Carillion, the support services company, is to sell its environmental consultancy business Enviros.Engineering, sciences and project delivery firm, Sinclair Knight Merz, is paying around £27m (net) in cash for Enviros. The final price is subject to completion of balance sheet adjustments.Carillion will used the funds to reduce indebtedness. The company has set itself a target of reducing net debt in the second half of the year from the £146m level at the half year stage.The company said earlier this month that it continues to perform well and remains on track to deliver materially enhanced earnings in 2009, despite challenging market conditions.