A council\'s attempt to pay men and women fairly for doing the same type of jobs means some staff face losing up to half their basic pay, claims a union.Local authorities across Wales are carrying out job evaluations, but Unison leaders say Bridgend council\'s approach is particularly brutal.First Minister Carwyn Jones, Bridgend\'s AM, is understood to be concerned about what is happening in his local council.The council said it was trying to achieve a fair pay structure.More than 5,500 staff at Bridgend council are affected by job evaluation with consultation on the plans continuing. Unison leaders told the BBC\'s Politics Show Wales that one teaching assistant currently paid a basic salary of just under £23,000 a year could expect to be paid just over £11,000.A manager on about £33,500 a year would go down to just over £26,000, while a more junior officer\'s basic pay would fall from around £25,500 to just under £18,000.Steve Belcher, Unison regional organiser, said he agreed with the principle of job evaluation to ensure equal pay but there needed to be \"meaningful consultation\".He said councils must treat the issue \"with the seriousness it deserves\".\"They [Bridgend council] are not offering to protect those who are at detriment,\" he said.\"They\'re not offering any back pay and perhaps worst of all, they\'re proposing to remove all of the terms and conditions such as unsocial hours, weekend working and things like that.\"Bridgend council estimates most staff will see their pay rise or stay the same but union leaders say the rises are sometimes as little as a few pounds a year.David Macgregor, assistant chief executive at Bridgend council, said the authority was in negotiations with trade unions and carrying out a 90-day consultation with staff.\"As an authority, we are trying to achieve a fair and equitable pay structure which is affordable in the current climate and avoids potential future job losses,\" he said.\"We are still in the process of rolling out a series of more than 60 roadshow events, and have also established a job evaluation hotline, a dedicated job evaluation section on the staff intranet site and one-on-one sessions with job evaluation specialists.\"This is a very important process and we are urging all staff to take full advantage of the various channels that are open to them for sharing their views, and to use their trade unions as part of this critical negotiation period.\"Ten of Wales\' 22 local authorities have completed job evaluations, which aims to ensure workers are paid the same for doing similar sorts of jobs, and five are in the process of doing so.Anna Freeman, director of employment at the Welsh Local Government Association representing local councils, said job evaluation was always tough for local authorities, and had just got tougher.\"It\'s been quite difficult to achieve for a whole range of reasons,\" she said.\"You will be aware of the equal pay claims and it\'s not always been easy to implement the schemes.\"There\'s been a lot of difficulties around negotiations around the terms and conditions that go with it and obviously now, the financial climate has changed out of anything we could\'ve ever imagined when we embarked on this in 1997.\"