Increased property development has resulted in a larger proportion of land with non-permeable surfaces which, when combined with prolonged periods of rainfall, can give rise to nuisance groundwater and flooding. Whilst traditional piped drainage systems require an outflow to storm drains or soak-aways, the Energy-Passive Groundwater Recharge Pump (EGRP) system empowers you to deal with rainfall at source, cost effectively, environmentally and with minimal disruption. EGRP, a worldwide patented technology, enhances and accelerates the soils ability to absorb water using the physical properties of hydrostatic pressure, a mild vacuum and gravity. Also, the devices themselves have no moving parts, require no external energy source and are self-cleaning.
To learn more about our EGRP Supported Infiltration Trench click here
Figures 1 to 6 below show a lateral cross section of EGRP devices as the ground goes through stages of wetting and drying. This process, repeated again and again over a period of time, creates numerous fissures around each device allowing water to travel down through the chambers where it is released into unsaturated soil strata up to 12 metres below ground level.
The EGRP system is vertically installed into the layer of earth between ground level and the water table, called the Vadose Zone. Typically this zone is made up of a variety of soil types which form many lateral strata of varying depths and which, depending on their content of clay, silt, sand and gravel respectively (and also level of compaction), can severely inhibit the grounds permeability as water becomes trapped between any impermeable layers of soil. The higher the clay and silt content the lower the natural permeability of the soil. Therefore, following bouts of heavy or prolonged rainfall the ground becomes saturated resulting in either nuisance standing water or water run-off causing flooding elsewhere.
The EGRP system tackles this problem by vertically breaching these impermeable layers and allowing water to reach lower unsaturated strata thus relieving saturation at ground level and equalising moisture content throughout the depth of the device. Over time, and following many cycles of wetting and drying, fissures are formed around the EGRP as shown in Fig. 5 & 6 above, which allows water to travel away from the devices, discharging directly into the ground. It is important to note that each EGRP is capped and that water finds its way into the system laterally and not vertically.
Ground Water Dynamics process for new enquiries:
PROBLEM - Client confirms why nuisance groundwater, saturation and/or flooding is causing disruption to their commercial, sporting or personal activities.
SITE INVSTIGATION – Site visit & investigation, obtain site services drawing including existing drainage assets (if any), identify site topology/local waterways.
ANALYSIS - Analyse local bore hole records, undertake a soil particle size distribution analysis to identify soil type, test infiltration rates.
DESIGN DRAWING - Create the design drawing showing the type, density and location of the EGRP devices (including any existing drainage assets).
RECOMMENDATION – A detailed proposal including risk assessment, method statement, schedule of works and design parameters for the proposed installation.
EGRP SOLUTION - A client specific bespoke system incorporating numerous EGRP devices installed at varying lengths with little or no disruption and requiring no outflow.
Key features of a Groundwater Dynamics EGRP solution:
Each EGRP device is capped before being inserted into a vertical bore hole 65mm in diameter and is positioned 20 centimetres below ground level. The bore hole is then top dressed with a free draining soil/sand mix before a turf core is replaced, a process which causes little or no disruption and avoids any form of settlement post install.
It then takes approximately 12 weeks for the soil to close in around the EGRP (as shown in Fig.1 above), a period we term as the ”acclimation period” after which the system begins to work. Groundwater finds its way into the system laterally before using the EGRP as an elevator shaft in order to access lower levels of unsaturated soil. Therefore instead of experiencing saturated ground near the surface, the system equalises moisture content throughout the depth of the bore hole, whilst the device stops the bore holes from closing in, which in turn creates permanent ”Aeration” across the whole installation. In dry and hot weather the EGRP system enables moisture to travel back to the surface which stabilises moisture content in the ground and rehydrates the root zone.
To learn more about our EGRP Supported Infiltration Trench please click here