BTS | HARDING PRIZE COMPETITION 2025
Table 1: Key determinants for WTP treatment requirements Determinant
EQS*
Nitrite Nitrate
Total Chromium (Of Which Hexavalent) Suspended Solids pH
Note: * Environmental Quality Standards (EQS) *
50 (3.4) <60 6-9
Drinking Water Standards (DWS)
Further, the site has a waste effluent discharge
/DWS* 30 50
Units µg/l mg/l µg/l mg/l
permit through the sewage network and can discharge trade effluent providing it meets the levels in the licence, determined by applying a scale factor to average data values for the site.
2.2.1. Slurry Treatment Plant (STP)
With the variable density tunnel boring machines (TBM) selected, an STP is a requirement to remove excavated material from the slurry and produce a ‘clean’ slurry back to the TBM for further excavation. Figure 1 shows an STP concept model as well as a
flow diagram for the process. With the material being re-used in onsite landscaping
activities ,it has been essential to control the water content of the produced spoil. To achieve this, one of the largest facilities of its kind was constructed with 24 mixed pack filter presses.
2.2.2. Water Treatment Plant (WTP) As part of the works package, Align JV has a permit to discharge treated water offsite providing it meets set criteria, as previously stated in the Table. Initially, the WTP onsite was not sufficient to treat water to these elevated standards. A new WTP was constructed that relies on a number
of treatment steps employing hydro-cyclones, disc filters, ultra-filtration, reverse osmosis, chlorination, and granular activated carbon (GAC). The new plant also regulates pH through acid/alkali addition.
2.3. UN Sustainable Development Goals At the Earth Summit held in Rio de Janeiro in June 1992 the UN set out Agenda 2021, which was adopted by its 178 member states. This outlined the necessity for a global partnership for sustainable development to improve human lives and protect the environment. Over the last 30 years, at various points this has been reviewed, expanded, and amended, and in 2015 came the 2030 Agenda for Sustainable Development with the 17 SDGs, as presented in Figure 3, to provide the enabling framework to make this achievable. Key areas where this project overlaps with the
UN aims are in the following SDGs: (6) ensuring the availability and sustainable management of water and sanitation for all; (12) by actively managing sustainable consumption of the potable water supply, and reducing reliance on the trade effluent licencing; (11) through sustainable industrialisation and fostering innovation in the production methods at the site; and, (14) ensuring safe environmental discharges thus conserving the local marine environments.
2.4. Sustainability Sustainability dates back through the ages. The rough form of its ethos is to optimise use of resource through greater awareness of how different actions can impact the local environments. Following through to the modern world, the evolution of the term can be traced to the forestry profession and its first use, in its
Above, figure 2: Water treatment plant at Align 16 | May 2025
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
