In this article from the Farmers Journal, Paul Mooney speaks to Joe O’Donoghue of Michelstown, who decided to fully contract out the construction of a road underpass on his farm.
When it comes to a farm building project some farmers choose to be involved from start to finish. Others take a different approach and hire a good professional, let them get on with it while they can concentrate on running the farm. Both options have their merits.
When dairy farmer Joe O’Donoghue of Michelstown, Co. Cork, decided it was time to invest in a road underpass he considered all options and eventually decided to contract out the complete job.
Joe farms with his wife Mary and their children at Pollardstown. Two- thirds of the land is on the far side of the road, and with this being the Michelstown to Araglen road “It’s quite busy.” Said Joe
“Getting the cows across took three people, one each side and one hunting them across.”
After doing his homework Joe agreed a price for the entire job with Croom Concrete in Co. Limerick.
“You could organize a digger yourself to dig up the road, and a crane to lift in the culvert. But this company is dealing with these issues every day of the week. I felt this was the way to go. I agreed on what I wanted with Joes Costello of Croom Concrete. He then did the drawings, he obtained planning permission, did the road traffic management. He built the tunnel and reinstated the road – he did everything from A to Z. And I have to say he gave a top class service.“
The road was closed on 11 April and reopened on 13 April with the tunnel structure in place. The cows went through for the first time ten days later and quickly got used to it. The road has been reinstated and hedge replanted in the banks. The underpass is 12m long, 3m wide and 1.2m high.
Joe Costello is a qualified engineer and is project manager with Croom Concrete, I asked him to outline the steps involved in the job.
“First, I did up the drawings and sought planning permission. There were a few issues. For example it was planning requirement that we put in a tank to catch and dirty water. We did the traffic management plan and obtained the license to close the road. Thankfully there was a good detour available. We applied to close the road during the Easter school holidays when traffic would be quieter. We got permission to close it for three days, as is normal.”
“In our experience it’s important to get all the culverts down on day one – that gives you the bit of scope to do the tidying up that comes next. After day three you must have the reinstated and open, or you won’t get a closure license again. You close the road from 8am on day one and by 6pm of day three it must be open.”
Digging out went according to plan. Before Croom Concrete gave a final quote they asked Joe O’Donoghue to dig two trial holes to a depth of 16 feet. Why so deep? The top of the culvert is two feet below the road surface. The culvert itself is 9 feet. Then we were putting in a tank another six feet lower again. That’s 17 feet in all.“We were lucky with the site. It was good ground to dig and there were no water mains or other services. If a fibre-optic cable is present, for example, that can add a lot to cost.”A six-inch bed of four inch down stone was placed level in the trench with a capping of four inches of dust which was well rolled. A laser was used to ensure the floor was level.
A 2,000 gallon tank was installed at each end of the underpass.
Eight of these big culverts were required. They weigh 12t and only two could be carried on each run of the truck. The culverts were lifted into place with Croom Concrete’s 80ft mobile crane.
Here we see a culvert being lowered into position. The lifting chains are fixed onto thee anchor points. The work is directed by the site foreman Ned Murphy. Each box culvert is cast with a male and a female end. This allows for each one to be fitted into the next, locking the tunnel together and giving a close seal. The crane driver will position each culvert as close as possible to its final placing.
If necessary a culvert will be nudged into place by the excavator. Once the trench floor is level the underpass will be level. Mastic sealant is squeezed into the joins to keep out dampness.
“We got all of the box culverts in place on day one.”
Joe Costello said.
“We started lifting them in at 4pm and finished at half nine.”
Once all eight culverts were in place the remaining trench outside the culverts is backfilled. Joe Costello places these “Lego” blocks at the sides to retain the backfill material.Manufactured by Croom Concrete, these blocks are four by two feet and weigh 1.6t. Like the popular toy they have dimples on top and recesses at the bottom and can be interlocked without the need for mortar. The box culverts are covered with a heavy plastic sheet and then four inch down, rolled in layers, to within four inches of the road surface. On top of this went three inches of wet 804, leaving one inch for a tar and chip layer.
A wall of Lego blocks is then built on top of the underpass, in the line of the hedge to support a soil bank. New hedging will be planted on this soil bank.
Next the Croom Concrete team moves to the tunnel approaches. The Lego blocks are used to build retaining walls on each side. According to Joe Costello, the blocks have the advantage of being quick to install and are of similar cost to a shuttered concrete wall.The side banks are then shaped and the approaches are linked up to the farms existing passages. The first 15 feet of road coming out of the underpass on each side is concreted. Here, on the yard side of the tunnel, proximity to a silage pit means the approach includes a 90-degree turn and the retaining walls are quite long.
At the outer end the tunnel road can take a more direct route. We see that the underground tank has been covered with slats and a galvanized safety manhole. They will be emptied with a vacuum tanker when required.
“I don’t know how often I will have to empty the tanks.” Joe O’Donoghue said.
“The cows are now using the underpass for over a month and everything is very clean.”The box culverts are made with a smooth finish floor. Croom Concrete placed two-inch layer of concrete on the floor for grip, strengthened with plastic fibre.
(Mooney, P. (2012). Road underpass high enough for a tractor. The Farmers Journal, 2nd June 2012, p.42 – p.43) – From the farmersjournal.ie