Why Booster Pump Placement Matters Near Streams

Umbilical manure application has become a go-to option for moving large volumes of manure efficiently while keeping heavy tanks out of the field. But with long hose runs, connections, and high pressures, failures can and do happen. One of the more concerning scenarios is a hose rupture or leak near a stream or drainageway.

Where we place the booster pump relative to that stream can make a big difference in how much manure is released if a failure occurs, and whether that release becomes an environmental incident or not. Hopefully you’ve heard the best management practice is to place the booster pump across the stream so the pressure is lower in the hose as it crosses the stream, but why?

The Scenario

Imagine an umbilical system crossing a small stream. Somewhere near the stream crossing, the hose develops a hole. This could be from abrasion, a weak spot, damage during setup, or even normal wear. The key question is:

·         Is that section of hose under high pressure or low pressure when the failure occurs?

That depends entirely on where the booster pump is located.

Two Booster Pump Options

Option 1: Booster pump on the near side of the stream

·         Pump → high-pressure hose → stream crossing → toolbar

Option 2: Booster pump on the far side of the stream

·         Pump → high-pressure hose → toolbar

·         Stream crossing is on the suction / low-pressure side of the booster

From a manure movement perspective, both setups can work. From a spill risk perspective, they are very different in how quickly we are going to leak manure.

Figure 1. Demonstration of how to fix a leak in an umbilical hose at the Manure Expo.

 

Why Pressure Matters When a Hose Leaks

The flow rate through a hole is directly related to pressure. For a small hole or tear, the leak rate is approximately:

Where:

QL is the leak flow rate

Cd is the discharge coefficient (typically 0.6 to 0.7 for sharp-edged holes, which we will assume (thought it does mean there is enough pressure to keep the hose rigid, which may not actually be the case

AL is the area of the leak (the cross sectional area of the hole)

Delta p is the pressure difference inside the pipe versus outside, which I’m being lazy and assuming doesn’t chance from the pre-leak conditions compared to when the leak starts (it does change and the pressure will go done, but how much depends on the relative resistances and gets a bit more math heavy then we need).

Rho is the density of the fluid

That square-root relationship is important. If pressure increases by a factor of four, the leak rate roughly doubles, and that is the basis of the recommendation. By controlling the location of the booster pump, we are controlling the pressure should a leak occur in the worst possible location, the hose in the stream.

A Simple Pressure Comparison

Let’s put some reasonable numbers to this.

Typical umbilical operating pressure downstream of a booster pump: 120 psi

Pressure upstream (suction side) of a booster pump: 30 psi

Let’s assume a 1” diameter hole, that manure has the same density of water, and we’ll set C_d = 0.65.

Option 1

Option 2

 

All that to say, by quadrupling the pressure (120 psi vs 30 psi) we doubled the rate of leakage (212 gpm vs 106 gpm).

 A low-pressure leak may be slow, noticeable, and more easily stopped before reaching water

Why the Stream Crossing Should Be Low Pressure

Placing the booster pump across the stream ensures that the hose segment near the waterway is operating at the lowest pressure in the system. That does three important things:

·         Reduces leak flow rate if damage occurs

·         Buys response time to shut down the system

·         Limits environmental consequences if manure reaches the stream

This is a classic example of risk-based design: assuming failure can happen and designing the system so that when it does, the consequences are minimized.

Positioning booster pumps so that environmentally sensitive areas, streams, ditches, intakes, and tile outlets, are exposed to as low-pressure hose as practically possible.

Practical Takeaways for Applicators

·         Always identify stream crossings during hose layout

·         Place booster pumps after the stream crossing, not before to minimize risk should a break occur.

 One last thought, is there a tank equivalent to this? Yes. If loading near the barn or in the field, look for the location that offers the least risk should a tank overflow occur. In particular this means looking for surface inlets around the loading area and trying to move as far from them as possible.

We can’t prevent every spill, but we can manage to minimize their occurrence and any negative environmental impact they may have.