Appearing before Gosforth magistrates on 18 November, Ibstock pleaded guilty to two charges of causing polluting matter to enter the Dewley Burn, contrary to section 85(1) of the Water Resources Act 1991. Ibstock was ordered to meet the Agency's costs of £1,185.
The company was fined £5,000 for the first incident, which took place on 20 February. An officer from Newcastle City Council, which regulates the site's emissions to air, alerted the Environment Agency to silt pollution in the burn.
The burn runs through a culvert underneath Ibstock's site. An Agency officer found a thick blanket of silt on the stream bed for some 700 metres downstream of the culvert.
The company stored large quantities of clay on a raised storage area. There had had been a history of silt pollution at the site, caused by surface water drainage taking clay into the watercourse. Ibstock had sealed off the drainage system and installed settlement tanks, with the effluent being reused on site. However, the Agency found two open drains near the storage area taking surface water directly to the burn.
Ibstock's environmental manager told the Agency that as part of the site's certification to ISO14001 the company had commissioned a plan of the drainage system to identify discharge points. However, the plan failed to identify the open drains involved in the incident - and despite routine environmental checks, staff did not appear to have noticed the silt pollution in the stream.
The second incident, for which Ibstock was fined £10,000, came to light on 13 March following reports of oil on the Dewley Burn.
An Agency officer found that diesel discharged from Ibstock's drainage system had polluted some 750 metres of the burn.
Investigation pointed to an earlier diesel spill at the site. Workers refilling a diesel storage tank had left it unattended, believing a switch would automatically stop the refuelling process.
This did not happen and the tank overflowed. The spill escaped the inadequate bunding around the tank, and entered the stream through a nearby drain concealed under pallets.
The case is an embarrassment to the company, whose recent environmental report says that "concern for the environment is a fundamental part of Ibstock's strategy".
Last year, a company audit of environmental management and protection measures awarded almost top marks to the Throckley site. Ibstock also boasts of its "outstanding achievement" with ISO14001, to which it is certified by the British Standards Institution at almost all of its 24 manufacturing sites, including Throckley.