by Salini Impregilo, the project involves significant surface and underground works.Both surface and underground works feature in the Foz Tua pumped storage project, in Portugal, and which is also at an advanced stage. The project involves construction of a 108m-high double-curvature arch dam.Developing hydropower where a new dam is not needed, efforts are pushing ahead in the US to exploit existing lock and dams structures, such as the run-of-river projects being undertaken by power company American Municipal Power (AMP) on the Ohio River. The plants under construction include 72MW Smithland.Statkraft may give the go-ahead this year for two run-of-river projects in Chile, following an acquisition in 2015. However, following a recent review of its investment programme it has yet to decide what action it will take.Many further projects are coming, and a few among those include recent awards for consultants MWH Global and ÅF, respectively, in South America, Europe and the Middle East.Malaysia: Ulu JelaiConstruction of the 383MW Ulu Jelai hydropower project, in Malaysia, has been underway since 2011 and is well advanced, including the recent milestone completion of the Susu roller compacted concrete (RCC) dam.Ulu Jelai is being developed by Tenaga Nasional Berhad (TNB) in Pahang state, approximately 200km north of the capital Kuala Lumpur. It is one of five hydro projects being built at present to help stabilise the power grid.The project is located on Bertam River, and involves major dam and tunnel works. The rated net head of the scheme is approximately 360m.Key features of the project include the Susu reservoir on Bertam River, and to which water is conveyed by transfer tunnels from the Lemoi and Telom rivers, running on opposite sides of the main river. Lemoi and Telom are tributaries of Bertam and naturally join the main river downstream of the project location but are being tapped with offtake weirs at higher elevations. The tunnels have lengths of 7.5km and 8.5km, respectively.Water flows from Susu reservoir down a 9.5m-diameter unlined headrace tunnel to the underground powerhouse complex, holding a pair of 191MW Francis turbines. Ulu Jelai is expected to generate approximately 326GWh of electricity annually.Salini Impregilo is main contractor on the scheme, which is nearing completion.The Susu RCC dam is more than 80m-high with a crest length of 512.5m. Its volume is approximately 750,000m3, the contractor said.The volume of other concrete works on the project is approximately 190,000m3. Surface excavations and earth moving has involved more than 3M m3 of material.Underground construction has been performed by both TBM boring and drill and blast excavation. In total, the project has called for excavation of 26km of tunnels and also the powerhouse cavern complex. The TBMs were used to bore 15km of tunnels, and 11km of excavation of undertaken by drill and blast.Salini Impregilo notes that the total underground rock excavation is approximately 800,000m3.
A deteriorating section of the fluming carrying water to Tarraleah power station has been repaired on time and in budget, improving the safety and condition of this important infrastructure. Generating energy from water over the long term requires significant on-going investment in the safety and performance of more than dams and turbines. Water conveyance infrastructure also needs regular attention to keep the water flowing across the many, often rugged, kilometres from storages to power stations."Across a century of hydropower development, Hydro Tasmania has constructed 55 major dams, 30 power stations, and hundreds of kilometres of waterways," said Hydro Tasmania's civil portfolio manager Neil Smith."Many of these assets were world firsts when they were built and continue to provide outstanding service to this day. But, like any valuable infrastructure, our hydroelectricity and water assets require on-going maintenance to perform well into the future."A timely and successful repair of a rapidly deteriorating section of the flume carrying water to Hydro Tasmania's Tarraleah Power Station has greatly improved the safety and condition of this important piece of water conveyance infrastructure, and ensured its reliable service in Tasmania's power system for at least another 50 years.And if that isn't cause enough for celebration, this repair has also been achieved within schedule and budget, using safe and innovative design and construction methods, and carefully considering the flume's heritage values.
Hydro projects of all stages continue to make Asia a growth sector, says Patrick Reynolds. Among the many hydropower projects in development in Asia, expansions are underway at the Baglihar scheme in India, the Tarbela dam in Pakistan, and Lamtakong Jolabha Vadhana pumped storage plant in Thailand.Also in Pakistan milestone progress has been achieved recently at Neelum Jhelum, and studies are advancing plans for Thakot and other projects in the Indus basin.A range of further supporting studies for hydro projects are underway in Nepal and Bhutan, respectively, and also Vietnam — including Lai Chai where works are advanced. A refurbishment project is in preparation for a key hydro scheme in Tajikistan.Nepal also has a focus on irrigation needs, including a wider examination of flood hazard risk.Himalayas/Central AsiaIndia: Baglihar-II The 450MW Baglihar-II project in Jammu & Kashmir, India, was inaugurated recently by Prime Minister Narendra Modi. Developed on the Chenab River, the project is the second stage of the Baglihar scheme and doubles the installed capacity at the site to 900MW. The Stage I plant was built over 2000-2008. Their joint output is expected to be approximately 4180GWh of electricity annually.Project developer is the Jammu & Kashmir State Power Development Corporation. Lahmeyer International — part of Tractebel Engineering, a division of ENGIE previously GDF Suez — is the Engineer-in-Charge of the Baglihar site, and since 1999 has had engineering responsibilities on both stages of the development.Contractor on both stages is Jaiprakash Associates. E&M supplier on Stage II are Voith Hydro and Andritz Hydro, and for Stage I were Voith Siemens and VATECH, respectively.Both stages are served by a 144.5m-high concrete gravity dam with an integrated overflow spillway. Each stage also features significant underground infrastructure. The intakes to both are located in the bank, immediately upstream of the dam.The stages have parallel diversion tunnels at the dam. The headrace tunnels also run together for most of their distance, and each has a 77m high surge shaft.The underground powerhouses of the two stages, each with 3 x 150MW Francis units, are close together — Stage II complex is located immediately upstream of the Stage I caverns. The cavern complexes are approximately 180m apart.Each powerhouse cavern is 50m high x 24m wide x 121m long; and, the transformer caverns are 24m high x 15m wide x 112m long. The caverns were excavated over 2011-2013.Downstream of each powerhouse complex are further underground works, located before the tailrace tunnels: the underground structures are ‘Collection Galleries’. For Stage I, the collection gallery is a single cavern; for Stage II, the system includes a lower gallery 20.6m high x 14m wide x 95m long, three 14m-wide riser shafts and a gate operating top gallery 9m high x 16m wide x 57m long.The tailrace tunnels are different, too — Stage I is short (130m), high (29m) and flow is free-flowing; Stage II is a 350m-long, 10m-diameter pressurised tunnel.Other projects on the Chenab that Lahmeyer has worked on include Sawalkote, Ratle and Pakal Dul.Separately, in Himachal Pradesh, Lahmeyer recently provided consultancy services for the Thana Plaun project being developed on the Beas River by Himachal Pradesh Power Corporation. The 187MW scheme involves dam works and an underground powerhouse, and is expected to generate about 530GWh annually.Pakistan: Thakot Investigations are underway to prepare a feasibility study for the Thakot hydro scheme being developed on the Indus River by Pakistan's Water & Power Development Authority (WAPDA).Thakot is being developed as a project of at least 2GW, and is located immediately upstream of the existing Tarbela reservoir. It is part of a cascade of large hydro schemes planned to be built on the river, and upstream projects include 2.4GW Patan and 4.5GW Daimer-Basha.Lahmeyer is working with local partners on studies for the three WAPDA projects — Thakot, Patan and Daimer-Basha, respectively.The next project upstream from Thakot in the Indus cascade is Patan, and others being planned include Dasu and Daimler-Basha, which is 315km upstream of Tarbela dam.For the Thakot project, WAPDA is seeking to exploit a head of approximately 180m between Patan and Tarbela. Planning studies for Thakot are investigating options for either a single project or a few created as a small, intermediate cascade, says Lahmeyer. Thakot dam site is at a narrow section of the river, just downstream of Besham.At Tarbela itself, WAPDA is currently constructing the 4th Extension Project at the site to add 1410MW by June 2017 — an earlier deadline to an accelerated programme, announced in January. The extension will increase the installed capacity at Tarbela to 4888MW.Civils works on the 4th Extension Project are being executed by SinoHydro, and the E&M package is being supplied by Voith Hydro. Consultants working on the project are Mott MacDonald and Coyne et Bellier with subconsultants MM Pakistan and ACE Pakistan. The consulting team has also undertaken studies for the 5th Extension project.Tarbela was completed in the 1970s, and generating units have been added in phases up to the early 1990s.An earlier project for Lahmeyer was a feasibility study review for the high-head, 34MW Harpo scheme, on a tributary on the Indus. Separately from Indus developments, WAPDA noted the milestone progress achieved in underground works in February, with a key tunnel breakthrough on the 969MW Neelum Jhelum scheme. The project is to be commissioned over the second half of 2017. Contractor is Chinese consortium CGGC-CMEC. Consultants are Neelum Jhelum Consultants, which is a joint venture of MWH, Norplan, Nespak, ACE and NDC.Tajikistan: Qairokkum rehab ILF is providing consultancy services to national utility Barqi Tojik for the rehabilitation, uprating and safety improvements at Qairokkum hydro plant, in Tajikistan.The 66-year old plant on the Syr-Darya River is to have its capacity increased from 126MW to 174MW, and various E&M and civil engineering packages of works undertaken for the rehabilitation.The project is also to deliver dam safety improvements, the quality of electricity supply, and climate change resilience.ILF will provide services during procurement and construction phases, and commissioning.Funding support for the scheme has been given by the European Bank for Reconstruction and Development (EBRD).The bank also — along with the World Bank and European Investment Bank (EIB) — has given funding support to the related CASA-1000 transmission line project, which will help Tajikistan export hydropower to the Kyrgyz Republic, Pakistan and Afghanistan. Mott MacDonald has also carried out climate resilience studies on Tajikistan's water sector for the Asian Development Bank (ADB).Nepal Consultants Lahmeyer, Total Management Services (TMS), Entura and Manitoba Hydro International (MHI) are working across a number of water studies and projects in Nepal. The different contracts range from flood hazard studies and providing consultancy services to the Nagmati irrigation scheme and development of Tanahu hydro project, respectively.Lahmeyer is working with local partner TMS on flood hazard studies in 25 key river basins — including a focus of mitigation measures in six catchments — for the Ministry of Irrigation. The studies were due for completion in the first quarter of this year.The client division managing the task is the ministry's Water Resources Project Preparation Facility (WRPPF), which has ADB funding support to focus on urgent projects to mitigate both climate change impacts and ensure sustainability of food supply.Separately, the ministry and ADB have commissioned Entura as lead consultant for the initial services of investigations and updating the feasibility study of the Nagmati dam, near Kathmandu.Following consultancy services will include detailed design of the dam and reservoir operation regime, and assistance with procurement for the construction stage of the project to be built in the Bagmati river basin.In hydropower, development services for the 140MW Tanahu hydro project — the country's first large storage reservoir — are being provided by Lahmeyer with the support of MHI.The consultants were appointed to the project last year by the developer, Tanahu Power Ltd, a special project company established by the Nepal Electricity Authority (NEA) to build and operate the scheme.Tanahu is located on the Upper Seti River, and key infrastructure includes a 140m high gravity dam, chute spillway, underground powerhouse and associated tunnels. The reservoir will have a sediment flushing capability to help maintain the active storage volume.Bhutan The World Bank has appointed ÅF — a Swedish engineering and consulting company — to undertake an environmental and sustainability study of the 720MW Mangdechhu hydro project, currently under construction in Bhutan.ÅF is more than half way through the assignment on the Mangdechhu project being built in Trongsa Dzongkhag district in the centre of Bhutan.The run-of-river scheme is designed to operate under a minimum gross head of 344m, and includes significant dam and underground works: a 101.5m high concrete gravity dam, diversion tunnel, 13.5km long headrace, and powerhouse caverns.The consultant is due to report its findings to the bank and Bhutanese authorities before the middle of this year. The work is being conducted in accordance with the Hydropower Sustainability Assessment Protocol, which covers a wide range of areas, including climate change and human rights.The Mangdechhu scheme is being developed by Mangdechhu Hydroelectric Project Authority — a joint venture of the governments of Bhutan and India, the latter providing most of the finance. The project is due for completion in 2018, generating more than 2900GWh/year, and supplying power domestically and to India.In fiscal year 2006-7, India's NHPC entered into an agreement with the Government of Bhutan to prepare a detailed project report of the proposed scheme, then envisaged with a capacity of 672MW. Feasibilities studies for the scheme were supported by Japan and Norway.SE AsiaThailand: Lamtakong Jolabha Vadhana PS, Phase 2 ÅF is supporting the Electricity Generating Authority of Thailand (EGAT) on the extension project to double the capacity of the 500MW Lamtakong Jolabha Vadhana pumped storage plant.The underground plant has two pump-turbines in operation, and was initially commissioned in 2002. The 500MW expansion project at Lamtakong Jolabha Vadhana is due for completion in late 2018.Lamtakong Jolabha Vadhana is located in Nakhon Ratchasima province, was the first underground plant hydro facility in Thailand and remains the principal plant supplying power in the northeast provinces, says Electricity Generating Authority of Thailand (EGAT). Its upper reservoir is on Yai Tieng Mountain, and the powerhouse in 350m underground.Phase 2 of the project will add two further 250MW units, taking the total capacity of the PS plant to 1GW. Work at the plant is also to include installation of two circuits of 95km-long high-voltage transmission lines to connect with the Tha Lan 3 substation, in Saraburi province.ÅF signed a contract with EGAT to provide a range of services while the extension project is executed under by an engineering, procurement and construction (EPC) contractor.The consultant's services include design review, project management, engineering and field services through all stages of execution, including commissioning.Vietnam: Lai Chau HEP ÅF is also active in neighbouring Vietnam, where the consultant most recent began work on the supporting the implementation of the environmental and social action plan for the Lai Chau hydro project.The 1200MW Lai Chau project is under development on the Da River, in Lai Chau province, in the northwest of the country close to the border with China. Construction of the 131m high roller compacted concrete (RCC) dam at Lai Chau was completed in mid-2015.Lai Chau is being development by Electricity of Viet Nam (EVN). ÅF has already been working on the project as sub-consultant to Power Engineering Consulting JSC No1 (PECC1), a former subsidiary of EVN, and the assignment continues to 2017.ÅF was awarded the environmental and social action plan contract by Son La Hydropower Management Board (SLaMB). The board and ÅF worked together previously on the 2400MW Son La project, on the same river and also featuring a major, 138m high RCC dam. Son La was completed in early 2011.The environmental and social action plan contract for Lai Chau is funded by KfW, and ÅF is already working on another contract in Vietnam funded by the German development bank — gap analysis on environmental aspects of a smart grid transmission project. ÅF says the contract is similar to the objectives at Lai Chau by checking environmental and social due diligence, in this case for 6 x 220kV transmission lines.