Controlling Intermediate Corners

Instructor:Dennis J. Mouland, PLS

© Witness Tree Consulting, Inc., 2011, All Rights Reserved

Course Objectives

• Define CIC’s for surveying purposes• Familiarize with background of various CIC’s• Discuss evidence analysis• Review use and application of CIC’s• Examine methods for restoration of lost CIC’s

The textbook:

www.blmsurveymanual.org/errata

Define

• What was the normal “level of control” set by the GLO?– Section and Quarter-Section Corners

• These are controlling, but intermediate…….• Intermediate to the normal level of control• But still control something• Line, and most proportioning

Some CIC’s exist due to procedure

• Meander Corners• Closing Corners• Crossing Closing Corners• Subdivisional Corners set previously

Others due to field conditions

• On-line Witness Corners• Line Trees• Witness Points

How do we know they exist?

• They must be in the official GLO/BLM record

• Always in the notes• Sometimes also shown

on the plat• If they were noted, you

MUST look for them• If found, they MUST be

used

22.46A pine, 36ins diam.

Chains

LT

WP

1/4

RECORD MEASURED

Lost 1/4

LT

WP

What CIC’s will do to your survey

We will discuss some of the CIC’s in detail:

Meander Corners

• Why set to begin with?• What is a meander line?• Why needed today?• If found, how does it control line?• Do we use it in proportions of lost corners?• Do we use it to set subdivisional corners?• If lost, should it be reset?

2009 Manual

• “A meander corner is established at every point where a standard, township, or section line or special survey boundary intersects the OHWM of a navigable stream or other meanderable body of water.”

(3-173)

MC’s

Meander Corners• Found?• Use to re-establish

meander line itself• Use to fix alignment at

that point of section line

• Use to set lost corners on section line

• Use to proportion subdivisional corners along section line

• Lost?• Must be re-established

to determine any riparian issues

• If there has been erosion or accretion, the original MC position must be determined AND a new MC set at the current OHWL

Lost ¼ Corner:

48.13 (R) = 8.1048.08 (M) X X= 8.09chs

Lost MC:

26.29 (R) = 8.1026.44 (M) X X= 8.15

On-line Witness Corners

• Why do WC’s exist?• What about off-line WC’s?• New policy in the 2009 Manual which aligns with

BLM internal policy• Always controls the alignment• Use differs between section corners and

quarter section corners

True Story

WC Sec. Cor.

¼ Cor.

Private Land

National Forest

Where Witness Corners might be a good idea!

WC 5.00

40.0

040

.00

1/4

WC WC

Record Measured Result

34.6

245

.22

34.6

2

5.024

40.1

96

WC 1/4

WC Section Corner

40.0

040

.00

Record

40.00 40.00

WC 5.00

Result

40.0

040

.00

40.00 40.00

WC

Controlling bearing pushed through at 5.00 chains (Record)

Brg Brk at Sec Cor

Line Trees

• Must be called for in the notes, and cite species, diameter, and distance to the nearest link.

• Courts have ruled that they are monuments of the original survey, which causes an angle point in the line.

• Used for proportioning lost corners and subdivisional corners. See BLM 6-28.

40.0

07.

54

1/4

Record

LT 32.46

¼ LOST

Measured

S1/16 to be set

Proportion for 1/4M= 47.45

M=32.40

47.54 = 7.5447.45 X

32.46 20.0032.40 X

Witness Points

• How differ from Witness Corners?• Sometimes referred to as “artificial line trees”• Utilized the same as line trees• Control line and alignment for lost corners and

subdivisional corners

Closing Corners(2009—7-45)

• When an original closing corner is recovered off the line closed upon and the new monument is established at the true point of intersection, the original position will control in the proportionate restoration of lost corners dependent upon the closing corner. In a like manner the positioning of sixteenth-section corner(s) or lot corner(s) on the closing line, between the quarter-section corner and the closing corner, will be based on the measurement to the original position of the closing corner.

CC CC

CC

1.21 1.21

2.06

1/4 Lost 1/41/4

N1/16ths to be set

True section corners at intersection pointsProportions go to original CC positions

Actual Section Corner

Lost/sub cors proportioned to orig point

CCSec Cor ¼ Cor.

¼ Cor.

1/16th to be set

R=40

.27

M=4

0.22

Fd. 0.28 links north of twp. line

40.27 = 20.2740.22 X X=20.24

MINUS 0.28 = 19.96

40.27 = 20.0040.22 X X=19.975

Crossing Closing Corners

• Closing corners in some cases have been established where a line of the survey crosses previously surveyed claim lines (section 3-74 “Intersecting and Terminating Section Lines”). These corners are established after a retracement of the line intersected and monumented when administratively required. In the past, these corners have been termed “crossing closing corners.” (2009—7-48)

CCC’s

• Will bend lines if it controls the line when created

• Can be used to proportion lost corners if it controls:– Non-rectangular corners– Subdivisional corners– Lost PLSS corners

When you find a CIC………

• Remonument as an AP• Take accessories• Make the details part of your record• Where on the line trees?

If they are lost………

• Was it ever retraced and shown off-line?– Re-establish by proper method (7-34)

• Never used by a survey?– May not need to be re-set

• MC’s always should be re-set• CCC’s usually should be re-set – B/B intersect• WP still needed?• CC’s adjusted once: then treated as equal

Rec. Measured

Remon as an APTake accessories

Conclusion

• CIC’s exist in the field• You must search the record for their existence• You must search for them in the field• You must use them as appropriate control for

the line as is, lost corners, or subdivisional corners to be set

• Their use is not optional• They will change your survey results

CONTROLLING INTERMEDIATE CORNERS

© Witness Tree Consulting, Inc., 2011, All Rights Reserved