2014-01-29_HYDROLOGY - P2009025 ‎(8)‎

• Permit No: P2009025
• IBM Index Class Name: HYDROLOGY
• Doc Date: 1/29/2014
• Doc Name: Baseline Hydrologic Monitoring Plan
• From: Black Range Minerals
• To: DRMS
• Email Name: TC1
• Media Type: D
• Archive: No

Appendix D — SOP for Stream Flow Measurement — Hansen Project 13
Table 3, Number of Subsections Based on Stream Width
Approximate Width,
in feet
Approximate Number
of Subsections
Approximate Distance between
Subsections, in feet
< 2
8- 10
0.2 -0.3
2- 4
10 -12
0.3 -0.4
4-10
12- 15
0.4 -0.7
10 -20
15 -20
0.7 -1.0
> 20
20-25
1.0-2.0
3.2.3 Required Measurement Conditions
In order to make a velocity -area discharge measurement, the following conditions are required:
1. The stream must be channelized: that is, observable banks must channel the stream flow
2. Depth must be greater than 0.2 foot across most of the cross section being measured
3. The stream must have measurable velocity of at least 0.2 feet per second (fps) in most of the cross
section, although the Pygmy meter is capable of measuring velocity as low as 0.070 fps
Conditions No. 2 and No. 3 often can be met in streams of very low discharge by conservatively modifying the
stream channel to produce a narrower and slightly deeper cross section in order to meet measurement
requirements. An effort will be made to find a channel that is straight, and relatively uniform in depth. The
channel may be modified, including removal of aquatic growth or ice, moving large stones which impact
velocity upstream or downstream of the cross - section, and narrowing or deepening of the cross section. By
rearranging small amounts of native rock or sand, the sampler will produce a measurable cross section. When
such modifications are made, great care must be exercised to avoid unnecessary movement of sediments or the
splashing of sediments or water onto field team members. After thus clearing the cross section, flow will be
allowed to stabilize before the current -meter measurement of velocities begins.
Current meter measurements are best made by wading, if conditions permit. Wading measurements have a
distinct advantage over measurements made from cableways or bridges in that it is usually possible to select
the best of several available cross sections for the measurement. The type AA or Pygmy meter is used for
wading measurements. Table 4 lists the type of meter and velocity method to be used for wading
measurements of various depths.
Table 4. Current Meter and Velocity Method for Various Depths
Depth
Velocity Method
in Feet
Meter
% of Depth)
1.5-2.5
Type AA
0.6
0.3 - 1.5
Pygmy
0.6
<0.3
Pygmy
0.5
Some departure from Table 4 is permissible. For example, if a type AA meter is being used in a measurement
section that has most of its depth greater than 1.5 feet, the pygmy meter should not be substituted for a few
depths that are less than 1.5 feet, or vice versa. The type AA meter should not typically be used in depths less
than 1.25 feet.
In the six - tenths depth method, an observation of velocity made at the vertical at 0.6 of the depth below the
surface is used as the mean velocity at the vertical. The five- tenths depth method will be used in very shallow
stream conditions, with depths of less than 0.3 feet. This method requires that the meter be set at one -half the
depth of water at the point, or at the lowest setting on the rod.
4153A.140129 Whetstone Associates •