In brief
- A cheap rock bid often means the hard material was never priced, so the cost returns later as a variation or a stalled site.
- Ask for the bid's assumption on rock depth, breaking method and haul distance, and check each against the site.
- Confirm the municipal engineer's office holds borehole or trial pit records for the plot before opening the tender.
Contents
A low rock excavation bid usually means the hard material was never priced. The tender may assume soft soil, shallow rock or short hauls, then meet the opposite on site. Underbidding on rock excavation puts clients at risk whenever the bill of quantities is silent on what counts as rock, how it will be broken and where the spoil goes.
What gets left out of a cheap rock excavation bid?
The omissions are predictable once you read the bill line by line. A bidder who wants the lowest number drops the slow, plant-heavy items and hopes the ground is easy. Common omissions include:
- Breaking or blasting method, and the compressors, hammers or drill rigs it needs.
- Haul distance to a tipping point the municipality accepts, plus the loading plant.
- Plant standby while concrete, steel or supervision waits.
- Dewatering if the cut reaches water.
- Reinstatement of the excavation, shoulders and any services crossed.
Ask each bidder to state, in writing, the rock depth and strength they assumed, the breaking method they priced, the haul distance and the disposal site. A bid that cannot name these has not priced the work. The municipal engineer's office can say what records exist for the plot and which disposal areas the council allows.
How do unrealistic tender allowances hide the real cost?
Unrealistic tender allowances shift cost from the bid to the construction period. The tender may allow a shallow rock line, a short haul, or a rate per cubic metre that only covers ripping soft material. When the excavator meets harder rock, output falls, the programme slips and the client faces a variation or a stopped site. The contractor may then claim the ground was unforeseeable.
General practice is to define rock for payment before tendering: what the specification calls rock, how it will be measured, and how a change in depth or strength is valued. Confirm those definitions in the project's specification and with the engineer, because they are contract terms, not rules of thumb. The same applies to working hours, since breaking rock in a residential area of Qardho may be limited by noise or safety concerns. Check what the contract allows before instructing night work.
How do you test a rock bid before awarding it?
Test the bid against the ground, not against the other bids. Walk the site and a recently excavated one nearby with the same plant. Ask what the excavator actually met, how long breaking took and where the spoil went. Request any borehole, trial pit or test records the client holds, and ask the municipal engineer's office whether it keeps logs for the area. If none exist, price a small investigation before the main tender, so bidders work from the same information.
Then compare bids item by item, not by total. A bid that prices rock breaking, haulage and standby separately is easier to audit than one lump sum. Check whether the rate rises with depth or hardness, and whether the contract lets the engineer instruct extra work. A high rate with clear measurement can cost less than a low rate that leaves the method open.
What to do next
Take the lowest bid and mark every item it leaves out: breaking method, haul distance, disposal site, standby and dewatering. Send those questions to the bidder in writing and give a deadline for answers. If the replies stay vague, ask the engineer to re-measure the rock before award, or budget an investigation first.
Frequently asked questions
Should the client pay for a ground investigation before tendering rock excavation in Qardho?
It usually costs less than the variations that follow an unpriced rock line. Ask the engineer what investigation suits the cut depth, and ask the municipal engineer's office what records already exist for the plot.
What should a rock excavation rate include?
Confirm with the engineer, but general practice is to price breaking, loading, haulage to an approved disposal site, standby, dewatering and reinstatement separately, so each can be measured.
Local reporting: this article is written for building work in Qardho and Puntland. Ground conditions, prices and rules differ between places; confirm the details for your own site.
Photo: Mcfly05, CC BY-SA 4.0, via Wikimedia Commons
