Monitoring well

Monitoring well

Provide controlled access to a selected subsurface interval, so GW levels, water quality, or hydraulic properties can be measured reliably.

Monitoring well purposes

Hydraulic head movement, GW sampling, site characterization

Hollow-stem auger works best in what material?

Soft, unconsolidated sediments

How does a hollow-stem auger work?

Auger stem is sealed at the bit by a removable plug, keeping cuttings and GW out while drilling. The sealed stem acts a temp casing, holding borehole open without a separate casing string. Plug is removed at target depth to allow soil sampling or well installation below auger bit. Plug can be reinstalled to continue advancing, or well screen and casing can be installed within open augers.

Well casing materials

rigid pvc, stainless steel

Rigid pvc

Strong, lightweight, chemically resistant for many GW conditions and commonly used for routine monitoring wells. Economical option.

Stainless steel

Very strong, preferred at greater depths. High corrosion-resistance: preferred where PVC combability or sorption could affect organic-contaminant sampling.

Single conventional well measures?

Head & samples water over 1 screened interval, blending signal across interval

Multilevel monitoring wells measure?

Head and water quality at multiple hydraulically isolated depths within same aquifer or across aquifers

Multilevel monitoring well configurations

Angled or vertical well cluster, vertical concentration profile

Angled well cluster

Wells installed at angles from 1 surface location, each screened at different depth (e.g., WW canal site)

Vertical well cluster

Wells installed vertically at 1 surface location, each screened at different depth (e.g., surface spill site)

Vertical concentration profile (well)

Single well blends concentration over its screen; discrete-level sample (e.g., from a drive-point profiler) resolve how concentration varies with depth.