Repairs to Lee Wood Road, which carries traffic around the village from Hebden Bridge to Slack Bottom and beyond, are likely to take months and cost at least £1million.
The repairs were delayed by heavy snow in March and have now hit technical problems, with the council now refusing to give a date for completion.
Coun Barry Collins told the Heben Bridge Times: “We are having to excavate to a depth of 4.5m below the road level to reach stable ground to find the new wall.
“The poor ground conditions and the depth of the excavation have reduced the length of wall which can be safely excavated to five metres at any one time as the edge of the excavation is unsafe and obviously poses a risk to workers on the site. This restricted working area has reduced the manpower that we can effectively employ at any time.
“We accept that this is obviously a problem and potentially extends the length of the project but that’s what we are facing in a technical sense.
“It is absolutely clear from the seriousness of the problems that we have uncoered on the hillside that this is going to be extremely expensive.
“I understand people’s concerns on the timescale and the disruption it is causing but given the scale of the problems we are uncovering, I’d prefer not to put a timescale on this.”
He told the HB Times that the council was awaiting the findings of a geotechnical report on Tentercroft and Hollins before it made any further decisions on additional works that may be required.
The council has conducted traffic surveys using speed guns and found that on average 93 cars passed through Heptonstall in an hour at an average speed of 12 miles per hour. The maximum speed recorded was 18 miles per hour.