Gage Location Specifications

Gage Installations - Location Specifications and Considerations for Upgrades

• 2020 Installation Plan - Priorities and details for 2020 installations

General Guidelines

FOR EACH LOCATION KEEP IN MIND:

Accessibility

• Ease of access to transmitter box to change batteries or remove for troubleshooting or repair.

Theft and Tampering

• This hasn’t been a significant problem, but something to keep in mind.
• Our strategy has been to label prominently and to make removal require intention

Safety

• The transmitter box must be able to be accessed safely.
• Some sites are in inherently dangerous locations especially during flooding (minimize additional potential hazards i.e. use of ladders, heavy swinging arms that don't have breaking winch, having to stand on edge of steep drop offs, etc.).

Data Reliability

• Sensor must be at same exact height in exact same position each time it is raised and lowered.

• Sensor must be perpendicular to ground.

• If on a cantilevered arm that raises and lowers, the arm must be level and static when raised.
• We must be able to accurately measure the height of the sensor over the local benchmark elevation. The height will be measured on initial install and then once or twice a year for verification.

Flood Height

• Sensors must be mounted above 60’ flood level.

• The USGS Carnation gage recorded 60’ flood was ~4.5’ higher than the Oct 22, 2019 flood.

• Height requirements for 2020 installations

Device Consideration

Antennas

• Must be mounted directly on transmitter box and cannot be extended.

Transmitters

• Mount transmitter as high as possible to improve line of sight and RSSI.
• Must be easily accessible from the ground or using a short ladder.
• Can be mounted separate from sensor.
• Cannot become submerged during flooding.

Sensors

• Can be mounted separate from transmitter.
• Cannot be mounted higher than the range of sensor (30’ sensor: 30’, 14’ sensor: 14’)
• Come with 6’ cable - can be cut.
• Can be ordered with longer cables (15 – 200').
• Will not give accurate readings if flood waters are within 10” of the sensor face.
• Can be submerged during flooding BUT, will not give accurate readings.
• Must be mounted directly over center of ditch/concrete pad.

Sensor Cone

• Emits an ultrasonic pulse with a 15° sensing cone.
• The higher the sensor, the larger the diameter of the sensing cone at the ground/water surface.
• Be sure the sensor is extended far enough from the mounting pole to not sense it.
• See Table 2. For cone diameters

Table 2. Ultrasonic Cone Diameters at Varying Heights

Distance from Sensor (ft)	Diameter of Cone (in)	Diameter of Cone (ft)
1	3.15	0.26
2	6.32	0.53
3	9.47	0.79
4	12.64	1.05
5	15.79	1.32
6	18.96	1.58
7	22.11	1.84
8	25.27	2.11
9	28.43	2.37
10	31.59	2.63
11	34.75	2.90
12	37.91	3.16
13	41.07	3.42
14	44.23	3.69
15	47.39	3.95
16	50.55	4.21
17	53.71	4.48
18	56.87	4.74
19	60.02	5.00
20	63.18	5.27
21	66.34	5.53
22	69.50	5.79
23	72.66	6.06
24	75.82	6.32
25	78.98	6.58
26	82.14	6.84
27	85.30	7.11
28	88.46	7.37
29	91.62	7.63
30	94.78	7.90

Links

• 2020 Installation Plan
• Gages