Executive Summary
· Building your first silage clamp in England typically takes 6–12 months from concept to first fill
· The process runs across three parallel tracks: design, planning, and SSAFO / Environment Agency compliance
· Early clarity on tonnage, crop type, clamp format, and location helps avoid redesign and delays later
· Most clamps require either agricultural permitted development or full planning permission, depending on size and site sensitivity
· All new or altered clamps must comply with SSAFO regulations, including impermeable construction and minimum separation distances from water
· Sloping-walled silage clamp design supports more consistent compaction, particularly at the shoulders
· Improved compaction and sealing help reduce effluent production and dirty water volumes
· Sloping walls also support cleaner drainage control and easier, more reliable sheeting
· The combined effect is lower environmental risk and simpler day-to-day compliance
· Good design and build quality make ongoing maintenance, operation, and silage management easier over the long term
Building your first silage clamp is a significant investment for any livestock farm. When designed and built well, it becomes a long-term asset that supports forage quality, efficient working, and regulatory compliance for many years.
In England, a new silage clamp typically takes 6–12 months from initial concept to first fill. That time is usually spent progressing three areas in parallel: design, planning, and SSAFO / Environment Agency compliance.
This roadmap outlines what to expect at each stage, and how a carefully engineered, sloping-walled silage clamp design can support both compliance and silage performance from the outset.
Step 1: Define your brief (2–4 weeks)
Before speaking to planners or engineers, it’s important to be clear about what the clamp needs to deliver for your business.
Key points to establish early include:
· Expected tonnage, crop types (grass, maize, wholecrop), and number of fills per year
· Preferred clamp format, such as a drive-over pad with walls or an open pad with interlocking block walls
· Location on the farm, considering traffic flow, proximity to feed areas, neighbouring properties, and distance from watercourses or boreholes
At this stage, it is also helpful to sketch rough dimensions to understand whether the clamp is likely to fall under or over 1,000 m², as this influences the planning route. Identifying obvious constraints, such as existing drains or overhead services, can also prevent issues later.
Early design input from ARK can help shape a brief that works for today while allowing flexibility for future growth.
Step 2: Planning route and timescales (1–4 months)
Most new silage clamps in England require either agricultural permitted development (prior approval) or full planning permission.
In broad terms:
· Clamps under around 1,000 m² that meet Part 6 GPDO rules often fall under permitted development.
· Larger clamps, sites close to housing, or those in sensitive areas usually require a full planning application.
Typical timescales include:
· Preparing drawings and supporting information: 3–6 weeks
· Prior approval decisions: usually 28 days
· Full planning applications: commonly 8–16 weeks, depending on site complexity
An early conversation with a specialist agricultural planner can help avoid delays and unnecessary redesign later in the process.
Step 3: SSAFO and Environment Agency compliance (1–2 months)
All new or substantially altered silage clamps must comply with SSAFO regulations, which are designed to protect watercourses from pollution.
Key requirements include:
· An impermeable base and walls resistant to silage effluent
· Design to recognised standards such as BS 8007 or BS 5502
· A minimum 20-year design life with routine maintenance
· A minimum separation of 10 m from inland or coastal waters
The Environment Agency must be notified at least 14 days before construction starts. Using a properly engineered and certified design helps make this process straightforward and reduces future compliance risk.
ARK designs clamps with these standards in mind from the outset, so compliance is built in rather than addressed later.
Step 4: Detailed design and specification (4–8 weeks)
Once planning and regulatory requirements are clear, detailed design begins. This is where ARK’s sloping-walled silage clamp design plays a central role.
Rather than vertical walls, ARK’s clamps use inward-sloping concrete walls, designed around how silage behaves in practice during filling, consolidation, and sealing.
Why ARK uses sloping walls
Sloping walls offer several practical advantages:
· More consistent compaction at the shoulders, helping silage settle evenly across the full width of the clamp
· Reduced pressure on the walls, as silage loads are directed down into the base rather than pushing laterally
· Easier sheeting and sealing, supporting a tighter, more reliable seal at the edges
· Safer, more efficient operation, with improved visibility and working clearance for loading machinery
ARK designs clamps around real farm workflows, including efficient trailer access, consistent consolidation across the clamp width, and integration with existing yards and feed faces. Clean and dirty water are clearly separated, and surface finishes, edge detailing, and safety features are specified to support grip, durability, and safe day-to-day use.
Supporting effluent control and environmental risk management
Alongside these operational benefits, sloping-walled silage clamps can also support effective effluent management.
By enabling better compaction at the shoulders, sloping walls help reduce the amount of free liquid released during fermentation. Fewer air pockets also limit secondary heating processes that can increase effluent production.
The wall geometry supports cleaner, more predictable drainage, with effluent flowing towards channels and collection points rather than pooling at poorly compacted edges. Sloping walls also make it easier to achieve a secure, consistent seal, helping to limit rainwater ingress, which is a major contributor to unnecessary effluent and dirty water volumes.
The overall effect is indirect but meaningful: less effluent created, lower escape risk, and smaller volumes of contaminated water to manage, supporting the underlying aim of SSAFO regulations through sound design and good on-farm practice.
Step 5: Construction and installation (2–4 months)
With approvals in place and the Environment Agency notified, construction can begin.
A typical build includes:
· Groundworks and sub-base preparation
· Installation of effluent tanks and pipework
· Concrete base pours and wall installation
· Finishing works such as kerbs, safety barriers, and drainage connections
Adequate curing time should be allowed before loading, and effluent systems should be tested before first use. Many farms aim to complete construction outside peak silage season to keep pressure on the programme to a minimum.
Step 6: Ongoing use and maintenance
Once built, the clamp must be kept in good repair and operated correctly:
· Address any cracks, joints, or leaks promptly
· Use good filling and sealing practices to limit effluent and oxygen ingress
· Keep records of designs, certifications, and EA notifications
A well-designed clamp makes both ongoing compliance and good silage management easier to maintain over the long term.