ELEVATIONS OF BENCH MARKS, OBSERVATION WELLS, AND 

PRODUCTION WELLS AT MATHER AIR FORCE BASE, 

SACRAMENTO COUNTY, CALIFORNIA, 1988

By M.E. Ikehara, W.F. McCaffrey, and J.S. Williams

U.S. GEOLOGICAL SURVEY

Open-File Report 88-716

Prepared in cooperation with the

U.S. DEPARTMENT OF ENERGY

AND U.S. AIR FORCE, AIR TRAINING COMMAND

o i

CTi 

CM 

CM

Sacramento, California 

1989
DEPARTMENT OF THE INTERIOR

DONALD PAUL HODEL, Secretary

U.S. GEOLOGICAL SURVEY

Dallas L. Peck, Director

For additional information 

write to:

Copies of this report may 

be purchased from:

District Chief 

U.S. Geological Survey 

Federal Building, Rm W-2234 

2800 Cottage Way 

Sacramento, CA 95825

U.S. Geological Survey 

Books and Open-File Reports 

Federal Center, Bldg. 810 

Box 25425 

Denver, CO 80225
CONTENTS

Page

Abstract .................................................................. 1

Introduction .............................................................. 2

Surveying procedure and accuracy .......................................... 2

Elevations of bench marks ................................................. 9

Elevations of observation and production wells ............................ 9

Summary ................................................................... 16

Reference cited ........................................................... 16

ILLUSTRATIONS

Figure 1. Map showing primary network of survey lines, bench marks 

with historic data, and new bench marks for which 

elevations were obtained in June 1988 .................

2. Map showing observation and production wells for which

elevations were obtained in June 1988 .................

Page

4

6

TABLES

Page 

Table 1. Summary of level closures for the five survey lines

comprising the primary network ................................ 8

2. Elevations determined from this survey and previous

leveling surveys for selected bench marks ..................... 10

3. Elevations and descriptions of new bench marks .................. 11

4. Elevations and descriptions of runway reference marks ........... 12

5. Elevations of measuring point for observation wells ............. 13

6. Elevations of measuring point and/or reference point of

production wells/ and adjacent land surface ................... 14

Contents III
CONVERSION FACTORS

For use of readers who prefer to use International System (SI) units, 

rather than the inch-pound terms used in this report, the following conversion 

factors may be used:

Multiply By To obtain

foot (ft) 0.3048 meter (m)

mile (m) 1.609 kilometer (km)

inches (in.) 25.40 millimeter (mm)

IV Conversion Factors
ELEVATIONS OF BENCH MARKS, OBSERVATION WELLS, AND

PRODUCTION WELLS AT MATHER AIR FORCE BASE,

SACRAMENTO COUNTY, CALIFORNIA, 1988

By M.E. Ikehara, W.F. McCaffrey, and J.S. Williams

ABSTRACT

Precise and accurate elevations of water-level-observation wells on Mather 

Air Force Base near Sacramento, California, were needed to determine the direction of ground-water flow at and near the base. A total of 19 miles of primary 

survey lines were run on or near Mather Air Force Base. The datum of these 

surveys is based on National Geodetic Survey bench mark Y952 about 1.5 miles 

south of the base at the intersection of Jackson Highway (State Route 16) and 

Excelsior Road. The accuracy of these levels, based on National Oceanic and 

Atmospheric Administration standards, ranged between first and third order. 

Elevations of 41 bench marks, 76 observation wells, and 15 production wells on 

Mather Air Force Base were determined by differential leveling during June 

1988. Levels were run to a designated measuring point on observation wells, 

to the pressure valve of production wells, to the land surface adjacent these 

wells, and to selected bench marks, some of which are on runways or taxiways.

Abstract 1
INTRODUCTION

This report documents the elevations of 41 bench marks, 76 observation 

wells, 14 active production wells, and 1 former production well (figs. 1 and 

2). Fourteen of the 41 bench marks were recently installed on Mather Air Force 

Base near Sacramento, California. This study was done by the U.S. Geological 

Survey, in cooperation with the U.S. Department of Energy and U.S. Air Force, 

Air Training Command, as part of the Installation Restoration Program. The 

Installation Restoration Program has the objectives of identifying, evaluating, 

and mitigating potential problems caused by past handling and disposal of 

toxic/hazardous materials at Air Force facilities. The ultimate goal of the 

program is to prevent movement of any toxic or hazardous materials into areas 

where health and property could be endangered.

One aspect of the Installation Restoration Program is to determine flow 

directions of shallow ground water by measuring depth to the water table at 

observation wells. Because of the small topographic relief near the base, 

precise and accurate elevations of the measuring point on the wells are 

required.

The purpose of this study was to determine elevations of various bench 

marks, observation wells, and production wells on the base to a common datum; 

in this case, the National Geodetic Vertical Datum of 1929. In addition, a 

number of bench marks on runways and taxiways were included in the level 

network.

Surveying on the base was accomplished through the efforts of several 

individuals. Access to sensitive areas on the base and to the observation 

wells was facilitated by Lt. Col. Richard Blank of the Environmental Management 

Section. Mr. Richard Udell, Base Surveyor, served as liason between base 

security, SAC security, and the surveying crews, provided information on 

existing base bench marks, and helped install new bench marks on the base.

SURVEYING PROCEDURE AND ACCURACY

The differential leveling surveys were completed during June 1988 with 

most of the work completed during the morning hours. Field weather conditions, 

such as temperature and wind, generally were moderate during the survey period 

and tended to reduce the magnitude of error caused by refraction, and expansion 

and contraction of survey rods.

Equipment used in the surveys included the Zeiss N12 1 automatic compensating level, maintained in adjustment, and Philadelphia rods of the Lietz Precise 

Series. Foresight and backsight distances were balanced to reduce collimation 

error.

of brand names in this report are for identification purposes only 

and does not constitute endorsement by the U.S. Geological Survey.

2 Elevations of Bench Marks and Wells, Mather Air Force Base, California
Bench marks used were previously established by the National Geodetic 

Survey, U.S. Engineering Department, and the U.S. Bureau of Reclamation. All 

elevations for the U.S. Geological Survey 1988 leveling surveys are based on 

the elevation of National Geodetic Survey bench mark Y952 f which was established in 1962 and is about 1.6 miles south of bench mark HG-1 (fig. 1). Bench 

mark Y952 is in the top of the concrete head wall of double box culvert A-5.92, 

southwest of the intersection of Jackson Road (State Route 16) and Excelsior 

Road. Bench mark Q955 is set vertically in the center of the north face of the 

concrete porch of the building at 9978 Folsom Boulevard. This bench mark, also 

established in 1962 by National Geodetic Survey, was leveled to but was found 

disturbed. Thus, it was not used in setting the datum for the Geological 

Survey 1988 leveling surveys because the concrete porch had cracked and 

settled.

A total of 19 miles were surveyed to form the primary network (fig. 1) . 

Survey line A, to the south, and line B, to the north, originated from bench 

marks off the base. Line C, comprised of seven segments, totaled 8.94 miles. 

Segment D2, 1.26 miles, was part of line D that was 3.55 miles in length. 

Segment E6, 0.80 mile, was part of line E that was 2.92 miles in length. 

Because segment D2 was adjusted on the basis of the closure of line D, 1.26 

miles was subtracted from 8.94 miles, line C's total length. The other 

segments of line C were then adjusted for a difference of 0.087 foot in closure 

for the remaining 7.68 miles.

The National Oceanic and Atmospheric Administration, Federal Geodetic 

Control Committee (1980) (formerly National Geodetic Survey) has defined 

standards of accuracy for vertical-control surveys. These standards are based, 

in part, on the distance surveyed. The maximum closures for survey lines are 

computed as follows: Second order, class I 6mmt^7 second order, class II 

8mm/K; and third order 12 mm/K, where K equals one-half the total survey line 

distance, in kilometers.

The accuracy of the U.S. Geological Survey 1988 leveling surveys is based 

on closure differences for the survey lines. Lines C and E are third order, 

and lines A, B, and D are better than third order standard of accuracy. 

Closure differences ranged between 0.001 and 0.087 foot and had an absolute 

average of 0.032 foot. Adjustments for the various survey line and segment 

closures were based on line length. A summary of the level closures for the 

five survey lines comprising the primary network (fig. 1) is given in table 1. 

Once the primary network was established, levels to the observation wells, the 

production wells, and other bench marks were run as closed survey lines from 

the primary network. Locations of observation and production wells are shown 

in figure 2.

Surveying Procedure and Accuracy 3
4 Elevations of Bench Marks and Wells, Mather Air Force Base, California
w

Cn 

<

CD ^<H3 «£)

0 O CDa

38°32'30'

yfl Tft ' % ... ' > V-S f^*" W^dC*'" y *"' V^ / x" /-- W^- f±fe^/ {* 1 .. v>iA- . -' d

^~

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Base from U.S. Geological Survey, 1:24,000 

Buffalo Creek, 1967; Carmichael, 1967

2 MILES 

J

2 KILOMETERS

a

FIGURE 1. Primary network of survey level lines, bench marks with historic data, and new bench marks for which elevations were obtained in June 1988.
Ol-h

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sOJ fty(Dnfa H Hl-h O

121°17'30

38°35

EXPLANATION

PRODUCTION WELLS 

OBSERVATION WELLS

fvMather Fields
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Surveying Procedure and Accuracy 7
TABLE 1. Summary of level closures for the five survey lines 

comprising the primary network

Survey Survey

line line

(fig. 1) segment

Survey 

line name

Survey

line 

segment 

length 

(miles)

Total survey 

line length Closure 

(miles) (foot)

Y952 to TBM Spike 

and return

3.35 +0.004

B Q955 to 101-221 

and return

2.2 + .004

Cl 

D2 

C3 

C4 

C5 

E6 

C7

TBM Spike to H-MB-NE 0.61

H-MB-NE to MD-NE X 1.26

MD-NE to RM17 1.34

RM17 to 101-221 0.95

101-221 to TP36 3.48

TP36 to TP12 ^.SO

TP12 to TBM Spike 0.50

Total for line C segments only

MB-NE to MD-NE 

to MB-NE

6.88

3.55

.087 

+ .001

TP12 to TP36 

to TP12

2.92 -.063

segment distances are included in totals for lines D and E, as

applicable.

8 Elevations of Bench Marks and Wells, Mather Air Force Base, California
ELEVATIONS OF BENCH MARKS

Elevations determined from this survey and previous leveling surveys for 

selected bench marks are shown in table 2. Elevations for previous leveling 

surveys were furnished by Mather Air Force Base, private contractors, and other 

Federal agencies. Bench mark X744 was found slightly damaged, in that its 

surface was scratched and dented. Bench mark 101-101, northeast of the merging of Lower Placerville Road and Hoffman Street, was found with its concrete 

base lying at a 45 degree angle; therefore, it was not included in the leveling 

network. Bench mark 396+50 is a U.S. Bureau of Reclamation bench mark set in 

November 1972 at milepost 7.5 of the Folsom South Canal.

Fourteen bench marks were established on June 1, 1988, by the U.S. Geological Survey and the Base Surveyor, four of which are on the base runways. 

Elevations and descriptions of these new bench marks are given in table 3. 

Other reference marks on the runway are described in table 4, which also lists 

the elevations obtained in 1988.

ELEVATIONS OF OBSERVATION AND PRODUCTION WELLS

The primary objective of this study was to determine the elevation of the 

point to which water-level measurements are referenced, known as the measuring 

point. For observation wells, the measuring point was identified by two 

hacksaw-cut grooves cut in the top of the steel casing. The hacksaw grooves 

had been established earlier and often were marked with white paint. The 

measuring point for wells where the casing was finished below grade was two 

hacksaw-cut grooves in the flange of a steel ring (for the cover plate) , 

cemented in place flush with the land surface. Elevations of each measuring 

point for 76 observation wells are shown in table 5. Data furnished from previous surveys also are shown, with the caution that these elevations may not 

necessarily be for the same place on the well, because the designated measuring 

points were established just prior to this survey.

The measuring point of production wells generally was a pressure line 

valve, which usually could not accommodate a survey rod owing to its location 

with respect to the pump and motor assembly. In such a situation, a reference 

point near the measuring point was surveyed to, and the difference between the 

two points was measured to determine the elevation of the measuring point. The 

elevations of the measuring point and/or reference point, and adjacent land 

surface for the production wells are given in table 6. A former production 

well, designated AC&W, no longer has a designated measuring point.

Elevations of Wells 9
TABLE 2. Elevations determined from this survey and previous 

leveling surveys for selected bench marks

[USGS, U.S. Geological Survey; MAFB, Mather Air Force Base; 

USED, U.S. Engineering Department]

Elevations, in feet

Bench

mark

(fig. 1)

Y952

Q955

101-020

101-066

101-067

101-072

101-075

101-142

101-143

101-144

101-208

101-215

101-221

101-222

101-223

101-227

101-228

101-229

101-249

X744

ALEX

USED 9578 (S-760)

USED WT

USED 6&G

USED G&G

396+50

uses

1988

__

--

118.92

125.67

123.84

82.37

81.60

128.62

149.43

150.20

78.80

79.96

88.54

88.52

90.69

72.34

72.38

73.27

81.59

94.25

76.90

85.63

85.67

86.99

88.90

142.88

MAFB

118.98

125.74

123.90

128.70

149.53

150.29

78.90

80.06

88.55

88.52

90.71

94.35

85.75

85.65

87.05

__

 

Private

contractor

119.15

125.74

82.44

81.67

149.53

150.29

94.34

77.00

85.72

87.05

__

Other

Federal

agencies

1 88.648

71.174

2 94.31

--

3 142.90

National Geodetic Survey bench mark on which leveling is based. 

2 U.S. Engineering Department bench mark, National Geodetic Survey value from 

1st order survey, 1944-45.

3 U.S. Bureau of Reclamation.

10 Elevations of Bench Marks and Wells, Mather Air Force Base, California
TABLE 3. Elevations and descriptions of new bench marks

Bench mark 

(fig. 1)

Elevation 

(feet)

Description

HG-1

H-MB-NE

H-MCH-SE

MD-NE

GC-SW

OOI

ALICIA

SAN

QUINN

JOHN

87.56 Brass tablet on southeast end of Mather Boulevard

bridge over Morrison Creek, near south entrance to

base, Wherry Housing Gate. Stamped HG-1.

113.75 Brass tablet on sidewalk at northeast corner,

intersection of Mather Boulevard and Branch Drive 

West. Stamped H-MB-NE.

103.83 Brass tablet on concrete pad for manhole cover at

southeast corner, intersection of Mather Boulevard 

and west entrance to Chapel #2. Stamped H-MCH-SE.

127.82 Brass tablet on concrete headwall of culvert at

northeast corner, intersection of Mather Boulevard 

and Douglas Road. Stamped MD-NE.

126.58 Brass tablet on southwest corner of bridge abutment on 

Eagles Nest Road across Morrison Creek at Mather 

Lake outlet, near entrance to Mather Golf Course. 

Stamped GC-SW.

140.50 Brass tablet on southwest corner of concrete pad for 

guardhouse at Douglas Road Gate. Stamped OOI.

73.85 Brass tablet on northwest side of concrete pad for 

observation well MAFB-58, which is southeast of 

gravel pits at southwest corner of base. 

Stamped ALICIA.

75.02 Brass tablet on southeast corner of concrete wall of 

Sacramento County sewer waste-treatment flowmetering station near southwest end of runway. 

Stamped SAN.

69.94 Brass tablet 38 feet southeast of center line of 

Perimeter Road in center of north concrete weir 

training wall beside enclosure 7100. Stamped QUINN.

67.10 Brass tablet on northwest side of concrete pad for

observation well MAFB-59, which is across road from 

jet test cell near southwest corner of base. 

Stamped JOHN.

Elevations of Bench Marks and Wells, Mather Air Force Base, California 11
TABLE 3. Elevations and descriptions of new bench marks Continued

Bench mark Elevation 

(fig. 1) (feet)

Description

4R 75.00 Brass tablet at center line of southwest end of runway

4R (22L); southwest side of intersection with 

taxiway G; 14 feet runway side of threshold. 

Stamped 4R.

4L 78.72 Brass tablet at center line of southwest end of runway

4L (22R); southwest side of intersection with 

taxiway E; 14 feet runway side of threshold and 

reference mark PK. Stamped 4L.

22R 91.78 Brass tablet at center line of northeast end of runway

22R, at northeast side of intersection with taxiway 

B; 14 feet runway side of threshold. Stamped 22R.

22L 95.97 Brass tablet at center line of northeast end of runway

22L, at northeast side of intersection with taxiway 

A; 14 feet runway side of threshold. Stamped 22L.

TABLE 4. Elevations and descriptions of runway reference marks

Reference

mark 

(fig. 1)

Elevation 

(feet)

Description

TACAN

PK

94.61 Painted circle on taxiway A, between northeast ends of 

runways 22L and 22R.

78.58 Steel pipe driven flush with pavement at center line 

of southwest end of runway 22R, at threshold; 

14 feet southwest of BM 4L.

ARS 82.40 Brass tablet centered between runways 22R and 22L;

southwest edge of taxiway D; known as Airport 

Reference Station. Set by National Geodetic Survey. 

Stamped ARS 1983.

12 Elevations of Bench Marks and Wells, Mather Air Force Base, California
TABLE 5. Elevations of measuring point for observation wells

[See figure 2 for location of observation wells]

Elevations, in feet

Mather 

Air Force 

Base well

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27B

27C

28

29

30

31

32

33

34

35

36

37

June 1988 

survey

131.68

130.78

128.04

173.38

135.21

98.34

74.75

76.06

79.36

81.11

80.38

96.52

92.21

92.45

92.12

120.04

121.66

119.78

131.40

127.00

127.79

132.67

132.42

126.80

125.41

122.80

147.93

147.56

135.20

131.27

134.25

92.98

93.53

80.88

81.33

80.65

82.27

78.82

Previous 

surveys

96.53

91.89

92.59

92.20

120.04

121.66

119.68

131.41

127.06

127.77

137.95

132.52

126.67

125.89

122.83

147.96

147.58

134.79

130.71

133.90

93.01

93.33

80.81

80.97

80.14

81.85

78.63

Mather 

Air Force 

Base well

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

75

76

June 1988 

survey

77.75

75.00

39.54

73.64

74.98

75.15

76.30

77.75

68.60

77.24

75.63

92.26

124.34

126.72

123.78

131.33

118.68

40.03

74.17

75.34

75.52

69.62

77.48

78.43

80.06

76.09

132.38

134.28

93.51

129.41

131.44

133.87

123.60

131.48

117.07

92.76

133.42

132.92

Previous 

surveys

77.79

75.03

39.06

73.16

74.74

74.97

75.49

76.94

68.31

76.53

75.32

91.47

123.43

126.35

122.08

133.43

117.70

39.19

73.40

74.38

74.60

69.10

76.90

78.13

78.99

75.08

123.30

128.71

93.03

129.08

130.77

133.40

123.51

128.22

116.95

92.67

127.38

123.33

Elevations of Wells 13
TABLE 6. Elevations of measuring point and/or reference point of 

production wells, and adjacent land surface

[MP, measuring point; RP, reference point; LS, land surface]

Production Designation Elevation 

well (feet)

Description

Base 1

Base 2

Base 3

Base 4

FH-1

FH-2

FH-3

MP 

RP

LS

MP 

RP 

LS

MP

RP 

LS 

RP

LS 

MP

LS

MP 

RP 

LS

MP 

LS

92.93

92.18

92.0

92.32

92.18

91.0

92.74

92.34

90.5

95.69

93.3

113.51

110.9

103.60

103.19

101.8

122.63

119.6

Top of pressure line valve 

Temporary point on building 

floor

Top of pressure line valve 

Concrete pad

Top of i-inch pipe elbow with 

sealant securing the 

flexible pressure line

Concrete pad below i-inch 

pipe elbow

Surveyed top of J-inch steel 

plate bolted to pump housing, 

with gauge fitting welded to 

other end of plate

Surveyed top of J-inch steel 

bracket bolted to pump 

housing. (Gauge is attached 

to movable pressure line, 

thus not surveyed.)

Top of pressure line valve 

Concrete pad

Surveyed top of pressure line 

valve

14 Elevations of Bench Marks and Wells, Mather Air Force Base, California
TABLE 6. Elevations of measuring point and/or reference point of 

production wells, and adjacent land surface--Continued

[MP, measuring point; RP, reference point; LS, land surface]

Production 

well

FH-4

FH-5

FH-6

GC-1

GC-2

K-9

JTC

AC&W

(former)

Designation

MP

RP

LS

MP

LS

MP

RP

LS

MP

LS

MP

LS

MP

RP

LS

MP

LS

RP

LS

Elevation 

(feet)

112.93

112.14

110.6

124.51

121.5

115.59

114.43

112.8

126.25

124.0

139.41

137.7

151.25

151.44

149.9

70.62

69.1

134.64

133.2

Description

Top of pressure line valve

Concrete pad

Surveyed top of pressure

line valve

Top of pressure line valve

Top of bolt on concrete pad

Surveyed top of 2-inch pipe

set at an angle on the

east side of concrete pad

Surveyed top of pressure

line valve

Top of horizontal pressure

line valve

Top of carpenters level

placed on horizontal

pressure line valve

Surveyed top of horizontal

pressure line valve

Surveyed top of 1-inch

diameter circular steel

protrusion on west side of

5-inch diameter discharge

pipe to south wall.

(Pressure line is movable,

thus not surveyed.)

Elevations of Wells 15
SUMMARY

Knowledge of the depth to the water table at Mather Air Force Base is an 

integral part of the Installation Restoration Program. Measurements made at 

water-level-observation wells and production wells on the base rely on accurate 

determinations of the elevations of the measuring points of these wells. Differential surveying produced accurate elevations for 76 observation wells, 15 

production wells, and 41 bench marks on Mather Air Force Base, all tied to a 

common datum the elevation of bench mark Y952, published in 1962.

REFERENCE CITED

National Oceanic and Atmospheric Administration, Federal Geodetic Control 

Committee, 1980, Classification, standards of accuracy, and general 

specifications of geodetic control survey: 12 p.

16 Elevations of Bench Marks and Wells, Mather Air Force Base, California