HOW TO CHECK IMPURITIES IN SAND ON SITE
· Any clay or silt will settle slowly on the top of the sand layer If salt is added in water one teaspoonful to a pint it will quicken the process and silt will settle in a layer on top of the sand layer Thickness of silt layer should not exceed one seventh or 6 % of that of sand below If thickness of the silt layer is more sand needs washing