Winter Groundwater Monitoring – West Sussex

Background:

Omnia were commissioned by our client to undertake winter groundwater monitoring for the 2025/2026 winter groundwater monitoring period (October to April) at a site in Chichester, West Sussex.  

The site was proposed to be developed from existing agricultural land use into new residential dwellings. Winter groundwater monitoring was required to assist with development of the site, specifically in relation the drainage design for the site. 

Scope of Works

An intrusive investigation comprising windowless sampling was completed in September 2025 to record the ground conditions at the site, and to install eight (8no.) winter groundwater monitoring locations for use during the 2025/2026 monitoring period. 

In October 2025, Omnia deployed groundwater level loggers in all eight monitoring wells, and a barometric pressure logger in one of the wells in order to obtain a continuous groundwater level data set for the winter monitoring period. Level loggers recorded measurements at 1 hour intervals, with monthly spot monitoring undertaken by Omnia to collect manual groundwater level readings for calibration and to ensure accuracy of the continuous monitoring results. 

Outcome

Omnia provided our client with a factual report of the works which included ground conditions encountered on-site, results of monthly manual groundwater monitoring and the results of the continuous groundwater monitoring. The report identified shallow groundwater levels of less than 1.00m bgl in areas of the site which were noted to have a potential impact on the development.