Rebuilding an ineffective pump station, a series:
Article Five, by Douglas Muscott CID, Lad Irrigation Co
The pipelines for the water inlet and return flow are now connected and we are ready to backfill the entire pump structure and compact the lifts of fill in preparation for concrete. This was a complex operation involving trucking the saved fill material back to the site and placing it where needed with the 590 excavator seen in the photos below. We also used the vibratory compactor attached to the excavator to make sure we have no dangerous settling after concrete is poured and water is turned on.
We have loaded the dump truck with clean fill material we saved from our original demolition. Our operator is placing it carefully into the bottom of the original excavation so we can compact it properly. We are taking extreme care not to come in contact with the existing steel pump structure and cause damage to our newly poured concrete box. Jack is shoveling fresh fill into places we will pack with our hand compactor.
With the vibratory compactor attached to the excavator, we can now pack the lifts of soil we have placed into the original excavation. This is a multi-step operation and we change between the three foot bucket and the “Hoe Pack” several times as we prepare the site for our concrete pump pad and electrical control center. The closest vertical pipe will house a 75 HP turbine pump and the far pipe will house a 50 HP turbine pump. The 4” black one will house a level control transducer. The bucket covers the return flow air vent.
Here we see the Hoe-pack compacting the pad site while Jack uses the hand compactor to pack between the vertical pump chamber pipes. The center vertical pipe will be a spare for now, providing a home for a backup pump if the customer chooses to add one at a later date. The concrete pad will be 18 feet wide and 22 feet long so he Hoe-pack is compacting the entire site which was measured out and corner pinned to define the needed work area.
The day turned very foggy with the temperature never above 32 degrees. Here Jack is holding the Lazerplane target, giving Mark a tone signal so he can level the pad site exactly to the sub grade needed for the concrete pad to set on. The excess compacted soil will be placed on the north side of the pumping structure and compacted around the inlet and return flow pipes and give Jack a firm footing to pour the concrete structures required there.
Below we see the overall view of construction standing on the east side of the site looking to the west. The pump pad sub grade is accurately set with our Lazerplane and the perimeter forms are set with four inches of pad fall from the waterbox to the south edge of the pad. Rick is running our hand compactor on the west side of the site which is where the return flow water will go to its appropriate pipeline. As will show in future articles, some of these pipelines are two way which complicates construction of the pipefitting down the road.
The electrical controls are prefabricated in our shop and pre wired by our licensed electricians. Looking from left to right we see the 200 amp meter base with 3” conduit incoming. Next to the meter base is our 5 KVA transformer to give 110V single phase power for convenience and lighting. Then is an empty space for a future pump controller if the customer decides to add the spare pump at a later date. Then there is the NEMA #3 pump control panel for the 50 HP Turbine pump which will be controlled by the white box which is a 75 HP VFD that will operate on a pressure transducer to maintain the customer defined set point for the hydraulic system.