1. Sizing the lagoon
Based on the regulations, which require 22 weeks storage
capacity, JMG recommends that 3,000 gallons is allowed
per adult animal. 2 calves / weanlings / followers can
be assumed to be equal to an adult animal. For example,
if you had 45 adult cows in total, then multiply that
by 3000 gallons and you get 135,000 gallon capacity needed.
2. Preparing the Excavated Hole
The excavated hole is to be dug to Jones McGirr and Co. Ltd drawings.
The four sides will slope down at 45 degrees, and not
vertical as with a slatted tank. The sides will be blinded
off with 2 inches of quarry dust or good quality topsoil
which is free of stones or roots. The floor will be covered
with 3 inches of pea gravel and the hole is ready to receive
3. Lining the lagoon
The lining membrane arrives on site in large rolls. Small
panels are then cut from these rolls and fitted into the
hole. The panels are overlapped, welded together and tested.
The liner is placed in the anchor trench around the perimeter
of the lagoon, then the trench is filled back in with
Lining The Lagoon
4. Fencing requirements
All lagoons have to be fenced with a 1.8m high woven
wire galvanised fence (BS1722 and BS4102), and a row
of barbed wire is put at the top of the fence all around.
The gateway in the fence will also be 1.8m high. Concrete
posts or galvanised 75 x 75 tubing bars are required
for the fence and these have to be 2.3m long. All posts
must be at least 400mm into the ground, surrounded by
concrete. A safety barrier is required around the agitation
pad. Tyre ropes are to be hung from the fence posts
and extended down into the lagoon for emergency escape.
|5. Agitation of the Lagoon
The lagoon can be agitated by both pump and propeller
type agitators. The pictures below illustrate how the
two different agitation systems operate.