During the 1999 bathing season, bathing water quality at Newhaven failed to
meet the mandatory standard. The town’s bathing water is the responsibility
of Southern Water, which reversed this trend in 2001, achieving a 99% pass rate.
Of 74 beaches monitored in Southern’s region, 73 have passed the mandatory standard.
Just one failed, in north Kent, where there is an issue over discharge from
a private cistern. In total, 54% of the beaches are also meeting guideline standards
promoted by the Environment Agency. This is a huge improvement when you consider
that in 1988, when Southern began its capital investment plan, only 40% of beaches
were meeting the mandatory standard.
It was decided early in the design stage that Newhaven STW would utilise a
compact gravity settlement system, the spiral separator (WWT September 2001),
which requires just 3-4% of the area used by conventional treatment processes.
Main contractor Miller Civil Engineering Services (now Morgan Est) and process
contractor Purac had a relatively smooth ride when it came to construction,
only an environmental survey of the site threw up problems. It was found that
land between Newhaven and Lewes, where Edmund Nuttall would be laying pipeline,
was inhabited by great crested newts, a protected species. Special netting was
erected to prevent newts entering the site and construction work was put on
hold until their breeding period was over.
Local residents’ concern was alleviated when Southern held public exhibitions
to detail its plans. To soften the visual impact the water company will also
landscape the area around the Newhaven site. Construction work began in October
1999 and consent was met in December 2000. The project took eighteen months
from commencement to completion. The £20M spent on the project included
all transfer work on the 11km pipeline and pumping station at Lewes.
Newhaven can now deal with 28.5Ml/d of wastewater, achieving 75% COD and BOD
removal across the plant and turbidity of 100ntu. The use of spiral separators
has revolutionised the treatment process. Driven by hydraulic powerpacks, they
are energy efficient, cheap to run and require low maintenance. They currently
achieve 5% solids removal in contrast to conventional technology in which 1-2%
can be expected. Southern Water is continuing testing in order to refine the
process further. The company admits it worked hard to get such efficiency in
the beginning – getting settings right, achieving the correct flow and coping
with influent levels. But from the outset Southern Water recognised the spiral
separator’s potential, investing £2M to develop the technology.
Southern anticipates the Newhaven plant will have a 15-20 year working life.
During this time the company sees no reason why the spiral technology should
not become commonplace throughout the industry. It even predicts a spiral separator
for final as well as primary settlement.
Nearly 40 miles along the coast, Ford aerodrome was chosen as the ideal site
for another STW. Ford was built to meet the Urban Wastewater Treatment Directive,
before its construction preliminary treatment only existed at headworks in Bognor
and Littlehampton. One of Southern’s largest plants, Ford STW provides treatment
for a combined population equivalent of 150,000, for the separate catchments
of Littlehampton and Bognor Regis.
The works consists of three primary settlement tanks, 30m in diameter, secondary
phase aeration lanes and four 30m diameter final settlement tanks. Ford runs
two process streams. Not only is Southern making a dramatic improvement to water,
it is producing a commercially viable sludge product. Sludge drawn off at various
stages in the treatment process then goes through anaerobic digestion. The digested
sludge is then processed from a liquid into a cake using centrifuges. The final
cake is 25% dry solids.
This material is sent through a further drying process to produce fertiliser
pellets. Ford, a regional sludge recycling centre, also deals with sludge from
satellite plants. It can handle 8,000 tonnes of dry solids a year, of that,
approximately 4,000 tonnes is imported as either cake or liquid.
A number of sites were assessed before Ford was chosen. Existing works in Littlehampton
and Bognor were obvious possibilities. In essence, this would have been Southern
Water’s cheapest solution. However, Ford stood out because it had potential
as a green field site. It was an old aerodrome, so space was not a constraint.
It was also an acceptable distance from the two head works. Once plans were
announced Southern met with local opposition, similar to that raised in Newhaven.
As well as running exhibitions, the company arranged a public meeting. Site
visits to operational STWs were organised for a council committee, to help them
understand how problem areas, such as odour, would be overcome. Local people
were consulted during the construction phase through a liaison group initiated
by the county council. Ultimately only three meetings took place because interest
waned once people were reassured of Southern Water’s intentions.
The project underwent two planning phases. Following the outline phase, the
water company made dramatic changes to the scheme which involved a further planning
phase and detailed application. This was largely due to a rearrangement of the
site to provide for secondary treatment. A series of design reviews were necessary
to comply with the Urban Wastewater Treatment Directive. Southern originally
intended to use a chemically aided primary settlement (CAPS) process, which
satisfied the directive, but met with local opposition because of a question
mark over standards of treatment. The government initially approved CAPS treatment
because effluent would be discharged into a high dispersion area, but after
residents met with Mr Meacher, the government reversed its decision, taking
away the natural dispersion provision, forcing Southern to provide secondary
The second phase of planning generated some 30 conditions. These included a
12m height restriction on all buildings, which meant the dryer building had
to be part buried. There is a 10m restriction on any future development, less
than the general provision of 15m. Extensive landscaping and tree planting has
been carried out around the site, to further limit visual impact. Construction
traffic could only use the A259, a lower coast road, and operational traffic
is not permitted to use the route through nearby Arundel in case it worsens
an existing bottleneck. There are stringent odour emission standards, hydrogen
sulphide levels must not exceed 1.3ppb at, or beyond, the boundary of the plant.
To achieve this the plant is fully enclosed, the sludge treatment system and
primary settlement tanks are covered and air is ducted back to a two-stage chemical
In addition, Southern Water was required to undertake an extensive archeological
survey of the site, before construction work began. The company spent considerable
time with the county archeologist and a specialised firm of archeologists. A
study of the proposed STW site unearthed artifacts from roman, bronze and iron
age periods, making it the second most important archeological site in the south
of England. The old aerodrome also relinquished an unexploded bomb, which required
a controlled explosion.
Work on the plant began in May 1999 and it was receiving flows for treatment
in October 2000, two months ahead of schedule. Plant design includes provisions
for future demand. Southern Water has consent to 2005, but a design horizon
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