1. 1 SUCTION DREDGING TECHNIQUES Placer Examination Techniques

2. 2 GENERAL PRINCIPLES The size of the dredge is directly proportional to the dynamics of the stream Width Width Depth Depth Thickness of the overburden Thickness of the overburden Logistics Logistics Size of dredge used by the operator Size of dredge used by the operator

3. 3 NUMBER OF PEOPLE  1 to 3 people  Small dredge (4-inch or less), 1-2 people  Medium dredge (4 to 6-inch), 2-3 people  Large dredge (6-inch plus), 3+ people  Although some prefer to dredge alone, efficiency drops and danger increases.

4. 4 NUMBER OF PEOPLE  One person operates the nozzle  Second person moves boulders and tends the dredge.  If water is deep, a third person is included as the dredge tender on the surface while 2 are always under water.

5. 5 NUMBER OF PEOPLE  1 person is 60% as efficient as 2 people Move boulders Move boulders Tend dredge Tend dredge Alternate with nozzle operator Alternate with nozzle operator Tender provides sample security on exams Tender provides sample security on exams Safer than working alone Safer than working alone

6. 6 DREDGE SELECTION  Large enough for the material being dredged  Enough suction to pull the material to the sluice  Deep enough water to float the dredge  Drafting  Deep enough to keep the intake submerged  Size is consistent with State regulations

7. 7 PERSONAL EQUIPMENT  Each examiner maintains his/her own equipment Wetsuits Wetsuits Face mask and snorkel Face mask and snorkel Gloves Gloves Footwear Footwear Knee pads Knee pads Weight belts Weight belts NEVER, EVER WEAR SUN SCREEN!

8. 8 TOOLS  Hand tools – pry bars  Long breaker bars  Come-alongs  Shovels and rakes  Rubber mallet  Rope  Crevice tools

9. 9 DEVELOPING A WORKING FACE  If a hole is not ready a working face is needed.  Move boulders and get them out of the way  Make a hole you can work in  Work upstream  Get it all and break up bedrock  Keep a controlled and consistent feed  Observe what you are dredging – check for Au

10. 10 AIR SUPPLY Two types of air supply 1.Snorkel Shallow water with thin gravel layerShallow water with thin gravel layer Easy maneuverabilityEasy maneuverability 2. Hookah Deep water – over 3 feet deep Deep water – over 3 feet deep Compressor, air lines, harness, regulator, reserve tank, filters, maintenance Compressor, air lines, harness, regulator, reserve tank, filters, maintenance

11. 11 SAFETY  Working under water, often swift water Under large boulders, stumps, embankments Under large boulders, stumps, embankments Limited visibility Limited visibility Moving heavy objects, carrying equipment Moving heavy objects, carrying equipment Depending on supplied air Depending on supplied air Extended periods in cold water Extended periods in cold water Possible contaminated water Possible contaminated water Using hand tools in conditions with limited visibility Using hand tools in conditions with limited visibility

12. 12 CERTIFICATION  Forest Service in California (Region 5) requires open diver certification