Sewage Pollution Towy Estuary
Carmarthenshire Fishermens Federation
Sewage Pollution Towy Estuary
Garth Roberts
June 2008.
A Sewage Overflow on 22nd May 2008, resulted in a serious pollution in the Towy
Estuary at Carmarthen. This brief paper discusses the aftermath, historical
background, perceived causes and implications.
CFF’s concerns about estuarial overloading, expressed formally in 2004, 2005 and
2006 were ignored. On behalf of all river and estuary users, we are now
calling for
a) an immediate and independent investigation into the management of
Carmarthen’s sewage system, with particular reference to the capacities,
screening and maintenance of in-line pumping stations.
b) a review of EAW’s Catchment Abstraction Management Schemes (CAMS)
procedures for regulated rivers with particular reference to the Towy and the
effects of climate change.
Introduction
The flow of the river Towy (afon Tywi) is partially regulated by releases from
Llyn Brianne storage reservoir. During dry weather, additional water is released
in compensation for potable water extracted at Nantgaredig.
The 24 km estuary is an EU designated Special Area of Conservation (SAC), as is
the inflowing Towy, also the finest sea trout river in Britain. It is here in
the estuary that all migrant fish and eel species undergo vital physiological
changes in their transitions from fresh to salt water and vice versa. The
estuary is used by anglers, coraclemen, seine netsmen, boaters, canoeists and
the annual Carmarthen River Festival. The health and cleanliness of the
estuarial waters is essential.
Carmarthen’s sewage is treated by Parcysplott Sewage Treatment Works (STW) which
is fed by gravity and several main sewer pumping stations. On 22nd May 2008, a 2
hour activation occurred of the Consented Storm Overflow (CSO) from the Pothouse
Wharf sewage pumping station on the Quay. Several subsequent events were
reported, allegedly with thousands of cubic metres of untreated sewage released
into the estuary, now described as being strewn with sewage litter. The imminent
Carmarthen River Festival was cancelled with local river users and canoeists
advised to avoid the estuary.
Raw sewage is aesthetically unpleasant and unhealthy for humans, through some
protozoans such as Cryptosporidiosis and Cyclosporiasis. Sewage is not normally
toxic to fish. Nevertheless, in the Towy estuary, long term water quality
problems associated with lowered dissolved oxygen (DO) are well documented. Such
sags can occur more commonly during high tides in warmer weather. The effects
are excaserbated by sewage
Discussion
The Overflow Incident was reported to CFF by Ian McCue, Chairman of the
Carmarthen River Festival (Appendix A). The follow-up report from EAW states
that Dwr Cymru’s preliminary enquiries revealed the system to be operating
correctly, with overflows attributed to excessive rainfall (EAW: Appendix B).
A total of four discharges with the same source were reported by Ian Mc Cue,
from 22nd – 28th May. Subsequent CFF enquiries have revealed such discharges to
be common in the estuary. Although the outlets are screened, complaints indicate
that unacceptably large matter can be discharged. There is anecdotal evidence
that the nearby Brickhouse Wharf Pumping station discharges into the nearby Nant
Tawelan causing “overpowering stinks”. The outfall from the Johnstown (old
creamery) Sewage Treatment Works (STW) is reported to cause similar problems.
Some remedial works are underway at the Pothouse Wharf outfall, during which,
unscreened sewage has been observed discharging.
Carmarthen’s antique sewerage system was anticipated in 1966 to have staged
upgrades to occur by 1971 and 1983. They failed to materialise until 1983 and
1998. CFF’s concerns about sewerage overloading, were overlooked by the recent
Carmarthenshire Unitary Development Plan and subsequently denied by Carwyn Jones
in 2006. Urban development in the Carmarthen area appears to be outpacing the
services infrastructure and threatens to destabilise the ecology of the river
system (Appendix C).
Under the higher tidal flows, the rapidly rising tide forces everything
previously flowing in the river channel downstream, back upstream past the town
as far as the upper tidal limits near Capel Dewi, before ebbing away at a much
slower speed than the rise. Following large overflow discharges, sewage debris
can litter the entire channel, up and downstream. During low river flows,
anglers near the Bypass report grey and strong smelling water lingering all day
regardless of tide state or any overflow events.
Rapid urban development is reducing the Towy’s capacity to withstand modern
day pressures. Water is abstracted variously from within the catchment but
mainly from Nantgaredig, already distributing to 400,000 consumers across
South Wales. There are some 50 STWs discharging into the catchment.
During dry weather, the river and estuary through-flow is augmented by extra
reservoir water. Abstraction normally takes place at night on weekdays which
means greater dilution of discharges by day. Twenty four hourly abstraction
takes place at weekends, with resultantly less dilution to counter similarly
less demand. Any increase in consented discharges could be capable of turning
the river into an open sewer. There is a constant threat from antiquated sewer
systems with storm-overflows, each of which can discharge raw excrement directly
into the river. They are to be found near virtually every town and village.
Conclusion
The events highlight the vulnerability of our river to the inadequacies of
compensating for human intervention. Overflow points are built into sewage
systems as 'safety valves' to act during any overloads caused by heavy
rainfall or blockages. Any frequently triggered operations indicate overloading
problems needing attention.
Changing weather patterns associated with global warming, expected to involve
dryer warmer summers and heavier rainfall events, have significant implications
for the Towy and Carmarthen. The night time abstraction regime is wasteful of
water but Carmarthen relies increasingly on the Towy to dilute its sewage –
increasingly more likely to overflow in its raw state.
EU's "Water Framework Directive" (WFD) is at present being subsumed into UK
legislation. Administered by the Environment Agency, the WFD details every
single aspect of our use of water, including through Catchment Abstraction
Management Schemes (CAMS) specifying abstractions and their environmental
effects on rivers. Unfortunately, their standardised calculations fail to take
full account of regulated rivers like the Towy, and those parts of rivers
downstream from their abstraction points. Any residual effects on the flows into
the Towy estuary are ignored. Although they may be picked up under some other,
often unrelated legislation requirement, the principles of any abstraction
regime remain paramount.
Recommendations
CFF’s concerns about estuarial overloading, expressed formally in 2004, 2005 and
2006 were ignored. On behalf of all river and estuary, we are now calling for
a) an immediate and independent investigation into the management of
Carmarthen’s sewage system, with particular reference to the capacities,
screening and maintenance of in-line pumping stations.
b) a review of EAW’s Catchment Abstraction Management Schemes (CAMS)
procedures for regulated rivers with particular reference to the Towy and the
effects of climate change.
Appendix A – Ian McCue’s Reports
The Overflow Incident was reported to CFF by Ian McCue, Chairman of the
Carmarthen River Festival.
Carmarthen River festival Cancelled as thousands of gallons of untreated
sewerage was discharged into the river Towy yesterday afternoon
As organisers of Carmarthen River Festival were preparing for the event by
Carmarthen Quayside last night, it was observed that raw sewage was pouring into
the river, right in the middle of town where the Carmarthen river festival was
due to take place. The river festival was due to take place next week, but as
the river bed is littered with sanitary towels ,condoms and human stools, the
organisers decided to cancel. No one is prepared to guarantee that the river is
safe and if it rains again there is a possibility that more sewerage will be
released
There have been a number of incidents of raw sewerage entering the Towy in
Carmarthen of late, reported to the authorities by the Coracle men and
Gwendraeth Valley Paddlers. It seems unbelievable that we live in a town where
if we have a heavy shower, the sewerage pumping stations can not cope and
therefore release untreated sewerage directly into the Towy.
Last night I saw how much sewerage was released to the river and was shocked.
On reflection I do not believe the river is safe! This is a huge blow as we
have been working very hard to promote the river and trying to get people to use
use it. Approximately 1,000 people took to the water in last years river
festival and had a wonderful time.
Tuesday
"Thousands of gallons of raw sewage pouring into the Towy at Carmarthen".
Tuesday tea time: massive release of untreated sewage into the Towy. DURATION 2
hours hundreds of sanitary towels, condoms, wipes and human stools released.
Sunday,
After rain more untreated sewerage SANITARY TOWELS, CONDOMS,WIPES AND HUMAN
STOOLS entered the river. We have video and pictures. EA Wales called and saw
sewage in river. They asked the welsh water employee present to clean the river
bed by the outlet to determine if the solid release happens again. DURATION of
pollution HOURS
Monday
After some rain, untreated sewage entered the Towy, composition as above, once
again I phoned the EA Wales to report .DURATION of pollution 2 HOURS
Tuesday and Wednesday
Pothouse wharf pumping station has dozens of workmen with huge amounts of
machinery working on it.
Wednesday
At 7-30 pm I went to have a look at Pothouse wharf outlet as after rain today it
would have been discharging, AGAIN IT HAS RELEASED SANITARY TOWELS, CONDOMS,
WIPES AND HUMAN STOOLS. DURATION AT A GUESS, AS IT HAS RAINED NEARLY ALL DAY I
WOULD ASSUME IT HAS BEEN DISCHARGING ALL DAY.
Appendix B - EAW’s follow-up report 23/1305 hrs
I have some feedback regarding the pollution incident in Carmarthen last
night.
the `incident' was reported by a member of the public at 17.48 on 22/5/08
it was Logged onto Environment Agency Wales National Incident Recording System
(ref 00589630)
Report was: `Reference pumping station at the Quay (Carmarthen) near the new
footpath across the Tywi. Sewage and raw human waste is discharging from a pipe
leading to said pumping station. Town has a "River Festival" coming up this
weekend and request that the problem is cleared up’.
the incident was initially assessed as a category 3
A Fax was sent to Dwr Cymru Welsh Water (DCWW) by EAW standby officer to notify
them of the problem
An EAW standby officer spoke to DCWW on 23/5/08 at 10.00 to follow up FAX
The DCWW explanation for the discharge is:
`Intense rainfall event yesterday at 16.45 for about 30 minutes. Pumping station
overwhelmed and discharged to storm for about 15 mins via consented CSO. P/S
operator showed festival organiser that the pumping station was operating
correctly and actually turned the standby pump on as well but it still couldn’t
prevent the storm discharge. DCWW meeting festival organiser and town council
today (23/5/08) at 14.00.
Selby Le Roux, EAW Environment Management team leader spoke to Ian McCue,
chairman of Carmarthen River Festival at 10.30 on 23/5/08 to supply feedback.
An EAW Environment officer assessed the impact of the discharge on the Tywi at
about 12.00 on 23/05/08 and was unable to see any sewage debris up or downstream
of the discharge point.
The pumping station is called Pothouse Wharf and the discharge is covered by a
storm discharge consent.
Appendix C - CFF - The History
The history of Carmarthen's sewage treatment is a sorry tale.
In 1957, a fish kill involving 1000 salmon and an unrecorded number of sea
trout, occurred in the Towy Estuary. The actual cause was unknown but in the
absence of any industrial source was attributed to DO sags.
In 1966, raw sewage was being discharged into the Towy Estuary from seven pipe
outfalls in the Carmarthen area. During the Public Inquiry into the Llyn
Brianne Reservoir River Regulation Scheme, held in Llandovery in December 1966,
it was anticipated that 'Stage One' - the partial macerating - chopping-up -
treatment of just 37% of the Carmarthen discharge of raw sewage would be
achieved by 1967, with 'Stage Two' (the remainder) completed by 1971.
Secondary (full) Treatment was to be operational by 1983.
The Planners for the West Glamorgan Water Board, stated that “…at no time
was the river flow below the Nantgaredig water abstraction to fall below 30
million gallons per day (mgd)..”. They acknowledged that the condition of
sewage and effluent discharges into the river at Carmarthen 'was
unsatisfactory'. Discharges then amounted to about 1mgd of untreated sewage
(excluding 'considerable infiltration') and milk effluent .
The proposed flow appeared to the River Authority ".....to have little or no
significance for fisheries conservation or the disposal of sewage effluent. Such
flows were very rare. From all points of view this was too low a figure".
After proposed improvements to sewage and effluent treatment, “…a flow of 130
- 140mgd would still be required for dilution”. Even then, a theoretical
acceptable oxygen demand would be exceeded during increased morning effluent
discharges.
The Authority's demands for a higher minimum flow were ignored by the
Inspector. The minimum flow was fixed, and remains today at 30 mgd – 1.6
m3/sec. When the river falls below a 'Prescribed Flow' of 150 mgd (7.9 m3/sec)
below Nantgaredig, flows are augmented by discharges from Llyn Brianne Reservoir
Carmarthen's 'Stage Two' treatment, promised for 1971, was not actually
achieved until 1986 - still only with partial treatment of raw sewage. Three
separate sewerage schemes were centralised at Parc-y-splott STW, increasing
the dry weather discharge and organic load by 80% from 2150 m3/day. Water
quality in the estuary was then so poor that an oxygenation plant to pump oxygen
directly into the water of the tidal reach was installed at Parc-y-splott at a
cost of £250,000. This proved to be totally ineffective. It was abandoned when
it was discovered that the discharge capacity should have been 17 tonnes per day
instead of its actual 2 tonnes.
Carmarthen’s planned improvements to the local sewers, did not fully
materialise until 1998 with the uprating by Dwr Cymru of Parc-y-splott to 'full'
secondary treatment, now consented to discharge over 9000 m3/d of treated
effluent. The nearby former joint creamery STW, no longer used for milk
effluent, treats high oxygen-demand refuse-dump leachate from Nant y Caws,
activated by Llangunnor sewage.
During secondary treatment, the sewage is stirred, aerated then settled. Only
the liquid effluent is discharged.
Despite Parcysplott’s improved performance, water quality remains a problem in
the estuary. Lowered levels of dissolved oxygen can still occur, especially
during summertime low river flows and spring tides. These are endemic, caused by
algal blooms and sediment disturbance, aggravated by sewage effluent . They are
capable of posing serious threats at times to all water life in the estuary.
In this Federation's submission to the 2004 Public Inquiry into
Carmarthenshire's Unitary Development Plan, we drew attention to the danger
posed to the Towy Estuary from overloading the sewage system by further
development in the Carmarthen area. The Inquiry Inspector, in his report stated
"
"...they (CFF) were concerned that the problems of sewage discharges into the
Towy estuary would be exacerbated by additional development around Carmarthen.
There were a considerable number of objections from the Environment Agency but
this particular matter, for which they have prime responsibility, was not
raised. In these circumstances, it would be inappropriate for the Plan to make
specific reference to this matter."
The failure of the inspector to follow up the apparent contradiction, makes a
mockery of the Public Inquiry process, and suggests a weakness on the part of
the Environment Agency in its statutory duties.
During 2004 and 2005, the Tywi, Taf and Gwendraeths Catchment Abstraction
Management Scheme (CAMS) procedure was actioned; with publication in 2006.
Despite an input by CFF, the scheme did not take into account fully the effects
and implications of river regulation or estuarial discharges.
In Oct 2006, CFF expressed our concerns to Welsh Minister Carwyn Jones at a WAG
Panel Meeting held in Carmarthen and received the following written response.
CFF:-
Rapid development in the Carmarthen area is placing an ever increasing effluent
load on the Towy Estuary already suffering endemic water quality problems. What
can WAG do to protect and ensure the future of this valuable resource ?.
WAG
Water Quality
I was surprised to read of your concern of the increasing effluent load from
Carmarthen having an adverse effect on the Tywi Estuary and that you believe it
is suffering water quality problems. Over the last 10 years or so the general
pollutant load to the Tywi estuary has almost certainly reduced particularly
from Parc y Splott Sewage Treatment Works (STW) which treats most of the sewage
load from Carmarthen itself. Both the sewerage system in Carmarthen and Parc y
Splott STW were upgraded in 1997 and this was followed by a marked improvement
in discharge quality
Any new development in Carmarthen will have increased the load on Parc y Splott.
The compliance record of the STW is very good, so it is unlikely that
development has had an adverse impact through waste water discharges.
References are available on request.
