Standard Operating Procedures for Surface Water Sampling

STANDARD OPERATING PROCEDURES FOR SURFACE WATER QUALITY SAMPLINGFIGURE 1. Float switch assembly installed into well screen PVC pipeFLOAT SWITCH INSTALLATIONFloat switches are intended to enable autosampler programs as water levels rise causing the float tocomplete the circuit. The float switches are connected to the autosamplers via half cables (ISCOpart # 790 and Sigma part #541), normally 25’ in length. The half cables are connected directly tothe float switch wires or via a two-wire junction wire. The ISCO half cables consist of only twowires whereas the Sigmas contain six (6). It does not matter how the ISCO half cables areconnected to the two wires on the float switch. However, when using the Sigma half cables, theblue and black wires must be connected to the float switch wires.The float switch consists of a donut-shaped float that moves up and down a rod with a retainingclip on the bottom. The ISCO and Sigma autosampler programs are triggered when the circuitcreated by the half cable and float switch is either opened (ISCO) or closed (Sigma). In order tochange whether the circuit is opened or closed under “dry” conditions, the donut-shaped float canbe removed, reversed and reinstalled. A test trigger should be conducted to ensure that the floatswitch is functioning properly prior to final installation and during maintenance events.The float switches are placed in the stream bottom and set to trigger the autosampler when thewater level rises sufficiently to engage the float. The float switch assembly can be mounted oneither a bedrock outcrop (preferred) or on a masonry brick or garden paver using 2” fence postmounting brackets. Ideally access to the float switch assembly will be unobstructed afterinstallation. Periodic cleaning and maintenance may be needed. Mounting to rock or brickrequires a hammer drill, masonry drill bit, generator, sledge hammer, anchor bolts and nuts, andan appropriately sized wrench. Prior to installation proper authorization shall be received inwriting from the land owner or managing entity.REVISED SEPTEMBER 2012 289