LOP C

Cross-sections, maps, and associated calculations such as extraction volumes, must be prepared under the direction of a State of California Licensed Land Surveyor or a legally authorized Professional Engineer and certified as to content and accuracy.

Monitoring cross-sections are permanent, monumented cross sections whose purpose is to document yearly and long-term changes in river channel elevation and morphology at extraction sites. They also aid in extraction planning and in estimation of volumes extracted.

Extraction zone cross-sections are temporary, seasonal cross-sections used for the planning an extraction, for estimation of the actual volume extracted, and for evaluating compliance with CHERT approved gravel plans. The extraction zone is the total area that will be extracted and/or graded as a result of gravel extraction activities.

A. Number and layout of required cross sections for an extraction project to follow the guidelines below:

1. A hypothetical center line for the river channel, measured equidistant from both banks and delineating the actively scoured channel (bankf'ull width) must first be established to determine the length of the project line.

2. If the radius of curvature is less than ten times larger than the average actively scoured channel width of the project reach, the reach is considered a bend. If the radius of curvature is more than ten times larger than the average actively scoured channel width of the project reach, the reach is considered straight.

4. Cross-sections shall be no more than 400 feet apart on bends and 500 feet apart in straight reaches. If the length of the project reach is not eveny divisible by 400 or 500 feet, the number of cross-sections should be rounded to the next larger number.

5. The first cross-section shall extend across the channel at the upstream limit of the project reach (entire project site); the last cross-section shall extend across the channel at the downstream limit of the project reach.

B. Cross-sections to extend completely across the river channel (so as to include all actively scoured channel width) and to temiinate either on banks in mature riparian vegetation (clearly older than 10 yr; DBH >4 in.), or on the 10-year flood terrace.

C. Two bench marks (permanent monuments) to be established for each bar above the watercourse's active banks and in positions such that they will not be eroded away by relatively frequent (<10 yr flow) events. Bench marks to be tied to a common vertical and horizontal control datum, the 1988 North American Vertical Datum (NAVD) and to the 1983 North American Datum (NAD), among all extraction sites.

D. Cross-section endpoints and tie points to be clearly monumented and labeled in the field and accurately located on current airphotos and maps. A common color of flagging, or environmentally benign painting to be used to mark cross-sections at all sites.

E. Cross-section endpoints to be placed far enough away from eroding banks that they will not be removed by relatively frequent flows (e.g., by floods smaller than the 10-year event).

F. Cross-sections to be resurveyed from the same endpoints each year New cross-sections to be added as necessary as the river's course shifts, and to be oriented approximately normal to the channel center line.

G. Pre-extracfion cross-secfion surveys need only include those portions of each cross-section inundated by the previous winter's highest flow. If the highest flow of the season occurs after the cross-section survey is completed, the cross-section must be resurveyed. AR monitoring cross-sections should be surveyed each spring, regardless of whether extraction took place in them in the previous year.

H. Post-extraction cross-sections need only be resurveyed through those portions of the cross-section altered by extraction, temporary stockpiles, road construction, and equipment storage areas.

I. Stake or spray paint the following points on the ground in each cross-section at time of survey (to facilitate the CHERT relating the cross-section at time of survey to the ground during field review):

1. water's edge on both sides of river; or if this is not practicable, stake at 10 ft offset (measured along ground surface) from water's edge. Position of stake to be included in survey.

2. on both sides of river, one hub (2 inch by 2 inch wooden stake), painted brightly and labeled, shall be driven in nearly flush with the ground at the survey point closest to midway between water's edge and cross section endpoint. Exception: this is not required if it would put the stake in a steep eroding bank.

3. Stakes should be labeled with the cross-section and station number (horizontal distance from left end point).

A. Number and layout of extraction cross sections for an extraction project to follow the guidelines below-

1. A hypothetical center line for the proposed extraction, located equidistant from both edges of the extraction zone and extending down its long axis must be established.

2. A minimum of 5 equally-spaced extraction cross-sections to be surveyed in each extraction zone or area.

3. Cross-sections shall be oriented perpendicular to the extraction center line.

B. Extraction cross-sections to be surveyed in prior to extraction, and used to design extraction and to estimate extraction volume.

C. Extraction cross-sections to be resurveyed after extraction is complete. Extraction cross- sections need not be resurveyed in subsequent years.

D. Extraction cross-sections require temporary (seasonal) monuments at each end, such as stakes or rebar, which can be relocated after extraction is complete.

E. Extraction cross-sections should be clearly staked and marked on the ground so that the CHERT can readily locate them in the field.

A. All Cross-Sections shall be prepared according to the following criteria:

1. Surveyed cross-sections shall be noted to the nearest 0. 1 ft and should include:

2. Cross-sections to be tied to a common vertical and horizontal control datum among all extraction sites. This is specified as the 1988 North American Vertical Datum (NAVD) and 1983 North American Datum (NAD) elevation for sea level.

3. Cross-sections at all sites to be plotted at the same simple, usable vertical and horizontal scales. All cross-sections must have a vertical exaggeration of 1O. Scales to use for cross-sections are as follows:

Cross-Section Width	Paper Size	Horizontal Scale
< 500 ft.	8 1/2" x 11"	1 in. = 100 ft.
500 ft. - 1200 ft.1 in. = 100 ft.	8 1/2" x 14"	1 in. = 100 ft.
> 1200 ft. - 1600 ft.	8 1/2" x 14" or 11" x 17"	1 in. = 100 ft.
> 1600 ft.	8 1/2" x 14" or 11" x 17"	1 in. = 100 ft.

Cross-sections can be cut and stacked so that whole cross-sections can be placed on one page. Cross-sections that are cut and stacked must be consistently presented each year.

4. Cross-sections to be surveyed and drafted consistently so that the right bank (RB) of the river as you face downstream is at the right side of the drafted cross-section-

5. Zero (0) distance in cross-sections to be at the left (LB) endpoint as you face downstream.

6. Cross sections to be plotted on gridded paper, where the grid logically corresponds to the scale at which the cross-section is plotted. We suggest a grid of 10 squares to the inch. Grid to be visible in the reproduced paper copies provided to the CHERT.

7. Cross sections to have clearly labeled vertical and horizontal axes. Each cross section should have its own horizontal axis to facilitate measurement of distances (rather than a single set of axis labels at bottom of page). Each cross-section should have its origin on a heavy grid line.

8. Any vertical or horizontal datum or endpoint changes should be clearly noted along with the length and direction of change(s) on the cross section plots.

9. Maximum distance between any two elevational points along a cross-section shall be 50 feet, including wetted portion. Exception: if ground outside wetted channel is essentially level for a distance of 500 feet, distance between points can be increased to 100 feet. All obvious breaks in slope must still be included.

10. Elevations, notations, etc. on the cross-sections shall be clearly legible.

11. Net cross-sectional area change pre-extraction to post-extraction, or post-extraction to next year's pre-extraction, as appropriate, should be calculated for each cross-section. Measurements and calculations should be included

12. The survey data for each cross section should be provided to the CHERT on a 3.5" diskette as a digital file in ascii text format (alphanumeric, tab-delimited). The data should be grouped by cross-section and organized from L bank to R bank, using the format below: An example is shown.

Point No.	Horizontal Offset	elevation	description
45	50	57.94	LB rebar
46	...	...	...

13. Cross-sections for planning extractions should be surveyed in late May of the year in which extraction is proposed. Cross-sections following mining to be surveyed as soon as practicable after mining ends, and definitely before winter high flows occur.

1. Where discernible, elevation and position of high-water marks for previous vanter's flow (floodmarks), these should be consistently determined among cross-sections

3. Cross-sections to include the river bottom (especially location of the thalweg) as well as the water surface. Water surface elevation alone is insufficient; the bed must be included.

4. Elevation and location of top of silt band ('bathtub ring") if visible at time of survey

6. Water discharge at time of survey (from nearest USGS gage) to be shown in cross- section legend.

7. Floodmarks, silt line, water's edge, monuments, CHERT reference stakes should all be clearly labeled in the cross-section and their elevations indicated.

8. For spring cross-section data all monitoring cross-sections shall include the current year's spring crosssection overlain on the previous year's spring and fall (if any) cross-sections. The area of actual extraction should be lightly shaded or hatched. Water-surface should be shown with a dotted line, and its date clearly indicated.

9. For pre-extraction survey, total volume changes in the previous year's post-extraction survey should be calculated using double end-area or computer generated digital terrain models. All measurements and calculations should be included and verified by a California Licensed Land Surveyor or appropriately authorized engineer.

10. For post extraction cross-section data, all monitoring cross-sections which overlap the extraction area shall include the cur-rent year's post extraction cross section data overlain on the current year's pre-extraction cross-section data and the previous year's post extraction cross-section data and the original prescription recommended by the CHERT. The post- extraction cross-section should be shown with a solid line, the pre-extraction with a dashed line. The actual area of extraction should be lightly shaded or hatched.

1. Spring extraction cross-sections shall include the spring cross-section data overlain on the CHERT approved prescription cross-section. The proposed area of extraction should be lightly shaded or hatched.

2. Post extraction cross-sections shall include the fall cross-section data overlain on the previous year's post extraction (if any) and the current year's pre extraction cross-section data and the CHERT recommended prescription cross-section. The actual area of extraction should be lightly shaded or hatched.

3. The net cross-sectionial area change pre-extraction to post-extraction should be calculated for each cross-section. Total volume extracted should be computed, using double end area or computer generated digital terrain models. All measurements and calculations should be included and verified by a California Licensed Land Surveyor or appropriately authorized engineer.

A. All site maps to be prepared on a color photocopy of an aerial photo from current year. Photos can be obliques for spring surveys. Site maps should show the river and the proposed extraction area. Site maps should have a scale of approximately 1:6000 (1 in = 500 ft).

B. All monitoring cross-sections should be accurately located and labeled on the site map. In particular, the end points of each cross-section must be located in their true positions, not just guessed at or estimated.

C. Pre-extraction photos should be taken when the river is low enough to see the channel. Earlier photos may be used for preliminary planning, but a current final set is required and should be used for the site map.

LOP Appendix C