A06 Specifications.docx

Salient Characteristics S20122 The USGS Water Science Center in Flagstaff, AZ needs to purchase one (1) Non-Calibrated Screw Meter and shipping case. This equipment is intended to be used for investigating changes in groundwater storage and determining aquifer properties. This equipment will be used to make repeat measurements of gravity at selected sites. The difference in gravity between successive measurements will be a measure of change in the mass of water present in the subsurface at the site.

NON-CALIBRATED SCREW METER

SALIENT CHARACTERISTICS:

1 EA, Non-Calibrated Screw Meter:

1. The USGS Southwest Gravity Program (which includes the Arizona, New Mexico, and California Water Science Centers) has constructed hundreds of concrete survey monuments for carrying out relative-gravity surveys. These monuments are critical because the meter must be placed in the exact same position and orientation during each survey. The meter must fit in the monuments that have indentations to locate the 3 legs of the meter. These legs are spaced 6.50 inches apart (between the reference and cross legs) and 7.75 inches apart (horizontal distance between the reference leg and long leg).

2. Shall be a portable, “all-in-one”, sealed, weather resistant type unit.

3. Shall have a metal, zero-length spring.

4. Shall have a data resolution of at least 0.001 mGal or less.

5. Shall have repeatability of at least 0.01 mGal or less.

6. Shall have a maximum measurement drift of less than 1.0 mGal per month when mature.

7. Shall have a minimum range of 50 mGal for gravity readings.

8. Shall have an operating range of -15° to +50°C (5° to 122°F).

9. Shall have rechargeable lithium batteries and charger.

10. Shall be capable of operating at least 10 hours on battery power.

11. Shall include operational software and handheld controller to show and record real-time data.

1 EA, Case:

12. Shall include shipping case for unit.