AgFirst Engineering has extensive experience in land drainage throughout New Zealand. The drainage of agricultural and horticultural soil is critical to ensure the ability to maximise production.
Soil drainage problems can occur as a result of many different soil characteristics, soil surface compaction, impervious water layers, rising water tables, surface water inflows and poor soil drainage characteristics.
The first most important issue when designing a land drainage system is to identify the cause of its drainage problem. This is often a result of a combination of different soil drainage impediments.
AgFirst Engineering can assist with the design of land drainage systems. To complete a land drainage design requires a number of stages:
Stage One: The site and underlying soils are investigated to determine the cause of the drainage problem. The site is surveyed, providing information on contour, open drain depths etc.
Stage Two: A drainage system is designed to over come existing drainage problems and provide the required drainage coefficients. In an orchard situation it is important that the design takes into consideration its potential for tree root infestation.
Stage Three: The implementation of the drainage design. In some situations this is a staged process that occurs over a number of years.
AgFirst Engineering has had considerable experience in the design of pumping stations for both small and large catchment areas. In most cases land drainage pumping stations will require a resource consent to discharge drainage water. Once design specifications are determined a resource consent must be applied from the Regional Council to enable the discharge to occur.
Pumping stations are often required for subsurface drainage systems due to insufficient outfall depth. It is critical that subsurface drainage pipe installation depth is not sacrificed as a result of a shallow outlet drain. Subsurface drainage pipe installation depth is critical to the effective operation of a land drainage system.