Gas Holder Station Dewatering and Desludging – North London

Region: North London

Client: Coleman & Co. Ltd /National Grid Property Holdings Ltd Involved Units: Eneotech Environmental Ltd

Execution Time: May 2010 – September 2010

Contract Value: £250,000

Projektdaten

Site setup

Dewatering of gas holders

Confined space entry in to gas holders

Desludging of gas holders

Cleaning of structures

Dewatering and management of recovered sludge

Ausgeführte Arbeiten

Tank Dewatering and Desludging

Industrial Waste Services

Project Data

Work Performed

Gas Holder Dewatering & Desluudging Works - North London

Eneotech Environmental Ltd. were asked by Coleman &

Company Ltd to fulfil the role of dewatering and

desludging subcontractor on the demolition works at a

National Grid Property former gas holder station site in

North London. Eneotech Environmental Ltd. are term

contractors to National Grid Property Holdings Ltd for

specialist groundwater remediation project. This project

marked a first in providing specialist subcontractor skills

to another facet of the former gasworks regeneration

programme.

The subcontract package was to firstly dewater 3no.

redundant gas holders. This water was to be pumped out

through a bespoke water treatment plant and disposed of

to sewer. Once access had been gained to the holder the

sludge had to be removed to allow the demolition

programme progress. The prime aim of the sludge

treatment was to reduce volumes to allow waste disposal

at another time.

The water treatment plant was designed to be able to

treat massive volumes of water (2000m3/day) which were

specified within a temporary discharge to sewer consent.

The treatment plant consisted of oil and sediment

separator tanks, air stripping tank, sand filters and

activated carbon filter. The plant was controlled by a

bespoke control panel with integrated level sensors,

motor starters and inline methane detector. This sensor

was calibrated for the discharge consent and ensured

real time confidence of the air stripping stage of the

treatment plant which was designed to remove the

methane from the dissolved phase.

Upon completing dewatering of the below ground gas

holder the roof was removed and a risk assessment was

carried out to determine the confined space entry options

with respect to site conditions. Primary access was to be

formed by a specialist system scaffold staircase tied into

the remaining structure. Secondary emergency access

was provided by a traditional pole and grip scaffold tower

with mid riding tripod sited at the top. Prior to use a full

mock emergency was carried out to ensure all operative

were aware of the risks posed by confined space and the

adopted evacuation procedure.

Eneotech Environmental Ltd had determined the most

effective way to reduce waste volumes, which the client

would have to dispose of, was via centrifuge treatment

which had never been used successfully on similar

projects until now. The basal sludge were pumped via

hydraulic pump back to sludge holding lagoons (below

ground holder) or were tipped into the lagoons by a road

sweeper (above ground holders). These materials were

normally tankered offsite for disposal, in this case the

material was to be the feed stock for the centrifuge. The

sludge was then pumped through the mobile sludge

dewatering centrifuge to produce a dewatered and

stackable sludge suitable for disposal. The water fraction

produced by the process was passed through the

established treatment plant prior to discharge to sewer.

Bilfinger Berger Environmental Ltd. reduced waste

volume by 75%.

Eneotech operates in Europe as a certified waste

disposal business with our own technical facilities and a

license to recycle or eliminate wastes of all kinds. We

offer a comprehensive range of modern services covering

every aspect of the treatment and disposal of

contaminated bulk materials. In many instances, we are

able to accelerate the official regulatory processes, all

with disposal security and integrity you can rely on.

We offer services to remove and dispose of difficult and

hazardous wastes from current and former production

facilities. These include specialist dewatering and sludge

removal services.

Our company Eneotech Environmental Ltd. ranks as one

of the most highly skilled and dependable services

providers specialising in site rehabilitation, waste disposal

and service platform preparation.

Head Office

Head Office Eneotech Environmental Ltd. 10 Station Road Chertsey Surrey KT16 8BE Tel: +44 (0)1932 577290 Fax: +44 (0)1932 571917 For more information email: info@eneotech.co.uk www.eneotech.co.uk

Northern Regional Office Eneotech Environmental Ltd. 7400 Daresbury Park Daresbury Warrington WA4 4BS Tel: +44 (0) 1928 737500 Fax: +44 (0) 1928 737699

Scotland Office Eneotech Environmental Ltd. Lochside House, 3 Lochside Way, Edinburgh EH12 9DT Tel: +44 (0)131 4522047 Fax: +44 (0)131 4522518