Every week across West Cumbria, green waste bins are filled with garden waste from homes and gardens. But do you know what actually happens to that material after it leaves your driveway?

 

At West Coast Composting, we work with Cumberland Council to transform green waste into high-quality PAS100 certified compost that can be used to grow healthy plants and improve soil.

 

Before explaining how the composting process works, it’s important to understand what can and cannot go into your green waste bin, as contamination affects the quality of the compost produced.

 What You Can Put in Your Green Waste Bin

 

Your green bin is for garden waste only. This includes:

 

• Leaves
• Hedge cuttings
• Dead flowers
• Weeds
• Prunings
• Grass cuttings
• Christmas trees (decorations removed and cut small enough for the lid to close)
• Twigs and small branches

 

What Cannot Go in Your Green Waste Bin

 

 The following materials cannot be collected in green bins because they contaminate compost:

 

• Soil, stones or rubble
• Food waste including fruit and vegetables
• Glass or metal
• Plastic, paper or cardboard
• Dog waste or cat litter
• Nappies
• General household waste
• Plant pots
• Animal bedding or faeces
• Daffodils or rhododendrons                                                                                                                                                                                                                                                                                If you have kitchen peelings, these are best composted at home in a domestic compost bin rather than placed in your green waste bin.

Do not bag your green waste.

Plastic bags contaminate the composting process and must be removed by hand.

 How Green Waste Becomes Compost

 Once the council workers have completed their area and their wagons are full, the green waste is brought in to West Coast Composting Ltd,  where the composting process begins.

 Producing certified compost requires a carefully controlled process that ensures weeds, pathogens and contaminants are removed.

 Here is how it works.

 Step 1: Green Waste Spread on the Yard

  Once the wagon has been weighed on our weigh bridge, the waste is mechanically spread in a designated area of the yard.

 At this stage the material is manually litter-picked by yard operatives to remove any obvious contamination.

 Step 2: Manual Sorting

 All green waste must be carefully sorted by hand to remove any non-compostable material.

 This stage is extremely important because:

 

• contaminants such as plastic or metal affect compost quality
• the finished product must meet PAS100 compost certification standards

Without this stage the compost could fail monitoring and sampling tests. You wouldn't believe the things we sometimes find in there! Secateurs,  fairy lights, garden knomes!

 Step 3: Material Shredding

 Once sorted, the material is shredded using a Doppstadt shredder.

 This machine reduces larger pieces into a consistent size so that the composting process can  begin efficiently.

 What shredding also does is:

 

• improves airflow within the compost
• speeds up decomposition
• helps reduce odours

 

The material is checked again during this stage to ensure contaminants are removed.

 Step 4: Windrows Are Formed

 After shredding, the material is placed into long piles called windrows.

 During the busiest summer period, the volume of green waste collected typically results in around one windrow being formed each month.

 Once a windrow is formed:

• no additional material is added
• the composting process officially begins.

 

Step 5: Monitoring and Sanitisation

 For the first four weeks, the windrows enter the sanitisation phase.

 During this time:

• temperature and moisture are monitored daily
• readings are taken at four points in each windrow

 To meet compost standards, temperatures must reach 55–72°C and be maintained for at least 15 days.

 

This heat kills:

 

• weed seeds
• harmful bacteria
• plant pathogens

 

The windrows are regularly turned using a 360 excavator, loading shovel or loadall to keep the material aerobic and biologically active.

 

Step 6: Stabilisation Period

Once the sanitisation temperatures have been reached and the material has broken down sufficiently, the compost enters the stabilisation phase.

 This lasts around four weeks.

 During stabilisation:

• decomposition continues
• temperatures gradually fall
• monitoring reduces to weekly checks

 The material becomes more stable and soil-like.

 Step 7: Screening (Trommelling)

 Once stabilised, the compost is processed through a trommel screening machine.This separates the compost by particle size.

 To meet PAS100 certification requirements, the finished compost must be 0–25 mm particle size.This produces a fine, consistent compost suitable for gardening and landscaping.

 West Coast Composting undergoes annual audits and sampling to maintain PAS100 certification.

 Step 8: Storage

Once screened, the finished PAS100 certified compost is transferred to the compost storage area.

 From here it can be:

• bagged
• loaded into bulk bags
• supplied loose for landscaping and agricultural use.

 

 Step 9: Oversize Material

Material that does not meet the size specification after screening is classed as off-spec compost.

This material is still organic waste and will either:

• be added into the next compost windrow, or
• be removed for land spreading.

 Nothing goes to waste.

Through this carefully controlled process, green waste collected from local homes is transformed into high-quality peat-free compost, helping return nutrients to the soil and supporting sustainable gardening across West Cumbria!

We regularly show videos and footage of the stages of the compost process and our firewood process on our social media channels. So follow us and you can see for yourself what goes on in our yard and how the compost is used throughout the community!

You can find us on Facebook, Instagram and Tiktok.