IMPERMEABLE AREA STUDIES

IMPERMEABLE AREA STUDIES

An Impermeable Area Survey is a requirement in understanding how sewer networks perform during periods of rainfall and to incorporate into hydraulic models. Surveying methodology is to use a variety of techniques to determine where the rainfall landing on roofs, pavements, roads and other hard standing surfaces ultimately drains to.

Rainfall run off entering the foul sewer network will cause excessive flows in pumping stations and treatment works and may cause polluted sewage to overflow into watercourses, hence the water companies are keen to identify any potential source of storm water entering the foul network.

Normal practice is to survey positions of highway storm drains and road gullies and to verify that they run to a storm sewer system, watercourse or soakaway and not the foul drainage network. Property roof drainage is surveyed at the sample rate as specified by the client and is indicatively shaded on base mapping as to which drainage system it ultimately finishes within. Techniques used in the field surveys include dye tracing, sound testing, rodding and portable CCTV surveying to assist in identifying storm connections into the foul network. Output of data is normally presented in MapInfo table format or AutoCAD drawing mark ups to the clients specification.

EXAMPLE IAS MAP INFO MARK UP

CONTACT US