They have refused you because the DVLA consider 1% as an indication of recent alcohol use, 1% is considered too high for someone they expect complete abstainence from. The normal green, orange and red CDT limits do not apply to those the DVLA deem to be dependent. They are looking for a score lower than 1%, generally around 0.7%.
The evidence the DVLA expect is a date of last drink logged with your GP and LFT's across the period returning results within the normal range. The DVLA do not tell you this is the evidence as they do not state what they do and do not want to avoid abuse of the system. LFT's and a last drink date backed by a GP is the only evidence they accept.