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Revised Measuring-Point Elevations for Selected Wells in the Waihee and Iao Aquifer Areas on the Island of Maui

The USGS has been working with the National Geodetic Survey (NGS) to update benchmark and well measuring-point elevations in central Maui as part of a groundwater availability study with the Maui Department of Water Supply. The purpose of this effort is to ensure that water-level monitoring wells used in this study are tied to a common and accurate vertical datum.

Benchmark and reference-mark elevations were determined by the NGS using differential GPS (Global Positioning System) methods during September 2-4, and November 18-20, 2003.

Well measuring-point elevations were determined by the USGS using vertical leveling surveys from NGS benchmarks and USGS reference marks during September 22-26, and December 15-19, 2003.

Measuring-point elevations for selected wells in the Waihee and Iao aquifer areas are provided below. The difference between the previously reported and the revised measuring-point elevation for each well is also provided. Leveling notes and photographs of the measuring points are available in well folders maintained by the USGS Water Resources office in Honolulu.

It is important to recognize that the revised well measuring-point elevations will result in a modification of the absolute water levels (referenced to mean sea level), but not the relative change in water levels measured over time (trend).

Historical water levels measured in these wells may be revised pending further research into possible causes for the differences between the previously reported and the revised well measuring-point elevations. Future water-level measurements will be based on the revised well measuring-point elevations.

An additional set of measuring-point elevations were updated to provide a common datum for a synoptic water-level survey conducted on May 17, 2005. Benchmark and reference-mark elevations were determined by the NGS using differential GPS (Global Positioning System) methods during May 10-12, 2005. Well measuring-point elevations were determined by the USGS using vertical leveling surveys from NGS benchmarks and USGS reference marks during September 19-23, September 26-28, and November 29 - December 1, 2005. A second table of the additional measuring-point elevations is provided below.

 

Related links:

Ground-Water Availability in Central Maui - Project description

Recent Hydrologic Conditions, Iao Aquifer area, Maui - Updated every three months

 

Well measuring-point elevations, in feet above mean sea level, for selected wells in the Waihee and Iao aquifer areas on Maui

Released January 6, 2004; Updated May 21, 2004 using final NGS benchmark elevations.

[RM, reference mark; MP, measuring point; ft, feet; --, no data]

Well name

State well number

Revised1

Previous

Difference2

Notes regarding previous well measuring-point elevations 3

Kupaa 1

5731-03

638.77

639.37

-0.60

C. Takumi Engineering report (1/31/00) provides MP elevation of 639.37 ft for top of casing, based on leveling from a benchmark elevation of 631.87 ft located about 200 ft from well (Exhibit A-1, Mink & Yuen, 6/21/99). Driller's well-completion report provides MP elevation of 638.10 ft for top of casing (5/20/99). No record of MP survey notes and initial benchmark. Wailani Drilling and Ed Valera (surveyor) combined trigonometric leveling (using a total station and vertical angles) from Tanaka's work and a carpenter's level to get the initial height of casing.

Kanoa TH

5731-05

303.56

305.22

-1.66

USGS reports MP elevation of 305.22 ft for top of casing, based on leveling from nearby RM - 1-inch pipe (1/22/03). RM elevation of 304.50 ft provided by C. Takumi Engineering. No record of RM survey notes and initial benchmark. K. Tanaka set the 1/2-in. pipe using trigonometric leveling (using a total station and vertical angles).

Kanoa 1

5731-02

308.14

--  

--

Driller's well-completion report has elevation of 309.15 ft for top of pump base plate (5/29/99). No record of MP survey or initial benchmark.

Kanoa 2

5731-04

280.48

--  

--

Driller's well-completion report has MP elevation 281.83 ft for top of sounding tube (6/7/00). C. Takumi Engineering report (Aug. 2000) has 281.38 ft for top of sounding tube (Exhibit A, Mink & Yuen, 7/12/00).

North Waihee 1

5631-02

283.76

285.23

-1.47

USGS reports MP elevation of 285.23 ft for top of measuring tube, based on leveling from nearby RM - 3/4 inch pipe (8/12/97). RM elevation of 266.63 ft given by W.S. Unemori Engineering. No record of RM survey notes and initial benchmark in well folder, however, Unemori confirms this elevation from their notes. From information provided by Reed Ariyoshi of W.S. Unemori, and Wendy Taomoto, MDWS, the best estimate of the difference between the top of the casing prior to pump installation and the measuring tube after installation is 1.01 ft (old casing higher in elevation). As a result, the old mp for data prior to August 1997, 284.78 ft, is very close to the new measuring tube elevation plus 1.01 ft (284.77 ft).

North Waihee 2

5631-03

283.62

--  

--

Height of measuring point modified after pump installation. Measuring tube modified twice since pump installation in 1997 and leveling on 8/12/97. USGS reports MP elevation of 284.39 ft for top of measuring tube on 8/12/97. USGS reports MP elevation of 284.33 ft for top of measuring tube on 3/30/99 after first modification, based on measuring up from base plate elevation of 284.11 ft. Previous leveling on 8/12/97 and 3/30/99 are based on RM (3/4-inch pipe) elevation of 266.63 ft provided by W.S. Unemori Engineering. No record of RM survey notes and initial benchmark in well folder, however, Unemori confirms this elevation.

Waihee TH A1

5631-01

246.17

248.05

-1.88

Driller's well-completion report provides elevation of 248.05 ft for top of drilling platform (10/15/74). Surveyed from State of Hawaii benchmark U-6: 250.37 ft (1974). No record of survey notes.

Waiehu TH D

5430-04

380.95

380.66

0.29

USGS reports MP elevation of 380.66 ft for top of 1.75-inch PVC casing, based on leveling from nearby RM - "X" chiseled in concrete at entrance to TH D shelter (8/23/85). RM elevation of 380.01 ft provided by Dan Lum, DOWALD (8/29/83). No record of RM survey notes and initial benchmark.

Waiehu Deep

5430-05

381.16

380.84

0.32

USGS reports MP elevation of 380.84 ft for top of 10-inch casing, based on leveling from RM - "X" chiseled in concrete at entrance to TH D shelter (8/23/85). RM elevation of 380.01 ft provided by Dan Lum, DOWALD (8/29/83). No record of RM survey notes and initial benchmark.

Waiehu TH B

5431-01

492.15

492.51

--

USGS reports MP elevation of 492.51 ft for top of 1.5-inch PVC casing (9/24/75). However, later field notes show top of casing as 491.79, and top of surrounding wooden box as 492.51. No record of MP survey notes and initial benchmark. Probably surveyed from State of Hawaii benchmark U-6: 250.37 ft (1974). Driller's report provides elevation of 493.97 ft for top of drilling platform. Well has been measured from top of wooden box since USGS started measuring well in July, 1982. Well modified 3/31/04 by USGS, adding 0.74 ft to top of PVC casing. Revised MP (top of PVC casing) combines changes due to recent surveying and modification. Elevation of top of box was lowered by 0.42 ft from results of 2003/2004 surveying.

Waiehu Heights 2

5430-02

338.05

--

--

Notes in well folder show pump refurbishment in 1998. Measurement tube likely installed at that time. No prior leveling notes or references in USGS well folder.

Waiehu TH E

5430-03

415.65

416.75

-1.10

Norman Saito Engineering Consultants, Inc. provides MP elevation of 416.75 ft for top of 1-inch casing (9/14/82). No record of MP survey notes and initial benchmark. Probably surveyed from State of Hawaii benchmark U-6: 250.37 ft (1974). Driller's report provides elevation of 415 ft for land surface.

Mokuhau 1 (Pump 2) 4

5330-09

353.37

353.79

-0.42

USGS reports MP elevation of 353.79 ft (12/1/99). No record of MP survey and initial benchmark. Dan Lum (DOWALD) provides MP elevation of 353.57 ft for access port at base of pump (1/17/72). H.A.R. Austin Engineering provides elevation of 353.17 ft for top of casing (6/4/53).

Wailuku Shaft 33

5330-05

32.33

32.17

0.16

USGS reports MP elevation of 32.17 ft for top of casing, based on leveling from Wailuku Courthouse NGS benchmark elevation of 331.066 ft (4/17/97).

Waikapu 1

5130-01

551.04

551.33

-0.29

USGS reports MP elevation of 551.33 ft for top of 6-inch coupling, based on leveling from RM - 0.5 inch pipe located on the east side of the concrete foundation (4/11/75). RM elevation of 550.61 ft provided by Norman Saito Engineering, based on leveling from Wailuku Courthouse NGS benchmark (12/74). Dan Lum (DOWALD) provides elevation of 552.08 ft for top of 8-inch casing, and 551.15 ft for top of conductor pipe (5/14/74).

Waikapu 2

5130-02

518.96

519.33

-0.37

USGS reports MP elevation of 519.33 ft for top of casing, based on leveling from Waikapu 1 well MP elevation of 551.33 ft (6/21/83). DOWALD as-built drawing provides elevation of 519.47 ft for top of 20-inch casing.

DWS Waikapu Mauka

5131-01

764.87

--

--

USGS surveying on 12/29/03 to top of 6-inch threaded coupling welded to plate that is welded to the top of the 18-inch casing (highest point after removing plug). CWRM well completion report and Water Resources International as-built drawing provides elevation of 764.7 ft for top plate welded to 18-inch casing. 

1 Revised well measuring-point elevations were determined by the USGS using vertical leveling from National Geodetic Survey benchmarks and reference marks in December 2003. NGS benchmark and reference mark elevations provided by NGS on 1/20/04. Leveling notes and photographs of the measuring points are available in well folders maintained by the USGS Hawaii District Office.

2 Difference calculated by subtracting the previous from the revised well measuring-point elevation.

3 All information contained in USGS well folder.

4 Maui Department of Water Supply refers to this well as Mokuhau Pump 2 (Well 502) whereas Commission on Water Resource Management well index refers to this well as Mokuhau 1.

 

 

Well measuring-point elevations, in feet above mean sea level, for selected wells in central Maui.

Released June 15 2006.

Well name

State well number

Measuring point elevation

Kihei Shaft Pump 1

4727-01

4.58

Kihei Exploratory

4824-01

594.30

Kihei Shaft Pump 3

4825-01

4.83

Maalaea Power Plant (Pump 1)

4829-02

16.93

Maalaea 272

4831-01

165.50

Puunene Airport Shaft

4928-02

50.08

Waikapu Shaft Pump 7

5128-02

5.37

Waikapu Baseyard

5129-02

227.36

Puunene Pump 9

5224-02

5.48

Puunene Pump 5

5226-01

4.62

Puunene Pump 6

5226-02

5.08

Puunene Pump 19

5227-05

74.50

Reynolds 2

5228-07

116.90

Maui Lani 2

5229-03

151.29

Kaheka Pump 18

5321-01

4.78

Central Power Plant

5327-07

3.86

Cannery Shaft

5328-01

4.28

Maui Central Park 1

5329-19

74.99

Maui Central Park 3

5329-21

51.28

Paia Pump 17

5422-02

5.05

Lower Paia Pump 16

5423-02

4.52

Sprecklesville Pump 4

5424-01

4.40

 

 

 

 

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