Lined Slurry Lagoons

Installing The Lagoon - A Brief Overview

• Once a farmer has decided that he is installing a lined lagoon, a representative of JMG will visit his farm, size up the correct lagoon capacity and give the farmer a drawing with the dimensions of the excavation to be dug.
• JMG or the farmer will source an excavation contractor who digs out the hole in the ground. On the last day of excavating, a representative will visit the site and advise the digger driver how exactly the ground should be prepared.
• A land drainage pipe is placed in the lagoon floor and brought to a nearby ditch, to take away ground water.
• The floor of the lagoon is covered with 3 inches of pea gravel (provided by the farmer).
• A leak detection system is installed in the floor of the lagoon (optional).
• An anchor trench is dug around the top of the tank for liner anchorage.
• The lagoon is lined with our 2.5mm HDPE Liner and welded together to form a 100% seal.
• A 1.8m fence is put around the lagoon, which has chainlink wire and a row of barbed wire on top of the fence (optional).
• The agitation pad is installed over the liner and this also includes a wheel stop and safety railing (optional).
• Finally a tyre rope is hung from the fence posts at suitable intervals and extended down into the lagoon. This is for emergency escape from the lagoon in the event of an accident (optional).

Key Steps:

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 liner.

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 earth.

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.

Jones McGirr & Co can also supply and install other mixing systems including a lagoon mixer/whisk and aerator. Please contact us for more information on this option.

Grant Approval

The lined lagoon qualifies for full Grant Approval under the Farm Nutrient Management Scheme (Northern Ireland), the Grant Scheme in Scotland and meets the requirements of CIRIA specification required for installations in England and Wales. It is important to note the following:

• Farrmers must supply their relevant environment agency with a completed SSAFO notification form signed by our engineer 28 days before the facility is first brought into use.
• Storage facilities must not be sited within 10m of a watercourse.
• Lined lagoons require 750mm freeboard.