United States
Environmental Protection
Agency
Municipal Environmental 'Research EPA-600/2-78-208
Laboratory December 1978
Cincinnati OH 45268
Research and Development
Demonstration of
Erosion and Sediment
Control Technology
Lake Tahoe Region of
California
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2, Environmental Protection Technology
3. Ecological Research
4, Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7, Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous-Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate .instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-208
December 1978
DEMONSTRATION OF EROSION
AND
SEDIMENT CONTROL TECHNOLOGY
Lake Tahoe Region of California
by
Charles A. White
Alvin L. Franks
California State Water Resources Control Board
Division of Planning and Research
Sacramento, California 95801
Demonstration Grant No. S803181
Project Officers
Hugh Masters
Richard Field
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08817
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
. CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research Labora-
tory, U. S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U. S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendation
for use.
ii
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FOREWORD
The U.S. Environmental Protection Agency was created because of increasing
public and governmental concern about the dangers of pollution to the
health and welfare of the American people. Noxious air, foul water, and
spoiled land are tragic testimony to the deterioration of our natural en-
vironment. The complexity of that environment and the interplay between
its components require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment
of public drinking water supplies and to minimize the adverse economic, so-
cial, health, and aesthetic effects of pollution. This publication is one
of the products of that research; a most vital communications link between
the researcher and the user community.
This erosion control project and report is intended to assist the State
and Regional Boards and other responsible entities in abating sediment and
erosion problems in existing residential developments and insuring that
adequate pollution control technology is incorporated into future develop-
ments. Only through vigorous control of existing pollution problems and
the absolute prevention of future problems from developing can high quality
waters be protected for current and future generations.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
iii
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ABSTRACT
A three-year project was conducted by the California State Water Resources
Control Board to determine methods of preventing and correcting erosion
problems which severely effect the quality of the waters of the State of
California Two-project sites were chosen in the vicinity of the Lake Tahoe
basin in California. One project site, Northstar-at-Tahoe, is a well planned
and constructed residential-recreational development constructed in the early
1970s. The cost of extensive predeveloped planning and erosion control at
Northstar is currently less than $400 per developed unit or residential lot.
With ultimate planned build-out, costs are expected to be reduced to $220 per
developed unit. The other project site, Rubicon Properties - Unit No. 2, is
an extremely poorly planned and constructed residential subdivision develop-
ment constructed in the late 1950s and early 1960s. The cost of complete
corrective erosion control at Rubicon Properties would range from $1,000 to
$3,000 or more per residential lot.
At both project sites, extensive hydrologic and water quality monitoring
programs were conducted to determine erosion rates and their impact upon aqua-
tic ecosystems. Monitored parameters included precipitation, snow depth,
stream flow, suspended sediment and concentration, and benthic macroinverte-
brate communities. Postdevelopment erosion rates at Northstar are estimated
to be 100 percent above predevelopment levels, resulting in only minor pertur-
bations of the benthic macroinvertebrate community of West Martis Creek.
Postdevelopment erosion rates within Rubicon Properties are estimated to be
over 10,000 percent above predevelopment levels, resulting in up to 99 percent
destruction of the benthic macroinvertebrate community in Lonely Gulch Creek.
At both project sites, extensive demonstrations were made of predevelopment
planning concepts, construction techniques, and corrective measures which may
be used to substantially reduce erosion and sedimentation problems associated
with developments which are typical to the subalpine to alpine Lake Tahoe
region of California. Analyses were made to determine cost and effectiveness
of the various erosion control techniques which were demonstrated at the
project sites.
This report was submitted in fulfillment of Grant No. S803181-01 by the
California State Water Resources Control Board under the partial sponsorship
of the U. S. Environmental Protection Agency. This report covers the period
from July 4, 1974, to July 4, 1977, and work was completed December 31, 1977.
iv
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TABLE OF CONTENTS
Section
II
III
IV
^i*- Page
Foreword ...
Abstract
Figures ^"V
Tables '."...!!!!.!.!!....!..!."
Acknowledgements ...'...
INTRODUCTION
A. Project Sites , 3
1. Northstar-at-Tahoe o
2. Rubicon Properties * r
B. Demonstration of Erosion and Sediment Control
Technology q
CONCLUSIONS AND RECOMMENDATIONS 10
PREDEVELOPMENT PLANNING AND PRELIMINARY SITE ANALYSIS
AT NORTHSTAR / 16
A. Introduction lg
B. Planning Team Identification 1!!!!!!!!!!!'!!! 18
C. Evaluation of the Prime Physical Features'and
Conflict Analysis 21
1. Vegetation 21
2. Geology and Soils !!!!!!!!!!!! 25
3. Drainage *" 2 5
4. Slope 07
5. Exposure and Snow Depth \'f'm 27
6. Conflict Identification Summary '.'.'. 29
D. Recommended Conflict Mitigation Measures 32
E. Revised Site Selection .!!!."!! 36
F. Ski Slope Suitability Model .'!.*!.*.*.'!.'.'.*!!! 36
G. Final Development Plan !!!!!!!*""* An
DEVELOPMENT CONSTRUCTION CRITERIA FOR NORTHSTAR 45
A. Logging Controls and Ski Trail Clearing 45
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TABLE OF CONTENTS
(continued)
Section Title
B. Site Specific Soils Analyses ......................
C . .Environmental Impact Reporting ...... .............. 4°
D. Planting and Revegetation Management Program ...... 54
E. Criteria Summary ........ . ......................... 63
V NORTHSTAR-AT-TAHOE: A WELL PLANNED AND CONSTRUCTED
RESIDENTIAL-RECREATIONAL DEVELOPMENT ................ 66
A. The Ski Area .- ....................... . ........... ••• 66
B. Street and Parking Lot Construction ............... 70
C. Condominiums ,. Village Center, and Homesite
Construction .......... . ......................... ' 2
D . Remaining Problems ...... . ......................... ^
E. Demonstration of Erosion Control Technology ....... 80
F. Northstar Cost Summary ... ............ ............. °2
VI RUBICON PROPERTIES: A CLASSIC EXAMPLE OF MASSIVE
EROSION PROBLEMS DUE TO POOR PLANNING AND
CONSTRUCTION PRACTICES .............................. 83
A. Erosion Problems ....... . .......................... °^
B. Roadway Construction Problems ..................... °s
C . Storm Water Drainage Problems ..................... 90
D. Maintenance Procedure Problems .................... 91
E . Other Problems ......... . .......................... - 92
F. Demonstration of Erosion Control Technology ....... 9^
G. Cost and Effectiveness . . .......................... 97
H. Recommended Control Measures ...................... 97
VII THE IMPACT OF DEVELOPMENT ON WATER QUALITY ............ 101
A. Introduction ......................................
B. Water Quality Monitoring Program ..................
C. Water Quality of West Martis Creek (Northstar) .... 104
D. Water Quality of Lonely Gulch Creek (Rubicon) ..... H6
E. Water Quality Modeling of Suspended Sediment
Transport .......................................
1 . West Martis Creek .............................
2 . Lonely Gulch Creek ............................
1 *^R
F . Summary and Conclusions ........................... x J0
VIII BEST MANAGEMENT PRACTICES FOR EFFECTIVE EROSION CONTROL 142
A. Introduction ................................... • • •
B. Cost Estimating Procedure ......................... 144
vi
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TABLE OF CONTENTS
(continued)
Section Title
IX
C. Temporary Sediment Control 145
1. Impermeable Berms 147
2. Straw Bale Sediment Barriers 149
3. Filter Berms 152
4. Filter Fences ...,.....; 154
5. Comparative Costs !|!!! 156
D. Drainage Control ............. 157
1. Curbs, Dikes, and Gutters 158
2. Drop Inlets ..; 158
3. Drainage Channels 160
4. Water Bars .., 163
5. Infiltration Trenches V 165
6. Sediment Retention Basins 168
7. Drainage Control,,,Cost-Effectiveness 170
E. Mechanical Stabilization of Over Suspended Slopes . 170
1. Curbs and Dikes for Bench Construction 171
2. Breast Walls 174
3. Slope Scaling and Overhang Removal 180
4. Contour Wattling .. 183
5. Other Methods 190
F. Permanent Vegetative Erosion Control 192
1. Cut Willow Stakes 193
2. Plants [[[ 195
3. Seed and Fertilization 199
4. Mulching Techniques 209
5. Wood Fiber Hydroseeding and Hydromulching 210
6. Straw Mulching 214
7. Chemical Tackifying Agents 219
8. Mulch Nets and Blankets 223
9. Fiberglass Roving 229
G. Comparative Erosion Control Costs 232
H. Preliminary Evaluation of Erosion Control
Effectiveness 233
INSTITUTIONAL PROCEDURES FOR EFFECTIVE EROSION CONTROL 237
A. General Waste Discharge Requirements 238
B. Specific Waste Discharge Requirements 238
C. A Case History 243
vii
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Section
X
Title
REFERENCES
APPENDICES
TABLE OF CONTENTS
(continued)
Page
247
APPENDIX A: Plant Propagation for the Revegetation of
Road Cuts and Fills in the Lake Tahoe
Basin •
APPENDIX B: Erosion Control Plot Descriptions
APPENDIX C: Water Quality and Environmental Monitoring
Data .,
APPENDIX D: Sources of Erosion Control Products and
Services
APPENDIX E: Glossary
APPENDIX F: Metric Conversions
252
280
324
362
371
379
viii
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FIGURES
Number
Pa
1-1 Erosion Control Project site locations /
1-2 Geology of Northstar-At-Tahoe „ ,
• .... ^
1-3 Geology of Rubicon Properties 0
.......... y
III-l The four cornerstones of the Planning Process
identified in the development of Northstar . 0 17
III-2 Northstar planning flow chart 19
III-3 Initial Northstar proposed development plan 20
III-4 Northstar vegetation density analysis 24
III-5 Northstar slope analysis 28
III-6 Northstar primary conflicts 30
III-7 Revised Potential Development Areas 31
III-8 Topographic base map of revised Northstar site 35
III-9 "Developable" areas at Northstar identified during
predevelopment planning process 37
111-10 Ski slope suitability model - computer output 39
III-ll Northstar site isometrics 41
111-12 Final Land Use Plan for Northstar 43
IV-1 Vegetative Mosaic of the Northstar development site ... 57
V-l Existing land use development at Northstar as of
July 1977 68
V-2 Well revegetated ski run at Northstar using
rhizominous wheatgrasses gg
ix
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Number Pa§e
V-3 Helicopter installation of ski lift towers reduces
ground disturbance at Northstar 69
V-4 Vegetation from native seed in topsoiled area at
Northstar after four years 71
V-5 Condominiums at Northstar situated in an area of
minimum environmental impact with little
disturbance to surrounding vegetation 73
V-6 Discharge of condominium parking lot runoff to
downslope undisturbed area at Northstar 73
V-7 Rock riprapped check dams protecting an area at
Northstar disturbed by the underground placement
of utilities 76
V-8 Erosion problems identified at Northstar 77
V-9 Oversteepened and eroding cut slope adjacent to the
parking lot at Northstar in the spring of 1975 79
VI-1 Rubicon Properties subdivision on the west shore
of Lake Tahoe 84
VI-2 Rubicon Properties project site 85
VI-3 Deposition of granitic sediments in Lonely Gulch
Creek resulting from erosion within Rubicon
Properties subdivision 86
VI-4 Steep roadways and oversteepened cut and fill slopes
within Rubicon Properties subdivision, Lake Tahoe
Basin 89
VI-5 Eroded and accumulated sediments at the toe of an
oversteepened cut slope within Rubicon Properties
subdivision, Lake Tahoe Basin, during the summer
of 1975 96
,VI-6 Oversteepened cut slope after application of
mechanical and revegetative erosion control
techniques with an estimated 80-90% effectiveness
in reducing erosion rates. Picture taken in the
summer of 1977 » 96
VII-1 Hydrologic monitoring sites within West Martis
Creek watershed (Northstar) 106
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Number , Page
VII-2 Schematic diagram of water quality monitoring sites
at Northstar 107
VII-3 Streamflow and snow pack water storage as measured
in West Martis Creek watershed from October 1974
through September 1976 109
VII-4 West Martis Creek macroinvertebrates, September
1974
VII-5 Lonely Gulch Creek water quality monitoring
diagram
VII-6 Streamflow as measured in Lonely Gulch Creek
at Gauge No. 5 119
VII-7 Lonely Gulch Creek macroinvertebrates, July 1975 ...... 122
VII-8 Lonely Gulch Creek macroinvertebrates, December
!975 122
VII-9 Lonely Gulch Creek macroinvertebrates, June 1976 123
VII-1Q Lonely Gulch Creek macroinvertebrates, October
1976 123
VII-11 Correlation of suspended sediment concentration
with Streamflow at Gauge No. 3, West Martis
Creek (Northstar) 0 128
VII-12 Suspended Sediment Load in West Martis Creek
(Northstar) as estimated by water quality
model from October 1974 through September 1976 130
VII-13 Correlation of suspended sediment concentration
with Streamflow at Gauges No. 5 and No. 6,
Lonely Gulch Creek (Rubicon Properties) 135
VTI-14 Suspended Sediment Load in Lonely Gulch Creek
(Rubicon Properties) as estimated by water
quality model from November 1972 through
November 1973 and from June 1975 through
September 1976 137
VII-15 Comparison of predevelopment and postdevelopment
suspended sediment yields at Northstar and
Rubicon Properties project sites 141
xi
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Number
Page
VIII-1 Steeply eroding cut slope adjacent to paved roadway
at the Rubicon Properties erosion control project
site 143
VIII-2 Impermeable berms .. 148
VIII-3 Impervious berm installation adjacent to a stream
channel at the Northstar erosion control project
site 149
VIII-4 Eroded soil material discharging to drop inlet ........ 150
VIII-5 Straw bale sediment barrier used to control problem
pictured in Figure VIII-4 150
VIII-6 Typical straw bale sediment barrier installation
1 C T
design * 1:>1
VIII-7 Typical pervious filter berm installation designs ..... 152
VIII-8 Filter fence installation adjacent to a stream
site I55
VIII-9 Typical filter fence installation design 155
VIII-10 Gully erosion on fill slope at the Rubicon
Properties erosion control project site
resulting from poor drainage control and
lack of vegetation • • 159
VIII-11 Severe erosion on fill slope at Rubicon Properties
erosion control project site caused by a break
in an A-C dike ; 159
VIII-12 Typical drop inlet installation designed to settle
and trap transported sediments .., 160
VIII-13 Corregated metal pipe used to direct drainage
across highly erodible fill slope 161
VIII-14 Erosion caused by uncontrolled drainage flowing
across highly erodible fill area 162
VIII-15 Rock lined drainage channel designed to correct
problem pictured in Figure VIII-14 162
VIII-16 Water bar installation on heavily traveled dirt
road at Northstar ..„ • 163
xii
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Numb er
Page
VIII-17 Closely spaced water bars on abandoned dirt road 164
VIII-18 Maximum water bar spacing for various slope
gradients and erosion hazard ratings 165
VIII-19 Typical infiltration trench design for percolation
of storm runoff from impervious surfaces 166
VIII-20 Infiltration trench sizing diagram 168
VIII-21 Suspended sediment settling basin for storm
runoff control. Continued maintenance is
required to assure adequate settling capacity 169
VIII-22 Cut slope reworking. The amount of reshaping is
dependent upon the slope of the natural terrain
above the road cut . 171
VIII-23 Sloughed and eroded soil material at the toe of
a steeply eroded road cut at the Rubicon
Properties erosion control site 172
VIII-24 Curb, gutter, and bench design for stabilizing
the toe of a steeply eroding cut slope 173
VIII-25 Typical rock breast wall design for the toe of
a steeply eroding slope 174
VIII-26 Gabion breast walls 177
VIII-27 Scaling an eroding cut slope 181
VIII-28 Contour wattling 185.
VIII-29 Contour willow wattling installation at the
Northstar erosion control project site 188
VIII-30 New growth on a successfully planted willow
stake 194
VIII-31 Container plants > -jog
VIII-32 Competition between artificially seeded plant
materials and native shrubs on a topsoiled
slope at Northstar m 2Q5
VIII-33 Seed and fertilizer placement on a level
unvegetated area by means of a range drill 206
xxn
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„ , Page
Number —B—
VIII-34 Wood fiber hydromulching with seed and fertilizer
in a one-step operation
VIII-35 Wood fiber hydromulching labor and equipment
unit cost as a function of amount of mulch
applied. Based on Caltrans contracts for
first half of 1976 21J
VIII-36 Straw mulch application to fill slope by means
of a straw blowing machine
VIII-37 Straw mulch application labor and equipment
unit cost as a function of mulch applied.
Based on Caltrans contracts for first half
of 1976 V'"
VIII-38 Chemical tackifier application labor and
equipment unit cost when applied as a water
base slurry with hydromulching equipment.
Derived from Caltrans contracts for first
half of 1976
VIII-39 Application of a chemical tackifier over straw
mulch using hydromulching equipment
VIII-40 Manual application of Excelsior R blanket over
a seeded and fertilized cut slope «••
VIII-41 Jute netting applied to a seeded and fertilized ^
slope »
VIII-42 Manual application of paper fabric blanket over
a seeded fertilized and straw mulched severely
2.2. b
eroding cut slope •
VIII-43 Penstemon plants planted on a slope covered with
paper fabric which helps retain the soil
moisture and inhibit erosion until plants are
well established 227
VIII-44 Labor requirements for the manual installation
of various erosion control netting and
blankets • • 228
VIII-45 Application of fiberglass roving with a
compressed air gun •
VIII-46 Hypothetical one hectare steep, eroding, cut
slope adjacent to a road surface
aciv
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TABLES
Number
Page
III-l Comparison of initial proposed development areas
with revised potential development areas 32
III-2 Summary of developable areas adjacent to West
Martis Creek 38
III-3 Final land use plan summary for Northstar 0.. 42
IV-1 Species composition of the vegetative subunits
at Northstar 58
V-l Northstar development schedule 67
V-2 Developed areas and percent of development
unit type in "developable" areas 74
VI-1 Estimated yearly erosion rates from the
upper 24.4 hectares of Rubicon Properties
from 1959 through 1976 89
VI-2 Erosion control costs at the Rubicon
Properties project site 9g
VII-1 Average suspended sediment concentrations
recorded at instream gaging stations on
West Martis Creek
VII-2 Results of Surber sampling at nine benthic
macroinvertebrate stations in the West
Martis Creek watershed
VII-3 Average suspended sediment concentrations
recorded at instream sampling site in
Lonely Gulch Creek above and below
development 121
VII-4 Results of Surber sampling at four benthic
macroinvertebrate stations on Lonely Gulch
Creek 124
xv
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Number
VII-5 Suspended sediment correlations for West
Martis Creek (Northstar) 129
VII-6 Postdevelopment suspended sediment contribution
to West Martis Creek (Northstar) for various
flow types 131
VII-7 Suspended sediment loads to West Martis Creek
as developed by water quality model 132
VII-8 Suspended sediment correlation for Lonely
Gulch Creek (Rubicon Properties) 134
VII-9 Suspended sediment contribution to Lonely
Gulch Creek (Rubicon Properties) for
various flow types
VII-10 Suspended sediment loads to Lonely Gulch
Creek as developed by water .quality model 138
VIII-1 Temporary siltation control equivalent
installation costs i56
VIII-2 Comparative breast wall construction
equivalent costs • 179
VIII-3 Comparative overhang removal and scaling
equivalent costs « 183
VIII-4 Estimated revetment cost for stabilization of
oversteepened slopes •
VIII-5 Willow staking equivalent cost •
VIII-6 Equivalent costs of plants for erosion control 200
VIII-7 Percentage composition of seed and fertilizer
mixtures used at the erosion control project
sites 202
VIII-8 Comparative labor and equipment costs for
various seed and fertilizer application
techniques •••• 208
VIII-9 Hydromulching and seeding costs y,.. 215
VIII-10 Straw mulching and seeding costs 2J.8
VIII-11 Recommended straw mulch tackifier application rates .... 220
anri
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Number
VIII-12
VII1-13
VIII-14
Estimated tackifier cost applied over straw mulch
Equivalent equipment and labor costs for
installation of mulch nets and blankets
Comparative equivalent unit costs for selected
erosion control methods used on oversteepened
slopes
Page
223
230
234
XV1X
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ACKNOWLEDGEMENTS
The California State Water Resources Control Board, Division of Planning and
Research, wishes to acknowledge the assistance rendered by the following
project cooperators, without which the erosion control demonstration project
would not have been possible:
United States Environmental Protection Agency
California Regional Water Quality Control Board,
Lahontan Region
Lake Tahoe Resource Conservation District
United States Soil Conservation Service
Burgess Kay, Consultant
El Dorado County
The property owners of Rubicon Properties Subdivision,
Unit No. 2
Placer County
Trimont Land Company - Northstar-At-Tahoe
California Conservation Corps
University of California, Davis
—Department of Environmental Horticulture
—Bixby Work-Learn Program
Lake Tahoe Community College
Lake Tahoe Basin Management Unit, United States
Forest Service
Weyerhaeuser Corporation
Conwed Corporation
Gulf States Paper Company
Grass Growers Corporation
Sta-Soil Corporation
Dow Chemical USA
Ludlow Textile Corporation
Eckbo, Dean, Austin, and Williams, Planning Consultants
Wilsey and Ham, Engineers
Special thanks must be accorded to Mr. David Gilpin and Mr. Thomas Jopson,
graduated student assistants from the University of California, Davis, who
provided invaluable assistance with the erosion control field work.
Mr. Kenneth Smith, graduate student assistant from the University of
California, Berkeley, and Mr. Royle Johnson of the State Water Resources
Control Board provided the project staff with assistance in the development
of a system to model suspended sediment loads at the project sites.
Mr. John Baker of the Regional Water Quality Control Board, Lahontan Region,
and Mr. Craig Lucy, graduate student assistant from California State
University, Humboldt, provided the necessary expertise in the monitoring and
xviii
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reporting of eroded sediment impact on benthic macroinvertebrates at the
project sites. Mr. Dennis Talbert's assistance with preparation of graphical
material presented herein was of immeasurable value, as was the assistance of
Carla Hancock, Judy Harris, Harkirin Kaur, Pat Lee, Anna Mori, Kathy O'Hare
Joy Tabura and Carolee Western from the State Board's Word Processing Center
in the preparation of the manuscript.
xix
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SECTION I
INTRODUCTION
In July of 1974, the California State Water Resources Control Board (State
Board) was awarded a Demonstration Grant by the United States Environmental
Protection Agency (EPA) to conduct a three-year project, "Demonstration of
Erosion and Sediment Control Technology". The State Board chose the Lake
Tahoe Basin vicinity of the Sierra-Nevada mountains as a candidate for this
demonstration because of the increasing concern over the impact that develop-
ment and construction activities are having in this region. The-results of
this project will be used by the State Board as a guide to the correction
of existing and the prevention of future erosion-related water quality
problems within the Sierra-Nevada mountains of California.
The State Board and California Regional Water Quality Control Board,
Lahontan Region, (Regional Board) are concerned about the impacts which
erosion and sedimentation from man's activities are having on water quality
and the aquatic environment. In the Lake Tahoe Basin, water quality related
erosion problems are manifest in a variety of ways even to the casual ob-
server. The most obvious impact is the increased turbidity during high-
surface runoff conditions, such as periods of snowmelt or rainstorms.
After short, intense summer rainstorms, the office of the Regional Board in
South Lake Tahoe is frequently contacted by irate vacationers and local
homeowners complaining about the unsightly brown water flowing into streams
tributary to Lake Tahoe. A certain degree of the suspended sediment flowing
to Lake Tahoe is from natural sources. However, what few people seem to
realize is that land disturbances associated with the construction and use
of homes, roads, schools, motels, parking lots, and other facilities which
allow hundreds of thousands of visitors and residents to enjoy Lake Tahoe
each year can vastly increase the rate of erosion and sediment yield from a
particular area. As an example, a study and recent report conducted by the
California Resources Agency finds that construction and development of
about 30 percent of the Upper Truckee and Trout Creek watersheds tributary
to Lake Tahoe have significantly increased erosion and sediment yield of
these two streams over what may be considered "natural levels" (1).
Aside from the lowered aesthetic appeal of sediment laden waters, there are
other more subtle and potentially more serious effects. A recent report
published by'EPA identified eroded sediments as constributing to the eu-
trophication or enrichment of Lake Tahoe in at least two ways (2):
-------
- By transporting associated nutrients, such as nitrogen, phosphrous,
and iron, to Lake Tahoe.
- By providing a suspended substrate (or microscopic platforms) which
support bacterial growth.
Lake Tahoe is renowned for its crystal clarity. This is primarily due to
its sterile or nutrient deficient condition which is a direct result of the
small watershed area to the water volume ratio of the Lake Tahoe Basin.
The total land surface area which contributes runoff to Lake Tahoe is only
slightly more than 1% times the surface'area of the Lake itself. As a
result, naturally eroded sediments and nutrients are contributed to Lake
Tahoe at a very slow rate. Evidence is accumulating, however, indicating
that man-made developments which surround Lake Tahoe are rapidly acceler-
ating the rate of nutrient and sediment transport to the Lake. This is
particularly noticeable in the littoral or shallow near-shore areas which
initially receive the increased sediment load and attached nutrients trans-
ported from the disturbed watersheds. In recent years, many Lake Tahoe
shoreline residents and visitors have complained that rocks in some near-
shore areas are much more "slippery and slimy" than they had been in the
past. The slime they refer to is certainly attached algae. This is verified
by recent investigations indicating that the rate of algal growth in
Lake Tahoe increased 90 percent during the period from 1960 to 1971 (2).
Not only do suspended sediment laden waters have a definite impact on the
Lake's water quality, they also have an impact on the aquatic life found in
streams. The impact on streams flowing in heavily urbanized watersheds
tributary to Lake Tahoe has been well documented (1,2,3). At one of the
project sites, aquatic life in a stream receiving eroded sediments has been
reduced up to 99 percent. The sediment laden waters reduce aquatic life by
two basic mechanisms:
— Deposition of suspended sediments
- Scouring of the stream beds
Sediment deposition will bury and smother aquatic life, thereby substantially
reducing their numbers. The scouring effect of heavily suspended sediment
laden waters during runoff periods is roughly equivalent to "sandblasting"
insect larvae and other aquatic life. Few species are able to withstand
such a two-pronged attack on their environment.
The Regional Board, the state agency responsible for adopting and enforcing
water quality standards in the California portion of the Lake Tahoe Basin,
is taking a leading role in preventing degradation of surface waters by
erosion and sedimentation. In 1975, the Regional Board adopted water quality
objectives for all of the Lake Tahoe Basin which, once achieved, will limit
the impact that erosion and sedimentation induced by man's activities will
have on the Lake Tahoe Basin.
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The problem now facing the State Board, the Regional Board, and all other
agencies and individuals interested in preserving the water quality of the
Lake_Tahoe Basin is identifying methods and procedures which may be used to
eliminate problems of the past, to prevent problems of the future, and to
achieve established water quality objectives.
Once a method is identified, the Regional Board can order the developer to
use specific methods through discharge requirements. In contrast to the
situation with wastewater treatment plants, California Law (Water Code,
Section 13360) permits the Regional Board to prescribe items required, such
as subsurface drains, rock walls, etc., for erosion and drainage control.
The purpose of the Demonstration of Erosion and Sediment Control Technology
Project is to provide a means of identifying the most cost-effective methods
and procedures required to achieve these ends.
A. Project Sites
Two project sites were chosen as part of the erosion control demonstration
project (See Figure 1-1). Initially, Northstar-At-Tahoe, a year-round
recreational-residential complex north of the Tahoe Basin in the Truckee
River watershed, was selected. Extensive planning and environmental con-
cern has been exhibited by its developers. The second site, Rubicon Proper-
ties Subdivision, on the west shore^of Lake Tahoe, was selected because it
represented the opposite end of the spectrum — a poorly planned, poorly
constructed, environmentally unsound development.
Both developments are located well above the typical winter snow line within
the Sierra-Nevada mountains of California, an area subject to harsh cold
winters and warm, relatively dry summers. The vast majority of the pre-
cipitation occurring in the region typically comes in the winter as snow.
Brief, but frequently intense, summer rainstorms can cause considerable
erosion, particularly in disturbed areas. The vegetation of the region is
extremely fragile and, once disturbed, is difficult to reestablished. Many
oversteepened slopes or disturbed areas have not revegetated or restabilized
in more than 20 years. Grasses introduced for erosion control, for example
may require repeated fertilization in order to survive. Native plant species,
while naturally adapted to the climate and soil conditions of the region
are slow growing, difficult to propagate, and do not provide sufficient '
ground cover in many instances.
1. Northstar-At-Tahoe
Northstar is ideal as a project site. Knowledge gained from studying the
development and its water quality impact should be readily transferable to
planning and construction activities in other critical areas with similar
soils. As a result of thorough planning and careful construction practices,
there were only a few, relatively minor problem areas remaining after con-
struction of the initial phases of the development.
-------
EROSION
CONTROL
LOCATIONS
ra '^y^r^-g
l-'.Jsyv'-. '•/••, 'i* —-..: y Jahoe Pi
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STATE
OF
CALIFORNIA,
39"CK
120 00'
KILOMETER
SCALE
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
EROSION CONTROL
PROJECT SITES
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
-------
Northstar is located on a 1,036 hectare (2,560 acres) tract in the West
Martis Creek watershed tributary to the Lower Truckee River as shown in
Figure 1-2. The elevation of the development varies from 1,775 meters
(5,823 feet) at the north end of the tract to 2,625 meters (8,612 feet) at
Mt. Pluto to the south. There is a ski area with six double chair lifts
and 115 hectares (284 acres) of cleared ski runs in the upper elevations of
the watershed. Residential-commercial complexes are in the middle elevations
with an 18-hole golf course at the lower elevations.
The geology of Northstar and the West Martis Creek watershed is typical of
the northern one-third of the Lake Tahoe Basin and Truckee River watersheds
which are covered by extensive flows of volcanic rocks of Tertiary and
Quaternary age (See Figure 1-2). Source areas of the older volcanics are
unknown but are believed to be near Mt. Pluto. Rock units of Tertiary age
consist of volcanic mud flow breccias and flows of andesite and latite.
The flows are extremely resistant to weathering and have only a thin layer
of soil, while the mud flow breccias are less resistant to weathering and
develop a deep soil. In general, the Northstar-at-Tahoe development was
provided with a relatively stable environment of Tertiary andesite. The
deep weathering in the mud flow portions provides a thick soil that supports
good vegetation, is relatively stable, and relatively pervious.
The upper portions of the watershed are vegetated by a thick, mixed conif-
erous forest. Middle to low elevations are vegetated by coniferous forest
with mixed sagebrush and manzanita. Mean annual precipitation is 80 centi-
meters. Much of the area was extensively logged as was most of the Tahoe
Basin in the 1800's. Only moderate logging activity has been conducted in
recent decades. The West Martis Creek watershed was recently subject to
only selected logging with no clear cutting prior to the construction of the
Northstar development. The only other significant predevelopment human
impact within the West Martis Creek watershed was the presence of sheep
herders at the lower elevation. Although this activity probably had con-
siderable impact on the open meadow and sagebrush lands, remaining impacts
appear to be negligible. The only evidence indicating the one-time
presence of sheep herders are a few structures and extensive irrigation
canals in the low lands that used to spread the flow from West Martis Creek
over a wide area to support range vegetation.
A complete discussion of the planning and construction methods that went
into the development of Northstar is included in Sections III through V of
this report. Section VII includes a discussion of the sediment and erosion
related water quality impact of the Northstar development.
2. Rubicon Properties Subdivision
Rubicon Properties has been in a continual state of residential lot expansion
and growth since 1945. In 1960 the final upper portions of the subdivision
were added. However, even in 1977 only about 50 percent of the 632 lots
are fully developed. The development runs from an elevation of 1,898 meters
at the shore of Lake Tahoe to 2,180 meters. Magnificent views of Lake Tahoe
are a principle reason for the continued expansion of the Rubicon Properties.
-------
LEGEND
Qal - Alluvium
01 - Lake Beds
Qaf - Alluvial Fan
Qm - Glacial Moraines
QPv- Latite (volcanic)
Tva - Andesite (volcanic)
Rock Contact
-—-Fault
U -Uplhrown Side
D -Downthrown Side
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
GEOLOGY
NORTHSTAR AT TAHOE
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
-------
Lonely Gulch Creek which flows through the; development, drains a 2.75 square
kilometer watershed reaching to the top of Rubicon Peak at an elevation of
2,799 meters.
In terms of water quality protection and degree of environmental impact,
Rubicon Properties is diametrically opposed to Northstar. Where Northstar's
developers expended significant effort to construct a well planned develop-
ment, the relative lack of planning at«Rubicon Properties is obvious.
Where construction practices used at Northstar were designed to have minimum
environmental impact, Rubicon Properties was constructed with environmental
disregard. Where the developers of Northstar continue to exhibit an ongoing
desire to maintain a minimal environmental impact and to correct remaining
minor problems, Rubicon Properties developers have long since sold all
interest in the subdivision and may in no way be held accountable for the
impact Rubicon Properties is having on water quality and the environment of
Lake Tahoe.
The geology of Rubicon Properties is typical of the conditions found in
much of the granitic southern two-thirds of the Tahoe Basin. The bedrock
of the Rubicon Properties area is granodiorite. The principal minerals in
this rock are: (1) quartz 15 to 32 percent, (2) plagioclase 43 to 55 percent,
(3) potassium feldspar 10 to 20 percent, (4) hornblende 1 to 8 percent,
(5) biotite -6 to 15 percent, and (6) augite -0 to 0.3 percent. In this
subalpine climate, the granodiorite weathers quite deeply and is subject to
both wind erosion and erosion from falling water where exposed and not held
in place by vegetation. Variations in the level of Lake Tahoe in past mil-
lenia have led to the formation of lake shore deposits above the present
shoreline of Lake Tahoe as shown on the attached geologic map (Figure 1—3)•
During the Pleistocene epoch, huge valley glaciers moved down the canyons
along the western side of the Lake scouring away all of the loose rock and
building great piles of morainal debris. During the period of maximum
development, these glaciers were as much as 300 meters thick and, in some
areas, covered all but the hightest peaks and ridges. The record of the
advances and retreats of the glaciers is preserved in these glacial sedi-
ments. Four main advances are known to be represented along the west shore
of the Lake.
These glaciers were especially important because they scoured away all of
the weathered rock in the Rubicon Properties and exposed fresh rock at the
surface. Granodiorite disintegrates along the boundaries between mineral
grains so that, although the grains still fit together in their original
position, the mass is loose, incoherent, and subject to considerable erosion.
The sand and silt, products of rock weathering, are carried into the Lake.
The majority of the Lonely Gulch Creek watershed is vegetated with a mixed
coniferous forest. Mean annual precipitation is over 100 centimeters. Very
little human activity was conducted within the watershed prior to the devel-
opment of Rubicon Properties subdivision, with the exception of extensive
logging which occurred in the late 1800's. Since the logging activities
-------
^.Itpl
^pm,,w \
*^l«LvtofesJ*l I v'x. ?.
•mm^tff:',
m(^^wli\
i'^r^i
Ql -Recent Lake Beds
Qg - Glacial Deposits
Qm - Glacial Moraines
Gr -Granite Intrusive Rock
Rock Contact
I mil*
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
, GEOLOGY
RUBICON PROPERTIES
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
1-3
-------
were conducted, the Lonely Gulch Creek watershed had an ample opportunity
to return to relatively stable preimpact conditions, prior to the construc-
tion of Rubicon Properties subdivision.
A complete discussion of the Rubicon Properties development is included in
Section VI of this report. Section VII discusses the erosion and sediment
related impacts of Rubicon Properties.
B» Demonstration of Erosion and Sediment Control Technology
In addition to documenting the water quality impacts of the Northstar and
Rubicon Properties developments, major emphasis of this erosion control
project has been placed on the implementation and demonstration of a wide
variety of erosion control techniques. At Northstar, the demonstration of
specific, in-place erosion control techniques was confined to the few re-
maining erosion problem areas within the development. A total of 50 plots
was established at Northstar to demonstrate the effectiveness of a variety
of slope and disturbed area revegetation and stabilization techniques. At
Rubicon Properties, the erosion problems were not confined to a few isolated
areas but rather encompassed the entire development. Erosion control demon-
stration work within Rubicon Properties was confined to the worst portions
within the Lonely Gulch Creek watershed. It is anticipated that the ef-
fectiveness of the demonstrated techniques will be reflected by the improved
water quality of Lonely Gulch Creek. Over 200 separate plots have been
established within Rubicon Properties to demonstrate a variety of erosion
control vegetation and stabilization techniques, either singly or in com-
bination. Section VIII describes the wide variety of erosion control tech-
niques which were conducted as part of this project. Appendix A describes
procedures for the propagation of plants suitable for the revegetation of
disturbed slopes in the Lake Tahoe region of California. Appendix B de-
scribes the specific plot locations at the two project sites where the
erosion control techniques were demonstrated.
-------
SECTION II
CONCLUSIONS AND RECOMMENDATIONS
1. Poorly planned, constructed, and maintained developments can result in
extremely severe erosion and sedimentation rates, which in turn can have
a massive impact upon surface water quality. This is exemplified by high
levels of suspended sediment, turbidity, sediment deposition, and the
destruction of aquatic life in streams whose watersheds contain such
improper developments.
2. Adequate technology exists to insure that properly planned, constructed,
, and maintained developments that cause land disturbances will have a
minimum, if not negligible, impact upon surface water quality from the
standpoint of erosion and sediment.
3. In insuring that future construction of residential and recreational
developments results in a minimum amount of erosion and sediment dis-
charge to surface waters, the planning concepts of (1) restricting land
uses to suitable sites which are capable of supporting the particular
use, (2) minimizing disturbed land surfaces, particularly road cuts and
fills, and (3) prohibiting land disturbances from encroaching upon
stream environment zones, are of premier importance. At a minimum,
thorough evaluation of a proposed development project site should
include detailed analysis of the natural vegetation types, vegetation
density, geology and soils, drainage, and slope. Erosion and sediment
control concepts and requirements identified in the predevelopment plan-
ning stages must be fully recognized and adhered to during and after
actual construction to minimize potential problems.
4. Adequate technology exists to substantially reduce the water quality
impact of poorly planned, constructed, and maintained developments of
the past. However, reducing erosion and sediment production rates
to predevelopment levels would be extremely expensive and difficult
in some cases.
5. Adequate regulatory and enforcement tools exist in the State of
California, as embodied in the laws of the State when implemented by
regulatory agencies, to insure that erosion and sediment control prob-
lems are prevented in the future and that past problems are corrected.
6. The lack of sufficient funds to correct erosion and sediment control
problems generated by past activities (prior to the advent of suffi-
cient environmental controls) is the primary roadblock to the adequate
10
-------
8.
10
11.
control of erosion and sedimentation resulting from construction
activities.
One of the erosion control demonstration project sites, Northstar-At-
Tahoe, is a well planned, constructed, and maintained year-round
residential-recreational development complex. Potentially adverse
environmental impacts of the development were mitigated by careful
planning, government regulations, and the implementation of proper con-
trol measures. The few remaining isolated sediment and erosion problems
within the development are primarily the result of departures from the
strict construction and management controls outlined in the planning
process.
The construction of Northstar-At-Tahoe has resulted in less than
100 percent increase in sediment yield to the West Martis Creek water-
shed above very low background levels. The effect of this increase on
the monitored aquatic life of West Martis Creek has been negligible.
The sources of this increased sediment yield include a few isolated
instances of oversteepened slopes, unrevegetated terrain, uncontrolled
drainages, and heavily travelled dirt roadways which involve less than
0.3 percent of the total development. Because of their isolated and
limited nature, the application of additional erosion control methods
should further reduce sediment loads discharged from the Northstar
development.
The cost of extensive planning activities and erosion control measures
implemented by the developers of Northstar-At-Tahoe is currently esti-
mated to be less than $400 per developed unit (condominiums or resi-
dential lots). With ultimate planned buildout, the cost per developed
unit at Northstar is estimated to be reduced to approximately $220.
Thus, the actual unit cost of effective preplanned erosion control at
Northstar is nominal.
The other erosion control demonstration project site, Rubicon Properties,
is a classic example of the extremely poor development practices which
have been conducted within the Lake Tahoe Basin in the past. From the
standpoints of erosion control, drainage control, water supply, roadway
construction, land capabilities, esthetic appeal, snow removal, and
general maintenance, the upper portion of Rubicon Properties is exem-
plary of a poorly planned, constructed, and maintained development.
The development and construction of the upper portions of the Rubicon
Properties subdivision has resulted in an estimated 10,600 percent
increase above the natural background sediment yield from the area prior
to the erosion control project. Evidence exists that indicates erosion
rates may have been as high as 100,000 percent above natural background
rates immediately after construction of the subdivision in the early
1960's. The main sources of the eroded material are oversteepened
slopes, unvegetated terrain, uncontrolled drainages, and abandoned dirt
roads which occupy 13 percent of the land surface within the upper por-
tions of Rubicon Properties subdivision. The impact on the monitored
aquatic life of Lonely Gulch Creek has been significant. Monitored
11
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species in the stream have been reduced in numbers by an average of
70 percent below the development. Peak instances of species reduction
have reached levels of over 99 percent. Species diversities in Lonely
Gulch Creek below the development have also been adversely affected.
12. Had El Dorado County adequately recognized the requirements of their
own subdivision ordinance in the late 1950's, it is unlikely that the
upper portions of Rubicon Properties would have been constructed. For
example, the county ordinance required that all cut and fill slopes
adjacent to roadways accepted by the county must be included in the
legal right-of-way. Had this been the case at Rubicon Properties, con-
siderably less land area would have been available for subdivision into
parcels (up to 13 percent less land). In addition, if the subdivision
had been constructed in conformance with county ordinances, the main
problem areas would have remained in single ownership, considerably
facilitating the solution of the problem.
13. One of the major obstacles to effective erosion control at Rubicon
Properties was the necessity to obtain permission from each of the 129
individual landowners to gain access to their property for purposes of
erosion control. At Northstar, where the majority of the remaining
problem sites are still owned by the original developer, problem cor-
rection, when necessary, is greatly facilitated.
14. The cost of constructing adequate erosion control facilities at Rubicon
Properties subdivision, such as those implemented as part of the erosion
control demonstration project, could be as high as $2,000 per existing
residential lot if conducted on a commercial basis. The additional cost
of effective drainage control and sediment catchment facilities would
add an estimated $1,000 per residential lot. Furthermore, the continua-
tion of residential building construction within the project site will
increase the impervious surface coverage from 16 to 36 percent within
that portion of Rubicon Properties at full build-out. Based upon land
use capability, ideal impervious coverage should not exceed one percent.
Even with the implementation of extensive erosion control techniques,
the increased runoff from impervious surfaces will create additional
erosion problems which will be even more difficult to control.
15. The implementation of disturbed slope stabilization techniques to achieve
control of erosion problems within Rubicon Properties is expected to
reduce the previously excessive sediment yield rates by about 80 to 90
percent. This level of treatment is significant and is roughly analo-
gous to "secondary treatment" for suspended solids removal as in a
sewage treatment plant. At Rubicon Properties, however, this "secondary
treatment" would result in erosion and sedimentation rates which are
still approximately 1,000 percent above natural background levels. The
addition of settling basins and sediment collection facilities at Rubicon
Properties would probably further reduce the sediment yield rates by an
additional 90 percent, which would be roughly analogous to "tertiary
treatment" of suspended solids removal in a sewage treatment plant. At
such treatment level, sediment yield rates at Rubicon Properties would
12
_
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16.
17.
18.
19,
20,
only be 100 percent above natural background levels and would be similar
to the low sediment yield rates generated by the Northstar development.
The cost to the county for eroded sediment cleanup and maintenance
within the upper portions of Rubicon Properties subdivision, prior to
construction of effective erosion control facilities, is estimated to
have been approximately $11,500 per year. The cost to the county to
conduct a project similar to the Demonstration Project at Rubicon
Properties, would be-$120,000. Based on the following assumptions, the
cost of effective erosion control would be amortized over a period of
12.5 years, and the additional cost of complete drainage control and
sediment collection facilities would be amortized over a 20 year period:
1) Negligible erosion and sediment control maintenance would be
required after such a project.
2) Only maintenance cost savings are ascribed to the cost of
effective erosion control, with no costs allocated to environ-
mental protection and enhancement.
3) The long-term increased maintenance cost rate is 6 percent
(27 year ENR construction index since 1950).
4) Money may be borrowed at 8 percent interest.
Erosion control measures, which may be applied to various erosion prob-
lems, are very site specific. Depending upon soil type, slope angle,
slope length, seepage areas, exposure, rockiness, elevation, and vari-
ous control measures, either singly or in combination, may achieve the
most cost-effective level of erosion control. Site investigations must
be made prior to the implementation and cost estimating of specific
erosion control projects.
The estimated commercial cost of erosion control at Rubicon Properties
was approximately $75,000 per hectare of disturbed slope surface. Tech-
niques ranged from simple seeding and mulch application with an estimated
commercial cost of less than $3,000 per hectare to extensive improve-
ments, including retaining walls, willow wattling, plantings, seedings,
and mulching at a maximum estimated commercial erosion control cost of
over $200,000 per hectare of disturbed slope surface. The cost of indi-
vidual revegetation techniques ranged from $3,000 to $20,000 per hectare.
In most instances, considerable additional funds were required for
mechanical slope stabilization prior to revegetation. As eroding slopes
become steeper and longer, the vegetative portion of effective erosion
control represents only a small portion of the total cost.
The use of straw mulch with a chemical or mechanical tackifier is among
the most cost-effective of erosion control and revegetation techniques
which were demonstrated at the project site. The establishment of vege-
tative cover by using a straw mulch does as well, or better, than other
demonstrated techniques, some of which are considerably more expensive.
The technique of contour wattling should receive greater use as a means
to mechanically stabilize and revegetate oversteepened slopes. The
13
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growth of other types of seeded or planted vegetation is noticeably
higher on slopes which have received a contour wattling treatment.
21. The use of rooted seedlings of native and, in some cases, exotic shrubs
is an effective means of revegetating and stabilizing disturbed areas
But is not feasible in many instances due to prohibitively jiigh plant
production costs. Currently, commercial production costs of' large quan-
tities of many types of rooted shrub seedlings range from $.50 to $1.00
per plant. Newer, more efficient propagation techniques used as part of
this erosion control project may reduce shrub production costs to less
than $.10'per plant.
22. Effective erosion control is extremely labor intensive. For example,
82 percent of. the cost of commerical willow wattling installation is
labor cost. Erosion control costs for large projects may be substan-
tially reduced by employing conservation corps workers to perform
unskilled tasks. Theoretically, overall costs may be reduced as much as
45 percent. The actual average cost of erosion control at Rubicon
Properties, using conservation corps workers where possible, was $58,200
per hectare of disturbed slope surface, which is a 33 percent reduction
in the estimated commercial cost of such an operation.
23. Strict adherence to certain existing county ordinances exacerbates ero-
sion problems and leads to higher erosion control costs. For example,
the requirement that paved road surfaces must be maintained with at
least a 7.9 meter width more than quadrupled the cost of erosion control
within certain portions of Rubicon Properties. Maintenance of a 7.9
meter road width led to the construction of expensive gabion retaining
walls ($60-$180 per meter) where a narrower roadway would accommodate
curbs, gutters, and benches at the toe of eroding cut slopes ($15 per
meter). The total cost to the county to conduct an erosion control
project similar to the Rubicon Properties project would be reduced by
25 percent if the need for retaining wall structures were eliminated.
24. Certain state, county, and utility district maintenance practices
increase the severity of existing erosion problems. Among them are:
The practice of removing accumulated sediments from the toe of
eroding slopes, thereby undercutting the slope, leads to fur-
ther destabilization. Better practice would be to move exist-
ing drainage further away from the toe of the slope or to
construct retaining structures at the toe of eroding slopes.
- Washing culverts and drains clogged by eroded sediments
increases the rate of downslope sediment transport. A better
procedure would include dry boring or reaming to remove sedi-
ments coupled with proper disposal of the waste earthen
material.
- Insufficient snow stakes can cause increased damage to curbs,
dikes, gutters, culverts, retaining walls, and slope toe
benches by snow removal equipment.
14
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Improper disposal of waste earthen material, such as "over-
the-bank" practices, increases sediment transport and hinders
the proper establishment of slope stabilization measures.
The application of road sand to facilitate winter travel, with-
out providing for the adequate removal of accumulated sand,
further increases the rate at which sediments are discharged
to surface waters.
Cleaning roadways of accumulated sediments by means of water
flushing or simple brushing generally increases the rate of
sediment discharge to surface waters. A better method is the
use of a vacuum sweeper to clean and properly collect and dis-
pose of the accumulated sediments and waste earthen materials.
15
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A.
SECTION III
PREDEVELOPMENT PLANNING AND PRELIMINARY SITE ANALYSIS AT NORTHSTAR
Intro duction
Northstar-At-Tahoe was planned as an all-year recreation and resort
community utilizing portions (1,036 hectares) of a privately-owned^
10,500 hectare tract north of Lake Tahoe in California. Northstar s
facilities include a major ski complex, summer recreational facilities,
condominium residences, a limited number of lot parcels for single-
family dwellings, an eighteen hole golf course, and a commercial
village center.
In planning Northstar-At-Tahoe, the developers were guided by a
philosophy which recognized the unique qualities and ecological
processes of the landscape and considered them to be the primary
determinants of the proper form of development. Considerable effort
was made in the planning process to insure that the Northstar-At-Tahoe
Development Plan would not violate the landscape, but rather work with
it to form a "harmonious relationship between man and environment." (4)
The four cornerstones of planning that were used in the preliminary
site and feasibility analysis at Northstar were the following (4)
1. Physical analysis
2. Market analysis
3. Profitability
4. Government coordination
The interrelationship of the four cornerstones of the planning process
used in the development of Northstar is depicted in Figure III-l. The
evolution of thorough planning, as exemplified by Northstar-At-Tahoe,
is not a straight-line process but a cyclical one by which the
developers were able to continually reevaluate all criteria as the plan
evolved to determine their validity and feasibility and, thus, to define
the directives leading to succeeding development stages. The continual
reevaluation of the four cornerstones of planning led to the creation
of an extensive development which minimized adverse environmental
impacts and produced a marketable product.
16
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The primary cornerstone of Northstar planning was the comprehensive
physical analysis of the original 10,500 hectare tract. Preliminary
investigations were conducted to identify which major aspects of the
site's environment, including geology, soils, slopes, drainage, access,
and what types of development could best serve (and be served) by the
natural character of the land.
After identifying the site's capabilities and limitations, the planning
turned to a determination of the public needs and interests for the
types of amenities, activities, and projected land capabilities of the
site. A market study was conducted to determine what the interests
and needs of the public were for potential types of development
activities such as:
1. Condominiums
2. Residential lots
3. Ski area development
4. Natural terrain
5. Other recreational activities
As the projected need and interests of the public were identified by the
market study, the profitability of providing the various amenities were
examined.
SOURCE:. EDAW for Trimont Land Co.
Pigure III-l - The four cornerstones of the Planning Process
Identified in the Development of Northstar
17
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The fourth and last of the basic cornerstones of planning used in
developing the Northstar project was close coordination with local,
regional, and state governmental agencies. During the late 1960*s
and early 1970's, when comprehensive environmental legislation and
ordinances were first emerging, the Northstar developers worked closely
and cooperatively with all levels of government.
Strict adherence to these planning criteria also provided protection
to local government. In many instances, local government has been
financially burdened by ill-fated developments, half-finished sub-
divisions, vacant lots, scarred land, and maintenance headaches.
While Northstar-At-Tahoe is relatively free of these problems, Rubicon
Properties, the second erosion control demonstration project site, is
a perfect example of the wide variety of burdens which are placed on
local government and on the environment as a result of inadequate
planning. The lack of adequate planning at Rubicon Properties will be
thoroughly discussed in a subsequent section of this report (see
Section V).
B. Planning Team Identification
In order to adequately address the four cornerstones of planning, a
multidisciplinary team of consultants was retained by the developer.
The various areas of expertise included the following:
1. Economics-marketing
2. Planning
3. Ecology
4. Soils-geology
5. Planning computer
6. Ski-hill planning
7. Golf course planning
8. Architecture
9. Engineering
10. Legal
A flow chart depicting the sequences of responsibilities is shown in
Figure III-2. Initially, the consulting engineers and the economics-
marketing consultants proposed the preliminary master plan
shown in Figure III-3 encompassing the entire 10,500 hectare tract.
This initial planning was based solely upon an initial market analysis,
existing site information, and cursory site investigation. The
initial proposed master plan was heavily dependent upon the obvious
physical features of the land. From this point on, the various com-
ponents of the master plan received intense scrutiny and revision.
The primary responsibility of the planning consultants was to determine
the feasibility of the initial proposed development plan as determined
by environmental considerations.
18
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0
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£
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SOURCE: EDAW for Trimont Land Co.
FIGURE 111-2. NORTHSTAR PLANNING FLOW CHART
19
-------
TRUCKEE
LAND USE !
LEG EN D
RESIDENTIAL
.05 DU./AC.
.10 DU./AC.
.25 DU./AC
.50 OU./AC.
1.00 00./AC.
2.00 OU./AC.
3.00 DU/AC
IO.OO DU./AC
LAKE
TAHOE
TAHOE
CITY
OTHER LAND USES
SOURCE: EDAV/for Trimont Land Co
o i 2
^ffi«Sr
SPECIAL RECREATION
ONTROPERTY
PROPOSE SCENIC HIGHWAY
INTERCHANGE
FIGURE IH-3
INITIAL NORTH PROPOSED DEVELOPMENT PLAN - 1967
20
-------
c- Evaluation of the Prime Physical Features and Conflict Analysis (5)
The critique by the planning consultants of the initial proposed de-
velopment plan was based upon"the degree to which the ecological
integrity of the site would be affected by the proposed development.
The ecological studies were concerned with vegetation, soils, geology,
and water balance of the property. A vegetation survey was made from
aerial photographs of the property. This, in turn, was related to
geologic and related soil types. Water balances for the property were
determined from climatic data from weather stations adjacent to the
Northstar property.
The complexities of the landscape were separated into individual
components. Each ecological or landscape component was mapped at
1:24,000 scale. This information was evaluated according to its
suitability for development. By overlaying the plan on each
landscape consideration, the areas for which the proposed develop-
ment conflicted with the ecological capability or which required
specific considerations were identified. Potential conflicts w&re
then summarized and identified on separate maps as primary and secondary
conflicts. The composite of these conflicts indicated the areas of the
plan, which should not be developed, and identified those areas which
possessed the greatest development potential.
The ski area and base area of the development plan were studied in
greater detail. This enabled jnore extensive analysis of the planning
determinants, further enabling these determinants to influence spe-
cific site planning configurations.
The following analyses of the vegetation, soils, geology, and water
balance were conducted in order to classify the information according
to its suitability for development.
1. Vegetation
The landscape of the Northstar property is dominated by a range
of vegetation zones from the lower elevations of Martis Valley to
the higher slopes of Mt. Pluto. A large portion of the beauty
the site derives from this vegetation and the environment of
each, development unit and lot depends upon the type of vegetation
in which each unit is set.
«
- Broad Vegetation Zones:
The vegetation was divided into major zones on the Northstar
property by the planners. The lower elevations along west
Martis Creek are in a Sagebrush and grass vegetation zone.
21
-------
This is in the driest part of the original tract. Next,
rising in elevation, one enters a Pine Forest-sagebrush
zone, then a mixed Pine-Fir Forest, and Fir Forest along
most of the higher elevation ridges. In addition, there are
local or "azonal" vegetation types, such as aspen groves,
meadows, willow thickets, mountain alder thickets, rock-
land, and fire types, such as brush fields and thickets of
young tree regeneration.
Vegetation Types
From the combination of these vegetation zones and the azonal
types related to other variables, a mosaic of vegetation
types result. This mosaic of vegetation types has an ex-
pression visually in age or size classes of trees, crown
density of trees and shrubs, and on structural elements of
vegetation. The following classification types were de-
veloped from aerial photographs of the Northstar property.
Structural Class of Vegetation or Ground Cover Type
C Conifer trees
H Hardwood trees
S Shrubs, i.e. manzanita or sagebrush
R Rock
B Bare Ground
Age Class (based on size of crown) of Conifers
0 Old, greater than 75 years
Y Young, less than 75 years
R Recent regeneration, less than 15 years
Density Classes of Crown Canopy (based on aerial photographs)
80 - 100%
60 - 80%
30 - 60%
5 - 30%
less than 5%
The structural elements of each, vegetation type were placed in
the denominator of a fractional symbol, while the age class and
two density symbols (one for conifer density and the other for
total woody vegetation density) were placed in the numerator.
Two examples follow:
OY22
CB
22
-------
This states that the cover is conifer vegetation (C) with
some bare ground (B); there are two age classes present,
old (0), and young (Y); and that the old age class is most
abundant (OY). The first density figure indicates that
total conifer density is 60 to 80 percent crown cover (2),
and that this makes up all the woody vegetation density
60 to 80 percent (2).
51
S
This indicates a cover type that is shrub (S), with less than
5 percent cover density (5), but 80 to 100 percent woody
vegetation cover (1) made up of brush.
From this vegetation classification, it was possible to
single out vegetation types and vegetation densities for
specific consideration and evaluation as their suitability
for development. Specific vegetation types are
Mixed Conifer
Pine Fir
Pine - Sagenrush.
Various
Ponderosa Pine, Jeffrey Pine,
Ledgepole Pine, White Fir, Red
Fir, Incense Cedar
Ponderosa Pine, Jeffrey Pine,
White Fir, Red Fir
Jeffrey Pine, Ponderosa Pine
Sage
Sagebrush - grass enclaves,
Aspen, Willow, Mountain Alder,
Manzanita, and meadow
Of these, only the last category of various species in small
areas was considered highly sensitive to development impact.
The Pine—Sagebrush category was considered less desirable
than the others from a visual standpoint.
Vegetation density was measured according to the percentage of
area covered by the vegetation crown as seen from the air.
The vegetation density map developed from this analysis is
depicted in Figure III-4.
Less than 5%
5 - 30%
Primarily open space
Desirable density for development
23
-------
LAKE
TAHOE
SOURCE: EDAW for Trimont Land Co.
KILOMETERS
FIGURE ill - 4
NORTHSTAR VEGETATION DENSITY ANALYSIS
24
-------
30 - 60%
60 - 80%
80 - 100%
2. Geology and Soils
Acceptable for development since no
more, than 30 percent would necessarily
be removed
Minor development problems since more
than 30 percent would be removed for
intensive development and, therefore,
the remaining vegetation becomes
less stable
Serious development problems since
50 to 60 percent would be removed
with the potential to seriously affect
the ecology of the remaining stand
All of the Northstar property is dominated by volcanic igneous
rock, except for some glacial deposits and alluvial areas in
Martis Creek Valley. The soils which are derived from the
weathering of these rocks vary in depth and development in re-
sponse to climate, nature of the bedding, and composition of
.the original rock. The higher elevation areas of the property
are characterized by shallow stony soils. Such soils are not
well suited for development.
The majority of the Northstar. development area is composed
of brown forest soils, 1 to 2 meters deep and moderately
stony. These soils occur on the property generally above 1,950
meters elevation and below 2,300 meters. The drier portion of
the property on the Martis Valley side is characterized by
darker, heavier soils developed on the andesite rock. The extent
of these soils can be related to the occurrence of sagebrush.
There are local areas of soils associated with poorly drained
areas, such as springs and meadows which will be different from
the other soil types. These meadows and seep area soils have
high moisture storage capacities (30 centimeters to 60 centimeters),
and also high nitrogen contents (approximately 9,000 to 11,000
kilograms per'hectare to a depth of 1.25 meters). They are
highly reactive and have a good capacity to absorb applied nutri-
ent and organic matter without discharge to groundwater in deep
seepage effluent.
3. Drainage
A water balance made by deducting expected losses from precipi-
tation on the property. Supporting data was gathered from
25
-------
the records of the Central Sierra Snow Laboratory at Donner Summit
and from the weather data at Truckee and Tahoe City. The analysis
indicated that the streamflow from the area accounts only for about
60 percent of the total estimated yield. Thus, there must be
considerable subsurface flow from the West Martis Creek Watershed.
This is not unreasonable considering the nature of the igneous rock
geology and the alluvial fill in the West Martis Creek drainage.
In addition to the water balance information, the following
stream classification was prepared by the Norths tar planners.
Intermittent Streams
Perennial Streams
Flood Plains
Those with only seasonal
flow
Small streams which flow
throughout the year
Streams with sufficient
flow such that a 25 year
flood must be provided for
with an additional 15
meter easement
Predevelopment surface storm or snowmelt runoff from the area
of the Northstar property was slight. The soils are very perme-
able and runoff coefficients are low. Some-concentration of
runoff did occur along skid trails and logging roads but, in
general, did not exceed the infiltration capacities of the soils.
However, it was acknowledged that there would be a change in the
runoff regime following development, particularly as affected by
impervious surfaces and changes in vegetation density.
The change in surface runoff patterns from the development area
was assumed to be proportionate to the impervious area of roofs
and road surfaces within each subwatershed. The location of
these impervious areas relative to the infiltration capacities of
intermingled land surfaces was a primary factor influencing de-
velopment concentration and spacing.
The overall objective of the design of surface runoff regulation
at Northstar was to contain runoff in channels or to infiltrate
the water without erosion. The variation and location of small
runoff surfaces necessitated the design of small drainage systems
which would not overload the infiltration capacities of the soil
nor the flow capacity of natural and artificial channels.
Particular attention was given to points of concentration, such
as road cuts, road surfaces, roof surfaces, and disturbed soil
areas. Once the runoff is concentrated into channels, additional
provision for energy dissipation is necessary due to the increased
flow rates. Concentration of runoff on newly disturbed soil
26
-------
surfaces, such as fill material, was recognized as a potentially
serious problem.
Slope
Slope steepness is the most important single determinant for
planning purposes, particularly from the standpoint of erosion
control. Not only does the cost and, therefore, the feasibility of
construction rise in direct proportion to the slope of the land
but also consequent erosion and sliding are liable to prove costly,
visually destructive, and detrimental to water quality.
Slope was categorized accordingly:
0-6% slope
7 - 11%
12 - 15%
16 - 25%
Over 25%
This represented the maximum desired
slope for roads under snow conditions
This represented the maximum desired
slope for roads under normal conditions
without snow
This represented the maximum slope
which should typically be considered
developable
'Under specific and exceptional
circumstances, it may be possible to
develop land in this category at very
low densities
Land in this category would not be
developed under any circumstances
The results of the slope analysis are shown in Figure IIL-5.
In Figure III-5, the darkest areas have slopes greater than
25 percent, while the lightest area is indicative of 0 to 6 percent
slope.
Exposure and Snow Depth.
From the existing record of snowfall in the area and with specific
reference to the 1967/68 season, some general estimates of snow depth
according to elevation for the site were made. Three major divisions
were determined to exist
Below 150 cm
150 - 230 cm
Over 230 cm
Average annual snow depth
Average annual snow depth
Average annual snow depth
The effect of snow depth on suitability for development depended on
more considerations than just elevation. Wind and exposure
27
-------
SOURCE: EDAW.forTrimontLandCo
NORTHSTAR SLOPE ANALYSIS
28
-------
determined the extent of the snow hazard. Estimated snow depths were
therefore correlated with an exposure map to produce the following
classifications:
Below 150 cm
150 - 230 cm
150 - 230 cm
150 - 230 cm
Over 230 cm
6. Conflict Identification Summary
Any direction
South facing slope
East and west facing slopes
North facing slopes
Any direction
By comparing the initial proposed development plan with clear over-
lays of the various physical features, it was possible to identify
where major or minor conflicts occurred between the proposed
development and the land use capability of the Northstar property.
The significance or magnitude of the identified conflicts was de-
pendent upon the degree to which problems arising in these areas
could be ameliorated. Typically, vegetation types and density,
soils, exposure, and snow depth were less serious constraints
than are slope and major drainage conflicts. Where several
conflicts or development constraints coincided, then the feasibility
of development was increasingly reduced. A composite map showing
these combined conflicts compared with the development plan served
as a guide for the best location for the eventual development of
Northstar-At-Tahoe.
In making the composite map (see figure III-6) primary, and second-
ary conflicts were.considered as follows:
Primary Constraints
Slope
Drainage
Areas with conflicts of either or b.oth of these primary constraints
were considered unsuitable for development.
Secondary Constraints
Vegetation types
Vegetation density
Soils
Exposure and snow depth
Conflicts arising from these secondary constraints represented
variances in cost and design controls rather than absolute
constraints on the feasibility of development.
This composite was made and entitled "Revised Potential Development
.Areas" (see Figure III-7). When combined with the initial proposed
development plan (see Figure III-3), it is apparent that the
total areas involved in the "potential" and the "proposed"
29
-------
LAKE
TAHOE
SOURCE: EDAW for Trimont Land Co.
FIGURE III - 6
NORTHSTAR PRIMARY CONFLICTS
30
-------
TRUCKEE
FINAL LAND
USE PLAN
LAKE
TAHOE
K!LOMETEBS.
. LEGEND
CONDOMINIUM GROUP 8 DU./ACRE
FAMILY 2 DU./ACRE
SCENIC HIGHWAY
COMMERCIAL FACILITIES
' "J SKI AREA ,
SITE AREA POTENTIALLY DEVELOPABLE
t; POTENTIALLY DEVELOPABLE W/RECOM-
MENDED MANAGEMENT CONTROL
SOURCE: EDAW for Trimont Land Co.
FIGURE III-7
REVISED POTENTIAL DEVELOPMENT AREAS - 1969
31
-------
TABLE III-l
COMPARISON OF INITIAL PROPOSED DEVELOPMENT AREAS
WITH REVISED POTENTIAL DEVELOPMENT AREAS
Initial Proposed Development
Revised Potential Development
Readily Developable
Developable with Management Controls
TOTAL
HECTARES
2,702
1,285
604
1,889
developments are not drastically different. Although the revised
potential development areas are 30 percent less than the original
proposed plan, the main difference involves the relocation of
development to more suitable areas. (The ski area was not
considered a part of the development since its determinants are
widely different from those of housing, roadways, commercial areas,
etc.) Table III-l compares the proposed developable areas
identified in the initial proposed development plan with the
potential developable areas identified after detailed review of the
environmental cons traints.
D. Recommended Conflict Mitigation Measures
Based upon the evaluation of the prime physical features of the Northstar
property, several recommendations were made concerning site selection,
manner of construction, and development feasibility. The recommendations
were made to guide development construction and lessen the impacts of
identified environmental conflicts.
Riparian Areas. The riparian areas are those along streams and around
springs where the vegetation is particularly dense due to available water
supply. These areas were recommended to be managed such that development
impacts would be minimized.
1. Any diversion reducing water available to a riparian channel should
be accompanied by thinning of the trees and vegetation to within the
supportable limits of the reduced water supply.
32
-------
2. Trees which may fall and block channels during floods, as well as
any fallen trees and logs adjacent to channels, should be re-
moved.
3. Trees which are close to the channel or in such a position as to
cause floating debris to lodge against them should be marked for
removal.
4. The cost of maintenance of riparian vegetation should be
covered by returns from harvest of suitable trees.
Aspen Groves. The aspen groves represent a great asset to the Northstar
development area. Their continued existence is dependent upon adequate
water supply. Any diversion of water from them was recommended to be
conducted with care since a thicket of dead trees could result. The need
to thin aspen stands which had grown to exceed their water supply was
identified.
Meadows and Willow Thickets. Meadows such as Sawmill Flat and
the Willow and Beaver Pond area within the West Martis Creek drainage
represented poorly drained soils, fairly high in fertility. The removal
of grazing from them would create a succession toward Willow and Alder
brush. In order to maintain herbaceous meadow vegetation, it was deemed
necessary to have either planned grazing, late fall burning, or mowing
of these meadows. The general principle was that the meadows, as they
existed, were the result of past effects of human use as well as their
natural environment. To the extent that a change in these conditions
would be brought about by the development, the meadows would also change.
Erosion Hazards. The specific soil and geologic types determine
the extent of possible erosion problems. Most erosion is the product of
road cut and fill operations. Road cuts must be kept to a minimum. The
revegetation of disturbed surfaces with native vegetation by encouraging
natural invasion or by artificial plantings was recognized as an
absolute necessity.
Fertilization. Most of the soils of the Northstar property are
high enough in fertility for native vegetation. However, any nonnative
or high density plantings that may be desirable for slope stabilization or
local landscaping would require fertilization. It was recommended that
this should be done only on those sites where fertilizer application
will not change the quality of water flowing from the area.
Rocky Areas. Rocky'areas are found throughout the Northstar property.
These outcrops were expected to inhibit development where the
rocks were loose, talus material lying at the angle of repose; undercutting
and frost would cause slope creep of rock debris.
Drainage. Drainage channels were to be provided at the toe of impervious
areas, such as road cuts or large impervious surfaces, such that gully
33
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formation would be avoided. This involved lined channels where the
runoff exceeded the infiltration capacity of the collection area.
Diversion of drainage to fill slopes or to the intersection of fill
slopes and natural slope grade was to be avoided unless a lined channel
was provided. Particular attention was needed at culvert and ditch
outlets. Physical structures for energy dissipation were needed if
there was insufficient natural capacity at the site to absorb the impact
of the concentrated flow. Concentrations of runoff greater than the
capacity of natural channels required lined channels. The inlets to
culverts behind fills required devices to trap debris and sediment from
entering the culvert.
High Infiltration Capacity Soils. The soils of the Northstar property
all have high infiltration capacities. They are typically brown forest
soils developed on andesite and have good structural stability. As a
result, the infiltration rates of undisturbed areas are very high. The
subsurface drainage is good due to the very permeable geologic strata.
The main recommendation for large surface runoff concentrations was
that, insofar as possible, high drainage flows should be directed to
natural channels. If high concentrations of surface runoff from roads
and other similar impervious areas are placed out on slopes of residual
soil, the water may wash deep new channels into the slopes. It was
recognized, however, that small discrete drainage water discharges
could be easily infiltrated in undisturbed areas adjacent to
development sites.
Water Quality. The good structural stability of the soils found within
the Northstar property was expected to result in water which clears
rapidly after storms and generally to have low suspended sediment
content. Therefore, any deterioration in water quality due to sediment
was expected to be related to disturbance mainly in the form of road
cuts and fills. It was recommended that fills be well compacted and
have drainage regulated so as not to adversely affect the low sediment
regime of the streams.
Slope Steepness. It was determined that areas of the Northstar property
with slopes less than 15 percent may be readily developed. Slopes
between 15 and 25 percent should be developed only under exceptional
circumstances. All development should be prohibited from areas steeper
than 25 percent.
Snow Depth. It was recommended that all developments should be
excluded from areas with greater than 229. centimeters of snowfall.
Exposure. It was recommended that all development be prohibited from
'north facing slopes with greater than 152 centimeters of snowfall. All
other areas would be able to sustain development from the standpoint of
exposure and snow depth.
34
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TOPOGRAPHIC
BASE MAP
OF
NORTHSTAR
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
TOPOGRAPHIC
BASE MAP
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
1 FIGURE NUMBER
III-8
35
-------
Revised Site Selection.
In 1970, based upon the continued reassessment of the four cornerstones
of the Northstar planning process (market study, profitability,
government agency co'ordination, and site analysis), the Northstar
developers made the decision to reduce the scope of the project to
approximately 10 percent of the original 10,500 hectare tract. The
reduced Northstar site was almost entirely within the West Martis Creek
watershed and entirely outside of the Lake Tahoe basin. The West Martis
Creek site was chosen due to location of ideal natural terrain for
a ski area within the upper portions of the watershed below the summit
of Mt. Pluto.
It was determined early in the marketings-economic analysis process,
that the inclusion of extensive ski facilities was essential for
the economic success of Northstar-At-Tahoe. Thus, the remainder of the
detailed planning effort was concentrated on the 1,036 hectare portion
of the original 10,500 hectare tract which contained the ski bowl and
proposed base facilities.
For the purposes of more detailed planning, a 1:4,800 scale topographic
base map with 15.2 meter contour intervals was prepared from aerial
photographs. Figure 111-^8 depicts the topographic base maps which were
prepared for the revised Northstar site. The Northstar planning
consultants then prepared an even more critical review of the
development potential of this area.
Further detailed review and evaluation of the prime physical features
Cslope, soils, vegetation type and density, drainage, exposure, and
visual amenities was made. Potential development areas were defined as
those areas which could be developed without any significant conflict
with the prime physical features of the landscape, potential development
areas with management controls were areas where conflicts did exist, but
where conflicts represented variances in the cost of development rather
than absolute constraints on the feasibility of development. A
summary of the developable land areas of Northstar within and adjacent
to West Martis Creek is shown in Table III-2. For the most part, the
ultimate development of Northstar-At-Tahoe conformed quite closely to the
areas identified in Figure III-9.
Ski Slope Suitability Model
It was determined that the final design of the entire development must-be
closely linked to the design and location of the ski area. Further study
of the area involved the use of computers for a more detailed analysis of
the ski hill area and the West Martis Creek watershed than would be
achieved by conventional methods.
36
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LEGEND
DEVELOPABLE LAND
0%-IS% SLOPE
DEVELOPABLE LAND
WITH FOREST
MANAGEMENT CONTROLS
.4
SOURCE: EDAW for Trimont Land Co.
KILOMETERS
r
FIGURE 111-9. "DEVELOPMENT" AREAS AT NORTHSTAR
IDENTIFIED DURING PRE-DEVELOPMENT PLANNING PROCESS
37
-------
TABLE III-2
SUMMARY OF DEVELOPABLE AREAS
ADJACENT TO WEST MARTIS CREEK
Development Areas
Potential
Potential w/Management Controls
SUBTOTAL
Nondevelopable Areas
TOTAL
HECTARES
59.2
96.0
155.2
880.8
1,036.0
The developers started with the establishment of.generalized criteria for
ski slope suitability based on comments provided by a variety of ski area
specialists. The criteria developed are a hierarchy of values ranked as
follows from most important to least important:
1. Slope
2. Surface water
3. Sun intensity
4. Snow depth
5. Vegetation type and age
6. Adjacent to streams
7. Vegetation density
On the basis of this value system, the developers were able to establish
a matrix for combining the computerized mapping of the individual
considerations. Slope and surface water criteria were of overriding
importance, in determining the location and extent of the ski area. A
composite computer printout of the entire hierarchy of values is
depicted in Figure 111-10, which portrays a summary evaluation of ski
slope suitability. The darker portions of Figure 111-10 indicate the
areas of the land most suitable for ski trail development. The lighter
portions are the least suitable areas. Those portions of the terrain
38
-------
ski slope
suitability
SOURCE: EDAW for Trimont Land Co.
FIGURE III-10. SKI SLOPE SUITABILITY MODEL
39
-------
adjacent to the surface waters of West Martis Creek were completely
eliminated from-consideration. Ultimately, the ski trails
crossed West Martis Creek in a few locations for purposes of access
only.
The ski slope suitability computer output was used to design the complete
system of ski trails which were then checkejl again in the field. With
the ski hill refinement provided by the computer program, Northstar's
developers were able to establish the extent and location of a variety
of development components: ski lifts, ski lodge and base facilities,
opportunities for ski-in/ski-out condominiums, and access requirements.
A variety of additional computer analyses were also conducted to
facilitate plan layout. These are exemplified by the site isometrics
analyses portrayed in Figure III-ll. The site isometrics allowed the
planners and designers of the Northstar development to gain a three-
dimensional appreciation of the terrain of the Northstar property. The
views depicted in Figure III—11 are looking to the southwest, up the
West Martis Creek Valley, from two different elevations.
G. Final Development Plan
Based upon the evaluation of the prime physical features of the Northstar-
star property and considerations pertaining to marketability, profits, and
government agency review, the final development design for Northstar-
At-Tahoe was prepared by the planning team. As was true for the
evaluation of the prime physical features leading to final site selection,
primary (slope and drainage) and secondary (vegetation type and density,
soils, exposure,, and snow depth) constraints were the main factors guiding
the final development layout design. Areas conflicting with the primary
constraints were considered unsuitable for development. Only in rare
instances and with additional expense were areas with primary constraints
developed.
Initially, the complete development of the Martis Creek watershed area"
was anticipated to extend over a period of approximately eight years and
include approximately 3,115 condominium-type units and 585 single—family
0.1 hectare lots. The planned land use includes, in addition to the
residential use, a village commercial area, highway service commercial
at the project entrance, ski resort, golf course, recreation center with
tennis courts and swimming pool, corporation yard for county maintenance
equipment, fire and police facilities, water treatment facilities, waste-
water reclamation facilities (for golf course irrigation), ski
maintenance area,-forest reserve, and open space area.
The Big Springs Inn, which serves the skiers at the base of the slopes,
has over 16,000 square meters of floor area. This inn contains space
for multipurpose food and beverage areas, small ski shops/accessories,
pubs, ski school and lockers, offices and emergency living quarters,
40
-------
.- *
ALTITUIE . 15
ALTITHIE . S
SOURCE: EDAW for Trimont Land Co.
FIGURE III - 11
NORTHSTAR SITi ISOMETRICS
41
-------
TABLE III-3
NORTHSTAR LAND USE PLAN SUMMARY
HECTARES
RESIDENTIAL
Single Family Homes
Condominium Units
' SUBTOTAL
COMMERCIAL
Village Center
Ski Area
Highway Service
SUBTOTAL
UTILITIES
County Services
Other
SUBTOTAL
ROADS AND PARKING
Condominiums
Village Center
Public Roads
SUBTOTAL
RECREATIONAL FACILITIES
Ski Trails
Golf Course
Other
SUBTOTAL
TOTAL DEVELOPED AREA
OPEN SPACE
Ski Area Open Space
General Open Space
Private Open Space
TOTAL PROJECT
PLANNED
14.7
21.0
35.7
1.2
4.0
0.8
7.0
3,2
4.9.
8.1
18.2
4.5
25.1
47.8
131.6
64.8
2.4
19.8. 8
297.4
413.1
281.3
44.0
738.4
1,035.8
PERCENT
3.4
0.7
0.8
4.6
ia.2
28.7
71.3
100.0
42
-------
KILOMETERS
SOURCE: EDAW for Trimont Land Co.
FIGURE 111-12. FINAL LAND USE PLAN FOR NORTHSTAR - 1970.
43
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auxiliary first aid, decks, and lounges. The village commerical
facility development is utimately planned to include medium and highrise
residential units, specialty shops, markets, multipurpose food and
beverage areas, and other retail service areas. At the present, however,
the village commerical area is less than 30 percent completed, with
10,700 square meters of floor space.
Fourteen ski lifts, principally radiating from the Big Springs Inn area,
are planned for the ski area which has a total area of approximately
486 hectares. These facilities are designed for an ultimate peak-day
capacity of approximately 10,600 skiers. Only six lifts and one tow
have been constructed. The ski facilities are essentially for the
preferential use of the Northstar-At-Tahoe Project residents; therefore,
the ultimate development concept provides for only a limited number of
day skiers. Table III-3 summarizes the final planned land use for the
Northstar-At-Tahoe, Martis Creek watershed area.
44
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SECTION IV
DEVELOPMENT CONSTRUCTION CRITERIA FOR NORTHSTAR
The planning process which produced the Northstar development did not end
once the final layout of the development had Been chosen. Considerable addi-
tional planning had to be conducted to address potential problems that could
appear during the construction phases of the project. Of particular interest
from the standpoint of effective erosion control were the various studies and
controls which were developed prior to the start of construction. These
included:
Logging Controls
Site Specific Soils Analysis
- Environmental Impact Reporting
- Vegetative Maintenance Recommendations
A wide variety of other preconstruction planning activities were conducted
to address problems pertaining to architectural design, sewage treatment,
water supply, parking configurations, specific recreational amenities, zoning
problems, development phasing, and traffic circulation. These subject areas
were not critical for the control of erosion problems and, thus, will not be
discussed.
A. Logging Controls and Ski Trail Clearing
The ski area at Northstar was designed to have minimum environmental
impact. Only narrow trail areas were cleared for ski runs which were
typically less than 50 meters wide. Less than 30 percent of the upper
watershed was cleared for ski trails. In most instances, storm runoff
and eroded materials from the initially disturbed ski trails were dis-
charged to adjacent undisturbed areas. This was accomplished by two
methods:
1. Sloping the cleared ski trail diagonally, across the "fall line"
or in a downslope direction. This allowed storm runoff and other
drainage waters to be "filtered" through adjacent undisturbed
areas.
2. Water bars and gently graded contours .were used extensively to direct
cleared slope drainage to adjacent undisturbed areas.
Logging and tree removal were required for the siting of development
structures and for the construction of ski runs. Criteria were
45
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established by the county to minimize adverse impacts on the terrain and
on water quality. Logging activities can cause extensive soil disrup-
tion and lead to increased runoff concentrations from disturbed areas
(6,7,8,9)0 Erosion rates from areas adversely affected by logging activ-
ities may increase dramatically. The following criteria were developed
at Northstar, as required by Placer County, to minimize these impacts:
1. General
- The natural ground surface was disturbed as little as possible
and rubber tired equipment was used whenever practicable.
- No stumping was permitted except where specified for structural
siting, hazard reduction, or other related purposes.
- Existing slash was disposed of offsite by hauling to a disposal
area or onsite by gathering and piling for burning.
- Existing grasses, weeds, ferns, and ground cover, such as squaw
carpet and manzanita, were left in essentially an undisturbed
state.
- No trail work was conducted without onsite expert supervision.
2. Trails and Lift Lines
- Falling timber into residual stands was avoided.
- Fallen logs, trees, stumps, and slash were removed from trails.
- Rocks over 60 centimeters in diameter were placed to the side
of trails.
- Any projecting boulders (over 2 meters) were drilled and
shot with low percentage dynamite.
- Berms on roads crossing trails were flattened on cut side
and rounded off on lower side.
- Small seedlings, buck brush, manzanita, etc., adjacent to
trails were left in place in order to feather edge.
- Decayed, old," or rotten downed timber was flattened by a
tractor or other equipment.
- Gouging soil with bulldozer blades was prohibited. Excavation
was only allowed to adequately divert potential storm and snow-
melt runoff.
- Logs snaked to a landing were thoroughly delimbed and sectioned
to minimize damage to residual undergrowth, ground cover^
and timber.
46
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- Stumps were removed either by splitting or by grinding. This
resulted in minimum ground disturbance.
3. Areas Between Trails
- Dead, damaged, diseased, or leaning trees were removed.
- Slash and debris on ground were flattened as much as possible.
- Willows, alder, aspen and seedlings in these areas were left
intact.
Site Specific Soils Analyses
Prior to the construction of each subunit of the development, detailed
soils reports were prepared to notify the design engineers of any
special problems which might be encountered. In addition, the soils
reports provided the appropriate construction criteria which were re-
quired in each instance. The following specific construction criteria
was provided by the individual soil analyses (10):
1. Trenching
- Clearing and grubbing was kept to a minimum in such a manner
that the existing natural appearance would be preserved or
reestablished at the end of construction.
- Top soil was usually thicker than 0.3 meter; therefore, top
. ...... soil was excavated to a maximum depth of 0.5 meter and stock-
piled separately for later use as the top portion of the back-
filled trench.
- Check dams were required for erosion control of the backfill.
They were installed across the trench where the ground surface
slope along the alignment was greater than 10 percent. Check
dams were also installed on the up-hill side of major creek
crossings to prevent direct discharge to surface waters.
The check dams were constructed by placing internesting "sack-
crete" from 0.3 meter above the top of the pipe to 0.15 meter
above the ground surface.
2. Roadway, Parking Lot, and Condominium Construction
That portion of the Northstar development which is most heavily
developed for residential and commercial facilities is located in
an area having silty top soil containing decaying vegetation and
roots, cobbles, and boulders in some areas. The topsoil is
underlain by sandy silt with a varying amount of cobbles and
boulders in brown-yellow tuffs and breccias of volcanic origin.
The original roadway alignments were covered by a thin growth of
grasses in places with localized thick pine needle covering below
47
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the trees and, in some areas, heavy brush and trees.
was very light, even in the spring and fall seasons.
Surface runoff
Only a few major construction difficulties were anticipated. These
included excavation in dense layers of cobbles and rocks with occa-
sional large boulders or bedrock and localized high groundwater
problems. The thickness of top soil to be removed and stockpiled
for later revegetation was determined in the field by the soil
engineer. It was kept at a minimum, however, consistent with
obtaining a reasonably good subgrade. For estimating purposes, an
average of about 0.5 meter depth of top soil removal was recommended.
Proposed cut slopes could be excavated at Northstar up to 2:1 with-
out creating exceptional erosion problems. When hard rock was
encountered, the cut slopes were steepened to 1:1 and even steeper.
Compacted fill slopes were not constructed steeper than 2:1 and
care was exercised in draining the surface of the adjacent areas
away from the slope face. Where natural slopes were steeper than
5:1, the surface was benched continuously to provide level steps
on which to base the fill. All fill slopes were compacted and
leveled to provide a surface free of loose material which would
be subject to erosion or sloughing.
C. Environmental Impact Reporting
To provide information to the county on the environmental impacts of
the various proposed subunits of the Northstar development, a series
of environmental impact reports were prepared by the development plan-
ners(ll). Not only did these reports assist the county in their obli-
gations of meeting the requirements of the California Environmental
Quality Act (CEQA) of 1970, but they also made recommendations to the
developers on how expected problems should be addressed. The recommen-
dations made in the environmental impact reports pertaining to erosion
control for trenching operations, roadways, and parking lot construction
were similar to those made in the various soil reports mentioned pre-
viously. The main thrust of the recommendations pertained to problems
expected to be encountered in the construction of condominium and
residential subunits.
1. Home Sites and Condominium Areas
The following criteria were used in determining which sites should
be developed for private home sites and condominium areas.
— Natural slopes should not exceed 15 percent.
- The soils must be structurally stable, not excessively stony,
and free of rock outcrops.
- Vegetation density of developable areas should not exceed
60 percent.
48
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- Development should not violate existing flood plain or wet
meadow areas. Existing water courses should not be altered.
The following is a brief summary of the environmental impacts
pertaining to erosion control and sediment transport which were
identified for a typical condominium construction site:
"Some ground compaction does result from the siting of
.condominium units. Rubber tired equipment, used where
possible, serves to minimize soil disturbance and, thus,
reduce erosion potential In the siting process. The
only major potential for erosion occurs on roadcuts and
fill areas,. The surface drainage is slightly increased
especially in paved areas due to a concentration of
runoff. Attention must be given to evenly distribute
the runoff to existing natural drainage channels.
trenches dug for utility and service may impede, to a
limited extent, subsurface drainage and create a visual
scar dividing the surface landscape for a short time.
Few, if any, areas pose revegetation problems if ade-
quate precautions are taken during construction (11)."
Recommendations for minimizing erosion control and sediment trans-
port problems for a typical condominium unit included:
- In those areas where ground cover has been removed due to
cuts and fills or other construction processes, revegetation
should take place to reduce erosion and, secondly, to lower
dust conditions.
- All cuts higher than 1.5 meters (.Vertical) should receive the
following special treatment.
. Cuts should be sloped to 2:1 and the upper portion
of the slope rounded off. A 2:1 slope is necessary
for adequate replacement of topsoil,
. Topsoil should be replaced to a depth of 15 centi-
meters on these cuts and then compacted with a
sheepsfoot roller*
. The topsoil should be replaced in the spring of the
year, allowing for a slight erosion of the exposed
subsoil, thereby resulting in a surface that will
greatly facilitate the bonding of topsoil to sub-
soil. At this time, hydromulching with. a. native
seed content and plantings for erosion control
should be conducted.
. Cuts that expose rock surfaces should be left as
such and treated as rock outcroppings, Such cuts
49
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should be made at the maximum safe slope and not at
the two 2:1 slope required for the replacement of
topsoilo
All fill slopes should be treated in the same manner as out-
lined for the cut slopes. Topsoil should be stockpiled at
several points along the access road right-of-way that are
convenient to the major cuts and fills that are involved.
This topsoil should be stripped from the road right-of-way
and cut and fill slope areas that are not excessively stony.
- Increased surface runoff must be recognized as an exponential
result of paving and surfacing.
- The increase in water runoff should be directed to natural
drainage channels to avert overland travel and resulting
surface erosion, stream sedimentation, and new surface
channels.
- All equipment should avoid rocky outcroppings due to fragility
of the vegetation characteristic to them and due to the possi-
bility of slope creep.
- All service utilities should be placed in common trenches to
minimize the number of trenches excavated per unit.
- Trees to be preserved should be wrapped, staked, or protected
by other means to avoid bark damage during the course of con-
struction. A rope barrier around groups of trees or other
vegetation would be adequate. No salt should be used on road
surfaces for winter safety, except where the addition of sand
provides inadequate safety control.
- Where sand is used on roads for winter safety, adequate catch
basins should be installed and serviced regularly in order to
provide for the settlement of particular matter from the pave-
ment runoff prior to any entrance to Martis Creek or any of
its drainages.
- Care should be taken to avoid aspen and other larger trees
during construction.
- West Martis Creek and any wet areas should not be crossed
with any vehicle or equipment during construction.
2. Foundation Systems
A further in-depth analysis was prepared to determine the compara-
tive environmental impacts of post and beam construction as opposed
to perimeter foundations for condominiums. Comparisons were made
from the standpoint of soil disturbance, area disturbance, and
50
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visual conflicts in areas of 0 to 15 percent slope and areas of 15
to 25 percent slope.
- The Disturbance of Soil for Foundations
Calculations demonstrated that the average volume of soil
removed per unit with the post and beam construction would
be 31 cubic meters. The average volume of soil per unit
utilizing a perimeter foundation would be approximately
20 cubic meters, which is 35 percent less than the post and
beam construction.
- Disturbance of Soil for Construction
Post and beam construction requires a continuous pathway
4 meters wide around the perimeter of each building group or
approximately 70 square meters per unit. This pathway serves
both foot traffic and traffic from the 60-ton crane which is
required for the replacement of the precast concrete footings.
The movement of the crane compacts the soil, necessitating the
removal of all vegetation in the area of the pathway, and
place in jeopardy all trees that are close to the edge of the
path. Perimeter foundations also require a 4-meter wide path-
way around each building group. However, this pathway serves
only foot traffic and occasional traffic light construction
equipment which deliver concrete blocks and reinforcing steel.
These materials are stockpiled within a 4-meter path for each
unit.
- Drainage and Revegetation
The soils of the Northstar property generally possess high
ecological suitabilities for buildings and do not pose many
problems with regard to a change in foundation type. The
recovery period for vegetation in these soils is generally
rapid depending on the extent of the original disturbance.
The main impact involved with post and beam construction on
slopes greater than 15 percent is the relative bearing capacity
of the soil. Due to the lack of substantial clay layers within
Northstar, the post and beam foundation type is a method in
which bearing capacity and soil drainage create few problems.
The perimeter foundation, on land with less than 15 percent
slope, creates less disturbed surface area and ground compac-
tion during construction than post and beam foundation types.
The foundation wall serves as a barrier to subsurface and
surface drainage for the entire 36 meter width of an average
condominium group. Due to the presence of a moderately high
water table in some units, changes in subsurface drainage were
expected to occur. In any seasonally wet area, it was recom-
mended that subsurface drainage pipe, block spacers or other
similar means be installed to enable drainage to be continuous.
In areas where downslope vegetation relies on subsurface water
51
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drainage, this installation is particularly important to insure
the stability of the vegetation. Surface drainage should be
directed to natural drainage channels. The soils of the lower
areas which support sage brush and Jeffrey pine contain higher
percentages of clay. The subsoil permeability and the soil
drainage is generally slower in these soils and this should be
accounted for by the installation of subsurface drains.
The post and beam construction on land with under 15 percent
slope was not expected to hamper the subsurface drainage to
any extent due to the fractured nature of soil. The majority
of subsurface drainage through the porous substrata would be
conducted around the embedded post. The construction process
of digging the holes and placing the post and beams disturbs
and compacts the soil to some extent but, due to the high rock
content of the soil, compaction would not necessarily create
revegetation or runoff problems. The post and beam construc-
tion on land with slopes greater than 15 percent results in
similar impact as those on slopes less than 15 percent. The
relative erosion potential increases from slight to moderate
in these soil types on areas greater than 15 percent slope
regardless of foundation type. Due to the particle size and
distribution of these soils, the erosion hazard does not pre-
sent extensive problems. If construction practices are care-
fully monitored, there should be no subsequent soil drainage
or revegetation problems on the site with either foundation
type.
- Visual Amenity
Post and beam construction provides an interesting and esthet-
ically satisfying design relationship between the building
and the land. This relationship is most appropriate in certain
situations, such as steep slopes (15 percent) where perimeter
foundations would present a massive and unpleasant face on the
downhill side of the unit; on rocky lands where it would be
extremely difficult to excavate for linear foundations or on
wetlands where no building contact with the surface is desired.
In almost every other situation, perimeter foundations that
are pleasantly detailed and planted are as esthetically accept-
able as post and beam construction. When post and beam con-
struction is to be used, it does provide the potential for the
accumulation of debris, vegetative, or other beneath the unit.
This condition must be overcome by active maintenance.
The environmental impact of post and beam construction is slightly
greater on slopes of 0 to 15 percent impact than that caused by
perimeter foundations. Specifically in the areas of soil compaction
and vegetative disturbance, these particular impacts do not increase
significantly on the steeper slope conditions and can be ameliorated
by thorough construction, supervision, and revegetation of disturbed
areas; Perimeter foundations on the steepest slopes have the
52
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esthetic disadvantage of massive downhill faces. Also, with param-
eter foundations, the amount of surface grading required for the
satisfactory drainage of surface water around the building creates
significant constraints in tight areas, such as the space between
buildings or between buildings and parking lots.
3. Village Center Commercial Area
The environmental impact report prepared prior to the construction
of the village center commercial area recognized the possibility
of a substantial impact. It was recognized that much of the area
would be paved or covered by other impervious surfaces.
The major drainage outlet from the Village Center discharges
directly to Martis Creek east of the village after passing through
an energy dissipator. The channel was rock riprapped at the out-
fall into Martis Creek to avoid extreme bank erosion. The total
runoff intensity for peak storm, calculated for a mean annual pre-
cipitation of 90 centimeters, was 3,110 cubic liters per second
with the velocity of 2.2 meters per second at the point of entering
Martis Creek. The major impacts are sand and sediment load from
road and walk surfaces and, secondly, possible vegetation and lim-
nological damage if calcium chloride is added to the sand applied
to road surfaces for winter safety. Based on Placer County
Maintenance Department estimates, the total volume for sand nor-
mally applied per year to an area comparable to the village center
and parking area is between 14 and 18 metric tons.
Recommendations given for mitigating adverse impacts due to the
construction of the Village Center commercial area included:
- In order to insure compliance with the Porter-Cologne Water
Quality Control Act (State of California) and Northstar's
internal quality control standards, it is recommended that
an adequate catch mechanism and energy dissipator, such as
"bubbleup" catchment basin and sediment pond or other simi-
lar devices be installed and serviced regularly in order to
provide for settlement of suspended sediment prior to outfall
into West Martis Creek. There should be no significant devi-
ation beyond natural background levels of turbidity and total
suspended dissolved sediment load.
The angle and slope of the outfall and the entrance of the
outfall at Martis Creek should be such that minimum streambank
erosion occurs at that point.
- All trees not marked for removal during the village construc-
tion should be chosen for their vigor as well as placement
purposes. These trees should be wrapped or protected by other
means to avoid damage during construction. Care should be
taken to avoid severe ground compaction or disturbance of tree
53
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roots. A radius comparable to one-sixth of the tree height
should be roped off or protected by other means to avoid this
excessive compaction and to allow for moisture and aeration in
the root zone.
- Pathways and walkbridges should be constructed to control
vegetation trampling and damage to creek and natural areas.
- Care should be taken to avoid overland flow where such flow
may result in accelerated erosion.
No salt should be used on road surfaces for winter except
where the addition of sand proves to be inadequate for safety
control.
D. Planting and Revegetation Management Program
Vegetation was recognized by the developers and planners as an integral
component of the Northstar environment (12). It was also recognized
that a development of Northstar's scope could not be constructed without
some initial damage to the native vegetation. The purpose of the
Planting and Revegetation Program at Northstar was to insure permanent
and rapid recovery of disturbed areas.
Vegetative Analysis
The vegetative structure or "mosaic" was carefully examined and mapped
at Northstar. The various subunits identified ranged from open, wet
meadows and dry, shrubby areas at low elevation to the Red Fir climax
communities on the upper slopes. The criteria which was chosen to char-
acterize the several subunits included: <
- The dominant species present.
- Age classes of the dominant species.
The presence of species with a capacity to reproduce even when
shaded by existing vegetation.
A total of 13 distinct subunits were identified within the West Martis
Creek portion of the Northstar Creek property:
1. The Open, Wet Meadow subunit is recognized by an abundance of wet
meadow grasses, Clover, Willow, and Alder, with scattered Jeffrey
Pines. The history of the subunit is mainly grazing and some creek
flooding. The meadow remains wet throughout the summer, due to
poor drainage, and supports numerous wildflowers.
2. The Riparian subunit is characterized by a narrow zone of wet
grasses and associated hardwood species of Aspen, Black Cotton-
wood, Willows, and Alders which create a winding strand of ri-
parian protection and habitat for associated fauna.
54
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3. The Wet Meadow-Forest subunit is in a visible state of change from
wet meadow grass, Aspen, Willow, and Alder, to a mixture with
Lodgepole Pine and White Fir invading from the exterior boundaries.
These areas are extremely sensitive due to the dependence on water
and the number of attractive wildflowers and hardwood species.
4, The Sage^Bitterbrush-Mule Ears subunit is the driest unit on the
property and is characterized by the low-lying shrubs and numerous
grasses and wildflowers. It occurs on the dark, heavy, high clay
containing soils developed from andesitic rock.
5. The Jeffrey Pine-Sage-Mule Ears subunit is an open, dry area
upslope from the creek and below the more heavily timbered areas.
The scattered pines make up less than 40 percent of the cover but
contribute significantly to the character of the subunit. This
subunit occurs mainly on soil type boundaries from less acid to
more acidic brown forest soils.
6. The Pine-Fir subunit represents an area which was, at one time,
strictly pine-sage but has now been invaded by White Fir, man-
zanita, and associated species.
7. The Ceanothus-Manzanita Brushfield subunit is historically related
to fire and depends upon fire for existence. The seeds of these
species require heat of 200-300° Fahrenheit to germinate but, once
established, sprout vigorously and tend to control the site.
A gradual invasion of the Tobacco Brush and Greenleaf Manzanita
by conifers over a 30- to 60-year period returns the site to its
coniferous cover. The units on the property represent two stages
of coniferous invasion.
8. The latter stage of the Ceanothus-Manzanita Brushfield subunit is
is characterized by a similar mix of Tobacco Brush and Green Leaf
Manzanita with a larger percentage of White and Red Fir. Some
Jeffrey Pine is present as a remnant of the original fire and some
younger trees have seeded along with the White and Red Fir but have
not competed as favorably.
9. The White Fir-Red Fir-Jeffrey Pine subunit in the early stage is
characterized by dense thickets of young White and Red Fir and
Tobacco Brush with some Jeffrey Pine present. This subunit is
generally the result of fire or clearcut logging and is one step
towards the climax on the successional ladder. This vegetational
subunit usually occurs on deep, brown forest soils such as Cohassett.
10.' The White Fir-Red Fir-Jeffrey Pine subunit in the latter stage has
progressed further in succession by shading out more of the bush
species as well as establishing a lower story of White Fir and Red
Fir seedlings. Some of the lower species present in the pure Red
Fir forest start to appear in this subunit under the mature White
and Red Fir.
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11, The Fir-rPine subunit is characterized by an upper story of mature
White and Red Fir with some Jeffrey and Sugar Pines and an under-
story of White and Red Fir.
12. The Red Fir - White Pine *- Jeffrey Pine subunit occurs above the
2000 meter elevation and covers the majority of the upper ski area.
Pinemat Manzanita replaces Squaw Carpet as the principal ground
cover in association with Tobacco Brush and Chinquapin.
13. The Red Fir forest is the climax community and is characterized by
heavy densities of Red Fir and small amounts of Chinquapin, Goose-
berry, and Thimbleberry, in openings where light reaches the forest
floor. Red Fir is the only major species tolerant enough to repro-
duce under its own heavy canopy.
The locations of each of these subunits within the Northstar Property
is. shown in Figure IV-1. The various plant species which were identified
within each of the suBunits are listed in Table IV-1. Once development
occurred within the various subunits, it was recommended that disturbed
areas should be replanted with species native to that subunit.
Revegetation Recommendations
The following recommendations were prepared by the Northstar planners to
serve as a revegetation guide for areas disturbed during construction:
1. Condominiums
- Concept
The condominiums have generally been designed to impart
minimal impact on the site with units clustered to pre-
serve open space. Native vegetation is preserved as much
as possible.
— General Recommendations
Remove brush to minimum of 50 feet from units for purposes
of fire safety.
Upper Condominium Hill and Middle Condominium Hill
Ground covers should be Pinemat Manzanita, Newberry
Penstemon, and Squaw Carpet.
Planting should occur after seeding disturbed areas with
grass-legume fertilizer mix with Mule Ears added.
Jeffrey Pine, Sugar Pine, and Red Fir are recommended
trees.
Recommended shrubs are Snow Berry and Thimbleberry,
neither of which creates a major fire problem.
56
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KEY
I-OPEN. WET MEADOW
2-RIPARIAN
3-FOREST, WET MEADOW
4-SAOE, BITTERBRUSH
5-JEFFREY PIME-3A6E
6-PINE-FIR
7-MAHZANITA-PINE (EARLY)
6-MANZANITA-PINE (ADVANCED)
9-FIR-PINE (EARLY)
10-FIR-PINE (ADVANCED)
II-FIR-PINE
12-RED FIR-WHITE FIR
13-RED FIR
FIGURE IV-1. VEGETATIVE MOSAIC OF NORTHSTAR DEVELOPMENT.
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TABLE IV-1:
SPECIES COMPOSITION OR THE VEGETATIVE
SUB-UNITS AT NORTHSTAR
No.
COMMON
NAME
SCIENTIFIC
NAME
1234
SUB-UNITS
5 6 7 8 9 10 11 12 13
1White Fir
2 Red Fir
3 Yarrow
4 Columbian Monkshood
5 Wild Onion
6 Mountain Alder
7 Serviceberry
8 Red Columbine
9 Pinemat Manzanita
10 Green Leaf Manzanita
11 Sagebtush
12 Lady Fern
13 White Brodiaea
14 White Mariposa Lily
15 Pussy Paws
16 Chinquapin
17 Indian Paintbrush
18 Squaw Carpet
19 Tobacco Brush
20 Rabbit Brush
21 Sierra Thistle
22 Meadow Daisy
23 Sierra Morning Glory
24 Sierra Shooting Star
25 Larkspur
26 Horsetail
27 Queen Anne's Lace
28 Gayophyturn
29 Gilia
30 Cudweed
31 Bigelow Sneezeweed
32 Cow Parsnip
33 Tiger Lily
34 Washington Lily
35 Brewer's Lupine
36 Mint
37 Yellow Mimulus
38 Monardella
39 Penstemon
40 Jeffrey Pine
41 Sugar Pine
42 Western White Pine
43 Lodgepole Pine
44 Rattlesnake Plantain
45 Aspen
46 Black Cottonwood
47 Yellow Cinquefoil
48 Bitter Cherry
49 Pinedrops
50 Bitterbrush
51 Huckleberry Oak
52 Buttercup
53 Sierra Currant
54 Sierra Gooseberry
55 Calif. Wild Rose
56 Thimbleberry
57 Willow
58 Elderberry
59 Snowplant
60 Groundsel
61 Wild Hollyhock
62 Spiked Mallow
63 Meadow Goldenrod
64 Swamp Whiteheads
65 Snowberty
66 Danelion
67 Clover
68 Mule Ears
69 Death Caraas
70 Various Grasses
71 Corn Lily
72 Sulphur Flower
73 Fireweed
Abies concolor
Abies magniflea
Achillea mittefolium X
Acomitium columbianum
Allium sp.
Almus tenuifoiia X
Amelanchier almitolia
Aquilegia truncata X
Arctostaphylos nev.
Arctostaphylos patula
Artemisia tridentata
Athyrium filix-femina
Brodiaea sp.
Calchortus venustus
Calyp tridium urab.
Castanopsis semp. i
Castilleia pimetorum X
Ceanothus prostratus
Ceanothus velutimus
Chrysothamnus naus.
Cirslum califomicum
(compositia) X
Convolvulus villosus
Dedecatheon j effreyi X
Delphinium scopulorum
Equisetum arrense
Eulophus bolander X
Gayophytum dittusum
Cilia sp.
Gnaphalium sp.
Helenium bigelovii X
Heracleum lanatum
Liliun parvum
Lilium washingtonianum
XXX XXXXX
x x y x x x
X X
X X
X
X X
X
X
X
X X
X
X
X
X X
X
X
\ X
X
X
X
X X
X X
X X
X X
X
Taraxacum sp.
Trifolium sp.
Wyethia mollis
Zigadensus venen.
Veratrum calif.
Eriogonum umbellatum
Epllobium angustifolium
X X
X X
Lupinus brewerii X
Mentha arvensis .X
Mimulus guttatus X
Manardella nana
Penstemon sp.
PInus Jeffrey! X X X X
Pinus labertiana
Pinus monticola
Pinus murrayana XXX
Plantago sp.
Populus tremuloides X X
Populus trichocarpa X X
Potentilla glandulosa X
Prunus emarginata
Fterospora androw
Purshia tridentata X
Quercus vaccinifolia
Ranunculus calif, X
Rlbes nevadense XXX
Ribes roezlii
Rosa sp. X X X X
Rubus parvlflorus
Salix sp. XXX
Sambucus caerulea
Barcodes sanguinea
Senecio triangularis
Sidalcea reptans
SIdalcea spicata X
Solidago elongata X
Sphenosciadium sp.
Symphoricarpos mollis
X
X
X X
X X
X
x'
XXX
X X
XXX
X
XXX
X
X
X
X X
X X X X X X
XXXXX X XX
XXX
X X
X
X
XXX
X XXXXX
X XX
XXXXX X X
XXXXX X X XX
XXX
X
X X
XXX
X X
X XXX
XXX
xxxxx x xx x
X XXXXX
X
X
x x x x
X
X X X X X X
X X
XXX X X
XX XX
XXXXXXX X
X XX
XXX XX
XXXXX
XX X X X X
XXX X X X X
X
58
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Tobacco Brush will seed itself naturally into the dis-
turbed areas but should not be permitted to immediately
take control around the units.
- Valley Condominiums
Plants should be Willow, Alder, Dogwood, Aspen, and
Black Cottonwood.
Willow and Alder may be pruned to maintain shrub forms
and reduce excessive water loss in the soil.
A grass mix favoring clover should be seeded in the wet
areas and the remaining areas seeded with regular grass-
legume mix.
Large groups of Aspen should be thinned and all decayed
and nonvigorous trees removed.
Invading pine and fir should be removed in order to
preserve the meadow quality of the existing mosaic.
No track or heavy equipment should be used in or tra-
verse the areas.
. Slash and heavy brush should be removed to reduce fire
hazard, enhance the appearance, and increase the recre-
ational use value.
2. Residential Lots
- General Recommendations
Jeffrey Pine infected with Limb Rust (Cronartuim filamen-
tosum) should be removed.
White Fir infected with mistletoe should be removed.
Slash, dead, or haggard trees should be removed. Small
rubber tired vehicles should be used for this operation
and no dragging over the surface should occur. All
material should be lifted and carried off site.
Existing trees may be pruned or removed in small numbers
to improve appearance and views.
Ground cover should be reestablished as soon as possible
after disturbance to reduce dust.
Pine-Fir subunits should be planted with Jeffrey Pine,
White Fir, Squaw Carpet, and Newberry Penstemon with
grass-legume mix plus Mule Ears and Brewers Lupine.
Fir-Pine subunit should be planted with Jeffrey Pine,
White Fir, Pinemat Manzanita, and Newberry Penstemon
with grass-legume mix plus Mules Ears and Brewers
Lupine.
3. Village Center
- General Recommendations
The area should be planted and managed for heavy impact
and use. Some water may be necessary for irrigation.
59
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Red Fir, White Fir, and Jeffrey Pine should be planted.
Consideration should be given to moving several larger
trees for more immediate impact.
Black Cottonwood, Aspen, Willow, Alder, Dogwood, and
Thimbleberry can all be used here but will require
irrigation.
Ground cover should be Squaw Carpet, Pinemat Manzanita,
and Newberry Penstemon.
Grass-legume mixture with fertilizer should be applied
to disturbed surfaces. For areas to be maintained as
grass, a clover mix should be used but will require
irrigation.
4. Living Area Recommendations
- Concept
Maximize the use of native materials for amenity and
utility purposes to combat undesirable noise, to create
shelter from wind or visual screening, create shade, and
regulate circulation with barriers. Hardwoods and soft-
woods should be kept as a mixture, where possible, to
take advantage of summer and winter conditions (shade,
snow).
- General Recommendations
t
Rapid growing hardwood species, such as Black Cottonwood
and Aspen, should be used on moist sites or where water
is available for an initial establishment period of
3 years. Both species are readily propagated in large
numbers.
. Pines and firs representative of each vegetation zone
should be planted to replace trees lost in development.
The maintenance of 30 to 40 percent crown cover density
is important to preserve the character of a "forest
environment."
. Barrier plants for visual screening, wind breaks, and
circulation control should be Alder, Mountain Dogwood,
and Aspen in moist areas, and Tobacco Brush and Service-
berry where water is not available.
. White Fir, Red Fir, and Tobacco Brush have dense foliage
and should be the most useful for noise control.
Singeing of trees when burning slash, burn piles will
cause browning of needles which will not drop for 2 to 3
years. Therefore, burn piles should be established on
road rights-of-way, building and ski terminal sites, and
as far from surrounding-vegetation as possible. Burning
should occur only after a good fall of snow since the
snow will protect the surrounding vegetation.
60
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5, Road Rights-of-r-Way
— General- Recommendations
. Cuts and fills should be covered with 6 inches of topsoil
as previously recommended.
. When natural revegetation does not occur, a grass-legume -
seed mixture with Mule Ears and fertilizer mix added
should be applied immediately prior to the first snow
fall. No watering should be done in the fall due to
possibility of false germination and resultant loss of
cover.
. Squaw Carpet and Newberry Penstemon should be used to
an elevation of 1,900 meters.
. Pinemat Manzanita and Newberry Penstemon should be used
over 1,900 meters elevation.
Other species should be used in accordance with the
subunit in which the cut occurs.
Considerations of safety, design, aesthetics, pedestrian
crossings, and snow removal must be made for each speci-
fic case.
6. Trails and Paths
- Concept
. Generally reduce impact to a minimum while aiding safety,
usability, and amenities.
- General Recommendations
. Trails not in the immediate development area (or not of
first importance for general circulation) should be marked
and layered with fir bark or moved annually to prevent
permanent compaction and subsequent erosion channels.
. All paths of primary importance in the development areas
should be hard surfaced and clearly marked to permit snow
clearance.
. Disturbed areas should be treated in the same way as
for cuts and fills in road rights-of-way.
Plant materials should be those most resistant to impact,
hardy, and prostrate. Such plants (as selected according
to the subunit through which the trail passes) include:
Snowberry, Thimbleberry, Serviceberry, Newberry Penstemon,
Pinemat Manzanita, and Squaw Carpet.
. A self-guided nature trail could be planned to pass
through the different ecological subunits with inter-
pretive information along the trail.
61
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Ski Slopes
— Concept
. Ski runs are areas of bare or partially bare ground which
should be vegetated to stabilize the slopes, reduce
soil erosion, maintain the visual character, and minimize
reradiation and early snowmelt in the spring.
- General Recommendations
Pinemat Manzanita, Newberry Penstemon, Tobacco Brush, and
Squaw Carpet should be planted on the ski trails as soon
as possible.
. Seeding with the same mix as for road cuts should be used
prior to snowfall. Seeds of shrubs recommended above
should be added when available.
. Green Leaf Manzanita should not be used and should be
eliminated when possible since it does not lie flat
with snow cover. The plant will stick through low snow
cover, hasten springmelt, and present a hazard to skiing.
Golf Course
- Concept
The detailed design of the golf course should adhere to
the natural topography as much as possible in order to
retain mature trees. Nevertheless, the golf course devel-
opment will tlireaten the Jeffrey Pine-Sage-Mule Ears
community due to the grading and irrigation.
- General Recommendations
. A drainage reservoir should be engineered to capture
the irrigation water return flows. Fertilizer and other
runoff would seriously alter the creek waters and valuable
water would be wasted without such a reservoir.
Since irrigation water will be available, Aspen, Cotton-
wood, and Jeffrey Pine should be planted.
White Fir should not be planted.
A clover mixture should be used within sprinkling dis-
tance of the groomed fairways.
It was estimated that the total disturbed area requiring revege-
tation following construction of the entire planned Northstar
development would be 65 hectares or about 6.3 percent of the
total 1,036 hectares of West Martis Creek Northstar property.
62
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The total number of plants estimated to be required to revegetate
this area was as follows:
1. Ground Covers and Shrubs
2. Hardwood Trees
3. Conifer Trees
Total
$152,410
11,280
22,560
$186,250
In addition, it was estimated that approximately one-half of the dis-
turbed 65 hectares would also require hydromulching with grasses and
native seeds.
E. Criteria Summary
The planning process conducted prior to the construction of Northstar-
At-Tahoe was extensive. Many of the problems plaguing other poorly
designed developments, both past and present, were avoided at Northstar.
Although costly at first, the type of predevelopment planning conducted
at Northstar is likely to be relatively inexpensive in the long run. As
will be discussed in later sections of this report, treatment of erosion
and sediment control pollution problems after the fact is extremely
expensive. In addition, the cleanup of erosion and sediment control
pollution problems, once a development is constructed, are many times
much less effective than if adequate precautions had been taken initially.
Dr. Paul J. Zinke, the consulting ecologist to the Northstar development,
summarized the attributes of the Northstar development planning in a
1971 report. Those points pertaining to erosion and sediment control
made by Dr. Zinke are as follows (13):
1. There has been an awareness of the value of the landscape and its
natural setting throughout the development of the project. This
awareness is an attempt to set economic and ecological objectives
on a parallel and reinforcing direction.
2. Logging operations for timber harvest in the 1950's were planned to
maintain a landscape value that was based on the natural integrity
of a forest landscape. Logging road locations and designs were
such as to keep erosion to a minimum. Logging roads generally
conform to the contours of the slopes. There was no clear cutting;
only thinning operations allowed.
3. Initial development potentials for the property were recognized as
being due to outdoor recreation and a need to maintain a favorable
environment established as an economic goal. The intent was to
develop Northstar for a market that would prefer a developed prop-
erty that is based on a sound environmental ecological basis.
4. The maintenance of year-round facilities at Trimont was recognized
as requiring planning for winter as well as summer ecological
impact. Clear waters and wooded slopes were recognized as being
principal environmental attributes of the area.
63
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5. The unique qualities and ecological processes of the landscape are
primary determinants of the proper form of development in the
Northstar area. There is evidence of awareness that the complex
landscape processes which brought about the present environment
will also ensure its continued stability if not drastically altered.
For purposes of ecological study, vegetation, soil, geology, topog-
raphy, and hydrology, all have received separate and complete
analysis.
6. Slope criteria were recognized as being of primary concern in deter-
mining developable area. In general, areas of greater than 15 per-
cent slope were considered inappropriate. Occasional development
of areas from 15 to 25 percent was considered possible only in
exceptional situations.
7. Hydrologic and drainage factors were evaluated for the property. A
water balance was prepared, identification of stream types was
made,, and the characteristics of subsurface aquifers were identified.
8. The property north of Lake Tahoe and south of Martis has an ecolog-
ical integrity that is based on a combination of geology and result-
ing soils, climate, topography, and finally the vegetation that is
adapted to these. The critique of the planning for the Northstar
property was based upon the degree to which the ecological integrity
of the site would be affected by proposed development.
9 Soil criteria for development were based upon a soil-type map com-
piled from an existing soil map for the Tahoe Basin, from the
geology map for the area, and from field reconnaissance of the
actual area. Any limitations or disadvantages for development from
the soil standpoint were noted. Areas that would not sustain devel-
opment were noted as being unsatisfactory.
10. Conflicts between preliminary development plans and ecological
integrity of the area were identified. Adjustments were made to
arrive at a final plan respecting the integrity of the site. Con-
straints were applied to the development based upon the vegetation,
soil, slope geology, snowfall, hydrology, and visual impact. The
primary constraints on development to protect the ecological integ-
rity were based on slope and drainage.
11. Computerized map printout and suitability models have been made for
the development which takes into account ecological criteria. The
computerized maps are on a one-acre basis, and there are individual
maps for each of the following ecological criteria. For vegetation
type; conifer age class, vegetation density, water types on the
site, snow depth, sun intensity maps for winter months, average
annual sun intensity, visual analysis model, topographic analysis,
aspect and exposure map, slope map, ski slope suitability map, land
development suitability model, and ski slope suitability map.
64
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12, Th.e beginning of detailed planning for the siting of roads, build-
ings, and other improvements in the Martis Valley area has been
marked by a continuous series of discussions pinpointing and dealing
with ecological opportunities of the site.
13, Ski area terrain at Northstar is less steep than other ski areas.
The ecological impact at the Northstar development, insofar as
erosion is concerned, will'be less than other ski developments due
to the 1esser steepness 6 f slopes. Ski areas are being developed
mainly for intermediate skiers. Continually, emphasis was placed
on the location of ski areas on smooth, rock-free terrain having
enough soil so low cover can become established for erosion control.
14. The siting of amenities, drainage works, power lines, and other
development features in the Northstar Basin area has been done in
such a way that the alteration of natural environment in the area
will be at a minimum.
15, There is every indication that the concern for the environment
represented by these measures will continue in the future.
The last point is of extreme importance. The best planning principles
could all be for naught if the continuing responsibility for the impact
of the development was not properly assumed. In the case of Northstar,
the original developers maintain a continuing interest in the develop-
ment. Although a small portion of the development is sold to private
ownership (less than 8 percent)., the vast majority of Northstar will
continue to be owned and operated by a single responsible entity (in
addition to the services provided by the county). The myriad of poten-
tial problems, which were recognized in the planning process, must con-
tinue to be addressed during the continued expansion and operation of
Northstar-At-Tahoe; thus, if the concern exhibited in the planning is
continued through the construction and maintenance phases, there is
considerable reason to believe that a development, such as Northstar,
would have minimal, if not negligible, adverse impact upon water quality
and the environment.
65
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SECTION V
NORTHSTAR-AT-TAHOE: A WELL PLANNED AND
CONSTRUCTED RESIDENTIAL-RECREATIONAL DEVELOPMENT
To a considerable degree, the actual construction of the Northstar develop-
ment was closely patterned after concepts developed In the planning stages.
The unique commitment of Northstar's developers to thorough planning and
careful construction has led to a well conceived development which has
minimized any adverse environmental impacts. Compared to most other past
and present developments of the Lake Tahoe vicinity, Northstar-At-Tahoe is
one of the best examples of a well planned and constructed residential-
recreational complex. As documented in Section VII of this report, erosion,
as measured by suspended sediment transport in West Martis Creek, was held to
about a one-fold increase over very low background levels. Such an accom-
plishment would be possible only through the most careful planning and con-
struction practices.
The ultimate Northstar plan calls for the construction of 132 hectares of ski
runs, a 68 hectare golf course, 585 single-family 0.1 hectare residential
lots, 3,115 condominium units, a recreation center, a 1.2 hectare village
commercial center, 10 hectares of utility and maintenance facilities and
48 hectare1of roadways and parking lots. However, as of 1977, less than half
of the originally planned development was constructed. Additional units are.
to be added as future markets conditions dictate. Only the construction of
ski runs is essentially complete. At present only 6 of the 14 originally
planned ski lifts have been constructed and only one-half of the originally
planned 18 hole golf course has been completed. Of the housing units, about
55 percent of the residential lots have been subdivided while only 25 percent
of the potential condominium units are built or under construction. Table
V-l describes the engineering, construction, and sales sequence of the
presently existing Northstar development units.
A. The Ski Area
Only in the most intense rainstorms (greater than 1.5 centimeters per
hour) and during rapid spring snowmelt is there any significant sediment
discharge to West Martis Creek from the ski area. The primary reason for
this is the fact that the watershed and terrain chosen is highly suitable
for the development of a ski area. The natural terrain is gently sloping
and the high natural percolation rate of the native soils prevents signif-
icant overland flow. Hence, the potential for significant erosion prob-
lems was reduced simply by proper site selection. Nonetheless, erosion
66
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Unit
Comdominiums
Homes ites
Commercial Area
. Ski Area
Recreation Center
. Stables
Golf Course
. Utilities
TABLE V-l
NORTHSTAR DEVELOPMENT
Engineering
1971-72
1971-73
1972
1970
1972-73
1973
1971-76
1971-72
SCHEDULE
Construction
1972-74
1972-73
1972-73
1971-74
1973-74
1974
1972-77
1971-73
Sales
1972-present
1973-present
1973-present
1973-present
1973-present
1973-present
1973-present
N/A
problems would have appeared had not careful construction practices been
implemented in the development of the ski area.
In most instances ski runs were cut on less than 3:1 (horizontal to
vertical) slopes and in diagonal patterns at an angle to the fall line.
This prevented the accumulation and concentration of runoff in disturbed
areas. Rather, any storm and snowmelt runoff from areas disturbed for
ski run construction is discharged to and "filtered" through, undis-
turbed buffer zones. On the steeper ski runs which could not be sloped
diagonally across the fall line and natural drainages, artificial water
bars and diversion structures were constructed. These structures effec-
tively divert runoff to adjacent undisturbed terrain, yet only create
gentle rolls on the ski slopes which do not pose a hazard to skiers.
Where possible, natural low-lying native vegetation was left undisturbed
to provide soil stabilization. This was accomplished, in part, by the
almost exclusive use of rubber-tired vehicles for tree removal and
slash disposal. Those areas where native low-lying vegetation was
heavily disturbed or naturally less dense were reseeded artificially,
the seed mixtures which were employed contained rhizominous wheat-
grasses and legumes and were irrigated where necessary.
On areas which are clear cut for ski runs, remaining tree stumps can
pose a hazard to skiing. Traditionally, the method used to mitigate
this hazard is the use of explosives or bulldozers to remove dangerous
stump material. This method usually results in considerable soil
disturbance and can lead to the channelization of storms and snowmelt
runoff. To avoid this problem at Northstar, all stumps were "flush cut"
where possible. However, in many cases, flush cut tree stumps left in
place had a tendency to "reappear", due to localized erosion or cause
rapid melting of snow over the stump, resulting in hazards to skiers.
To alleviate this problem at Northstar, without resorting to explosives
or heavy equipment, problem stumps were first split with special
equipment, with the pieces then pulled out using light tractors. This
67
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DIRT ROADS
§§§$3 GOLF COURSE
KILOMETERS
FIGURE V-1.
EXISTING LAND USE DEVELOPMENT AT NORTHSTAR AS OF JULY, 1977.
68
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Figure V-2. Well revegetated ski run at
Northstar using rhizomimous wheatgrasses
Figure V-3. Helicopter installation of ski lift
towers reduces ground disturbances at Northstar
69
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procedure substantially reduced the amount of disturbed soil yet
provided an easier-to-maintain, obstacle-free ski run.
In most instances, ski lift towers were installed by rubber-tired over-
land vehicles. Although some disruption occurred, it was not extensive
due to the usually gentle terrain in which they were installed. In
order to prevent extensive disruption in critical areas, helicopter
construction was employed for the erection of a ski lifts which
traverses steeper, more erosion prone terrain. By eliminating all heavy
equipment, substantial disruption of the natural terrain by vehicular
traffic was prevented.
B. Street and Parking Lot Construction
In most developments, nonrevegetated and oversteepened cut and fill
slopes associated with road and parking lot construction are the primary
source of eroded sediment material contributing to water quality problems.
Improperly controlled runoff from the impervious road surfaces frequently
aggravates the problem. Although the majority of excess sediment trans-
port at Nort-hstar appears to also derive from these sources, the problem
is much less severe than frequently encountered in other developments.
Considerable attention has been paid to the reestablishment of vegetation
on the cuts and fills adjacent to the roadways and parking lots at
Northstar. Although the developer did not strictly employ all of the
recommendations made in the "Northstar Planting and Revegetation Manage-
ment Program" described in Section IV, considerable effort was made in
reestablishing vegetation on disturbed slopes. The primary vehicle to
accomplish this was the practice of topsoiling. Prior to the excavation
for a roadbed or parking lot site, the upper 0.25 to 0.50 meters of
natural topsoil was stripped and stockpiled in a. adjacent storage area.
Care was taken to insure that the topsoil material would not be stock-
piled in areas subject to concentrated storm or snowmelt runoff or other-
wise potentially threaten the water quality of West Martis Creek. Once
the roadway or parking lot was fully excavated, the topsoil was replaced
on the adjacent exposed cut and fill slopes. In most cases, the cuts
were no steeper than 1%:1 (horizontal to vertical) and the fill slopes
no steeper than 2:1. In all cases, soil excavated from one of the
vegetation subunits identified in the "Northstar Planting and Revegeta-
tion Management Program" was replaced in the same subunit. This insured
that propagation of native plants from seeds contained in the topsoil
would not be in conflict with the natural vegetation of each subunit.
Furthermore, native seeds had a better opportunity to germinate and
survive in zones of their preferred habitat. Approximately 7,800 cubic
meters of topsoil were required to cover 4.7 hectares of disturbed
slopes at Northstar. The average unit cost of the complete topsoiling
operation was $4 per cubic meter.
Generally, reestablishing native vegetation by stockpiling was very
successful. In a few instances, slopes which were too steep to be
properly topsoiled were left bare. In other instances, the topsoil
70
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Figure V-4. Vegetation from native seed in
topsoiled area at Northstar after four years
site was too dry or there was insufficient seed material to generate
satisfactory growth. In these cases, various planting techniques were
demonstrated by the Soil Conservation Service (SCS) under a cooperative
agreement with the Northstar developers. Demonstrated methods included
the following:
1. Hydromulching of slopes with various grass and legume seed
mixture.
2. The planting of native and nonnative shrub seedlings.
The location and description of these demonstration seedings and plant-
ings are included in Appendix B.
Considerable effort was also expanded on the adequate control of runoff
and drainage from impervious road and parking lot surfaces. Where
possible, runoff is collected from impervious surfaces in small amounts
and discharged at numerous locations to undisturbed areas where the
native soils are sufficiently pervious to allow complete percolation. In
areas where complete percolation is limited by local soil conditions or
the amount of runoff is extremely high, drainage waters are collected
in nonerodible rock-lined drainage swails and discharged directly to
West Martis Creek. The former method of percolation is far superior.
The erosion control project staff was unable to locate any discharges of
this nature which exceeded the capacity of the soil or caused erosion
problems. In those locations where discharges to undisturbed areas
71
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were used, the drainage waters would have to travel overland for 100
meters through heavily vegetated terrain before reaching downslope
dis turbances.
Direct discharges to West Martis Creek, whenever monitored, clearly
resulted in lower stream water quality. As documented in Section VII,
however, these discharges do not appear to have harmed the aquatic life
of West Martis Creek. In most instances, the sediment discharged to the
creek in this manner was not eroded from the rock-lined drainage swales
but was of some other origin. Typically, sediments were transported to
the swales from eroding slopes and from winter road sand. Without
settling and/or percolation facilities, suspended sediments, once eroded,
are readily transported to West Martis Creek by the artificial drainage
swales at Northstar.
C. Condominiums, Village Center, and Homesite Construction
The primary reason potential erosion and sedimentation problems were
held to a minimum at Northstar was that the majority of the development
was confined to the portions of the West Martis Creek watershed which
were most amenable to development. Ideally, as identified by the
Northstar planners, this meant restricting construction of commercial
and residential buildings to areas with less than 15 percent natural
slope or with insensitive vegetation types. However, the portion of
the property which conformed to this criteria was fairly limited. Thus,
the areas which were actually developed, or are planned for development,
extend somewhat beyond the area defined as "developable" or "developable
with forest management controls" (see Figure III-9). A summary of
development confinement to areas defined as ideally developable is
presented in Table V-2. As indicated in the table, fully 30 percent
of the existing development (excluding the ski area, golf course, and
roadways) are beyond the boundaries of what was originally defined
"developable". However, in all cases, building construction has not
taken place on terrain steeper than 25 percent, with the vast majority
occurring on terrain less than 20 percent grade. Based on the water
quality monitoring program discussed in Section VII, only minor and
isolated erosion and sediment control problems have resulted from
extending development to these areas. The principle sources of eroded
sediments are the larger and frequently oversteepened cut slopes which
are required when construction occurs on steeper terrain. Where possible,
the excavated cuts and fills were revegetated by topsoiling, however,
the steepest slopes were frequently left unvegetated and highly erodible.
An additional erosion problem associated with the construction of condo-
minium, homesites, and commercial buildings is the undergrounding of
utilities, such as water distribution lines, trunk sewers, and electric
and cable TV service. At Northstar these operations were usually
performed conjunctively with construction of roadways and building units.
Occasionslly, the undergrounding of utilities necessitated the excavation
of easements through steeply sloping, previously undisturbed terrain.
To stabilize these areas satisfactorily, water bars and erosion checks
were placed across the disturbed easements to drain runoff to adjacent
72
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Figure V-5. Condominiums at Northstar situated
in an area of minimum environmental impact with
little disturbance to surrounding vegetation.
Figure V-6. Discharge of condominium parking
lot runoff to downslope undisturbed area at
Northstar.
73
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TABLE V-2
DEVELOPED AREAS AND PERCENT OF
DEVELOPMENT UNIT TYPE .IN
"DEVELOPABLE" AREAS^'—'
Development
Unit Type
1977
Land Use
Total
Area
(hectares)
"Develop-
able"
ULTIMATE
Land Use Plan
Total %
Area "Develop-
(hectares) able"
Commercial 9.73
Utilities 5.97
Co ndominiums 19.56
Residential Lots 47.66
TOTAL 83.92
38%
31%
71%
82%
70%
15.52
6.52
79.09
86.33
187.46
58%
23%
66%
80%
66%
A/ "DEVELOPABLE" means areas with less than 15% slopes and vegetation
which can sustain development with "forest management controls".
_B/ AREAS are those areas defined by unit boundaries, not the areas
which are covered by just impermeable surfaces.
undisturbed areas. Along with the replacement of native seed-rich top-
soil, the erosion checks greatly facilitated the rapid reestablishment
of vegetation.
For the most part, extensive erosion control facilities were not required
for the Northstar condominiums, village center, and homesites. This is
primarily due to the planning expenditures made in centering these
portions of the development in areas most amenable to construction
activities. The total cost of the basic improvements for the Northstar
condominium, village center, and homesite units was $4,800,000. This
included the cost of roadways, parking lots, utilities, and other
"prebuilding" development amenities. Of this total amount only $79,584
or 1.66 percent, was spent on special erosion control methods. Among
these special erosion control methods were the following:
1. Check dams and erosion baffles.
2. Rock riprap energy dissipators.
3. Rock riprap 'V ditches.
4. Rock riprap drainage channels.
5. Rock riprap slope protection.
6. Top soil removal, storage, and replacement.
74
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Not included with these "special" erosion control methods were the
cost of what may be considered normal or standard structures such as
A-C curbs, dikes and gutters, drainage culverts, drop inlets, and
perforated groundwater collection pipes. The total cost of all the above
facilities, including special erosion control, amounted to $510,866 or
less than 11 percent of the total "prebuilding" development cost.
D. Remaining Problems
In spite of the considerable effort taken by the Northstar planners and
developers, certain erosion and sedimentation related problems were
created by the development. In most cases these remaining pollution
sources were identified as potential problems during the planning of
Northstar. Although recognized in the planning phase, adequate mitiga-
tion measures were not immediately carried through to the construction
and maintenance phases. As a result the water quality monitoring pro-
gram, described in Section VII of this report, has documented an esti-
mated one-fold increase in the sediment yield of the West Martis Creek
watershed. In addition, a water quality computer simulation program was
used to identify the specific location and relative contribution of sus-
pended sediments being discharged by various portions of the development.
Five areas were documented as the significant areas of erosion affecting
the water quality of West Martis Creek. If these remaining problem
sources were corrected within Northstar, post-development erosion and
sediment transport levels would be reduced to very low pre-development
levels in all but the most intense and severe storm runoff events.
Figure V-7 indicates the location of major remaining sediment and erosion
problems identified at Northstar.
1. Unrevegatated Oversteepened Slopes
These remaining problem areas were mainly centered around the west
village center parking area, the wastewater treatment plant, and
Northstar Drive. The main source of sediments eroded from over-
steepened slopes was from the west village parking lot. Here,
drainage from the almost 0.75 hectares of disturbed slopes reached
suspended sediment levels of 7560 ppm. The average concentration
recorded in 19 samples taken during rainstorms and snowmelt runoff
events was 1,732 ppm.
In many cases, the slopes adjacent to the west parking lot are 1.5:1
(horizontal to vertical) or steeper. These slopes are generally too
steep for the technique of topsoiling. No other attempt was made
to revegetate these slopes by the Northstar developers. The
apparent reason for these large, unstable cut slopes was that if
* they had been cut at a less severe angle, they would have produced
longer, more visible scars. In addition, there were no other
areas within the development which were better suited for the
construction of a parking lot facility necessary for access to the
ski area. Similar to the cut slopes for the parking lot, Large
cut slopes were also created by the construction of the wastewater
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Figure V—7. Rock rip-rapped check dams protecting
an area at Northstar disturbed by the underground
placement of utilities
treatment plant. In both cases, the cut slopes intersected semi-
permeable hardpan layers supporting perched water tables during
spring snowmelt conditions. The hardpan layers are the remnants of
buried Pliocene stream beds.
Northstar Drive exhibited erosion problems similar to, but less
significant than, the parking lot and wastewater treatment plant
cuts. In this case, no groundwater table was pierced during road
construction activity, so the problem consists of road sand and
eroded sediments from an unvegetated fill slope carvied by storm
and snowmelt runoff. Differences in suspended solid concentrations
of up to 100 ppm have been measured in West Martis Creek from above
to below the road's crossing for the stream.
2. Urban Runoff
The principal source of measureable urban runoff is from the village
center commercial area and adjacent condominium units. To a large
degree, suspended sediments contained in urban runoff originates
from the oversteeped slopes described above. However, a large
part is apparently contributed by winter road sand and dirt trans-
ported to the parking lot areas by vehicular traffic. Accumulated
urban runoff at Northstar is discharged to West Martis Creek at
two major points near the confluence of the West and East Forks
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FIGURE V-8.
EROSION PROBLEMS IDENTIFIED AT NORTHSTAR, 1974-1976.
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of West Martis Creek. The "village culvert" discharges accumulated
storm and snowmelt runoff from the village center (and most of the
parking lot area) to the West Fork above the confluence. A rock-
lined-drainage ditch discharges accumulated storm runoff from a
portion of the parking lot, condominium units, and Northstar Drive,
about 100 meters below the confluence. The maximum recorded
suspended sediment concentration recorded at these two sites were
1,188 ppm and 5,500 ppm for the village culvert and rock-lined-
drainage ditch, respectively. The average of 50 samples collected
at these two sites during runoff conditions is 394 ppm.
The potential for urban runoff problems to develop at the village
culvert was clearly recognized in the planning process at Northstar.
As part of the environmental impact report prepared prior to the
development of the village center, the following recommendation
was made (11):
"In order to insure compliance with the State of California's
Porter-Cologne Water Quality Control Act and Northstar's
internal quality control standards, it is recommended that an
adequate catch mechanism and energy dissipator such as
"bubbleup" catchment basin and sediment pond or other similar
devices be installed and serviced regularly in order to pro-
vide for settlement of suspended sediment prior to outfall
into Martis Creek. There should be no significant deviation
beyond natural background levels of turbidity and total sus-
pended dissolved sediment load. The construction of a catch-
ment mechanism and sedimentation provision as recommended
above should slow the drainage water to a velocity equal to
or less than Martis Creek and will minimize the ^cutting and
carrying power of the water as well as the size of particles
carried by Martis Creek."
However, there was never any suspended sediment settling or catch-
ment basin installed as recommended. Had such a facility been
adequately designed, installed, and maintained, suspended sediment
discharge to West Martis Creek from the "village culvert" would
have been greatly reduced.
The village culvert drainage area possesses two factors that tend
to increase its effect on the stream. First, the parking lots
drain to drop inlets which transport the flow directly to the
stream through the village culvert. Second, during the winter
months, a moderate amount of sand and salt used on highways and
at the entrance to Northstar is tracked to these lots and deposited
by warm dripping cars. This deposition is not a serious problem
under most winter conditions because the majority of the sediment
is removed from driving surfaces by periodic snow plowing. However,
during periods of winter thawing, significant levels of salts and
suspended solids appear to be discharged from these surfaces. This
discharge, in combination with the erosion from the cuts, appears
to have significant effect on the water quality of the lower
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Figure V-9. Oversteepened and eroding cut slope
adjacent to the parking lot at Northstar in the
spring of 1975
watershed. For example, water sampling on February 19, 1975,
established the village culvert as the sole source of pollution
for the West Fork of West Martis. Its flow of 14 liters per
second with a concentration of suspended sediments (S. S.) of
1,072 ppm, turbidity reaching 330 FTU, and a concentration of total
dissolved solids (TDS) of over 500 ppm adversely affected stream
water quality to the confluence of East and West Forks of Martis
Creek (S. S. = 1240 ppm; TDS = 170 ppm). These conditions to
persist to reduced degree for some distance further downstream.
3. Unvegetated Ski Run and Uncontrolled Drainage
The transport lift area is located just above the village center.
For the period of May 9 to 22, 1975, water containing 3,200 to 6,090
ppm suspended solids concentration flowed across this skiing.thorough-
fare and entered the West Fork of West Martis Creek near the bridge
to the recreation complex. The problem was the result of a drainage
culvert from a condominium unit depositing its flow on an unrevege-
tated ski run and transport lift area. This flow created up to
0.5-meter deep gullies near its source. There was also up to 10
centimeters of sheet erosion on the open slopes and up to 0.25
meter deep gullies formed near the confluence with the West Fork.
This problem was further compounded by heavy vehicular and ski
traffic during the spring snowmelt period which had a tendency to
further disturb the unrevegetated terrain.
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4. Heavily Travelled Dirt Road Drainage
The only dirt road at Northstar which receives heavy traffic during
runoff events is the access road to the ski maintenance area.
During periods of heavy spring snowmelt and runoff, road drainage,
extremely high in suspended sediments, enters the East Fork of
West Martis Creek at the point of road crossing. The creek crossing
is located at a low point where the road slopes down to the creek
from both directions. Although streamflow is directed under the
roadway, drainage from snowmelt collects at the low points and
enters the creek. Suspended sediment concentrations as high as
4,169 ppm have been detected in the road drainage. During spring
snowmelt conditions, the instream suspended sediment concentration
of the East Fork has gone from near zero to 100 ppm.
Were it not for the vehicular traffic during the springtime, this
dirt road would not pose much of a problem. Maintenance vehicles
and other traffic clearly aggravate the situation by disrupting
the road surface causing the area to become extremely muddy. The
ultimate solution would be to pave the road surface to eliminate
the disruption caused by vehicular traffic. Also required is
adequate drainage of storm flow from the road surface to the East
Fork. Because of this single suspended sediment problem source in
the East Fork the yearly suspended sediment yield of this portion
of the West Martis watershed was increased approximately 3 to 4
times above natural background levels. -
5. Uncontrolled Drainage at the Base of the Ski Bowl
These problems located high in the watershed at the base of the ski
area are only noticeable during periods of extremely high storms or
snowmelt runoff. Because of the design and layout of the ski bowl,
erosion problems have been held to a minimum. Except during high
runoff conditions, surface runoff is almost completely percolated
to groundwater. At the base of the ski area, the groundwater is
tapped by means of a perforated pipe collection system to serve as
a source of domestic water supply. With the exception of some
springs and the water system bypass, very little surface flow
appears at the base of the ski area except during extremely high
runoff conditions. At these times, disturbed areas on unstabilized
drainage channels do contribute to higher than background levels
of suspended sediment in the West Fork of West Martis Creek.
Demonstration of Erosion Control Technology
It must be emphasized that, although a few isolated instances of inade-
quate erosion control exists at Northstar, the vast majority of the
development is an extremely well planned, designed, and constructed
example of proper erosion control methods and procedures. In order to
demonstrate additional erosion control technology, the remaining prob-
lem areas at Northstar were selected for concentrated extra effort. The
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demonstration of permanent vegetative erosion control and/or drainage
control facilities was demonstrated on: (1) steeply cut slopes
adjacent to the West Village parking lot and adjacent to the waste-
water treatment plant, (2) cut and fill slopes adjacent to Northstar
Drive, (3) the unrevegetated and poorly drained ski run near the base
of the transport lift, and (4) the heavily travelled dirt road adjacent
to the East Fork of West Martis Creek.
Fifty-two different demonstration plots and sections were established on
the cuts adjacent to the parking lot, the wastewater treatment plant,
Northstar Drive, and the unrevegetated ski run. A variety of different
erosion control techniques were demonstrated at those sites, including:
1. Contour willow wattling
2. Willow staking
3. Native shrub plantings
4. _Rock lined drainage ditches
5. Rock breast walls
6. Slope scaling
7. Overhang removal
8. Grass seed and fertilizer drilling
9. Grass seed hydromulching rates
10. Grass hydroseeding rates
11. Straw mulching rates
12. Various mulch tackifiers
13. Various fertilizers at differing rates
A complete description of the individual techniques and procedures of
those measures listed above is included in Section VIII. Diagrams and
tables listing the various plot and section treatments at Northstar are
included in Appendix B. Several of the revegetative plantings had to
be reconducted at Northstar in order to establish sufficient growth for
effective erosion control. Many of the original techniques were unable
to establish viable plant growth. The hydromulching techniques, partic-
ularly when an additional tackifier was used, did somewhat poorer than
straw mulching. The use of willow wattling vastly increased the success
of any other revegetation technique used with it. At Northstar, the
best revegetative growth for purposes of erosion control was achieved
by the following procedure:
1. Removal of all overhangs at the crown of the slope and scale
slope surface of loose material.
2. Contour willow wattling placed on slope at 2.0 meter intervals.
3. Hydroseeding slope with at least 100 kg/hr seed mixture.
4. At least 280 kg/ha 16-20-0 fertilizer applied with hydroseeding.
5. Straw mulch blown on slope at a rate of 4500 kg/ha.
6. Straw tackifier used at twice manufacturers recommended appli-
cation rate.
Please refer to Section VIII for an in-depth description of these and
other revegetation methods.
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At Northstar, the installation of a wide variety of different temporary
sedimentation control devices were demonstrated adjacent to the golf
course construction site. In the first half of November 1975, the
following were installed:
1. Filter fabric fences
2. Impervious berms
3. Pervious filter fabric berms
4. Bervious sand core berms
These devices were installed so as to provide the waters of West Martis
Creek with sufficient protection during the construction of the second
9 holes of the Northstar golf course. All the above listed methods
performed well but began to show signs of failure after about 9 months
exposure to the elements. In particular, the exposed filter fabric of
the filter fences began to degrade because of the exposure to ultra-
violet radiation in sunlight. As are the other erosion control methods,
the construction of the various temporary siltation control methods is
described in detail in Section VIII.
F. Northstar Cost Summary
Northstar is basically a well planned, constructed, and maintained
development north of the Lake Tahoe Basin, which has minimized potential
adverse environmental impacts. The total cost of the residential,
commercial, and condominium development (not including land costs) was
about $28,000,000(14). The costs of the additional recreational
amenities of the development such as the ski area, the golf course, the
recreation center, and equestrian center, were an additional $8,000,000.
By assigning the entire cost of the predevelopment planning to
environmental impact mitigation and erosion control, the following cost
summary may be made:
1. Predevelopment erosion control $280,000
2. Erosion control construction 80,000
*i
Total $360,000
Thus, the $360,000 spent for the effective erosion control at Northstar
between 1970 and 1973 represents less than 1.3 percent of the total
development cost.
As of 1977, there was a total of about 930 developed condominiums and
residential lots at Northstar. The total cost of erosion control per
currently developed unit is $390. The complete development plan at
Northstar calls for a total of over 2,000 developed condominiums and
residential lots. The cost per developed unit (in 1973 dollars) is
estimated to be reduced to $220 per unit at full development. As shown
by this analysis, effective predevelopment planning as conducted at
Northstar is an extremely cost-effective method of erosion control.
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SECTION VI
RUBICON PROPERTIES: A CLASSIC EXAMPLE OF MASSIVE
EROSION PROBLEMS DUE TO POOR PLANNING AND CONSTRUCTION PRACTICES
Rubicon Properties is diametrically opposed to Northstar in terms of the water
quality protection and the degree of environmental impact. Northstar's de-
velopers went to significant effort to construct a well planned development;
Rubicon's developers did little planning. Northstar was constructed with
minimum environmental impact; Rubicon Properties was constructed with little
environmental awareness. The developers of Northstar exhibit a desire to
maintain a minimal environmental impact and to correct remaining minor
problems; Rubicon Properties' developers have long since sold all interest in
the subdivision and cannot be held accountable for the impact Rubicon
Properties is having on water quality and the environment of Lake Tahoe.
Rubicon Properties is a single-family residential subdivision on the west
shore of Lake Tahoe, eight kilometers north of Emerald Bay on State Highway
89. There are 632 subdivided parcels in this subdivision of which less than
one-half are currently built upon. Approximately one-third of the 128 hectare
subdivision is within the Lonely Gulch Creek watershed. The entire Lonely
Gulch Creek watershed, as modified by drainage patterns within the develop-
ment, covers 288 hectares. The watershed ranges from the mouth of Lonely
Gulch Creek entering Lake Tahoe at an elevation of 1,898 meters to the top of
Rubicon Peak at 2,799 meters. The highest point within the subdivision is
2,127 meters. With the exception of the riparian zone adjacent to Lonely *
Gulch Creek, the watershed is covered with a relatively dense mixed coniferous
forest down to the Lake's shore.
The original land from which Rubicon Properties was subdivided was a 160
hectare parcel held in single ownership. By 1945, several land exchanges
and sales had taken place, Rubicon Land Company had been formed, and the
lower portions of the original parcel were subdivided. In 1958, 1959, and
1960, the remaining portions of the original parcel, situated higher in the
watershed, were also subdivided, resulting in the development we have today.
That portion of Rubicon Properties subdivision specifically chosen for detailed
analyses and implementation of erosion control measures was the uppermost 24.4
hectares within the Lonely Gulch Creek watershed to the west of State Highway
89 (See Figure VI-2). The soils of this portion of the subdivision are
designated by a recent soil survey (15) as "Meeks" very stoney, loamy, coarse
sand, with 30 to 60 percent slopes (MsG). This soil type is representative of
the type of granitic soils found in approximately two-thirds of the Lake Tahoe
Basin. Erosion hazard is described as being moderate, in undisturbed areas,
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Figure VI-1. Rubicon Properties
subdivision on the west shore of Lake Tahoe
to high, in disturbed areas. This is due to a low percolation capacity of the
soi^, leading to rapid runoff. As a result, the area of the subdivision is
classified by the Tahoe Regional Planning Agency (TRPA) in their lowest land
capability class (16) which allows only a one percent impervious surface
coverage. Furthermore, TRPA has designated "General Forest" as the
appropriate land use. However, due to certain "grandfather" clauses in the
TRPA charter, residential construction in Rubicon Properties continues to this
day.
A. Erosion Problems
When the erosion control project was first started, the land coverage
within the area identified for the project site was as follows:
1. Impervious coverage
on private lots
2. Impervious county
road surfaces
1.15 ha.
2.73 ha.
5%
11%
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LEGEND
PROJECT SITE
DISTURBED AREAS
EXISTING HOUSES
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
RUBICON PROPERTIES
PROJECT SITE
100 200 300 400
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
SCALE (METERS)
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3. Disturbed and unvegetated 3.26 ha. 13%
surfaces
4. Undisturbed area 17.22 ha. 71%
Total 24.36 ha. 100%
Currently, only 19 percent of the lots within the project site have resi-
dences constructed on them. With 100 percent build-out in the future, it
is estimated that the total area of either impervious surfaces or dis-
turbed, unvegetated slopes would constitute almost 50 percent of that
portion of Rubicon Properties designated as an erosion control project
site. This is clearly a substantial increase over the "maximum" 1 percent
average identified according to the land capability and erosion hazard of
the development site. Not only does land disturbance associated with
home and road construction lead to higher erosion rates, but concentrated
runoff resulting from impervious roof tops and road surfaces further
increases the problem. The harm caused by concentrated runoff was
unintentionally demonstrated by one homeowner who kept a small flow of
water (less than % liter per minute) trickling through an outside spigot
during the winter of 1976 to prevent pipes from freezing. This very
small concentrated flow resulted in a one meter deep and one meter- wide
eroded swail in his front yard the following-spring.
Figure VI-3. Deposition of granitic sediments
in Lonely Gulch Creek resulting from erosion
within Rubicon Properties subdivision
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The majority of the 3.26 hectares of disturbed, unvegetated slopes have
not supported any vegetation for the entire 18 years since they were
first excavated. Embankments which were originally cut with 1:1 or
greater slopes have eroded to 1%:1 slopes or less. Even the exposed
granitic layers have probably weathered away at an average rate of 2 to 5
centimeters per year. In most cases, the eroded or weathered material
was continually deposited in asphalt concrete drainage/troughs at the
slope toe adjacent to the paved roadways which zigzag up the hillside.
The deposited material remained in these troughs only until the next
rainstorm or heavy snowmelt at which time it was rapidly transported down
slope through an interconnected system of impervious ditches, culverts,
swails, 'and troughs until it was discharged to Lonely Gulch Creek and,
subsequently, to Lake Tahoe.
Longtime residents of the area have indicated that fishing Lonely Gulch
Creek was a common occurance prior to construction of the development;
(the creek apparently sustained a healthy trout population). Prior to
the early 1930's, development consisted of 1 residential estate which
tapped Lonely Gulch Creek for hydroelectric power generation and inci-
dental domestic water supply. Since the upper portions of the develop-
ment were added in the late 1950's, it is extremely unlikely that any
trout could survive in that portion of the stream affected by runoff from
the subdivision. Indeed, as discussed in Section VII, benthic
macroinvertibrate populations monitored between 1972 and 1976 have shown
up to a 99 percent reduction in aquatic life in affected downstream
portions.
Clearly, the upper portion of Rubicon Properties subdivision has been
the site of massive erosion since it was constructed in 1959. Through
discussions with local residents, the State Board staff has been able to
estimate the original configuration of the unstable cut and fill slopes.
By comparing their estimates of prior conditions with current slope con-
figuration, the amount of material eroded from the erosion project site
since 1959 was estimated to be 6,255 cubic meters or 8,660 metric tons.
Thus, an average of 1,975 metric tons per square kilometer per year are
estimated to have eroded from the project site between 1959 and 1976..
As discussed in Section VII, the current sediment discharge from the
project .site was estimated to be 366 metric tons per square kilometer
per year for 1975 to 76. Based upon this analysis, it must be assumed
that considerably more sediment was eroded from the upper portions of
Rubicon Properties immediately after construction than is currently being
eroded. This is quite reasonable in view of the fact that over a period
of 18 years the original slopes within the development had been eroded to
less severe slope angles, more nearly approaching the angle of repose
of the soil. This action has led to the gradual "natural" stabilization
of some slopes during the period from 1959 to 1976. Assuming a straight
line curve between 1959 and 1976, Table VI-1 depicts the estimated
erosion rate for each year of this period.
Although predevelopment water quality and hydrologic monitoring was
nonexistent, water quality of the undisturbed 2J5 hectares of Lonely
Gulch watershed above Rubicon Properties is assumed to be representative
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of predevelopment conditions for the entire watershed. The upper por-
tions of the watershed have not been significantly disturbed, since logging
operations were last conducted over 100 years ago. Based upon the water
quality monitoring program described in Section VII, the natural background
level of erosion for the upper, undisturbed portions of Lonely Gulch Creek
watershed is 3.43 metric tons per square kilometer per year. The geolo-
gic configuration and soil type found in the upper portions of the sub-
divisions are slightly different from the upper watershed. Nonetheless,
it has been assumed that the natural background rate of 3.43 metric tons
per square kilometer per year is a reasonable assumption for all undis-
turbed portions of the watershed. Thus, the monitored average erosion
rate of 366 metric tons per square kilometer per year for the period of
1973 to 76 is a 10,600 percent increase above assumed natural background
levels. Even more astounding is the possibility that the initial erosion
rate after the construction of Rubicon Properties, as depicted in Table
VI-1, may have been as high as 3,669 metric tons per square kilometer per
year - over a 100,000 percent increase above assumed natural background
levels.
From the standpoint of erosion control, the upper portion of the Rubicon
Properties subdivision is clearly representative of a poorly planned,
designed, and constructed development. Had the county with jurisdiction
properly exercised the constraints which were embodied in their own
subdivision ordinance in 1959, the upper portions of Rubicon Properties
might never have been constructed. The county subdivision ordinance
in effect in 1959 required that the county road right-of-way must include
all road cuts and fills associated with road construction (17). Currently
about 90 percent of the disturbed slopes within Rubicon Properties lie
outside the county maintained road right-of-way. Had the ordinance been
enforced, there would have been over 14 percent less developable land
available for subdivided residential lots. This may very well have
discouraged the developer from the standpoint of anticipated revenue.
Even if the development had still been constructed, adherence to the
subdivision ordinance would have left the majority of the most severe
erosion problems under single ownership, which would have greatly facili-
tated problem correction.
The poor planning and construction of the upper portions of Rubicon
Properties goes beyond generating excessive erosion and sedimentation
problems. Improper or inadequate roadway construction, domestic water
supplies, storm water drainage facilities, sewage treatment facilities,
and lowered aesthetic appeal are also embodied in Rubicon Properties
subdivision.
B. Roadway Construction Problems
The roadways within the upper subdivision pose a maintenance problem
for the county, and will continue to be a problem even with erosion and
sediment under control. Several roads have grades in excess of 15 percent.
Once again, the county subdivision ordinance, which allowed a maximum
grade of 12.5 percent in 1959 (17), was ignored by the developer and not
enforced by the county. Even 12.5 percent is very steep as compared to
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Figure VI-4, Steep roadways and oversteepened cut and fill slopes
within Rubicon Properties subdivision, Lake Tahoe Basin
TABLE VI-1
ESTIMATED YEARLY EROSION RATES
FROM THE UPPER 24.4 HECTARES
OF RUBICON PROPERTIES FROM
1959 THROUGH 1976
Erosion Rate
Erosion Rate
Year
1959
1960
1961
1962
1963
1964
1965
1966
1967
(Metric Tons/ha/yr)
36.20
34.10
32.00
29.90
27.80
25.70
23.60
21.50
19.40
Year
1968
1969
1970
1971
1972
1973
1974
1975
1976
(Metric Tons/ha/yr)
17.30
15.20
13.10
11.00
8.90
3.66
3.66
3.66
3.66
4-Year
Average
Natural background erosion rate monitored from undisturbed
watershed = .0343 metric tons per hectare per year (1973, 1975-76)
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current standards. The maximum road grade currently considered practical
for access in mountainous regions is 6 percent. The primary reason^for
this is the difficulty of removing snow on steeper roadways. In addition,
ice formation on steeper grade makes access extremely difficult for
standard automobiles and poses a severe traffic hazard. As the upper
portions become developed further, it is anticipated that the level of
winter road traffic will continue to increase, further increasing the
road hazard.
Snow removal equipment has an extremely difficult time within the upper
portions of Rubicon Properties, particularly in very severe winters.
The large vehicles have problems negotiating the extreme switchback
turns which exist in the subdivision and frequently cannot gain traction
on the steep road surfaces. Furthermore, the close proximity of the
steep road cuts to the road surface severely limits the amount of snow
storage area. As a result, the snow removal equipment invariably operates
too close to the fill side of the roadway, rupturing curbs, dikes, and
gutters. These breaches in the roadside structures cause further overland
discharge and erosion problems.
C. Storm Water Drainage Problems
Because of the extremely steep terrain and high percentage of disturbed
land and impervious surfaces (29 percent), adequate drainage control in
the upper portions of Rubicon Properties is extremely difficult.
Drainage ditches, curbs, and gutters, culverts, and sectional downdrains
used within the development are generally undersized for the extreme
flows which occur during high runoff events. The adequacy of these
facilities is further decreased by constant clogging with eroded soil
from the disturbed terrain. Prior to the erosion control project,
substantial areas within the development did not even have dikes to
prevent road surface runoff from flowing over adjacent fill slopes. One
slope, a 0.4 hectare fill area, lost at least 1.0 meter of soil, averaged
over the entire slope face, due to the absence of dikes. The drainage
ditches used to convey snowmelt or storm runoff are all unstable, unlined
eroded swails. In many instances, flow from corrugated metal pipe culverts
was allowed to spill over unstable steep soil surfaces prior to discharge
to the Lonely Gulch Creek. The result has been the appearance of several
deeply eroded artificial swails.
While the current level of development has created substantial areas of
disturbed or impervious surfaces, it is nothing like the level which
would be reached upon full development of the subdivision. The existing
drainage facilities are inadequate for the current level of development
(16 percent impervious surfaces). With full development (37 percent
impervious surfaces), drainage problems will be considerably magnified.
Without substantial revamping of the drainage facilities and complete
erosion control, Rubicon Properties will not be able to bear the load of
full development without major failures of the existing drainage system.
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D. Maintenance Procedure Problems
Numerous improper or questionable maintenance practices have been observed
to be conducted within Rubicon Properties subdivision by the various local
maintenance and utility agencies. These practices generally increase the
rate and/or the amount of erosion which-would otherwise occur within the
subdivision. The most visible of improper maintenance practices is the
application of sand to road surfaces in the winter time without adequate
. provisions for cleanup and removal of applied sand. Depending on the
severity of the winter, anywhere from 10 to 40 metric tons of road sand
are applied to 2.5 kilometers of roadways within the Rubicon Properties
project site annually. This applied road sand may account for 5 to 25
percent of the suspended sediment load which has been monitored in Lonely
Gulch Creek. In most years, only token attempt is made to cleanup and
remove applied road sand. This is generally performed by a mechanized
roller broom. This technique removes the road sand from the street
1 surface (only to be redeposited in roadside ditches or downslope areas)
and does little to reduce the amount of road sand which is eventually
washed into Lonely Gulch Creek and Lake Tahoe. A more appropriate
procedure would employ vacuum type brooms for the removal and proper
disposal or reuse of the waste road sand. In addition sediment catchment
basins or drop inlet structures should be provided to collect any
remaining waste road sand which could be washed from the road surface.
Other maintenance practices also increase the rate and/or amount of
sediment yield from the Rubicon Properties project site, or otherwise
increase the severity of the development's erosion problems. Among
them are:
1. The practice of removing accumulated sediments from the toe of an
eroding slope which undercuts the stability of the slope and leads
to an increased erosion rate. Better practice would be to move
existing drainage further away from the toe of an eroding slope, or
construct a retaining structure.
2. Washing culverts and drains clogged by eroded sediments increases
the rate of downslope sediment transport. Better practice would
include the dry boring or reaming of the culverts to remove
sediments coupled with the proper disposal of the waste earthen
materials. >
3. Insufficient snow stakes can result in increased damage to curbs,
dikes, gutters, retaining structures, and slope toe benches by
snow removal equipment.
4. Improper disposal of waste earthen material, such as "over-the-bank"
practices, increases sediment transport and hinders the proper
establishment of slope stabilization measures. Better practice would
include the disposal of the waste earthen material to a land fill or
the washing and reuse of the material as winter road sand.
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5. Negligence in providing revegetation or other stabilization to areas
disturbed for the connection of sewer and water laterals or other
underground utilities. Frequently, the disturbed surface acts as a
channel for upslope storm runoff or snowmelt runoff. Better practice
would include immediate restabilization using vegetation, mulch, nets,
blankets, waterbars, check dams, or other devices.
In most instances it appears that these improper practices are conducted
as a result of ignorance on the part of the maintenance workers, the lack
of proper equipment to perform the task, and the intransigence of manage-
ment to provide the proper incentives.
E. Other Problems
In addition to development problems which increase erosion rates, there
are also a number of other problems within Rubicon Properties subdivision.
These additional problems also substantiate the considerable lack of
planning and environmental awareness which preceded construction of this
development.
1. Domestic Water Supply
The sole source of domestic water supply is a small storage and diversion
facility on Lonely Gulch Creek. The original diversion, initiated in
the early 1920's, was for hydroelectric power generation and the
incidental domestic use of one estate. Since that time, the manner,
location, and duration of the water use of water diverted from Lonely
Gulch Creek has changed—all in probable violation of California water
rights law. Currently diverted water is used to supply approximately
300 households solely for domestic supply, some of which are not even
located on the original parcel. Furthermore, the original seasonal use
(May-September) has been extended to year round use.
The foregoing, however, is not as severe as the fact that there simply
is not sufficient streamflow in Lonely Gulch Creek to provide a safe
supply for the subdivision. Although the subdivision is less than 50
percent built-out, streamflow is frequently reduced to zero as a result
of the diversions for domestic supply. In 1976, a very dry year, there
were 25 twenty-four hour periods when streamflow was zero. Even in
1973, an average water year, there were periods of several days when
streamflow was zero. Had the most recent upper portions of the
subdivision not been added on in the late 1950's, there would be
sufficient streamflow in the creek to provide for the complete build-out
of the original subdivided parcels. However, even if this were the
case, streamflow in Lonely Gulch Creek would frequently be reduced to
zero. This would still have caused significant damage to the aquatic
life and riparian vegetation of Lonely Gulch Creek.
At the present, development of additional sources of water supply are
somewhat dubious due to current uncertainty of water rights and water
availability within the Tahoe Basin as a whole (18, 19). Clearly, the
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developers of Rubicon Properties subdivision, and the local agencies,
and the utilities did not consider the long-term water supply problem
which would be encountered upon complete build-out of the development.
2. Sewage Treatment
Prior to 1973, domestic sewage waste within Rubicon Properties was
treated individually by septic tank and leachfield systems. However,
very few homes were existing in the upper portions of the development
where the thinnest soils are found/ For this reason, potential health
problems did not appear. At full build-out, the upper portions of
Rubicon Properties subdivision would have been unable to support septic
tanks and leachfield systems sufficient to serve over 100 single family
residences located on less than 25 hectares of land. The possibility of
health problems would have been increased further by the large cuts and
fills adjacent to the roadways. Domestic sewage disposed in leachfields
would certainly have resurfaced at several locations within the
subdivision. Springtime snowmelt seepage areas and very small perenial
springs are manifest throughout the area, particularly on road cuts.
The installation of a regional sewage collection system in 1973 ended
the threat to public health resulting from further expansion and use of
septic tanks and leachfields. However, the undergrounding of the
collection system substantially increased the .sediment yield and erosion
rate during construction. This occurrence, again, emphasized the
extreme fragility of the area and the adverse impacts imposed by
conventional construction practices.
Potential sewage treatment problems have not been eliminated with the
addition of a sewage collection system. Providing adequate sewage
treatment and disposal facilities is a problem currently facing not only
Rubicon Properties but most of the Lake Tahoe Basin. Rubicon Properties
subdivision receives sewer service from the Tahoe City Public Utility
District (TCPUD). The TCPUD is a member of Tahoe-Truckee Sanitation
Agency (TTSA), the regional entity designated to treat and dispose of
wastewater from the north and west shores of Lake Tahoe and the Truckee
River area downstream to Truckee. Wastewater treatment and disposal
facilities are presently under construction by this agency.
In a June 19, 1975, action, the State Water Resources Control Board set
maximum seven-day average flow limitations for all districts, including
TCPUD, that are served by TTSA. This will effectively limit the number
of additional sewer connections allowed in individual districts, which
in turn will limit the number of existing unimproved subdivided lots
which can be built upon. An estimate of remaining available connections
for TCPUD and North Tahoe Public Utility District (NTPUD) is set at
1,258 single family dwelling unit equivalents. In the TCPUD and NTPUD
combined, there exist 6,200 undeveloped lots.
A treatment plant expansion could occur; however, no design, financing,
or environmental documents have been prepared for such a project. As
with other aspects of Rubicon Properties subdivision, the developers,
local regulating agencies, and utilities gave little considerations to
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the sewage treatment problems which would surely occur with the
development of the upper portions of the subdivision.
3. Aesthetics
One visit to Rubicon Properties gives a clear indication as to why it
was developed in the first place. The location of the subdivision
affords the resident and visitor a spectacular view of the Lake Tahoe
Basin. No doubt this fact was on the developers' mind when judging the
marketability of the development even before the first bulldozer swath
was cut. Because of its location on steep terrain, a "staircase" effect
is created by the road switchbacks. Each successive level of resi-
dential lots allows a clear view of the Tahoe Basin over the roof of the
downslope neighbor.
While the location of Rubicon Properties offers a spectacular view from
the development, the series of switchback scars are readily visible from
many parts of the Tahoe Basin; a highly visible testimony to man's impact
on the Lake Tahoe Basin.
F. Demonstration of Erosion Control Technology
The upper portion of Rubicon Properties subdivision is a unique and
classic example of all around poor planning and construction practices.
Seldom is it possible to find such extensive erosion, drainage, water
supply, sewage treatment, road maintenance, and aesthetic problems all
concentrated in a single subdivision. However, from the standpoint of
demonstrating erosion control technology, it is a concentrated repre-
sentative sample of the most severe types of erosion problems. These
problems are found throughout the Lake Tahoe Basin and other rapidly
developing mountainous regions of California. Large cut and fill slopes,
steep cut and fill slopes, small cut and fill slopes, abandoned dirt
roads, heavily traveled dirt roads, clear cut vacant lots, and various
examples of concentrated drainage problems are all found within the
upper portion of Rubicon Properties subdivision.
Rubicon Properties also offers an excellent site for demonstration of
erosion and sediment control technology because the impact of uncon-
trolled erosion and sedimentation has been well documented within Lonely
Gulch Creek. Section VII describes in detail the monitoring program
which was conducted in the Lonely Gulch Creek watershed to document the
water quality impact of development there. Because of the successive
switchback layers of the subdivision, the impact of the most severe
erosion problems found within the subdivision are concentrated within
the Lonely Gulch Creek watershed.
In June 1975, the staff of the State Board in agreement with the staff of
the Regional Board, selected portions of Rubicon Properties as a project
site to supplement the effort already being conducted at Northstar.
The project site was identified as the area shown in Figure VI-2. By
working from the highest to the lowest points within the project site,
within the time (July 1974 through July 1977) and funding constraints
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of the program, it was felt that the most severely eroded sediment
discharges to Lonely Gulch Creek could be progressively corrected.
The first major obstacle which was encountered involved obtaining per-
mission to gain access to eroding property from every effected landowner
within the project site. A high level of response and support was
gained from the respective landowners, but much staff time, including
legal staff support, was required to gain the required permission. By
the time the necessary license agreements were fully executed in the
fall of 1975, very little time remained for construction of erosion
control facilities prior to winter snowfall. When erosion control
problems within a development are the responsibility of a single owner
similar to the Northstar development, the logistics of effective erosion
control are greatly facilitated.
During the summer and fall of 1976 and spring of 1977, a wide variety of
erosion control techniques were demonstrated at Rubicon Properties.
Ninety percent of all disturbed areas, including the most severe, were
treated. Demonstrated erosion control techniques included the following:
1. Rock and gabion breast wall
2. Gabion retaining walls
3. Relocation of curbs, dikes and gutters
4. Overhang removal
5. Slope scaling '
6. Contour willow wattling
7. Willow, staking
8. Various seed mixtures
9. A variety of hydromulching application rates
10. Straw mulching
11. A variety of straw mulch tackifiers
12. A variety of mulch nets and blankets
13. Rock lined channels
Complete detailed description of these and other erosion control techni-
ques are included in Section VIII. Appendix B describes the location
of the various methods demonstrated within Rubicon Properties. A total
of 117 herbaceous seeding "plots" and 20 "sections" containing shrub and
tree plantings are located within the Rubicon Properties project site.
The total land area treated amounts to approximately 2.9 hectares of
eroding cuts, fills, slopes and other eroding, unvegetated problem sites.
Little was done to correct the extreme drainage problems which accompany
and exacerbate the erosion and sedimentation problems. Drainage control
within Rubicon Properties would be an extremely expensive proposition
and would have required about 50 percent more funds than were available.
Project funds were used to correct drainage problems most directly related
to, or causing, erosion problems. Construction of curbs, dikes, gutters,
and retaining walls, for example, enhance drainage control while at the
same time correcting erosion problems. The cost of drainage structures
should not be assigned solely to erosion control; part should also be
assigned to drainage and flood control.
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Figure VI-5. Eroded and accumulated sediments at toe
of oversteepened cut slope within Rubicon Properties subdivision,
Lake Tahoe Basin, during the summer of 1975
Figure-VI-6. Oversteepened cut slope after
application of mechanical and revegetative erosion
control techniques with an estimated
80-90% effectiveness in reducing erosion
rates. Picture taken in the summer of
1977
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Cost Effectiveness , .:.-.'...-"' ••••:":• --• • ,~
A qualitative evaluation of the erosion project at Rubicon Properties
has been made. According to county personnel, 1977 is the first year
in memory when massive cleanup efforts were not required following
snowmelt and rainstorms. Admittedly, 1977 has been a very dry year with
little snow. However, near normal precipitation conditions were recorded
in May 1977. No substantial cleanup operations were required during
this month. Prior to installation of erosion control measures at Rubicon
Properties, the county would typically spend approximately $11,500 per
year for county personnel and equipment (230 hours of a two-person crew
per year plus equipment) to unclog culverts and cleanup erosion problems
within the project site. The total cost to the county of El Dorado and
the State of California to install the extensive erosion control measures
within the project site are listed in Table VI-2. The actual total unit
cost of the erosion control project at Rubicon Properties, including the
assumed value of other contribution of labor, equipment, and material,
is estimated to be $41,621 per hectare. The unit cost to perform an
equivalent project on a commercial basis, based on individual unit
cost estimates provided in Section VIII would be over $76,000 per hectare.
Thus, if the0 following assumptions are valid:
1. Negligible erosion and sediment control maintenance would be required
after a project similar to the one conducted at Rubicon Properties.
2. The long-term increased maintenance cost rate is 6 percent (based
upon the 27 year Engineering News Record construction cost index
average since 1950) .
3.
Money may be borrowed by the county at 8 percent interest.
Then, the cost of erosion control, such as that conducted at Rubicon
Properties, would be amortized over a 12.5 year period. This analysis
also assumes all erosion control construction costs are charged against
the county maintenance budget only. This means that none of the erosion
control costs are assigned to environmental protection, enhancement, or
to other entities besides the county. Thus, erosion control is clearly
feasible, particularly if support is provided from sources other than
from just the directly benefiting and/or directly responsible entity.
H. Recommended Control Measures
Based upon an early assessment of the effectiveness of the methods
employed at Rubicon Properties, it is possible to make preliminary con-
clusions regarding effectiveness and cost of specific erosion control
techniques. For a more detailed discussion of erosion control methods
and their effectiveness refer to Section VIII.
General recommendations on individual erosion control methods are ex-
tremely difficult to make. Application of each method is highly site
specific. Different erosion control methods may be best applied, either
singly or in combination, to different sites depending on conditions.
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There is no one "best" method to control all erosion problems. At a
minimum, the following are the major criteria which must be evaluated
prior to selection of particular erosion control methods:
1. Soil (or subsoil) type, particle size and nutrient content
2. Slope length
3. Slope angle
4. Drainage patterns
5. Climatdc conditions
6. Soil moisture
7. Exposure and aspect
8. Surrounding vegetation types
9. Underlying geology and location of seepage areas
If any one of the above criteria changes from one site to the next,
recommended erosion control methods for a specific site may require
substantial alteration. All erosion control techniques demonstrated
at the Rubion Properties project site achieved some degree of initial
success. It is too early to determine a significant difference between
techniques or combinations of techniques, particularly as to their long-
term effectiveness. The best yard stick available to measure success
at this early date is simply the treatment cost.
The establishment of vegetation using seed and small amounts of fertilizer,
followed by a straw mulching and tacking process is generally the least
costly method. However, on steep, rocky terrain, even several seeding
and straw mulching-tacking operations may not be successful. In such
cases, the use of mulch nets and blankets, although frequently five
times as expensive, may be the only technique which can successfully
revegetate such a severe site. Similarly, the use of willow wattling,
though extremely expensive, vastly increases the chances of establishing
vegetation on difficult sites. The following control methods appear to
be the best techniques for successfully controlling erosion problems such
as those found within Rubicon Properties. At other locations however,
other methods may achieve a higher degree of success depending on the
prevailing site conditions. Section, VIII of this report offers a more
detailed discussion of all erosion control construction techniques
demonstrated at Rubicon Properties.
1. Slope Preparation
Slope preparation is frequently the most important step in controlling
erosion. This includes the diversion of drainage waters away from
unstable slope areas, removal of loose rock and debris, and the
removal of overhangs from the top of an eroding slope. The top
portion of an eroding slope should never be steeper than the lower
portions. If possible, the entire slope should be laid back to the
angle of internal friction (angle of repose) of the soils found at
the site. If this is not possible the use of extensive mechanical
stablization, such as revetments or willow wattling, will be
required.
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TABLE VI-2
EROSION CONTROL COSTS AT RUBICON
PROPERTIES PROJECT SITE
DIRECT EXPENSES
County Road Crews and Equipment
Special Equipment Rental
Gabions and Rock Fill
Unskilled Youth Labor
20,000 Rooted Plants
Miscellaneous Materials & Equipment
Subtotal
$51,000
17,000
23,000
23,000
15,000
5,000
$113,000
CONTRIBUTIONS OF OTHERS
(Equipment) Soil Conservation Service
(Labor) Forest Service & Homeowners
Subtotal
TOTAL
2,000
3,000
$ 7,000
$120,000
Total Land Area Treated =2.90 Hectares
Average Unit Cost = $41,621 per Hectare
Estimated Equivalent Commercial Cost = $76,849 per Hectare
2. Contour Willow Wattling
Contour willow wattling is an extremely effective method of con-
trolling erosion on excessively steep and lengthy slopes (both cut
and fill). However, care must be taken in the installation of this
method. The best time for installation is in the early spring or
late fall. Summer planting is discouraged because of the high
transpiration losses suffered by a fully leafed willow branch prior
to the growth of a new root system. Without willow wattling, the
establishment of vegetation on sandy-type soils with slope angles
greater than 2:1 is next to impossible. Even if contour willow
wattling does not root and grow, it provides flexible mechanical
stabilization which then enables other vegetation to take root and
grow.
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3. Straw Mulching
Almost all planting techniques demonstrated at Rubicon Properties
have high degrees of initial plant growth and survival. However,
drought tolerant herbaceous seeding, followed by straw mulching and
tackifying appears to be the most cost-effective all around
treatment for many sites. Generally, a complete straw mulching
treatment may be applied on a commercial basis at rates ranging from
$3 000 to $3,500 per hectare. This makes it one of the most
inexpensive techniques demonstrated. A "tacked straw" treatment
provides a flexible, strong, light reflective, moisture retentive
matrix, and ample protection for seed germination and plant growth.
Superior stands of grass and shrub seedlings have been observed on,
most plots which received a straw mulch treatment. However, in the
case of a straw mulching treatment, as with all other seeding
techniques, provisions should be made for reapplication of seed,
fertilizer, straw, and tackifier if the first application is not
successful due to adverse climatic conditions.
4. Slope Toe Foundations
Adequate slope toe foundations are essential to provide stability to
an eroding slope. At Rubicon Properties, 0.9 meter to 2.7 meters
high retaining walls were used to provide adequate slope toe
protection. These were generally used where existing paved street
surfaces were equal to, or less than, their minimum allowed width.
El Dorado County ordinances require that paved road surfaces must be
maintained at a certain percentage of the available right-of-way.
Within Rubicon Properties, the required paved road width was
generally 7.9 meters. In areas where sufficient paved road surface
was present, existing curbs, dikes, and gutters were removed and
replaced further into the right-of-way at a greater distance from
the slope toe. This eliminated the need to construct large walls to
provide adequate slope-toe protection. Reconstruction of the curb,
dike and gutter system could be performed at costs ranging from 10
to 25 percent of the cost of breast walls or retaining walls. Had a
minimum paved road surface not been required at Rubicon Properties,
relocation of existing curbs, dikes, and gutters could have been
universally applied as the means of providing adequate slope-toe
stabilization. This would have reduced the unit cost of erosion
control within Rubicon Properties from over $41,000 per hectare to
less than $26,000 per hectare. This represents a cost savings of
over 35 percent.
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SECTION VII
THE IMPACT OF DEVELOPMENT ON WATER QUALITY
A. INTRODUCTION
As part of the Erosion Control Demonstration Project the State Water
Resources Control Board (State Board) has conducted an extensive
monitoring program at the two project sites. The emphasis of the program
has been placed upon determining to what degree suspended sediment is
generated by the Northstar and Rubicon Properties developments. In
addition, the degree to which the respective streams are affected by
erosion has been thoroughly documented by this study, Water quality
monitoring programs have been conducted at both Northstar and Rubicon
Properties. The following parameters were monitored as part of this
Erosion Control Demonstration Project:
Streamflow
Suspended sediment concentration
Precipitation
Benthic macroinvertebrates
Snow depth and snowmelt (Northstar only).
The purposes of the monitoring program were threefold: (1) to determine
the location and extent pf any high sediment yield from within the
respective developments, (2) to establish, if possible, a measurement of
the total sediment mass emission from each development and from various
portions of each development, (3) to make a comparison, if possible, of
post-development sediment yield with estimated predevelopment conditions.
A digital computer and a water quality modeling program were used to
handle the extensive amount of streamflow and suspended sediment data.
The program also allowed the State Board staff to estimate the total
suspended sediment mass emission for both predevelopment and postdevelop-
ment conditions at Northstar and Rubicon Properties. The formulation and
operation of the water quality model is described in.a subsequent part
of this section.
B. WATER QUALITY MONITORING PROGRAM
The following methods and procedures were used to monitor and collect
data pertaining to erosion and sediment yield from the Northstar and
Rubicon Properties developments.
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Streamflcw
Stevens Type F water stage recorders positioned in stilling basins
directly upstream from sharp-crested weirs were used to provide
continuous streamflow data. The recorders were manually reset on a
weekly basis. Continuous streamflow recordings were then digitized in
terms of stage height versus time using a Bendix Data Grid Digitizer and
stored on magnetic computer tape.
Suspended Sediment Samples
Suspended sediment field and laboratory procedures were those established
by Burgy and Knight for use by the State Board for the assessment of silt
and sediment pollution problems (20). Samples were collected using an
integrated suspended sediment hand sampler designed by Robert H. Burgy.
Samples were collected upstream and downstream of areas of man-made land
disturbance where possible. Direct discharges of suspended sediment into
streams were also collected by grab sampling.
Suspended sediment was analyzed using the Total Suspended Matter (Non-
filterable Residue) method as described by the U.S.G.S.(21). The water
sample is filtered through a predried, tared 2.1 centimeter glass fiber
filter (Reeve Angel, Grade 934AH) in a Gooch crucible. The filter and the
crucible are then dried at 103 degrees centigrade and cooled in a
desiccator to room temperature. The samples are then weighed and the
results are reported as parts per million suspended sediment.
Benthic Macroinvertebrates
Benthic macroinvertebrate communities, mostly aquatic insects which
inhabit the stream bottom in their immature stages, were sampled in
several areas near Northstar and Rubicon Properties, above and below
zones of land disturbance. Similar investigations in other areas have
shown that the structure and population of macrobenthic communities were
adversely affected below areas where sediment has been discharged into
streams. This relationship suggests that benthic macroinvertebrate data
may be used to indicate that excessive sedimentation has occurred in
suspected areas. In addition, it offers an assessment of the direct
impact that silt has on aquatic biota.
Surber sampling of a one square foot section of stream bottom for each
sample was the method of collection employed for benthic macroinverte-
brates(22). Due to the rocky substrate of the stream bed and the shallow
depth of the streams, it was decided that Surber sampling would be the
most efficient and effective collection technique. Using the Surber
square foot sampler, Needam and Usinger(23) determined that the 194
samples were required for an estimation of total wet weight, and 73
samples were needed for an estimation of total numbers of bottom
organisms to attain significant figures a.t the 95 percent level of
confidence. However, only two or three samples were needed, at the
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95 percent level of confidence, to insure that at least one member of
each of the commonest genera of bottom organisms would be present.
Allen(24) and Davis(25) discovered that when samples are taken at places
selected by the eye to be as environmentally similar as possible, there
is a smaller range of variation between samples. In gridded or
randomized series sampling, the coefficient of variation in Allen's
sampling was between 0.4 and 0.5. In sampling uniform areas, the
coefficient of variation was about 0.2.
In this study, an attempt was made to sample riffle areas of the same
depth, velocity, and substrate type. Stations, where three to four
samples were taken, were located above and below areas of man-made land
disturbance and sediment discharges according to the recommended methods
of Cairns and Dickson(26). Where possible samples were taken well above
a sediment discharge, immediately downstream of the discharge, and at
various locations well downstream of the discharge to determine the
linear extent of damage. For some streams at Northstar, it was impossible
to obtain samples above the discharge from clear-cut ski runs.
Macroinvertebrates collected from each square foot of substrate were
placed in Mason jars with a preservative of 50 percent alcohol (95
percent), 5 percent glacial acetic acid, 10 percent formalin, 3 percent
glycerine, and 32 percent distilled water by volume. The samples were
then dyed red with a rose bengal solution to facilitate hand picking of the
benthos from the bottom substrate and ditritus. The macroinvertebrates
were sorted and identified to the lowest practical taxonomic level,
(27,28,29) counted and weighed (i.e., dry weight at 103 degrees centigrade
for one hour).
Species diversity indices were calculated using numbers and weights for
each station. The diversity index chosen was the Shannon-Weaver formula(30)
based on information theory. The diversity index was calculated as:
d" = -ZN±/N (In N±/N)
where "N" is the total number of individuals and "N-j_" is the total number
of individuals in each genus.
In addition, the diversity index was partitioned into two subcomponents:
(a) species abundance or richness as represented by the number of
species, "S", and (b) evenness as represented by e=d/log2S, where "e" is an
index of distribution of individual organisms among species(31).
The approximate _t-test(32) was used to determine statistically signifi-
cant differences between stations in regards to total numbers per square
meter (density). This test is recommended for sample means whose
variances are heterogeneous. In contrast, a t-test defined by
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Hutcheson(33), as recommended by Burgy and Knight(20), was used for
comparing diversity indices. The lattery-test employs the variances of
the diversity indices calculated from each station in computing t_ and in
computing the degrees of freedom. Since, in all cases, the upstream
stations are considered to contain the natural benthic community of each
stream, the downstream stations were examined to determine whether
deviations from the normal community existed.
Percent similarity was also determined between stations to identify
differences in community types. Percent similarity is defined as:
PS = 100-0.5 E (a± -
1 is the percent of
is the percent of
where "S" is the total number of species present, '
individuals in species "i" in community "A", and "t
individuals in species "i" in community "B"(34).
Precipitation
Battery operated, heated (either electric or propane), recording rain-snow
precipitation gages were used to monitor precipitation amounts and
intensities. The recorders were reset on a weekly basis.
Snow Depth and Water Content (Northstar only)
Snow course stations were established and samples were taken according to
procedures established by the U. S. Soil Conservation Service(35) and used
by the California Department of Water Resources. Samples were taken by
steel snow sampling tubes and weighed on a scale calibrated in inches of
water. Five samples per snow course were taken on a bimonthly to monthly
basis. Snow depth, water content, and snow density data, and a qualita-
tive description of apparent soil moisture were recorded for each snow
course.
C. WATER QUALITY OF WEST MARTIS CREEK (NORTHSTAR)
The 10,500 hectare watershed of Martis Valley Creek is located immediately
north of Lake Tahoe; however, West Martis Creek, the area of investigation,
contains only 1300 hectares. Mean annual precipitation ranges from 60 to
100 centimeters from the lower elevations to the top of Mount Pluto
falling mostly as snow. The stream flows down a moderately steep course
until it reaches Martis Creek in the valley floor.
Soils of the watershed are principally weathered andesite derived from, a
central ridge of volcanic material which divides Martis Valley Creek
watershed from Lake Tahoe. Higher elevations are characterized by shallow,
stony soils with a small amount of organic matter and a low moisture
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storage capacity. Middle elevations have loam and clay loam forest
soils. Soils of the lower elevations are composed of alluvium material
of which much of the valley floor is composed.
Upper ridges of the watershed sustain a fir forest with descending
elevation, this converts gradually to a pine forest and thence to a
sagebrush-grass zone. Riparian areas are heavily vegetated by willows,
alders, and other water-loving species.
The Northstar-At-Tahoe development, which occupies a substantial portion
of this watershed (75 percent), has been thoroughly described in Sections
III through V of this report. Under predevelopment conditions, runoff,
and suspended sediment concentration levels were probably quite low.
There was some runoff from skid trails and logging roads, but flows did
not usually exceed the infiltration capacity of the soils'. Surface flows
at lower elevations in the watershed were fed by springs and groundwater
seepage. Any overland flow was contained in naturally stabilized
drainage channels.
In order to determine the change, if any, in sediment yield for the West
Martis Creek watershed after the development of Northstar, the
environmental monitoring sites shown in Figure VII-1 were established.
A schematic diagram shown in Figure VII—2 further depicts the relative
layout of significant drainages within the watershed as altered by the
Northstar development and the location of the suspended sediment sampling
sites.
Streamflow
The following continuous streamflow recording gages were established in
the West Martis Creek watershed:
Gage No. 1. Situated above a 1.22 meter rectangular sharp-
crested weir. Located near the Big Springs day lodge on the
West Fork of West Martis Creek. Drainage area above this point
is 294 hectares and extends to the summit of Mount Pluto at an
elevation of 2,620 meters. Approximately 113 hectares of forest
land have been cleared for ski trails. Flow over this weir
is principally overland flow as spring water is collected via
an underground collection system above this point. Groundwater
collected by this system is transported either to the water
treatment plant or through a bypass structure to the V-notch
weir (Site 5).
Gage No. 2. Situated above a 90 degree V-notch, sharp-crested
weir. Located on the East Fork of West Martis Creek above the
confluence with the West Fork. The drainage area above this
point is 471 hectares. A 200,000 cubic meter storage reservoir
is located 2.4 kilometers above this sampling site. All
upbasin surface runoff is collected by this reservoir which
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KEY
I L- STREAM FLOW GAUGING
o
STATION
SNOW COURSE
RECORDING RAIN a SNOW
PRECIPITATION GAUGE
WEST MARTIS CREEK
-*»- ELEVATION CONTOUR (f»*t)
WEST MARTIS WATERSHED
ABOVE GAUGE NO. 3
FIGURE VII-1. HYDROLOGIC MONITORING SITES
WITHIN WEST MARTIS CREEK WATERSHED (NORTHSTAR).
106
-------
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<-> (K
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107
-------
only briefly overflows in the springtime of normal and wet
years. A groundwater collection system is located above this
reservoir. A bypass valve spills excess water to the east fork
about one-third of a mile below the reservoir. Extremely low
flows have been observed in the east fork at this point due to
the limitation of bypass flow from the groundwater collection
system when the treatment plant is functioning.
Gage No. 3. Situated above a 1.83 meter rectangular
sharpcrested weir. Located on West Martis Creek below a bridge
approximately 0.2 kilometer north of the golf course club
house. Total drainage area above this point is 1,308 hectares.
The majority of the Northstar development is above this point.
Gage No. 4. Situated above a 1.22 meter rectangular
sharpcrested weir. Located on unnamed tributary to Martis
Creek. Drainage area above this point is 220 hectares.
Meadow, pasture, and timber areas are located above this
sampling point.
Figure VII-3 is a graph of the total monthly flows monitored at Gage No. 3
for the duration of the erosion control project. Also plotted is the
monitored extent of the snow pack water content during 1975 and 1976.
Based upon the theoretical unimpaired runoff in the Truckee River
watershed, water year (October-September) 1975 was 13 percent above the
average runoff conditions for this area.. On the other hand, water year
1976 was 62 percent below the average runoff conditions. The difference
in water years was mainly attributable to the lack of substantial
snowfall during 1976.
Snow Depth and Water Content
Six snow courses were established at Northstar to monitor snow depth and
water content of the snow pack. The snow courses were located
approximately in the middle of the succeeding 150 meter elevation contour
interval from the top to the bottom of the West Martis Creek watershed.
The snow courses were located as close to the center line of the watershed
as was practical. Snow depth and snow pack water content measured at
each snow course were assumed to represent the average conditions for the
particular 150 meter contour elevation interval within which it was
situated. A summary of the estimated water content for each snow course is
presented in Table C-l, Appendix C.
Precipitation
The electrically heated recording rain-snow gage at Northstar was located
at the Water Treatment Plant near the base of the ski hill. The primary
purpose of this gage was to identify periods of rainfall for the purposes
of the water quality model. This model will be described later in this
section.
108
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The most intense rainfall recorded at Northstar occurred on September 10,
1975. This storm lasted about one hour and had an intensity of
approximately 2.5 centimeters per hour. This intensity is indicative of a
greater than 20-year storm based upon existing records for the area. The
highest nonsnowmelt streamflows were also recorded on this date.
Suspended Sediment Samples
A total of 571 suspended sediment samples were collected at 31 sampling
sites around the West Martis Creek and adjacent watersheds. The relative
locations of the 31 sampling sites are indicated schematically in Figure
VII-2. The description of the individual sampling sites appears in
Table C-2, Appendix C. A summary of the data collected at each sampling
site appears in Table C-3.
Suspended sediment concentrations clearly fluctuated greatly. In most
instances, the suspended sediment concentrations appeared to be roughly
proportional to the type of runoff conditions and the instantaneous
runoff rate. This relationship was closely investigated in the
development of the water quality model for Northstar and will be discussed
later in this section.
The highest suspended sediment concentration recorded in runoff from the
entire watershed (as measured at Gate No. 3) was 606 parts per million.
This sample was collected when the streamflow rate was 625 liters per
second during the peak spring snowmelt on April 24, 1975. During this
same period, runoff tributary to West Martis Creek from areas disturbed
by the Northstar development reached suspended sediment concentrations
of 6,029 parts per million (Site 28, 5-22-75).
The highest suspended sediment concentration at Gate No. 3 during
rainfall conditions was 526 parts per million. This occurred on
September 10, 1975, during the most intense storm recorded for the
duration of the erosion control project. The flow rate at Gate No. 3
when the sample was taken was 240 liters per second. Runoff from
disturbed areas tributary to West Martis Creek exceeded 8,000 parts per
million in certain instances. The maximum recorded suspended sediment
concentration in the total runoff from the up-basin ski area on this date
was 4,871 parts per million at a flow of 62 liters per second. A summary
of the average suspended sediment concentrations monitored at the
instream gaging stations on West Martis Creek is presented in Table VII-1.
Analysis of the water quality data shows that suspended sediment
concentrations for a given flow rate in the West Martis Creek drainage
system are highest during rainstrom events. The lowest concentration
occur during periods of low flow when snowmelt or rainstorm runoff is
absent. Suspended sediment concentrations typically found during
snowmelt conditions, while not as high as during rainstorms, averaged
4-8 times that of low flow conditions.
110
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TABLE VII-1
AVERAGE SUSPENDED SEDIMENT CONCENTRATIONS
RECORDED AT INSTREAM GAGING STATIONS
ON WEST MARTIS CREEK
AVERAGE SUSPENDED SEDIMENT CONCENTRATION (ppm)*
Gage No. 1 Gage No. 2 Gage No. 3
Low Flow
Rainfall
Snowmelt
4.2 (12)
944.0 (7)
33.4 (16)
4.2 (13)
53.7 (16)
28.9 (36)
* number of samples taken indicated in parenthesis
7.9 (13)
115.0 (20)
28.5 (43)
Benthic Macroinvertebrates
Biological sampling stations at the Norths tar development were selected
to illustrate effects on aquatic benthic macroinvertebrates by specific
local land disturbances. The following biological sampling stations,
located as shown in Figures VII-1 and VII-2, were established on West
Martis Creek:
Station WM-I. An unnamed stream at Big Springs about 15 meters
upstream of the main ski lodge. The station was discontinued
after the September 1974 sampling period when it was covered to
improve ski safety. This station was chosen as the site
furthest above development in the watershed. Although most of
the ski area is above this station, there is little adverse
effect since much of the runoff from the ski area percolates into
the ground in underdrains installed for the Northstar domestic
water system and here enters the stream.
Station WM-II. About 15 meters upstream of the water storage
tanks and above the uppermost area of condominiums on the West
Fork of West Martis Creek. This station was chosen to
represent the macrobenthic community just above the Northstar
development complex and was thought to be a community relatively
"undisturbed" by pollutants.
Ill
-------
Station WM-III. Just above the first major culvert (Village
Culvert) discharge on the West Fork of West Martis Creek. This
station represents the macrobenthic community just above the
discharge of the Village Culvert (Village Center commercial
area). Though this station would receive runoff from
unrevegetated sections of the ski area and uncontrolled
drainages, it was intended to serve as a reference station to
compare with Station WM-IV.
Station WM-IV. Just below the discharge point of the Village
Culvert on the West Fork of West Martis Creek. It was antici-
pated that the discharges from this ^culvert would have a great
impact on the macroinvertebrates at Station WM-IV due to the
heavier loading of silts and sediments and parking lot runoff
(oils and grease).
Station WM-V. About 50 meters upstream of Northstar Drive
Stream crossing on West Martis Creek. This station was
established as a reference station for Station WM-VI.
Station WM-VI. About 15 meters downstream of Northstar Drive
Stream crossing on West Martis Creek. This station is
immediately below the discharge from two large drainage ditches
from condominiums and parking lots and is below an extensive
fill area on Northstar Drive. The roadway fill shows signs of
erosion into West Martis Creek. The macrobenthos at Station
WM-VI were expected to be more adversely affected from local
surface runoff than were the macrobenthos at Station WM-V which
was more remote from direct influences of point discharges
to West Martis Creek.
Station WM-VII. Just upstream of Gage 3. This station was
assumed to be adversely affected as it received runoff from the
entire Northstar development, including the golf course which
was constructed and completed during this study.
Station WM-VIII. Just upstream of Gage 2 on the East Fork of
West Martis Creek. This station was to serve as a reference
station to compare with "reference" stations on West Martis.
As the only unnatural sources of silt and sediment are from a
dirt road crossing 2.4 kilometers upstream, it was originally
assumed that this station represented a "natural" or "clean-
water" community. Unfortunately, however, the East Fork of
West Martis is a controlled flow and it is possible that this
condition could affect the benthic population.
Station WM-IX. About 100 feet above Gage 4. Station WM-IX is
the other "clean-water" or "normal" community reference station
in this unnamed tributary to Martis Creek. A limited number of
112
-------
cattle are pastured about one-half mile upstream. There is no
development or unnatural soil disturbance such as roadways,
buildings, etc. in this watershed.
The results of the benthic macroinvertebrate monitoring program are
summarized in Table VII-2.
In all of the five sampling seasons, only one season showed any
significcant differences between stations of .the standing crop estimate
(number/meter ). This occurred at Stations WM-III and WM-IV sampled on
September 1974. As can be seen in the graph (Figure VII-4), all orders
Insecta and Oligochaeta had a significantly lower population at Station
WM-III, below the discharge of the Village Culvert, than the reference
Station WM-III, which is upstream of the Village Culvert. The total
number of families declined from 21 above to 18 below the Village
Culvert. However, this decrease in families is not significant as the
diversities of these two communities are not significantly different.
The Diversities recorded there were also two of the highest diversity
indices recorded during the entire West Martis study (Table VII-2).
The September 1974 macroinvertebrate collection could not be correlated
to water quality as there was no background data available at that time
However, the significant differences in standing crops between Stations'
WM-III and WM-IV were obviously due to discharges from the Village
Culvert. Accumulated sediment in the rock lined ditch below the culvert
outlet suggested that discharges of suspended sediment did occur due to
previous construction activities, winter road sanding activities, and
exposed road cuts in the parking lot area.
The July 1975 collection revealed a general decrease in species abundance
and standing crop from Station WM-III to Station WM-VI. This is most
likely related to the steady increase in average suspended sediment
concentrations between Gage No. 1 and all the water sampling points
through to Station WM-VI (from 18.8 parts per million to 73.3,
respectively, during the first six months of 1975).
The December 1975 collection revealed some perturbations at Stations WM-II,
WM-III, and WM-IV, where low diversities were found. Though water quality'
sampling was limited to spot sampling during low flows and runoff events
after July 1975, siltation problems were still evident. High runoff
suspended sediment concentrations were observed in the upper watershed
near the affected stations. Drainage from the T-l lift above the Village
Culvert had an average of 2,866 parts per million and a maximum of 8,339
parts per million, while Village Culvert averaged 688 parts per million
and a maximum of 1,093 parts per million during runoff events. Down-
stream near Station 4, the average runoff conditions were 1,791 parts per
million, with a maximum of 6,757 parts per million. In previous stud-
ies (3), runoff conditions of lower concentrations (100-1,200 parts per
million) had a far more severe impact on the macroinvertebrate community
than is seen in this study of the West Martis Creek watershed as affected
by the Northstar development.
113
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114
-------
1,100
1,000
000
800
600
500
400
300
200
100
0
WEST MART IS CREEK
MACRO INVERTEBRATES
SEPTEMBER, 1974
LEGEND
N
a
*_
tPH
EPHM - EPHEMEROPTERA
PLEC - PLECOPTERA
TRIC - TRICHOPTERA
DIPT - DIPTERA
COL - CQLEOPTERA
OLIG - OLIGOCHAETA
PLE
OLIG
Figure VII-4. West Martis Creek Macroinyertibrates, September 1974,
The June 1976 collection revealed unusually low'diversities. This was
probably due to the low flows (due to drought conditions) and lack of
flushing action which created deposits of sediment. Sediment deposits
were also seen along the stream banks in the November 1976 collection, but
not so heavy as in the June collection period. There were three small
rainfall events in the fall which could have aided in flushing some excess
sediments downstream. This could be seen in the November 1976 collection
as diversity indices and evenness estimates improved.
Although Surber sampling stations for benthic macroinvertebrates were
established to monitor areas in the Northstar development where sediment
and erosion problems were suspected to occur, the macrobenthic community
only suffered minor pertubations. The results did not illustrate the
impact which has been observed in other studies which have documented the
impact of eroded sediments on benthic macroinvertebrates(3,36,37). The
primary reason for an absence of perceptible impacts on the macrobenthic
community is the extremely low sediment yield for the Northstar
development. The suspended sediment load computer-simulation program,
discussed later in this section, has shown that the Northstar
development has resulted in a less than one-fold increase in suspended
115
-------
sediment yield above natural background levels. While this increase has
been perceptible from a water quality monitoring standpoint, it does not
appear to have resulted in an adverse impact on the macrobenthic community.
D. WATER QUALITY OF LONELY GULCH CREEK (RUBICON PROPERTIES)
The watershed of Lonely Gulch Creek has 275 hectares with a mean annual
precipitation of 104 centimeters mostly as snow. The stream follows a
moderately steep course until it- reaches Lake Tahoe at Rubicon Bay
(Figure VII-5).
The soils of the watershed are entirely a decomposed granite formation,
except at lower elevations near the lakefront which consists of glacial
moraines. The upper reaches of the study area are dominated by
moderately deep to shallow, coarse textured rocky soils over weathered
granitic bedrock; the lower reaches by a zone of gravelly and stony soils
with pans formed in glacial moraines and outwash. Adjacent to the lake
deep soils on alluvial fans and outwash are found. Most of the watershed
is covered with a relatively dense mixed coniferous forest down to the
lakeshore.
Before it receives any discharge from disturbed lands, Lonely Gulch Creek
flows into a small reservoir used for domestic water supply. Below this,
the Creek flows through the Rubicon Properties Subdivision, the main land
disturbance in the watershed. Steep roadcuts (30 to 45 percent, up to 25
meters long) and homesite excavations have created an accelerated source
of fluvial sediment. Rubicon Properties is thoroughly described in
Section VI of this report.
Additionally, during the spring and summer of 1973, extensive sewer
construction occurred in the Rubicon development and along Lonely Gulch
Creek. The stream bank was altered to accommodate the sewer line and
the line also crossed the Creek at the lower end of the Subdivision.
The locations of the various streamflow gages, water quality sampling
sites, biological sampling stations, and the precipitation gage are
shown in Figure VII-5. These monitoring locations were established to
determine the comparative sediment yield and water quality impacts of
the undisturbed upper watershed (2.37km ) with the heavily disturbed
lower watershed (0.38 km ) •
Streamflow
The following continuous recording gages were established in Lonely Gulch
Creek to monitor streamflow:
Gage No. 5. Situated above a 1.22 meter rectangular sharp-
crested weir. Located just below the domestic water supply
storage reservoir on Lonely Gulch Creek. Drainage area above
this point is 237 hectares of undisturbed watershed.
116
-------
LEG END
OLOGIC
STATIONS
[ j BIOLOGICAL SAMPLING
O WATER QUALITY SAMPLING
SITE
WEIR WITH STArL REPORDLR
-•*- DRAINAGE PATTERN
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
LONELY GULCH CREEK
WATER QUALITY
MONITORING DIAGRAM
100 200
I I
SCALE (METERS)
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
117
-------
Gage No. 6. Situated above a 1.22 meter rectangular sharp-
crested weir. Located 180 meters above mouth of Lonely Gulch
Creek and below all major land disturbance in the Lonely Gulch
Creek watershed. Total drainage area above Gage No. 6 is
""5 hectares.
Figure VII-6 is a graph of the total monthly flows monitored at Gage No. 5
during the periods which the gage was maintained. Substantial amounts of
water are diverted above Gage No. 5 for domestic water supply for Rubicon
Properties Subdivision. As was true in West Martis Creek, streamflow in
Lonely Gulch Creek in 1976 was substantially lower than 1975 streamflow
due to the considerably reduced winter precipitation levels during 1976.
Precipitation
The propane heated recording rain-snow gage at Rubicon Properties was
located near the upper water supply storage tank off of Highland Drive.
As was true at Northstar, the primary purpose of the precipitation gage
was to identify periods of rainfall for use with the water quality model.
Although several rainstorms occurred in the Lonely Gulch Creek watershed,
none of the observed storms were as intense as the one recorded at
Northstar on September 10, 1975. The most intense storm of record
occurred on August 16, 1976, with a maximum intensity of 1.0 centimeter
per hour. Total rainfall for a two-day period starting the previous day
was 8.25 centimeters.
Suspended Sediment Samples
A total of 301 suspended sediment samples were collected within the
Lonely Gulch Creek watershed during the periods of September 1972 through
September 1973 and June 1975 through September 1976. The relative
locations of the sampling sites are indicated in Figure VII-5.
Descriptions of the individual sampling sites appear in Appendix C, Table
C-4. A summary of the data collected at each site appears in Table C-5.
Variations in the suspended sediment concentration were extremely
erratic due to the extensive concentrated disturbances and erosion
sources in an extremely small watershed. For example, small amounts of
eroded sediment might build up in one location after a series of small
runoff events. The initial stages of a subsequent large runoff event
would then have an astronomical suspended sediment concentration. The
highest concentration of suspended sediment in runoff within Rubicon
Properties Subdivision was 231,000 parts per million. The highest
instream sediment sample was collected where Lonely Gulch Creek passes
under State Highway 89 with a concentration of 15,200 parts per million.
In all cases, the suspended sediment concentrations were dramatically
higher during periods of rainstorm runoff than during snowmelt runoff.
It was estimated that at the peak of a two-day, 5.54-centimeter
rainstorm on October 10 and 11, 1975, that up to 15 metric tons of
118
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ER RESOURCES CONT
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STREAMFLOW
LONELY GULCH CREEK
FI«UKE NUMBER 1
VII- 6 |
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
CO
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119
-------
suspended sediment were being discharged to Lonely Gulch Creek in a
single hour.
These high rates of sedimentation have devastated Lonely Gulch Creek.
Above the first sediment discharge point from Rubicon Properties
Subdivision, Lonely Gulch Creek has the appearance of a small pristine
mountain stream. However, by the time it has wound its way down through
the Subdivision, Lonely Gulch Creek is choked by deposited sediments.
The deposition is evidenced to some degree by the reduction of recorded
suspended sediment concentrations as the stream gradient decreases
towards Lake Tahoe. This is due to increased settling and suspended
sediment deposition. The highest suspended sediment levels on Lonely
Gulch Creek were at Rubicon Glen Drive (Site 34) and Highway 89 (Site 35),
less than 100 meters downstream from the most severe sediment discharges
from Rubicon Properties Subdivision and about 900 meters above Lake Tahoe.
By the time a slug discharge of suspended sediment to Lonely Gulch Creek
has reached Gage No. 6 (Site 36), only 150 meters above Lake Tahoe,
suspended sediment concentrations are usually quite diminished.
A summary of the average suspended sediment concentration monitored at
the instream sampling stations above and below Rubicon Properties
Subdivision is presented in Table VTI-3.
Benthic Macroinvertebrates
The following biological sampling stations, located as shown in
Figure VII-5 were established on Lonely Gulch Creek:
Station LG-1.
100 meters above all road and land development
The Creek in this area is typical of a Sierra
disturbances.
Mountain forest stream.
Station LG-II. 70 meters above Station LG-III and approxi-
mately 200 meters below Station LG-1. It is above a large
swale which drains the steeper and more extensive roadcuts of
Rubicon Properties. Although this station receives minor
drainages from roadcuts and fills, it serves as a "reference"
station for Station 3.
Station LG-III. 50 meters below the start of road and
subdivision disturbance and about two meters below the first
three drainage swales which collect most of the street runoff
from the roadcuts.
Station LG-IV. 25 meters above State Highway 89 and 250 meters
below Station LG-III. It was below most of the drainage swales
which collect surface runoff from Rubicon Properties.
As in a previous study of Lonely Gulch Creek(3), the downstream stations
had lower standing crop estimates (Total No. Individuals/m ), lower
120
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TABLE VI I-3
AVERAGE SUSPENDED SEDIMENT CONCENTRATIONS
RECORDED AT INSTREAM SAMPLING SITES IN
LONELY GLUCH CREEK ABOVE AND BELOW DEVELOPMENT
AVERAGE SUSPENDED SEDIMENT CONCENTRATION (ppm)*
Low Flow
Rainfall
Snowmelt
ABOVE
DEVELOPMENT
1.3 (38)
20.8 CIS)
9.1 (41)
BELOW
DEVELOPMENT
12.9 (36)
1798.1 (33)
434.6 (45)
* number of samples taken indicated in parenthesis
diversities, and, ±n most cases, lower species abundance than the control
Station LG-1 for all periods of collection. "Reference" Station LG-II
also contained a higher standing crop estimate and a equal or higher
species abundance than downstream Station LG-III for all periods of
collection. The results of the benthic macroinvertebrate monitoring
program conducted in the Lonely Gulch Creek watershed are summarized
in Table VII-4. Figures VII-7, 8, 9, and 10 graphically depict the
standing crop estimates for the July 1975, December 1975, June 1976, and
November 1976 sampling periods respectively. The increasing impacts, as
one moves downstream, are clearly indicated by the reduced numbers of
individuals in representative orders at each successive downstream
station.
The decrease in species abundance, diversity, and standing crop estimates
in the downstream macroinvertebrate communities is well correlated with
the downstream increase in suspended sediment for the July and December
1975 collections. Runoff into Lonely Gulch Creek below Station LG-II
ranged from 1,500 - 250,000 parts per million in drainage ditches and
culvert outlets. However, during the December 1975 - June 1976 sampling
period, no significant rainfall events took place to create the heavy
silt laden runoff as seen in previous sampling. The snowmelt produced
little runoff and low flows due to the very light winter. Consequently,
121
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1,100 •
1,000 •
900 •
800 •
CM
B
o: • 700 •
Ul
„ 600-
^>
o SOO -
g 400-
300 -
200-
100
LONELY GULCH CREEK
MACROINVERTEBRATES
JULY
LEG
-
-
•
al
S3
EPHU
^
d
3
I
•
H
_J
33 2
PLEC '
, 1975
END
EPHM - EPHEMEROPTERA
PLEC - PLECOPTERA
TRIC - TRICHOPTERA
DIPT - DIPTERA
OLIG - OLIGOCHAETA
•
^r
a IK Ht4
to mm «P <•
ft
1,
5p
TRIC DIPT
H
O
_l
|~o
•ffl
1 1
Jil
Dlolia
LIB
Figure VII-7. Lonely Gulch Creek
Macro invertebrates., July, 1275.
1,100 •
1,000
900 •
800 -
CM
E
a: 700 -
UJ
„ 600
o 500 -
g 400
300
200
100
0
LONELY GULCH CREEK
MACROINVERTEBRATES
DECEMBER, 1975
LEGEND
<»
HE
EPHM-
PLEC -
TRIC -
DIPT -
OLIG -
p
1_ Tfl Tn
u. ^H^H nMN|H
to to to o to <* «» <» «>|HM PLEC TRIC
EPHEMEROPTERA
PLECOPTERA
- TRICHOPTERA
DIPTERA
OLIGOCHAETA
B
-, n
jM|atl H^n^
;*p3 53Jg3
DIPT OLIG
Figure VII-8. Lonely Gulch Creek
Macroinvertebrates, December, 1975.
122
-------
1,100 •
1,000-
900 •
CM 800 •
5 700-
0.
I
_j
i
o e
H
to
_i
PLEC
H
o
LONELY
MACRO
J
GULCH CREEK
NVERTEBRATES
UNE, 1976
LEGEND
EPHM - EPHEMEROPTERA
PLEC - PLECOPTERA
TRIC - TRICHOPTERA
DIPT - DIPTERA
OLIG - OLIGOCHAETA
H
.
B
H-RIC
"
u> ta
_i _i
0 »0
DIPT OL
[.
IG
Figure VII-9. Lonely Gulch Creek
Macroiiwertebratea, June, 1976.
1 , 1 00 -
1,000-
900-
800-
E
-------
TABLE VII-4
RESULTS OF
UNITS
2
Number/m
No. of Families
Diversity
Evenness
SURBER SAMPLING AT FOUR STATIONS ON
DATE OF
COLLECTION
7-08-75
12-08-75
6-18-76
10-04-76
7-08-75
12-08-75
6-18-76
10-04-76
7-08-75
12-08-75
6-18-76
10-04-76
7-08-75
12-08-75
6-18-76
10-04-76
LONELY GULCH
LG-I
1542
1321
2125
1560
20
19
14
14
2.497
2.247
2.150
2.207
0.58
0.53
0.56
0.58
LG-I I
398
945
1465
496
14
12
13
14
1.962
1.464
1.582
2.072
0.51
0.41
0.43
0.54
LONELY GULCH CREEK
STATIONS
LG-III
244
245
1366
99
11
12
13
09
1.988
1.996
1.405
1.938
0.57
0.56
0.38
0.61
LG-IV
267
277
1652
19
09
12
14
04
1.913
2.077
1.846
1.352
.60
.58
.48
.67
low flows and low suspended sediment created few interstation
differences between species abundance and standing crop estimates for the
June 1976 collection. Station LG-I was decreased to only 14 families
probably because the low flow drought conditions eliminated the rarer
families. Changes in water level or current have been known to change
whole communities (38,39,40).
In the four month period preceding the November 1976 sampling period,
three rainstorms produced runoff in drainage ditches which discharged
just above Station LG-III producing an average runoff concentration of
6,600 parts per million and a maximum of 15,157 parts per million in
Lonely Gulch Creek at Station LG-III. The drainage ditch above Station
LG-IV had an average runoff concentration of 10,211 parts per million and
a peak value of 32,756 parts per million. Lonely Gulch Creek at Station
LG-IV had an average runoff condition of 7,183 parts per million of
suspended sediment. The results of these storms, runoff, and low
baseline flows could be seen in the stream substrate.
124
-------
During all sampling periods, Station LG-1 had the "normal" substrate of
cobble, pebble, gravel, and some sand while Station LG-II had the same
except for a slightly higher percentage of sand and some silt. At
Station LG-III, the cobble was "cemented" in by sand and silt while at
Station LG-IV it was completely overwhelmed by a silty sand with the
cobble, pebble, and gravel buried beneath. The effect of these substrate
conditions on the macrobenthic community is obvious. The macrobenthic
community at Stations LG-III and LG-IV were almost eliminated in the
November 1976 sampling period. The need for sound land management and
effective erosion control practices is amplified by the results of this
study. High suspended sediment concentrations coupled with low flow
conditions have created an adverse effect on the macroinvertebrate
community of Lonely Gulch Creek and nutrient contributions from suspended
sediment.
The ongoing erosion control work in the Lonely Gulch Creek watershed at
Rubicon Properties will be monitored in the future for its effectiveness
in stream recovery and lessening sediment loading to Lake Tahoe.
E. WATER QUALITY MODELING OF SUSPENDED SEDIMENT TRANSPORT
In order to determine mass emission rates for suspended sediment from
both the'Northstar and Rubicon Properties developments, a simple "model"
to predict these loads was sought. Suspended sediment transport at both
the project sites had a seemingly proportional relationship with the
amount of streamflow. This first task was to determine the type of
relationship that would reliably predict the suspended sediment
concentration for a given streamflow. Because continuous streamflow
recordings were available at three streamflow gages in the West Martis
watershed and two in Lonely Gulch Creek,, such relationships would define
the amount of suspended sediment transported past each gage for any given
period of time.
Admittedly, such an approach is simplistic, as suspended sediment
levels can be quite different for a given flow level depending on whether
a sample is taken at the beginning or end of a runoff period. Nonetheless
the project staff felt that a well correlated average relationship between'
these extremes would yield acceptable estimates of overall suspended
sediment mass emission rates. Certainly such relationships, if reasonably
well correlated, would yield acceptable estimates for comparative purposes
(.i.e., post-development versus pre-development, or upstream versus
downstream sediment loads).
Initially, one mathematical expression relating suspended sediment to
streamflow was sought for each streamflow gaging station. However,
correlations for such a single expression were generally extremely low.
From this point, the project staff sought to define more than one
expression at each gaging station depending on the varying types of
runoff. The following runoff types were identified and defined:
125
-------
Rainstorms. These runoff periods were defined by the recording
precipitation gages at Northstar and Rubicon Properties. An
added requirement of these periods was that they must cause a
perceptible rise in at least one of the recording streamflow
gages.
Stage I Snowmelt. These periods were defined as beginning when
snow first remained without melting at the start of the winter
season and ending when the maximum runoff period was reached
in the spring. Early snowstorms which melted immediately during
the fall were treated as rainstorms.
Stage II Snowmelt. These periods began after the peak runoff
period was reached in the spring (i.e., the end of Stage I) and
ended when diurnal streamflow fluctuations from snowmelt were
no longer significant and runoff approached low flow levels.
Low Flow. These periods occurred from the end of Stage II
snowmelt until the commencement of Stage I snowmelt the
following winter, except as interrupted by snowmelt conditions.
In all cases, suspended sediment concentrations were assumed to never be
less than that defined by the mathematical expression for low flow. The
various mathematical expressions defining suspended sediment concentra-
tions for a particular flow type were derived by means of linear
regression analysis. In all cases, linear regression gave better
correlations than did exponential, power law, or logarithmic curve fits.
Once the suspended sediment versus flow relationships were established
with well defined periods of applicability, they were combined with
previously digitized streamflow data to produce estimates of suspended
sediment concentrations and sediment mass emission rates on a daily basis.
At each streamflow gage and each streamflow type, the data was summarized
on a daily, monthly, and, where possible, yearly basis. These
summarizations for each gage appear in tabular form in Appendix C, Tables
C-8 through C-13.
WEST MARTIS CREEK
The basic equations correlating suspended sediment concentration (SS mg/1)
with streamflow (Q I/sec) for each of the streamflow gages are given in
Table VII-5. In most instances, confidence levels based on a Student s
t-distribution analysis were greater than 99 percent. In all cases, well
correlated relationships could not be developed for low flow conditions;
thus, for low flow, the average recorded suspended sediment concentration
was used irrespective of streamflow. This is a reasonable simplification
due to the relatively insignificant sediment concentration found during
low flow periods. Fluctuations in the assumed suspended sediment
126
-------
concentrations during low flow period yield an insignificant variation in
overall calculated sediment mass emission rates.
Considerable problems were encountered in trying to determine suspended
sediment relationships for predevelopment conditions in the West Martis
Creek watershed. Only scattered water samples had been taken at a low
frequency and usually during only low flow conditions. However, at the
site designated Gage No. 3 (Site No. 3) for the erosion control project,
nine samples at various streamflow rates had been collected prior to
July 1971. This was before extensive construction activities began at
Northstar. Unfortunately, turbidity (JTU) was the only parameter recorded
which could be related to suspended sediment concentration levels. To
provide a reliable substitute for direct suspended sediment samples, a
linear regression analyses was performed to correlate turbidity (JTU)
with suspended sediment (mg/1) for 28 samples collected at Gage No. 3
between October 25, 1974, and May 29, 1975. The data correlated extremely
well with a confidence level greater than 99.99 percent, as determined by
a Student's t-distribution analysis. Thus, using this suspended sediment
versus turbidity relationship, suspended sediment concentrations were
estimated for the nine predevelopment samples. The maximum estimated
suspended sediment concentration developed in this manner was 73 mg/1 for
a predevelopment rainstorm (November 25, 1970) sample taken at Gage No. 3
when-streamflow was 340 I/sec. The turbidity recorded at this time was
12.0 JTU.
A graphical presentation of the suspended sediment concentration versus
streamflow relationships for Gage No. 3 is shown in Figure VII-11. The
relationship for the various postdevelopment flow types are indicated
by the solid lines as compared to the estimated predevelopment
relationship for all flow types by the dashed line. As seen in Figure
VII—11, the primary departure from predevelopment suspended sediment
concentration appears to occur during rainfall and "Stage I" snowmelt
conditions.
The relative suspended loads for the .various postdevelopment flow types
are listed in Table VII-6. In most instances, the majority of suspended
sediment load to West Martis Creek occurred during snowmelt periods,
principally during the heavy spring-melt period. The only apparent
exception to this was runoff from the Northstar ski area during water
year 1975. The vast majority (79.3 percent) of the suspended sediment
load that year came during rainfall periods. A partial explanation is
that much of the overland flow from the ski area is percolated and
intercepted by a groundwater collection system for water supply purposes.
This results in only very intense rainstorms actually producing any
measurable overland flow. The water intercepted by the collection
system is usually discharged back to West Martis Creek immediately after
collection, except as needed for domestic supply. The collected
groundwater flow typically has very low suspended sediment concentrations.
A graphical presentation of the suspended sediment loads in West Martis
127
-------
CORRELATION OF SUSPENDED SEDIMENT CONCENTRATION
WITH STREAMFLOW AT GAUGE * 3
WEST MARTIS CREEK (NORTHSTAR)
LU
o
2
O
O
Ul
o.
CO
1,000
800
.PREDEVELOPMENT
(ALL FLOW TYPES)
STAGE I
SNOWMELT
STAGE II
SNOWMELT
10 20 40 60 80 100 200 400 600800 1000 2000
STREAM FLOW ( LI TERS/SEC.)
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
STREAMFLOW
WEST MARTIS
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
1
FKURE NUMIER
VII-11
128
-------
TABLE VII-5 s
SUSPENDED SEDIMENT CORRELATIONS FOR
WEST MARTIS CREEK
RUNOFF TYPE CONVERSION*
Gage No.
1. (lust below maioritv of ski area")
Rainfall SS=75.9(Q)+151.
All Snowmelt Types SS=1.82(Q)+1.00
Low Flow SS=4.18
Gage No.
Rainfall
Stage I-
Stage II
Low Flow
Gage No.
Rainfall
Stage I
Stage II
Low Flow
Gage No.
All Flow
* Note: -
2. (on East Fork, West Martis Creek,
SS=3.49(Q)-49.82
SS=2.78(Q)-55.33
SS=.326(Q)-4.70
SS=4.01
3. (on West Martis Creek below all dc
SS=1.14(Q)-68.4
SS=.397(Q)-34.3
SS=.078(Q)+1.90
SS=7.75
3. (Pre-development)
Types SS=.121CQ).+.085
SS = Suspended Sediment Concentration
Q = Streamflow (I/ sec)
DATA
POINTS
7
16
12
at confluence
15
27
10
13
jvelopment)
18
28
10
13
9
Cmg/1)
PERCENT
SIGNIFICANCE
>99%
>99%
N/A
with West Fork)
>95%
>99%
>98%
N/A
>99.9%
>99.9%
>99.9%
N/A
>99%
Creek during 1975 and 1976 is presented in Figure VII-12. By comparing
this graph to Figure VII-3, it is possible to see how suspended
sediment loads do fluctuate with various levels and types of streamflow
within West Martis Creek.
Suspended sediment loads at Gage No. 1 are representative of the
disturbances within the ski area portion of the development. Gage No. 2
loads are representative of input from the East Fork of West Martis
Creek, while Gage No. 3 loads are assumed to represent the total sediment
load from the entire upstream watershed. Thus, any increase in sediment
load between Gage No. 1 and Gage No. 3, minus the East Fork input, is
assumed to be from the heavily developed portions of the Northstar
development (condominiums, roadways, Village Center, parking areas, etc.).
129
-------
SUSPENDED SEDIMENT LOAD
IN WEST MARTIS CREEK (NORTHSTAR)
ESTMATED BY WATER QUALITY MODEL FROM
OCTOBER, 1974 THROUGH SEPTEMBER, 1976
cc
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130-
120-
no
100
90-
80-
70
60
50
40-
30
20
10
0
SNOW
- SPRING
>•»
i—
a
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a
o
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MELT ^
, 1975
r-T
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1974
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1975
RAINSTORMS
s FALL,
^SNOWME
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IT
SPRING, 1976
\ RAINSTORMS
— X — 1 CA 1 1 IQ7fi —
\ 1 rALL, iy /o
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£• fe
1 1
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-3 0
-------
TABLE VI I- 6
POST-DEVELOPMENT SUSPENDED SEDIMENT CONTRIBUTION
TO WEST MARTIS CREEK (NORTHSTAR) FOR
VARIOUS FLOW TYPES
FLOW
TYPE
Low Flow
Rainfall
Snowmelt
Total
Low Flow
Rainfall
Snowmelt
Total
% OF
TIME
39
5
56
100
46
4
50
100
SUSPENDED SEDIMENT LOAD (METRIC TONS)
GAGE
0
47
12
59
0
0
0
0
#1
-
.08
.54
.34
.96
-
.03
.05
.11
.19
% GAGE #2 %
- WATER
0.1
79.3
20.6
100.0
- WATER
15.8
26.3
57.9
100.0
' GAGE #3
°/ •
/a
YEAR 1975 - -
0.
5.
12.
18.
58
35
21
14
3.2
29.5
67.3
100.0
8.
48.
179.
236.
46
66
SO
42
3
20
75
100
.6
.6
.8
.0
YEAR 1976
0.
3.
11.
15.
65
03
72
40
4.2
19.7
76.1
100.0
3.
11.
12.
27.
29
76
89
94
11
42
46
100
.8
.1
.1
.0
Table VII-7 is a summarization of the suspended sediment load per unit
area from the various portions of Norths tar as calculated in this manner.
The postdevelopment loads are compared with the estimated predevelopment
suspended sediment load from the entire watershed. Lacking any
significant detailed information on tributary predevelopment loads, the
total predevelopment suspended sediment load was estimated for the
postdevelopment years for which, streamflow records existed. Had the
Northstar development not occurred, the unit suspended sediment load would
have been an estimated 12.34 metric tons per square kilometer compared to
an actual 24.12 metric tons per square kilometer for water year 1975. For
water year 1976, a much drier year than 1975, suspended sediment load
would have been an estimated 1.47 metric tons per square kilometer
compared to an actual 2.85 metric tons per square kilometer. Thus the
overall postdevelopment loads are estimated to have increased almost 100
percent due to the construction of Northstar. For water year 1975, unit
131
-------
TABLE VI I- 7
SUSPENDED SEDIMENT LOADS TO WEST MARTIS CREEK
AS DEVELOPED BY WATER QUALITY MODEL
SUSPENDED UNIT LOAD PERCENT
SEDIMENT TRIBUTARY (METRIC INCREASE
LOAD AREA TONS /KM2) ABOVE
srtllRfiK f METRIC /TONS') ("KILOMETERS ) YEAR BACKGROUND
WATER
Ski Area 59.96
Development 156 . 82
East Fork 19.62
Total W. Martis 236.40
ESTIMATED P REDEVELOPMENT
Total W. Martis 161.43
WATER
Ski Area .642
Development 11.89
East Fork 15.40
Total W. Martis 27.93
ESTIMATED PREDEVELOPMENT
Total W. Martis 19.29
YEAR 1975 - -
2.94 20.39 65 %
5.43 28.88 134 %
1.43 13.72 11 %
9.80A/ 24.12 95 %
CONDITIONS FOR WATER YEAR 1975
13. OS?-/ 12.34
YEAR 1976
2.94 0.22 -85 %
5.43 2.19 49 %
1.43 10.77 630 %
9.80^/ 2.85 94,,%
CONDITIONS FOR WATER YEAR 1976
13. 08^./ 1.47
A/ Total area above Gage No. 3 minus area above storage reservoir
B/ Total area above Gage No. 3 including area above storage reservoir
132
-------
suspended sediment loads for the heavily developed portion of the West
Martis Creek watershed are estimated to be increased 134 percent above
predevelopment levels. The majority of this increase comes from
disturbed slopes, unrevegetated areas, concentrated runoff, and winter
road sanding operations associated with the development. Nonetheless, it
must be realized that the suspended sediment increase in West Martis
Creek due to development within the watershed has not been excessive.
As was mentioned in the section discussing benthic macroinvertebrates,
this doubling of suspended sediment load has apparently had minimal
impact on aquatic life in the stream. It is likely that those areas that
are producing higher than background levels of sediment yield may be
controlled in the future by application of additional erosion and
sediment control technology.
LONELY GULCH CREEK
The basic equations correlating suspended sediment concentration (SS-mg/1)
with streamflow (Q-l/sec) for the two streamflow gages on Lonely Gulch
Creek are listed in Table VII-8. Gage No. 5 monitored streamflow in
Lonely Gulch Creek above Rubicon Properties Subdivision, while Gage No. 6
monitored streamflow below the development. The suspended sediment
versus flow relationship for Gage No. 5 has been corrected for any
settling that might occur in the small reservoir just above Gage No. 5.
Samples collected above the reservoir usually had 10 percent greater
suspended sediment concentration than did samples collected just
below the reservoir. The significance levels computed for the
correlated suspended sediment versus flow relationships are less than
those developed to represent conditions in West Martis Creek. Any
relationship between runoff, erosion, and sediment transport in
Lonely Gulch Creek is complicated by: (1) the comparatively small size
of the watershed, (2) the extremely high levels of concentrated
erosion, (3) the erratic deposition and resuspension of large sediment
particles depending on the local stream gradient and instantaneous
flow rate, and (4) the loss of streamflow as percolating groundwater
in the lowest portions of the watershed. Although the correlation
of low flow suspended sediment levels at Gage No. 6 is extremely poor
(77.2 percent), the significance of low flow conditions in comparison
to rainfall and snowmelt contribution is minor. Similarly, even
though the significance levels of rainfall and snowmelt (94.5 percent
133
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TABLE VII-8
SUSPENDED SEDIMENT CORRELATIONS FOR
LONELY CREEK GULCH
RUNOFF TIME
CONVERSION*
DATA
POINTS
PERCENT
SIGNIFICANCE
Gage No. 5 (above all development)
All Flow Types SS=.043(Q)+0.85
Gage No. 6 (below all development)
Rainfall SS=38.1(Q)-656.
All Snowmelt SS=.853(Q)-14.5
Low Flow SS=.024(Q)-1.29
70
>99.9
7
36
24
>94.5
>92.5
>77.2
* Note: SS = Suspended Sediment Concentration (mg/1)
Q = Streamflow (I/sec)
and 92.5 percent) are slightly lower the 95 percent limit usually
considered acceptable, their relationships are felt to be reasonable
estimates of expected suspended sediment levels in Lonely Gulch Creek.
Unfortunately, there is a complete lack of information on the level of
suspended sediment and erosion rates in the Lonely Gulch Creek system
prior to development. This problem was circumvented by assuming that
sediment yield per unit area monitored at Gage No. 5, above the entire
development, would be considered representative of predevelopment
conditions for the entire watershed.
A graphical presentation of the suspended sediment concentration versus
Streamflow relations at Gage No. 5 and Gage No. 6 is shown in Figure
VII-13. The below-development relationships are depicted by solid lines,
134
-------
CC
LU
I-
LU
o
o
o
a
LU
C/3
LU
a
a.
CO
CORRELATION OF
SUSPENDED SEDIMENT CONCENTRATION
WITH STREAMFLOW AT GAUGES #5 & #6
LONELY GULCH CREEK (RUBICON PROPERTIES)
GAUGE#6 RAINFALL
.GAUGE* 6
SNOW MELT
GAUGE # 5
ALL FLOW TYPES
GAUGE #6
LOW FLOW
20
40 60 80 100 200 400 600 800 1000
STREAM FLOW (LITERS/SEC.)
2000
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
STREAMFLOW
LONELY GULCH
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOSY
FltURf NUMIEft
VII-13
135
-------
TABLE VII-9
SUSPENDED SEDIMENT CONTRIBUTION TO LONELY GULCH CREEK (RUBICON)
FOR VARIOUS FLOW TYPES
FLOW
TYPE
% OF
TIME
SUSPENDED SEDIMENT LOAD (METRIC TONS)
FOR TOTAL PERIOD OF RECORD^7
GAGE #5
GAGE #6
Low Flow
Rainfall
lowmelt
43
3.37
5.26
11.33
16.8
26.4
56.8
1.61
119.29
210.53
0.5
36.0
63.5
19.96
100.0
331.43
100.0
A/ Period of record includes 27 months of data at Gage #5 and Gage #6 from
November 1973 through October 1974 and June 1975 through August 1976
whereas the above-development relationship is shown by a dashed line.
A substantial jump in rainfall and snowmelt runoff suspended sediment
concentrations occurs between Gage No. 5 (above development) and Gage
No. 6 (below development).
The relative contribution of suspended sediment load for various flow
types is presented in Table VII-9. As was true of the West Martis Creek
system, the majority of the suspended sediment load is contributed during
the winter months and peak spring snowmelt period. The most intense
conbribution occurs during rainfall periods. Although only 3 percent of
the period of record was during rainstorm events, fully 36 percent of
suspended load monitored below the Rubicon Properties development
occurred at these times. A graphical presentation of the suspended
sediment loads in Lonely Gulch Creek during the period of record is
presented in Figure VII-14. By comparing this graph to Figure VII-6,
it is possible to see how suspended sediment loads are related to, and
fluctuate with, various levels and types of streamflow within Lonely
Gulch Creek. Figure VII-14 demonstrates the vast increase in sediment
load between Gages No. 5 and 6.
136
-------
1
>
\
o
in
(H1NOW/SN01) QV01
137
-------
TABLE VII-10
SUSPENDED SEDIMENT LOADS TO LONELY GULCH CREEK
AS DEVELOPED BY WATER QUALITY MODEL
TOTAL PERIOD OF RECORD^/
SOURCE
SUSPENDED
SEDIMENT
LOAD
rMRTRIC
TRIBUTARY
AREA
CTCTT.OMETER2)
UNIT PERCENT
LOAD INCREASE
(METRIC TONS/KM2) ABOVE
( YEAR ) BACKGROUND
Upper Watershed
Development
Total Watershed
8.129
138.228
147.357
2.37
0.38
2.75
3.43
366
53.6
10,600 %
1,460 %
A/ Period of record includes 27 months or data at Gage #5 and Gage #6 from
November 1973 through October 1974 and June 1975 through August 1976
B/ Upper watershed values are assumed to be representative of background
~ levels for entire watershed
A further comparison between background and development suspended sediment
yield conditions within the Lonely Gulch Creek watershed is given in Table
VII-10. As shown, the suspended sediment load per unit area jncreases
from 3.43 ton/km2/year from the upper watershed to 366 ton/km /year from
the Rubicon Properties development. This is a 10,600 percent increase.
The total yield from the entire watershed is increased 1,460 percent to
53.6 tons/km2/year. As was indicated by the results of the benthic
macroinvertebrate monitoring, this massive sediment load to Lonely Gulch
Creek has had a severe impact on the aquatic life of the stream.
F. SUMMARY AND CONCLUSIONS
One of the most significant results of the suspended sediment sampling
program at Northstar was that it enabled the project staff to determine
the location and relative severity of erosion problems remaining after
initial construction. Clearly, the land disturbance created in the con-
struction of Northstar was held to a minimum. Due to conscientious
138
-------
planning, development, and construction practices, only scattered
instances of detectable erosion problems still remain. They are
discussed in Section V of this report and are listed as follows:
Problem 1. Oversteepened and unrevegetated slopes adjacent to
parking lots and roadways. This problem was mainly located near the
wastewater treatment plant, Northstar Drive, and the Village Center.
Eroded sediments from these locations discharge to West Martis Creek
just above and below its confluence with the East Fork. A
substantial effort was made by the project staff to control erosion
from these sources (see Appendix B). The total oversteepened,
unrevegetated slope area was less than 0.5 hectare.
Problem 2. Urban runoff from the Village Center commercial area.
A large portion of the suspended sediment came from sources
mentioned in Problem 1 above. Nonetheless, a portion derived from
dirt loosened from vehicular traffic in the Village Center area and
from winter road sanding operations.
Problem 3. Uncontrolled drainage flowing over an artificially filled
and unrevegetated ski run. The areal extent of this problem was
about 0.6 hectare near the Village Center. This problem was further
compounded by disturbance caused by skiers and maintenance vehicles
in the late spring when little snow cover remained.
Problem 4. Heavily traveled dirt road adjacent to and crossing the
East Fork of West Martis Creek. The problem here was greatest during
spring snowmelt when continuous vehicular traffic would loosen the
roadbed, allowing it to be washed into the creek.
Problem 5. Remaining uncontrolled drainage and unrevegetated areas
located near the base of the main ski bowl.
Clearly Problems 1 and 2 were the most significant and the most difficult
to control, although occasional higher suspended sediment concentrations
were recorded elsewhere.
Urban runoff, combined with drainage from oversteepened and unrevegetated
slopes near the Village Center, was the most frequent and readily
discernible source of sediment discharges to West Martis Creek. A large
part of the problem was due to a lack of adequate sediment retention
facilities for drainage from the Village Center commercial area. A
planning recommendation made prior to the construction of Northstar's
Village Center anticipated that sediment retention facilities would be
required to meet water quality standards. However, such a sediment
catchment facility was not provided when the Village Center and its
drainage appurtenances were constructed. Although such a catchment
139
-------
devise was not added as part of this demonstration project, addition
of such a structure in the future, coupled with careful maintenance,
would substantially lower the sediment yield from the Village Center.
It must be emphasized, however, that although the construction and
development of Norths tar has led to a 100 percent increase in the amount
of sediment yield, the impact on aquatic life in West Martis Creek has
been negligible. Although sampling stations for Benthic
macroinvertebrates were established to monitor areas in the Norths tar
development where siltation and erosion problems were suspected to occur,
the macrobenthic community suffered only minor perturbations. The
majority of the remaining sediment transport and erosion problems within
the West Martis Creek watershed can be further reduced by further
revegetation and adequate drainage control. As part of the erosion
control project, considerable emphasis was placed on revegetation of
disturbed areas and some minor drainage control (see Appendix B) . By
implementation of these measures, it is believed that suspended sediment
transport from the the Northstar development has been further reduced.
Within the Lonely Gulch Creek watershed, on the other hand, it was
impossible to determine the relative significance of a number of
different sediment discharges from Rubicon Properties Subdivision. All
discharges from culverts, ditches, and drainage swales had extremely high
levels of transported sediments. While sediment discharge per unit area
of watershed above the development was estimated at 3.43 tons/sq km/year,
the average estimated discharge from the development was estimated to be
366 tons/sq km/year. This represents a 10,600 percent increase above
estimated natural background levels. A graphical comparison of
predevelopment and postdevelopment suspended sediment yields at the
Northstar and Rubicon Properties erosion control project sites is
depicted in Figure VII-15. The difference is not only in suspended
sediment yield, but also the differing impact of suspended sediment
discharge between Northstar and Rubicon Properties is readily apparent.
An almost one-fold increase in sediment yield within the West Martis
watershed after development had negligible impact on the monitored
benthic macroinvertebrates. Within Lonely Gulch Creek, however, total
numbers of macroinvertebrate individuals were reduced to as low as 1
percent of the density found upstream of suspended sediment discharges.
The average density of individuals downstream of discharges to Lonely
Gulch Creek during 1975 and 1976 was 32 percent of that found upstream.
Nunfcers of different families and diversities of the macroinvertebrate
populations were also substantially decreased. Average diversity, a
measure of the overall "health" of an ecologic system, was lowered from
2.28 at an upstream station to 1.80 for downstream stations heavily
affected by suspended sediment scour and deposition.
While the development of Northstar-At-Tahoe has had a minimal and per-
haps acceptable impact upon West Martis Creek, the development of Rubicon
Properties has led to the totally unacceptable destruction of Lonely
Gulch Creek.
140
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NORTHSTAR - AT - TAHOE
RUBICON PROPERTIES
FIGURE 3DT-I5. COMPARISON OF PREDEVELOPMENT AND POSTDEVELOPMENT
SUSPENDED SEDIMENT YIELDS AT NORTHSTAR AND RUBICON PROPERTIES
PROJECT SITES.
141
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SECTION VIII
BEST MANAGEMENT PRACTICES FOR EFFECTIVE EROSION CONTROL
A. Introduction
A primary objective of this report is to provide timely information on
the cost-effectiveness of erosion control methods which could be applied
to erosion problems typically found in the Tahoe-Sierra region of
California. Because of time, funding, and site limitations, the
California State Water Resources Control Board (State Board) was unable
to demonstrate all erosion control techniques that, might conceivably be
used in the environment of the Tahoe-Sierra. With these limitations in
mind, the project staff chose to implement and demonstrate those methods
which:
- appeared to be the most cost-effective,
— appeared to be environmentally sound,
the project staff could utilize to develop reliable cost-
effectiveness data which otherwise would not be available,
emphasized source control, rather than treatment after the
fact,
- emphasized revegetation, and
- could be easily implemented using unskilled labor, or, if
skilled workers and special equipment are required, could be
•implemented with a low unit cost.
In addition to the above criteria the erosion control project staff
placed the most emphasis on those techniques which could be applied to
very steep (2:1 or greater) cut and fill slopes (see Figure VIII-1).
Very steep slopes are common throughout the Tahoe-Sierra region where
extensive past construction activities have been relatively unregulated.
Not only do they represent the greatest erosion problem and source of
waste sediments transported to the streams and lakes of the region, but
they are also the most expensive and difficult problems to control. In
addition, those techniques which are applicable to very difficult steep
slopes are generally appropriate methods for controlling erosion prob-
lems on less severe sites. Several other documents published by the
Environmental Protection Agency (41, 42, 43, 44) provide a general, and
in some cases quite specific, discussion of the broad spectrum of erosion
and sediment control technology currently available. These documents
should be consulted for further information on techniques not covered
by this project or not included in this report. No attempt has been made
to reproduce information which is adequately discussed elsewhere.
142
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Figure VIII-1. Steeply eroding cut slope adjacent to paved
roadway at the Rubicon Properties erosion control project site.
The erosion control methods discussed in this report are subdivided into
the following categories.
1. Temporary Slltation Cpiitrol - Includes filter berms, filter fences,
straw bale sediment barriers and impervious berms. These methods
are used for temporarily controlling siltation from on-going con-
struction activities and short-lived disturbances (less than 1/2
year). It is fully anticipated when using temporary siltation con-
trol methods that they will be replaced by other permanent methods
within 1/2 year.
2. Drainage Control - Includes berms, dikes and gutters, drop inlets,
rock lined channels, water bars, diversion dikes, percolation
trenches and sediment retention basins. These methods are used to
control storm drainage and prevent overland flow from eroding dis-
turbed soil surfaces or other highly erodible areas.
3. Mechanical Stabilization of Oversteepened Slopes - Includes curbs,
dikes, benches, breast walls, retaining structures, slope scaling,
overhang removal, and contour wattling. These methods are used to
prepare and stabilize oversteepened slopes to a degree sufficient
for the establishment of vegetation.
4. Permanent Vegetative Erosion Control - Includes willow staking,
seeding, planting, mulching, fertilization, and irrigation. These
methods are viewed as the most appropriate means of stabilizing
disturbed areas. If used alone, vegetative erosion control methods
143
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can be expected to achieve a considerable degree of success on less
severe slopes (less than 2:1) where drainage control is not a prob-
lem. However, on steeper slopes (greater than 2:1) or areas with
drainage problems, permanent vegetative erosion control methods
must be combined with drainage control and mechanical stabilization
techniques.
B. Cost Estimating Procedures'
The equivalent costs of erosion control methods used as part of the
Erosion Control Demonstration Project are developed from actual material,
equipment and labor requirements at the project sites, except when other-
wise noted. The following assumptions were used in developing the
equivalent cost estimates presented herein, and are presumed to be
representative of conditions found in the Tahoe-Sierra region of
California.
1. Adverse climatic conditions, such as storms or high winds, are
considered not to cause hindrances or delays in the installation
of the erosion control methods.
2. Except as otherwise specifically noted, wages and equipment costs
are based upon data published by CalTrans (45) as of June 30, 1976,
plus an additional 10 percent allowance for profit.
3. Except as otherwise specifically noted, total labor costs are
assumed to be $16.25 per hour, including wage (10.75/hr), social
security C6%), workmen's compensation insurance (10%), unemployment
insurance C5%), and an additional 25 percent to cover overhead,
supervision and profit. For comparative purposes, labor costs
including overhead and supervision, for county workers and unskilled
conservation corps workers are assumed to be $10.00/hr and $5.00/hr,
respectively. Much of the erosion control work described herein
is very labor intensive. Where possible, for each erosion control
method, the percentage of the total cost attributable to labor
costs at $16.25 per hour is identified. If different unit labor
costs are expected, overall cost estimates should be revised
accordingly.
4. All mulching and seeding techniques requiring hydromulching or
straw blowing equipment are assumed to be conducted by competitive
commercial enterprises. Labor and equipment costs for hydromulch-
ing and machine straw mulching are derived from CalTrans "mulch-
in-place" contract figures for the first half of 1976. It is
assumed that the CalTrans contract amounts include direct and
indirect labor and equipment costs, insurance, overhead, supervi-
sion, and profit. Materials costs are considered separately.
5. Except as otherwise specifically noted, all materials costs are
equivalent to retail costs quoted by the various manufacturers,
distributers or suppliers of materials used at the project sites
144
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c.
including estimated shipping costs as of June 30, 1976. Storage
costs are not included.
6. Except as otherwise specifically noted, the person-hours assumed
to be required to complete a particular task are based upon the
observed county and conservation corps person-hours required to
perform the task at the Erosion Control Project demonstration
sites. Although erosion control labor costs are based upon commer-
cial wage scales, no allowance for increased work efficiency has
been included in the cost analysis. This was justified because, in
several instances, observed installation times using county person-
nel and unskilled workers were less than or equivalent to manufac-
turers estimates or estimates by others based upon the use of
skilled or semi-skilled labor. In one case a gabion manufacturer
estimated that labor requirements for gabion installation varied
from 2.0 to 2.6 person-hours per cubic meter of gabions filled.
Experience at the project sites indicated that gabion installation
required about 2.17 person-hours per cubic meter of gabions filled.
In another case, a report C46) describing willow wattling installa-
tion and cost indicated that a semi-professional 7-man crew could
install wattling at about 2.70 meters per hour. Unskilled workers
at the erosion control project site were able to install wattling
at a site of about 3 meters per hour. Thus, using these two cases
as indicators of work crew efficiency it is assumed that, for the
type of work involved, there are not significant differences in
efficiency between unskilled and skilled landscape laborers.
7. The equipment-hours, other than for hydromulching and straw
blowing, are based upon the needs of a 5-person work crew assigned
to a particular erosion control task.
8. As a basis for cost estimates, the minimum land area requiring ero-
sion control work is considered to be one hectare. It is assumed
that this is a large enough area to attract substantial competitive
bidding for a .contract to perform the erosion control tasks. Labor
and equipment transportation, start up, and shut down costs are
considered to be negligible.
9. Maintenance costs are not included; once the initial erosion con-
trol work has been completed, such costs are considered to be
nominal.
10. Design costs are not included in these cost estimates.
Temporary Sedimentation Control
Methods described in this section are intended only for temporary con-
crol of erosion problems, not for long term or permanent erosion control.
Situations when temporary sedimentation control methods are used include:
145
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- on-going construction activities
— emergency situations
post-construction periods until permanent control methods are
firmly established.
Temporary sedimentation control does not necessarily prevent localized
erosion. Its basic purpose in and around the Lake Tahoe Basin is to
prevent erodible materials from being transported to surface waters.
The Regional Water Quality Control Board requires that eroded earthen
materials must be contained within the construction site or property
boundaries. Measures must be taken to prevent off-site transport by
vehicles, wind and water.
1. Control of Sediment Transport Directly Due to Vehicular Traffic -
The main concern is with the transport of earthen material off of
the property by construction vehicles. Control measures include:
Well defined access drives to the project, limited to as few
as possible.
a.
b. A clean base material, such as granitic gravel, on all access
drives. Volcanic "cinders" are not considered to be "clean",
since they have a large percentage of fine particles, and
larger particles tend to break down when subjected to loads.
Cinders should not be used in any application where there are
no down-gradient sedimentation control facilities.
c. Equipment having a significant amount of mud, etc. attached
to it should be washed before leaving the property.
2. Control of Sediment Transport Due to Wind - Limiting the area of^
soil disturbance as much as possible by holding equipment operating
areas to a minimum is the best preventative measure. Other measures
include wetting problem surfaces or covering them with plastic
sheeting, gravel, mulch, fiber netting, asphalt emulsion, or plastic
emulsion.
3. Control of Sediment Transport Due to Water Flow - Water flow stem-
ming directly from human activities such as washing, surface wetting
and irrigation, can and should be limited. Special measures must
be employed to control storm and snowmelt runoff and thereby pre-
vent sediment transport.
The Lake Tahoe Basin and vicinity is subject to heavy snowfall during
the winter months, and, in most cases, extensive construction activities
during this period are not practical. Furthermore, local regulatory
agencies do not allow earth disturbing activities between October 15 and^
May 1 of the following year and require that all projects be "winterized"
by October 15 of each year. "Winterization" means complete installation
of all necessary1 temporary and/or permanent erosion and sediment control
facilities.
146
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Ideally, temporary sedimentation control facilities should be designed
to withstand tributary runoff flows due to a storm of a given recurrence
interval. For design purposes, the Regional Water Quality Control Board
(Regional Board) uses a 20-year, 1-hour storm as the critical design
storm. The Regional Board recommends use of the SCS triangular hydro-
graph method for determining tributary runoff from a specific site during
the design storm. This method is further discussed under infiltration
trench design.
1. Impermeable Berm
An impermeable berm is generally constructed by forming an earthen dike,
covering the dike with impermeable plastic sheeting, and placing clean
gravel on the lower edges of the plastic as shown in Figure VIII-2 (see
Section A-A), or burying the edges to a depth of about 10 centimeters.
A storage dike" (see Figure VIII-2, Case A) should be positioned at the
down gradient end of the disturbed soils area such that all flows from
the project site are retained by it. Diversion dikes, as shown below
point C", may be necessary. The storage should be extended uphill a
distance »L' as identified in Figure VIII-2, Case A, to maximize storage
capacity.
The height of the down-gradient perimeter of the storage dike should be
based on storage requirements determined by an estimation of maximum
runoff flow to the berm in a 20-year, 1-hour design storm. To decrease
runoff to the storage dike, a diversion dike may be used to divert run-
off above a disturbed area (Figure VIII-2, Case B). Care must be taken
in the design and placement of diversion facilities to prevent erosion
on adjacent areas due to channelization of flow and discharge. Figure
VIII-3 depicts a typical impervious berm installation.
As a minimum, the following design criteria should be included in speci-
fications for the construction of impervious berms:
a.
b.
c.
d.
e.
f.
the berm shall be constructed of available earthen material
mounded to a height of at least .33 meter,
the sides of the berm shall Be laid back to a slope of no
greater than 1.5:1,
the surface of the berm shall be free of rocks or protrusions,
translucent plastic sheeting with a thickness not less than 6
mil shall be placed over the earthen berm,
the outside edges of the plastic sheeting shall be covered
with clean gravel or buried to a depth of 10 centimeters,
the dike shall be frequently inspected and repaired if
necessary, and
147
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148
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Figure VIII-3. Impervious berm installation adjacent to a
stream channel at the Northstar erosion control project site.
g. the impervious berm shall be removed once permanent erosion
and drainage control measures have been completed and are
established.
2. 'Straw'Bale'Sediment Barriers
A straw bale sediment barrier is generally constructed by laying bound
straw bales to form a wall or barrier. The function of a straw bale
sediment barrier differs from an impervious berm in that it is designed
to pass water while filtering and blocking transported sediments. Straw
bale sediment barriers are useful not only in constructing extensive
barriers for the prevention of sediment transport from construction
sites but also in preventing transported sediment from being discharged
to specific points, such as drop inlets. Figure VIII-4 depicts a typical
erosion problem discharging to a drop inlet. Figure VIII-5 depicts a
straw bale sediment barrier designed to prevent such a discharge. Once
the problem is corrected at its source, the straw bales should be removed.
Since straw bales eventually decompose, they should be replaced or
removed prior to such an occurrence. Installed straw bale sediment bar-
riers must be inspected frequently to be sure that their structural
integrity is maintained and that Joose straw is. not being washed into
drainage systems. When mixed with mud and water, loose straw forms a
sticky mass which can easily clog culverts, drop inlets, or other drain-
age strutures.
An added benefit of straw bale sediment barriers is once construction
activities have halted, and permanent erosion control measures are
149
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Figure VIII-4. Eroded soil material discharging to drop inlet.
Irt
Figure VIII-5. Straw bale sediment barrier used to
control problem pictured in Figure VIII-4.
150
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TIGHTLY ABUTTED
STRAW BALES
EMBEDDED TO A
DEPTH OF 10 cm.
STRAW BALE SEDIMENT BARRIER
Figure VIII-6. Typical straw bale sediment barrier installation design.
established the straw bales may be used as a mulch to aid in the estab-
lishment of vegetation on the disturbed landscape. Because of the straw
bales' exposure to the elements, it is unlikely that the straw could be
applied in a mechanical mulching operation. However, the "weathered"
straw mulch may still be readily applied by hand.
A typical straw bale sediment barrier installation is depicted in Figure
VIII-6. As a minimum, the following design criteria should be included
in the specifications for the construction of straw bale sediment
barriers:
a.
b.
c.
d.
straw bales shall be placed in a row on the contour with ends
tightly abutting adjacent bales,
each bale shall be embedded in the soil to a minimum depth of
10 centimeters,
the straw bale sediment barrier shall be inspected frequently
and repaired if necessary, and
the straw bales shall be removed once permanent erosion and
drainage control measures have been completed and are
established.
151
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Surface contact between the straw bales and the ground surface is some-
times a problem, particularly if the bales are insufficiently embedded.
Portions of broken bales placed beneath the barrier will assure contact
and provide more complete filtration. An optional added specification
could also provide for the anchoring of the straw bales by means of
re-bar or stakes. Such a specification would be required if the barrier
were potentially subject to high flows or other stress.
3. Filter Berms
A filter berm is constructed in the same manner as an impervious berm
with the exception that the berm is constructed of material designed to
permit the passage of water, and at the same time filtering transported
sediments. Filter berms do not require the extensive storage areas
required by impervious berms. They eventually become clogged with the
sediments they are designed to remove. Frequent inspection and contin-
ued maintenance of a filter berm installation is required to insure
satisfactory performance. Maintenance may involve simple cleaning of
the filter berms, or, in some instances, require complete replacement
of sections of the berm.
Adequate filtration by a filter berm is based on proper pore size in the
filtration media. For example, gravel filters will not provide adequate
filtration of most suspended sediment material. Two typical designs for
acceptable filter berms are shown in Figure VIII-7. At a minimum the
following design criteria should be included in the specifications.
CLEAN GRAVEL
OVER CLEAN
SAND CORE
PERVIOUS
SAND CORE FILTER BERM
FILTER FABRIC OVER
CLEAN GRAVEL
BURY FABRIC
ENDS TO DEPTH
OF 10 cm
PERVIOUS
FILTER FABRIC BERM
Figure VIII-7, Typical pervious filter berm installation designs.
152
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For the construction of a sand core filter berm:
a. the sand core filter berm shall be constructed of coarse clean
sand with not more than 5 percent (by weight) of the particles
less than .06 mm in diameter,
b. the sand core shall be mounded to a height of not less than 30
centimeters,
c. the sides of the sand core shall be at a slope of not greater
than 1.5:1,
d. the sides of the sand core shall be covered with clean gravel
to a depth of not less than 10 centimeters, and
e.
not more than 5 percent (by weight) of the gravel shall have
diameters larger than 5 centimeters, or less than 1
centimeter.
For the construction of a filter fabric berm:
a. the filter fabric berm shall be constructed using a core of
clean gravel with not more than 5 percent (by weight) of the
gravel having diameters not larger than 5 centimeters, nor
less than 1 centimeter,
b. the gravel core shall be mounded to a height of not less than
30 centimeters,
c. the sides of the sand core shall be at a slope of not greater
than 1.5:1,
d. the gravel core shall be free of any protrusions,
e. over the gravel core shall be placed filter fabric material,
f . the outer edges of the filter fabric shall be buried at the
base of the gravel core to a depth of 10 centimeters, and
g.
clean gravel shall be placed to a depth of not less than 10
centimeters along the inside and outside base of the berm.
For both the sand core and filter fabric berms, the following specifi-
cations should be included:
the filter berm shall be inspected frequently and repaired if
necessary, and
the filter berm shall be removed once permanent erosion and
drainage control measures have been completed.
153
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4. Filter Fences
Filter fences control controlling siltation in the same manner as filter
berms. Filter fences are particularly advantageous where space is
limited. Impermeable dikes, straw bale sediment barriers, and filter
berms can require up to 2-meter wide strips for their construction
F?Serfences, on the other hand, can be placed in less than 5 meter
strips around a disturbed site. Figure VIII-8 depicts a typical filter
fence installation designed to protect a stream from siltation generated
by the construction of an adjacent golf course.
A diagram showing a typical filter fence installation procedu^ is Pre-
sented in Figure VIII-9. At a minimum, the following design "iterxa
should be included in the specifications for the construction of filter
fences:
the fence shall be constructed of cross woven welded wire
fence material with openings not greater than 10 cm x 10 cm,
b the welded wire fencing shall be securely attached to fence
posts firmly planted in the ground at spacings not greater
than 3 meters,
c the fence posts shall be located on the down slope side of the
* fence and extend at least .5 meter above the ground surface,
d. the welded wire fencing shall be tensioned between fence posts,
pervious filter fabric shall be placed on the up slope side of
the fence with a portion folded over the fence top and with at
least .25 meter remaining at the toe which will be buried,
the filter fabric shall be attached in such a manner as not to
rend or tear the fabric,
a.
e.
f.
g.
h.
i.
k.
on the up slope side of the fencing, the foot of the fabric
shall be buried to a depth of not less than .25 meter,
replaced soil shall be firmly tamped after the filter fabric
foot has been placed,
all operations involving the construction of the filter fence
shall be conducted so as not to tear or otherwise increase the
porosity of the filter fabric,
once constructed, the filter fence shall be frequently
inspected and repaired if necessary, and
the filter fence shall be removed once permanent erosion and
drainage control measures have been completed.
154
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Figure VIII-8. Filter fence installation adjacent to a stream
channel at the Northstar erosion control project site.
DRAPE FILTER FABRIC
OVER FENCE AND FASTEN
WITH TIE WIRES
AFFIX WELDED
WIRE FENCING
TO POSTS
FILTER FABRIC FENCE
PLACE FENCE
POSTS ON CONTOUR
BURY TOE OF
FILTER FABRIC
IN TRENCH ON
UP SLOPE SIDE
Figure VIII-9. Typical filter fence installation design.
155
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5. Comparative Costs of Temporary Siltatibri Control Methods
The cost of constructing temporary siltation control facilities may vary
widely depending on availability of materials and type of construction
sites, including the space available for siltation control facilities.
Table VIII-1 lists the equivalent cost of the various types of siltation
control facilities constructed at Northstar erosion control project
site. Cost estimates are based on assumptions listed earlier in this
section and include one-time installation costs only.
Although the above costs are only estimates, it is possible to say that
the filter berms and fences are roughly twice as costly as a simple
impervious earthen berm. On the other hand, an impervious berm requires
a considerable amount of water storage space behind the berm to effec-
tively settle suspended sediments. The cost of committing such space is
not reflected in these estimates.
The straw bale sediment barrier (intermediate expense) has the added
advantage that the materials may be reused as mulch. The filter fence
also has the advantage that its materials may be reused. These savings
are not reflected in the above- cost estimates. Although filter fences
have received little use in the Tahoe-Sierra area, it does appear that
their expense and effectiveness are highly competitive with other tempo-
rary sedimentation control devices.
TABLE VIH-1
TEMPORARY SILTATION
'CONTROL
EQUIVALENT INSTALLATION 'COSTS
,.
Impervious Earthen
Berm (30 cm high)
Straw Bale Sediment
Barrier
Sand Core Filter
Berm (30 cm high)
Filter Fabric
Berm (30 cm high)
Filter Fabric
Fence (50 cm high)
MATERIALS
.30
1.80
4.33
4.00
2.00
UNIT 'COSTS ($/METER)
EQUIPMENT LABOR
1.18 1.60
2.71
1.18 1.60
1.18 1.60
1.18 3.88
TOTAL
3.08
4.51
7.11
6.78
7.06
156
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D. Drainage Control
When considering methods required for the effective control of erosion
and sedimentation, adequate control and drainage of storm waters is of
primary importance. It makes little sense to commit a large effort to
the establishment of permanent erosion control by means of revegetation
if storm waters are allowed to wash everything away. Uncontrolled runoff
from impervious surfaces can easily cause significant erosion problems
even if the majority of an erosion control project site is adequately
revegetated Not only will uncontrolled storm runoff generate localized
erosion in drainage swales and channels on the construction site, but it
will also cause further erosion problems elsewhere if allowed to dis-
charge to natural channels and streams which are not large enough to
handle excessive storm water flows. These off-site erosion problems
man± ±n the f0rm °f increased streambank erosion and channel
Effective drainage control is based on two principles:
1. all concentrated runoff should be carried in non-erodible ditches
and swales,
2. when possible, all storm runoff from impervious surfaces must be
infiltrated with no direct discharge to surface waters.
If these two principles are universally applied, in conjunction with
effective revegetation of disturbed areas, erosion problems will be
significantly reduced, if not eliminated. In all future construction
in the Tahoe-Sierra region these two basic tenets must be adhered to.
The application of this drainage control approach to past construction
sites may be difficult. In many cases the amount of im^rvious surface
coverage vastly exceeds the capacity of remaining pervious areas to
percolate storm runoff. In other instances, there is not sufficient
space for^ the installation of runoff interception works or percolation
trenches due to the close proximity of impervious surfaces to stream
zones or due to intervening steep or difficult terrain.
The Rubicon Properties erosion control project site is in an area where
all these difficulties are encountered. Totally effective drainage
control at such a site would be very expensive. In locations such as
Rubicon Properties where effective percolation of storm drainage is
prohibitively expensive or impossible, the erosion control program must
concentrate heavily upon stabilization of disturbed slopes and construe-'
tion of non-erodible drainage swales. If transport of sediment to surface
waters remains a major problem, sediment retention basins would then be
required to further reduce the sediment load. A small sediment retention
basin can be quite effective in reducing sediment load during storms,
but would not be effective as a percolation pond to substantially limit
peak storm water flows from impervious surfaces.
157
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This section on drainage control is not intended to be a design handbook
for drainage control structures. For the appropriate design and sizing
of particular drainage control structures, a registered civil engineer
should be consulted. Various publications by the EPA (41, 42, 43) offer
details on the design and layout of several drainage control facilities
not discussed in this report including: check dams, chutes and flumes,
erosion checks, Fabriform Erosion Control Mats, flexible downdrains,
and level spreaders. The project staff did not feel they would be
effective within the project sites, or in the surrounding vicinity.
Drainage control methods and structures which are mentioned are xncluded
because:
they are fundamental to effective drainage/erosion control,
they are or have been frequently omitted from projects in the
Tahoe-Sierra region of California,
their effectiveness has been demonstrated or observed within
the project sites and/or surrounding vicinity.
1. Curbs, Dikes and Gutters
Curbs, dikes and gutters are
(Mechanical Stabilization of
a slope toe bench. They are
able surfaces to appropriate
lined ditches, or a properly
more fully discussed in the next section
Oversteepened Slopes) as a means to provide
also used to direct runoff away from erod-
discharge points such as drop inlets, rock-
sized percolation facility.
Figure VIII-10 shows the gully formation that occurred when street drain-
age was allowed to flow uncontrolled down an unstable fill slope. During
a 15-year period it is estimated that at least 1,800 metric tons were
eroded from the slope.
Proper maintenance of curbs, dikes and gutters is essential. Figure
VIII-11 shows the result of a breach in a dike at Rubicon Properties.
Over one hundred metric tons of soil were removed from this unstable
fill slope in one snow melt season.
'2. Drop Inlets
The usual purpose of a drop inlet (D.I.) structure is to collect and
direct, via underground conveyance, storm water runoff to an appropriate
discharge point. An important addition to drop inlet design CSee Figure
VIII-12) is provision for settling and retention of suspended sediments.
Actual sizing for such a structure is dependent upon:
size of runoff area tributary to the drop inlet,
expected suspended sediment load to the drop inlet,
- frequency of runoff conditions, and
expected frequency of maintenance.
Design and spacing of such structures should be conducted by a registered
civil engineer. Effluent from the drop inlet should be directed to non-
erodible conveyance facilities and infiltration structures. A good rule
158
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Figure VIII-10. Gully erosion on fill slope at the^^ RuMcon™Properties
erosion control project site resulting from poor drainage control, and
lack of vegetation.
Figure VIII-11. Severe erosion on fill slope at Rubicon Properties
erosion control project site caused by a break in an A-C dike.
159
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REMOVEABLE
GRATE
FLOW
N\NN \\-\N
TO INFILTRATION
ALLOW ACCESS
FOR EASY -Vv
CLEANING XX
CONCRETE
OR CMP
Figure VIII-12.
Typical drop inlet installation designed to settle
and trap transported sediments.
of thumb would be to design drop inlet structures to settle and remove
90 percent of anticipated suspended sediments at design flow conditions.
If oil and grease in the storm runoff is expected to cause additional
problems, "T" type entrance to the effluent line must be provided. This
will effectively block oil, grease and other low density contaminants
from being discharged to surface water or subsequent infiltration
facilities.
The effectiveness of drop inlet structures designed to settle suspended
sediments will quickly diminish if they are not adequately maintained.
This is particularly true if the drop inlet collects runoff from eroding
surfaces.
3. Drairiage Channels
If the collected runoff must be directed overland to an appropriate dis-
charge point, the use of rocklined (or similar) drainage channels is
recommended. The reasons for this are:
- aesthetic natural appeal,
- non-erodible surface,
160
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low cost, and
high surface "roughness" which dissipates the erosive energy
of the flowing water.
The last factor, that is energy reduction of the flowing water, can be
further enhanced by drop structures or energy dissipators.
Use of rock-lined channels is limited to gentle slopes. For steeper
slopes other methods such as sectional downdrains, or culverts, as
pictured in Figure VIII-13, must be used. Figure VIII-14 depicts the
type of problem that can arise if collected drainage waters are allowed
to flow uncontrolled over an erodible surface. Approximately 20 metric
tons of soil were eroded in a single snow melt season at this site.
Figure VIII-15 depicts a rock lined channel which was designed:and
installed to correct this problem.
Costs of rock lined channels are dependent upon size, equipment access,
and availability of rock material. The rock channel pictured in Figure
VIII-15, which is approximately 30 cm deep, 100 cm wide, 100 meters long,
located in a readily accessible area, and constructed of readily avail-
able stone from adjacent areas, would cost $12.36 per meter based upon
the assumptions listed at the beginning of this section. If rocks had
to be -purchased and transported to the site the cost would be expected
to increase by an additional $1.75 per meter.
Figure VIII-13, Corrugated metal pipe used to direct drainage
across highly erodible fill slope.
161
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to
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}-i
T3 O
0) rt •
tO Ctf
3 60 -l «H
60 O
•H O
Br_t J3J
162
-------
If only infrequent very low flows are directed to overland channels on
very gentle slopes, an alternative to rock lining may simply be channel
vegetation. Vegetative techniques are'described in a subsequent section
entitled "Permanent Vegetative Erosion Control". Methods which are
applicable for vegetating small channels include:
willow staking,
- contour wattling,
•seeding with mulch nets and blankets, and
-seeding with fiberglass roving.
4. Water Bars
Water bars can be effectively employed to prevent storm runoff from
developing and accumulating eroded sediment on heavily travelled or aban-
doned dirt roads and trails. By breaking up an extended erodible surface
into a series of smaller areas with separate drainages, storm runoff
flow velocities and quantities can be significantly reduced. Figure
VIII-16 depicts a typical water bar installation on a heavily travelled
dirt road at the Northstar erosion control project site. Prior to instal-
lation of the pictured water bar, road drainage resulting from snow melt
and rainfall flowed down the road and discharged directly to a stream
which passed under the road at a low spot. Heavy vehicle traffic pulver-
ized the road surface resulting in a sediment-laden discharge to the
Figure VIII-16. Water bar installation on heavily travelled dirt
road at Northstar.
163
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stream. After construction of the water bar pictured in Figure VIII-16,
road drainage was diverted to a densely vegetated area which effectively
intercepted and filtered the drainage water prior to dishcarge to the
stream.
Good judgement must be used in the design and location of water bars.
Figure VtlI-17 depicts an extremely close spacing of large water bars on
an abandoned dirt road at the Rubicon Properties erosion control project
site. Prior to the installation of the pictured water bars, erosion from
this dirt road was extreme. Furthermore, accumulated runoff had caused
increased erosion down gradient from the road. Not only will such large
water bars or similar barriers act to divert surface drainage to more
stable areas, but they will also discourage further vehicular use of the
road which could disrupt revegetation measures. As a guide, Figure
VIII-18 may be used to determine the maximum spacing for water bars for
various slope gradients and soil erosion hazard ratings. The data shown
in Figure VIII-18 is based upon information prepared for use by the
U. S. Forest Service CIS, 47). Erosion hazard rating is based upon the
area 'below the road or tract.
In addition to proper spacing as indicated in Figure VIII-18, water bars
should discharge into undisturbed areas, rock ground, or areas well
protected with vegetative cover. Water bars should also be located to
accept and redirect runoff from lateral disturbed areas or other trib-
utary areas.
~
Figure VIII^17» Closely spaced water tars on abandoned dirt road.
164
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5. Infiltration Trenches
The best approach to reducing erosion generated by storm runoff is to
percolate drainage from all impervious surfaces. In most instances
impervious surface runoff cannot be discharged to surrounding undis-
turbed areas for percolation without causing substantial erosion problems
The Regional Water Quality Control Board, Lahontan Region, requires an
adequately designed percolation trench for runoff control in the California
portion of the Lake Tahoe basin. Figure VIII-19 depicts a typical cross
section design for an infiltration trench. In addition to the configura-
tion depicted in Figure VIII-19, a well designed infiltration trench
will also have a provision for overflow to a storm water system in the
case of:
1. failure of the infiltration trench due to clogging by deposited
sediments, or
2. storm intensities greater than the "design storm".
80
MEDIUM (moderate)
LOW (slight)
20 30 40
SLOPE GRADIENT (%)
Figure VI1I-18. Maximum water bar spacing for various slope
gradients and erosion hazard ratings.
165
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HEADERS ANCHORED
BY ROCK BACKFILL
AND CRADLE
5 x 15 cm. HEADER
CRADLES SPACED
AT INTERVALS AS
ivy DETERMINED BY
^ ENGINEER.
Figure VIII-19. Typical infiltration trench design for percolation
of storm runoff from impervious surfaces.
Infiltration trench life expectancy can be vastly increased by the use
of sediment traps to remove suspended sediments before discharge to the
trench. However, drop inlets or similar structures placed as an inter-
mediate treatment device between the impervious surface and the xnfxl-
tration trenches cannot be expected to be totally effective in removing
all sediment from the storm runoff. Thus, any infiltration trench xn-
stallation should provide for removal of the rock backfill and accumu-
lated sediment depositions. The removed rock backfill can be washed and
reused or replaced with new rock. If oil and grease deposits, whxch
could clog and reduce trench effectiveness are anticipated, adequate
attention must be given to the separation of such substances from the
runoff prior to discharge to the trench.
The final design of infiltration trenches and other appurtenances should
be left to a professional engineer. The Regional Water Quality Control
Board, Lahontan Region, uses the following relationship as a guideline
for the sizing of infiltration trenches (48):
166
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f
L = A-Q
[(W-P) + .67 (D'P)] + [.33 0>W)1
(Equation VIII-1)
where: A =
area of impervious surface contributing runoff to
infiltration trench (square meters)
L = length of the trench (meters)
W = width of the trench (meters)
D = depth of the trench (meters)
P = percolation rate of the soil in which the trench is placed
(cm/hr)
T = storm duration (hours)
Q = unit runoff from impervious surface area (cm). The value
of Q is determined by using the SCS triangular hydrograph
method (49, 50, 51) as follows:
Q =
(R - I + S)
(Equation VIII-2)
R = depth of rainfall (cm)
I = initial abstraction which is the maximum amount of rain-
fall that can be absorbed on the impervious surface with-
out producing runoff. It is empirically assumed that
I = 0.25 (cm).
S = maximum potential difference between R and Q, accounting
for minor permeability of an impervious surface. S = .508
(cm) for precipitation ranging from 0 to 30.5 centimeters.
The reasons that the SCS method was chosen over the somewhat simpler
rational method include:
1. it is still simple and relatively straightforward,
2. it is based upon a "triangular hydrograph" and therefore acknowl-
edges the variation in runoff rates during a typical storm,
3. it accounts for surface retention (surface wetting) or "initial
abstraction" which the rational method does not consider.
The Regional Water Quality Control Board, Lahontan Region, requires
infiltration trenches on new projects in the Tahoe area to have a 95
percent reliability. Therefore, infiltration trenches are designed
such that the probability of overtopping is no more than five percent.
Since the probability of an event being equalled or exceeded at any time
is equivalent to the inverse of the return period of the event, a ,
20-year storm is used as a basis for design. Furthermore, it is assumed
that a one-hour duration rainstorm is the most critical runoff event.
Other assumptions which are used with the above analysis include:
- trench sidewall percolation is one-third that of the trench
bottom per unit area, and
- the porosity of the rock backfill used in the trench is .33.
167
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36 40 44 48 52 56
PERCOLATION RATE (cm/hr.)
Figure VIII-20. Infiltration trench sizing diagram.
Figure VIII-20 is a graphical representation of Equation VIII-1 for a
variety of infiltration trench widths and depths for South Lake Tahoe.
Basically, the wider and/or deeper the trench, less trench length is
needed to infiltrate runoff from a given area. For the Lake Tahoe
vicinity of the Sierra Nevada the following are acceptable precipitation
values for a design 1-hour rainstorm with at least a 95 percent
reliability.
South Lake Tahoe
North Lake Tahoe
Truckee
R (centimeters)
1.78
1.91
1.30
6. Sediment Retention Basins
The purpose of a sediment retention basin is to trap and retain sediment
generated by construction activities. Construction of permanent sedi-
ment retention basins is the "last line of defense" against off-site
sediment pollution. They should be utilized only if drainage control
and stabilization of disturbed areas prove inadequate.
Figure VIII-21 depicts a sediment basin located in a poorly designed and
developed subdivision within Lake Tahoe Basin. Due to the large area of
168
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Figure VIII-21. Suspended sediment settling basin for storm runoff
control. Continued maintenance is required to assure adequate
settling capacity
disturbed slopes and the considerable runoff from impervious surfaces,
the pictured sediment basin is the most practical means of preventing
sediment pollution.
When properly designed, constructed, and maintained sediment basins are
capable of removing a high percentage of both coarse and fine suspended
sediment from storm water runoff. Large basins require formal design by
a professional civil engineer.
Sediment basins must be located so as to maximize effectiveness, mini-
mize cost, minimize additional disturbance and facilitate access for
maintenance. Detailed design criteria are completely dependent upon
site specifics. Actual design of settling basins may vary considerably
from location to location. When possible, however, the following cri-
teria should be considered:
hydraulic capacity sufficient to handle a 50-year storm,
overflow rate sufficient to settle and retain 90 percent (by
weight) of the anticipated suspended sediments in the runoff
from the tributary area in a 20-year, 1-hour storm,
dam embankments completely stabilized with side slopes no
steeper than 2:1,
- easy access for maintenance and cleanout of deposited
sediments.
169
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7. Drainage Control Cost-Effectiveness Analysis
No attempt has been made to determine the relative cost and effectiveness
'of drainage and runoff control techniques. The primary reason for this
being that the-State Board was unable to construct and specifically
demonstrate the majority of these methods at the project sites due to
their relatively high cost. Furthermore, the situations encountered at
the project sites were not conducive to construction and effective appli-
cation of the majority of these methods.
Mechanical Stabilization of Oversteepened Slopes
Oversteepened, unrevegetated slopes, with inadequate drainage contrpl,
are perhaps the most significant source of eroded material in the Tahoe-
Sierra region of California - and the most difficult to control. In
most cases, current governmental controls and grading ordinances will
prevent the generation of highly erosive, oversteepened slopes in the
future. The problem therefore, is centered around the correction of
existing problem areas which were created prior to the establishment of
effective controls.. Large oversteepened areas are widespread and
clearly evident throughout the Tahoe-Sierra. Large cuts and fills can
be found adjacent to federal, state, county, and private highways and
roads. Similarly, quarries, gravel pits, and building construction have
left large areas of unstable eroding slopes.
Stabilization of bare soil areas, as addressed in this report, has
emphasized revegetative techniques as the cheapest and most effective
method of controlling erosion. Gently sloping bare soil areas usually
require only simple seeding or planting; oversteepened slopes require
either reduction of slope steepness or extensive efforts to mechanically
stabilize the slope face until revegetative plantings are sufficiently
established.
In many instances, reworking an oversteepened slope to form a less
severely sloping area may be impractical. Figure VITI-22 depicts two
slope profiles which illustrate this point. In Case "A" the previous
steeply cut slope Cdashed line] is located in an area where the natural
undisturbed terrain is gently sloping. Thus, by constructing a small
retaining structure at the slope toe and reworking the face to a 1%:1
slope, the total slope length is only slightly increased. Case "B",
differs only in the slope of the undisturbed natural terrain above the
cut slope face. If the same small retaining structure is provided and
the cut face is reworked to a l%jl slope, the overall slope length is
increased by 300 percent. The only alternatives are to:
1. construct a higher retaining structure,
2. move the slope toe further out into the roadway,
3. rework the cut face to an angle somewhat steeper than 1%:!, or
4, combination of the above.
170
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GENTLY SLOPING
NATURAL
TERRAIN
STEEP
NATURAL
TERRAIN
REWORKED
SLOPE FACE
(solid line)
RETAINING
STRUCTURE
CASE 'A1
CASE 'B1
Figure yiIt-22. Cut slope reworking. The amount of reshaping is
dependent upon slope of the natural terrain above the road cut.
The majority of this section is devoted to describing specific ways in
which steep slopes may be sufficiently reworked and stabilized to allow
revegetation. The last part of this section is devoted to a discussion
of other mechanical slope stabilization techniques which do not rely
entirely on revegetation to provide ultimate erosion control. By incor-
porating the following procedures, major slope reworking, leveling,
and lengthening should not be required in most instances.
1. Curbs and Dikes for Bench Construction
Many existing oversteepened cut slopes, such as pictured in Figure
VIII-23 are continually undercut at the slope toe by uncontrolled drain-
age water or road maintenance crews.
In these cases, either slope toe foundations are non-existent or they
have been placed too close to the slope to provide sufficient protec-
tion. The slope toe pictured in Figure VIII-23 does have an asphalt-
concrete (A-C) dike and gutter. However, because of the excessive
steepness of the overlying unrevegetated slope and the dike's close
proximity to the slope, the dike and gutter are. continually buried by
sediment eroded from the slope face. During every runoff event the
deposited material is readily swept away, only to be replaced once again
by further deposition of material eroded from the slope face.
At the erosion project sites, much of the recurring sediment deposition
at the slope toe was directly attributable to frost heaving and wind
171
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Figure VHI-23. Sloughed and eroded soil material at toe of steeply
eroding road cut at the RuBicon Properties erosion control project site.
erosion, rather than erosion induced by running water. This was partic-
ularly true when the unvegetated slopes were steeper than the angle of
internal friction Cangle of natural repose) of the local soil. At the
Rubicon Properties project the soil was decomposed granite for which the
angle of internal friction is approximately 35 degrees (1.5:1). The
soil at the Northstar project site was comprised primarily of volcanic
material also with an angle of internal friction of about 35 degrees.
The easiest and least expensive manner of correcting problems created by
unstable slope toes at the project sites was to move the slope toe fur-
ther away from the slope face and protecting the toe from further ero-
sion. Gutters and dikes originally placed too close to a steep (2:1
or greater) slope were moved away from the toe and backfilled to create
a less steeply sloping (less than 2:1) bench. Figure VIII-24 illustrates
the bench which is created by moving the curb and gutter a sufficient
distance away from the toe of the original slope. The eroding soil
material which would slough over the original curb and into the gutter
is shown as the cross-hatched area in the figured
A reconstructed gutter will not be effective in the long run if addi-
tional sloughing is not controlled. The remainder of the slope face
must be stabilized.
Maintenance of curbs and gutters is essential, particularly in harsh
climates such as at Tahoe. A total of 1,225 meters of reconstructed
curbs and gutters were installed at the Rubicon Properties project site
172
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CONSTRUCTED SLOPE
/ TOE BENCH
CONSTRUCTED
CURB 8 GUTTER
PAVEMENT
ORIGINAL CUT
SLOPE FACE
SLOUGHED
MATERIAL FROM
SLOPE FACE
ORIGINAL ROLLED
CURB a GUTTER
Figure VIII-24. CurB, gutter, and Bench design for staBilizing the
toe of a steeply eroding cut slope.
in 1976. The equivalent cost Csee cost assumption at Beginning of
this section of this type of installation ranged from $12.32/meter to
$19.28/meter. The average unit costs for installation of curBs and
gutters at the RuBicon Properties project site are as follows:
1225 Meters of Reconstructed'Curbs'arid Gutters
LaBor Cat $16.25/hr)
Equipment (CalTrans rental rate)
Material (..23 metric tons/meter at
$14.30/metric ton)
TOTAL AVERAGE COST
'Equivalent Unit Cost ($/meter)
$7.77
4.56
3.29
$15.62/meter
Approximately one-third of the $15.62/meter unit cost of curB and gutter
work represents the cost of grading and resurfacing prior to placement
of the curB. Two thirds of the cost is for the actual placement of the
curB. If a consideraBle amount of original paving or curB and gutter
structures must Be removed, the unit cost would Be increased
suBstantially.
173
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In many cases the simple reconstruction of a curb and gutter system fur-
ther from the slope toe may not be feasible. The range of alternatives
includes construction of breast walls and other retaining structures.
2. Breast'Falls
Breast walls may be used to provide a slope toe "foundation" if it is
not feasible to reconstruct a curb and gutter system further away from
the slope toe. Breast walls do, however, have a considerably higher cost
than does the curb and gutter replacement mentioned above. A definite
advantage of the large rock breast walls is that they are imposing struc-
tures and are far less likely to be damaged by road maintenance equip-
ment than are low-lying dikes. In all cases, plans for the construction
of a breast wall' structure must be supervised by a registered civil
engineer. The possibility of wall failure and damage to life and prop-
erty requires that walls be carefully designed and constructed.
Rock Breast Wall
Figure VIII-25 shows the typical construction profile of a breast wall
using large (•25 - 1.0 meter) rocks. The following specifications are
suggested for use in the construction of this type of structure:
ROCK PLACED
WITH 6 = 1 BATTER
AND THREE POINT
BEARING.
ORIGINAL CUT
SLOPE FACE
ORIGINAL ROLLED
CURB 8 GUTTER
PAVEMENT
BACKFILL AND
LOUGHED MATERIAL
Figure VIII-25.
Typical rock breast wall design for the toe of a
steeply eroding slope.
174
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a. Rock breast walls shall be 1.0 to 1.5 meters high.
b. Rock used shall be between .25 and 1.0 meter in diameter.
c. The rock breast wall shall be laid upon solid foundation
material or well-tamped earth if such earth would not be
subject to erosion.
d. A minimum amount of excavation into the slope shall be per-
formed to provide a foundation for the rock breast wall.
The breast wall may not be placed such that it reduces the
road surface to less than the minimum required dimensions.
e. The rocks shall be laid with at least a three point bearing
on the foundation material or on previously laid rocks.
f. The rocks shall be placed such that their centers of gravity
are as low as possible, with the bedding planes sloping in-
ward toward the slope toe.
g. The rock breast wall shall be constructed such that the
external wall face has a 6:1 batter.
h. As the rocks are placed, fill shall be laid behind and
around the rocks and tamped thoroughly.
i. In addition to fill, live willow branches shall be placed in
the interstices of the rock wall as it is constructed. The
basal ends of the willow branches shall extend into the back-
fill behind the rock breast wall.
j. The rock breast wall shall be constructed such that a bench
with a maximum slope of 2:1 and a minimum slope length of two
meters can be filled behind the rock breast wall.
k. The top layer of rocks must be placed in a closely adjacent
and continuous manner to minimize gaps.
1. In the case of rock breast wall constructed adjacent to a
paved or impervious surface, drainage system shall be placed
at the outside toe of the rock breast wall directing drainage
waters to an appropriate disposal area and preventing erosion
of the foundation material and undercutting the rock breast
wall.
The above sample specifications are intended, only as a guide, and must
be modified to fit the particular situation.
Gab ions
In addition to the use of large rocks for the construction of breast
walls, gabions with cobblestone sized rocks may also be used. Gabions
175
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are rectangular compartment containers fabricated from a triple twisted
hexagonal mesh of heavily galvanized steel wire. Figure VIII-26 depicts
a typical one tier and two tier gabion breast wall installation. Exca-
vation of the site for the placement of the gabions is similar to the
procedure described for rock breast walls. For easy handling and ship-
ping, gabions are supplied folded into a flat position and bundled
together. Each gabion is readily assembled by unfolding and binding
together all vertical edges with lengths of connecting wire stitched
around the vertical edges. The empty gabions are placed in position and
wired to adjoining gabions. They are then filled with cobblestone sized
rock (10 - 30 centimeters in diameter) to one third their depth. Two
connecting wires are then placed in each direction bracing opposing
gabion walls together. The connecting wires prevent the gabion baskets
from "bulging" as they are filled. This operation is repeated until
the gabion is filled. After filling, the top is folded shut and wired
to the ends, sides and diaphragms. During the filling operation live
rooting plant species, such as willow, may be placed among the rock
material similar to the operation described for rock breast walls. If
this is done, some soil should be placed in the gabions with the
branches and the basal ends of the plants should extend well into the
backfill area behind the gabion breast wall.
The total labor requirement for the construction of a gabion structure
is estimated by one manufacturer to vary from 1,5 to 2.0 person-hours
per cubic yard (2.0 to 2.6 person-hours per cubic meter). At the
Rubicon Properties project site gabion structures were installed using
low cost unskilled labor at a rate of 1.66 person-hours per cubic yard
(2.17 person-hours per cubic meter), including the loader operator's
time in filling the gabion structure with rock.
The simplest gabion structure is a .91 meter high wall using one tier
of gabions. A second tier of gabions can be placed on top of the first
tier and set back 30 centimeters without any significant design con-
straints. Gabion walls which are higher than two tiers (1.8 meters),
however, do require significant additional design constraints. Such
higher "retaining wall" structures must be well designed under the
supervision of a registered civil engineer. The higher the retaining
wall structure, the more likely it is to fail unless it is well
designed. As higher tiered walls are designed and used, the basal
foundation of the wall must be increased and/or counterforts must be
used to brace the wall against the tipping force of the material re-
tained behind it. In all cases, the retaining wall must be structured
such that the "righting moment" of the wall is at least 1.5 times the
"tipping moment" created by the retained material.
Breast Wall and Retaining Wall Costs
Breast walls were used extensively at the Rubicon Properties project
site as a means of stabilizing the toe of oversteepened, eroding slopes.
In some cases the average slope steepness was as high as 1:1. In the
few instances where the eroding slopes were steeper than 1:1, 2.7 meter
gabion retaining walls were used to reduce the average slope steepness
176
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above the wall to 1:1 or less. The following breast walls and retaining
walls have been installed at Rubicon Properties as part of the Erosion
Control Demonstration Project:
1.3 meter high rock breast wall
0.9 meter high gabion breast wall (1 tier)
1.8 meter high gabion breast wall (2 tier)
2.7 meter high gabion retaining wall C3 tier)
TOTAL
Length
350 m.
1500 m.
450 m.
200 m.
2500 m.
In addition to the above walls, two sections, totalling 50 meters in
length, of a 0.6 meter high rock wall were constructed at the Northstar
project site using manual labor only. The rocks used for the Northstar
walls were up to 40 cm in diameter and weighed up to 50 kilograms, other-
wise known as "two-man rocks".
Table VIII-2 presents the equivalent unit materials, equipment and labor
costs for the construction of a variety of breast wall structures. The
commercial delivered price of all rock at the project site is assumed to
be $8.40 per ton. A 0.9 meter high wire mesh gabion basket costs approx-
imately $9.80 per meter of length. Little equipment was required for
construction of the 0.6 meter "two-man" rock breast wall due to the
entire rock placement operation being conducted by manual labor. For
the larger rock breast walls, a heavy duty loader with a cost of $27.00
per hour is required continuously. In the case of the gabion structures,
however, the heavy duty loader is required for a small percentage of
total construction time, for the gabion filling operation only. If
organized efficiently, the filling operation can proceed quite rapidly
compared to the rest of the gabion construction procedure. As stated
at the beginning of this section, the total cost of labor is assumed
to be $16.25 per person-hour.
The total cost of any particular wall type is greatly influenced by the
highly variable unit cost of materials and labor. For example, if large
boulders suitable for rock breast wall construction are present at a
prospective erosion control site, the total cost of 1.0 meter rock breast
wall could be reduced to $50.00 per meter. Similarly, if an unskilled,
low cost labor force (e.g. $5.00 per person-hour total unit labor cost)
could be used to set up and wire gabions together, the total cost of a
0.9 meter gabion breast wall could be reduced from $58.61 per meter to
less than $45.00 per meter. Less expensive sources of rock could fur-
ther reduce the gabion structure's unit cost.
Concrete gravity walls, or counterforted reinforced concrete walls, were
not used at either the Rubicon Properties or Northstar project site for
two primary reasons:
a.
b.
their relatively unnatural appearance, and
their extremely high costs.
178
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TABLE VIII- 2
COMPARATIVE BREAST WALL CONSTRUCTION
EQUIVALENT COSTS*
UNIT COST ($/METER)
WALL TYPE
0.6 meter "two-man"
breast wall
1.0 meter rock
breast wall
1.35 meter rock
breast wall
0.9 meter gabion
breast wall
1.8 meter gabion
breast wall
2.7 meter gabion
retaining wall
MATERIALS
rock 4.00
11.04
13.80
22.40
44. .80
72.80
* Based upon documented construction at
assumptions at front of this section.
EQUIPMENT
2.91
22.62
28.28
5.71
11.42
18.56
project sites
LABOR
22.94
27.50
34.38
30.50
61.00
99.13
and stated
TOTAL
29.85
61: 16
76; 45
58.61
117.22
190.48
A 1.0 meter concrete gravity wall, for example is estimated to cost
approximately $150.00 per linear meter. The higher expense is due pri-
marily to the cost of materials and labor required for the construction
of the wooden forms necessary for the in-place fabrication of the concrete
walls. Preformed concrete walls may be somewhat cheaper, but still not
competitive with rock or gabion walls.
Other materials, such as redwood planks or railroad ties, may be used in
the construction of breast walls or retaining structures. Use of these
materials has not been evaluated at the project site. In the case of
the railroad ties, a firm supply of these items was not found. In the
case of redwood, the project staff did not believe the construction of
retaining structures was an appropriate use of this limited resource.
Furthermore, the cost of the skilled carpentry labor required for the
construction of these walls would have prohibited their construction
using limited project funds. The cost of constructing a 0.9 meter red-
wood retaining wall is estimated to be approximately $45.00 per meter.
Two-thirds of this cost ($30.00) would be for materials.
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Breast Wall Effectiveness
Determining which type of slope toe stabilization method to employ is
almost entirely dependent upon the cost of the particular structure.
Any sound structure which provides dependable protection for the slope
toe is sufficient. Porous walls, such as wooden walls, gabions, or
ungrouted rock structures, are preferable. Such structures, if properly
designed and constructed, will allow for the easy passage of surface
water yet retain the eroding soil material. In a few cases at the
Rubicon Properties project site, the interstitial spaces in the rock-
wall structures were too large. These spaces allow for the passage of
seepage water, but they also allowed soil to erode through the wall.
Problems such as these can be prevented by careful construction practices,
Frequently, gabions are criticized as being unattractive "bird cages".
It is argued that such "unsightly" structures should not be used for
erosion control in highly visible areas, such as adjacent to roadways.
Indeed, if large rocks are readily accessible, inexpensive, and near to
a proposed erosion control site, they should be used in the construction
of large rock walls. If rock must be imported, it is likely that the
cost of breast wall construction would be somewhat lower if gabions are
used. Because of the high porosity of a filled gabion, soil can be
placed in the gabion or will gradually filter into the voids. This will
allow vegetation to establish itself on and around the gabion structure.
The gabion structures used at the project site have not been in place a
sufficient length of time to evaluate the success of establishing vege-
tation. Those areas where willows have been placed in and around the
gabion structure, however, are expected to rapidly produce good vegeta-
tive growth and cover.
3. Slope'Scaling arid Overhang Removal
Proper slope scaling is a frequently neglected integral step in the
stabilization of eroding cut and fill slopes. This is particularly true
if the erosion control measures are installed some time after the orig-
inal slope disturbance took place. If gullies, rocky areas, or other
unstable sites are allowed to remain without proper treatment, the estab-
lishment of vegetative cover on an eroding slope will be considerably
more difficult. It is far more cost-effective to adequately prepare an
eroding slope prior to revegetation, than to come back time and time
again to replant these disturbed areas. Figure VIII-27 shows a work
force scaling an eroding cut slope.
Rocks pictured in Figure VIII—27 were subsequently used elsewhere to
rock-line and stabilize an eroding drainage swale.
Slope scaling should be conducted after breast walls or other bench
structures are formed at the toe of the slope. Exceptionssare very
large rocks or stumps which may require prior removal to avoid damaging
the slope toe structure. The following is an example set of specifica-
tions which may be used to describe the scaling process:
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Figure VIII-27. Scaling an eroding cut slope.
Scaling Process Specifications
a. All loose materials, exposed rock, and uneven surfaces shall
be scaled and removed to the toe of the slope.
b. Precautions shall be taken to insure the safety of workers on
steep slopes C2:l or greater) by means of safety ropes and
harnesses anchored securely to the top of the slope.
c. While removing large rocks from the slope, adequate precau-
tions shall be taken to control their movement.
d. If the scaling is being conducted on a cut slope adjacent to
or above a travelled roadway, the passage of traffic on the
roadway adjacent to the section being scaled shall be restric-
ted during periods when scaling is being conducted.
e. All scaled materials shall be immediately removed from the
road surface and stockpiled at a site approved by the project
engineer. In no case shall scaled material be placed within a
gutter or drainage swale, nor shall it be placed on a road
surface for longer than an 8-hour period.
f. Scaled material shall be stockpiled in locations not subject
to concentrated runoff. Siltation berms and impervious cover-
" ings must be used to prevent erosion from the stockpiled area.
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Overhangs, as defined in this report, are the excessively steep portions
of eroding slopes, with slopes greater than 1:1, such as are frequently
found at the crown of eroding cuts. When cut slopes are initially exca-
vated, overhangs are usually non-existent. However, if the majority of
a steeply cut slope remains unstabilized after initial excavations, the
mid portion of a slope will generally erode more rapidly than the remain-
der of the slope. The erosion will continue until a slope angle equal
to or less than the angle of internal friction of the soil has been
achieved. The crown of the slope usually erodes more slowly than the
mid-portion due to vegetation in undisturbed, natural terrain above the
lip of the slope. Although the overhangs are more stable than the
remainder of the slope, they will continue to erode, albeit more slowly.
If plantings are placed on the lower portions of the slope without over-
hang removal, they may become buried or otherwise disturbed by material
sloughed from the overhang. Furthermore, overhangs are frequently
near vertical. Unless such areas are rounded and reduced in steepness,
it.is difficult, if not impossible, to establish plantings.
Overhang removal should also be conducted after construction of breast
walls or other slope toe stabilization structures. Again the only
exception is in the case of large stumps or boulders. Figure VIII-27
depicts a manual overhang removal operation. Over 95 percent of all
overhangs at the Rubicon Properties and Northstar project sites were
removed in this manner. Following is an example set of specifications
which may be used.
Overhang Removal Specifications
a.
b.
c.
Any overhang areas steeper than 1:1 (horizontal to vertical)
at the slope crown shall be regraded and rounded to a maximum
slope of 1.5:1.
All trees to be removed from the overhang area shall be
clearly marked by the project engineer.
Soil removed from the overhang shall be placed behind the
slope toe stabilization method (i.e., curb, breast wall,
retaining structure) employed at the toe of the slope.
Scaling and Overhang Removal Cos ts
At the Rubicon Properties project site, approximately 300 cubic meters
of overhang material were removed and placed as fill behind breast walls
and A-C dikes at the toe of eroding slopes. With the exceptions of the
use of the loader for pulling trees and stumps and a backhoe for remov-
ing 51 cubic meters of overhang, all scaling and overhang removal were
performed by manual labor. Manual removal of overhangs required about
2.5 hours per cubic meter of overhang. A current construction cost
estimating handbook (51) indicates that loosening of earth by hand with
a pick requires 2.0 - 4.0 hours per cubic yards (2.6 - 5.2 hrs. per
cubic meter).
'3.82
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TABLE VIII-3
COMPARATIVE OVERHANG REMOVAL AND S GALING
EQUIVALENT COSTS
UNIT COST C$/CTJBIC METER)
ACTIVITY
MATERIALS
Manual scaling and
overhang removal with
aid of loader in
removing stumps
EQUIPMENT
1.91
Overhang removal
with backhoe
Overhang removal
with crane*
2.13
6.47
* Estimated rate of removal same as for Backhoe.
4.87
5.47
7.00
11.94
Table VIII-3 illustrates the costs of overhang removal and scaling as
experienced at the Rubicon Properties project site. Manual scaling and
overhang removal is considerably more expensive than more mechanized
methods employing heavy equipment such as backhoes and cranes. However,
in many instances cut slopes are so long that it is difficult to find
equipment with sufficient reach to allow removal of the overhang at the
slope crown. Furthermore, the labor force used at the Rubicon Properties
project site was so inexpensive that the unit cost of manual scaling and
overhang removal was essentially equivalent to the unit cost of renting
mechanized equipment to perform these tasks.
An additional cost of scaling and overhang removal is the cleanup of
debris which may be deposited at the toe of the slope. At the Rubicon
Properties project site, the average unit cost for debris cleanup on
roadways adjacent to cut slopes was $4,086.00 per hectare of cut slope
surface. Approximately 60 percent of this cost is for labor and 40
percent is for equipment needed to transport waste debris to an appro-
priate disposal site.
4. Contour Wattling
"Contour Wattling" was described by Kraebel £52) as early as 1936 in a
USDA circular, but has seen little practical use in the United States
outside of limited experimental applications. Kraebel defined "contour
wattling" as "the packing of lengths of brush into continuous thick
'cables' partially buried across a slope at regular contour intervals
and supported on the lower side by stakes". Experimental work on con-
tour wattling prior to this report has been conducted by the Department
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of Environmental Horticulture, University of California, Davis, and the
California Department of Transportation (CalTrans) as a means of control-
ling erosion on steep embankments adjacent to state highways in the Lake
Tahoe Region of the Sierra Nevada. Contour wattling is particularly
effective on slopes which approach, or are steeper than, the friction
angles (angle of repose) of the local soil. Advantages of contour wat-
tling are as follows:
1. The placement of wattling bundles into the eroding slope provides
local stabilization to the upper .2 to .3 meter of soil surface.
This prevents down slope movement of surface soil.
2. Contour wattling rows placed at repeated intervals effectively
break a relatively long slope into a series of benched and shorter
slopes. During heavy rains these repeated barriers prevent the
formation of large gullies. Wattling rows act as effective minia-
ture "percolation trenches" during a heavy runoff condition. This
is particularly true if the contour wattling rows are left slightly
exposed.
3. By keeping the soil in place, contour wattling allows the establish-
ment of vegetation on a denuded slope. A slight bench is formed at
each wattling row allowing for the germination and growth of seed
material placed there either artificially or by natural processes.
If the wattling bundles are made up of sprouting species, the root-
ing of the wattling itself will provide effective stabilization of
the slope surface.
4. One of the best means of mechanically stabilizing steep slopes
outside of ext nsive (and expensive) engineered retaining structures.
Contour Wattling Procedure
The following general procedure, adapted from Leiser (46), should be
specified in the installation of contour wattling (see Figure VIII-28):
a. Wattling bundles shall be prepared from live shrubby material,
preferably of species which will root, such as willows.
b. Wattling bundles may vary in length, depending upon material
available. Bundles shall taper at the ends. Butts of stems
shall be from 2 to 4 centimeters in diameter.
c. Stems shall be placed alternately in each bundle so that
approximately one-half of the butt ends are at each end of the
bundle.
d. When compressed firmly and tied, each bundle shall be 20 cen-
timeters in diameter plus or minus 5 centimeters.
184
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185
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m.
n.
Bundles shall be tied on not more than 40 centimeter centers
with two wraps of hinder twine or heavier tying material with
a non-slipping knot.
Bundles shall be prepared not more than one day in advance of
placement except that if kept covered and wet they may be
prepared up to seven days in advance of placement.
Grade for the wattling trenches shall be staked with a hand-
held level, or similar device, and shall follow the horizontal
slope contours.
Trenches shall be one meter vertical spacing or other as speci-
fied by the project engineer.
Bundles shall be laid in trenches dug to approximately one-half
the diameter of the bundles with ends of bundles overlapping
at least 30 centimeters. The bundles shall be as long as
necessary to permit staking as specified below.
Bundles shall be staked firmly in place with vertical stakes
on the downhill side of the wattling, not more than 0.5 meters
on center and vertical stakes through the bundles on not more
than 1.0 meter centers. Where bundle overlap occurs, an addi-
tional stake shall be used at the mid-point of the overlap.
Bundle overlaps shall be tied with a vertical stake through
the ends of both bundles.
Stakes shall be construction stakes C5 cm x 10 cm x 61 cm or 5
cm x 10 cm x 91.4 cm diagonal cut).
All stakes shall be driven to a firm hold and a minimum of 45
centimeters deep. Where soils are soft and 61 centimeter
stakes are not solid (i.e., if they can be moved by hand) 91.4
centimeter stakes shall be used.
Work shall progress from the bottom of the cut or fill toward
the top, and each row shall be covered with soil and packed
firmly behind and on the uphill side of the wattling by tamp-
ing or by walking on the wattling as the work progresses, or
by a combination of these methods.
The downhill "lip" of the wattling bundle may be left exposed
when staking and covering are completed.
must be rigorously adhered to.
However, step
"m"
Willows were the only plants used for contour wattling as part of this
erosion control project, although other quick rooting and sprouting
species may also be used.
The timing of willow cutting and cutting site selection can make a great
difference in productivity of any willow wattling operation. When a
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Variety of sites are available, the following criteria should be con-
sidered before making a final selection. First, try to schedule willow
wattling for late fall or early spring, when willows are dormant or
nearly dormant. Results at Rubicon Properties show markedly increased
growth and survival of wattling cut and placed in May and September,
over wattling cut and placed in June and July. Special handling, such
as covering wattling with wet tarps during transport and frequent irri-
gation after placement may improve results of summer wattling. However,
results at'Rubicon Properties, even with this special handling were poor
in comparison to early spring and late fall wattling. • Second, the
growth habit of the willow plant is important. Shoots, 2-3 meters
long with few cross branches and few dead branches, are the most desir-
able. These branches form more uniform and easily tied bundles, and the
plants' growth habitat is more open and easier to work in. Third, the
willow cutting site must contain enough satisfactory wattling material
to justify the time required to conduct the cutting operation. Gener-
ally speaking, if 'approximately 400 square meters of willow plants are
available in a single area, the area is cost-effective to exploit.
Fourth, the actual travel time to the cutting site is important. Cut-
ting sites used as part of this erosion control project have ranged from
4 kilometers to as far away as 40 kilometers from the installation site.
Substantially greater transportation distances would increase wattling
costs considerably.
An adequately equipped and experienced five-person work crew should be
able to cut, collect, and bundle one hundred 2.5 meter wattling bundles
from one site in one 8-hour period. A production rate of two to three
wattling bundles per person-hour may be reasonably expected. The only
equipment required for the task of willow cutting and wattling bundling
are: pruning shears, binder's twine, a sharp knife, a long bed half-ton
pick up truck, a large tarp, and the necessary safety equipment, such as
hard hats and gloves. A chain saw can be used to speed up the willow
cutting operation, but is extremely hazardous and requires experienced
personnel and additional safety equipment. An electric strapping tool
requiring a portable generator was experimented with, but was found to
be no more efficient than manually tied twine for tying the wattling
bundles together. Furthermore, aesthetic and environmental objections
might be raised over the use of nondegrading plastic strapping material.
Several tasks relating to wattling installation should be completed
prior to the arrival of the wattling bundles at the project site. First,
the alignment of the contour wattling rows must be determined. An ini-
tial stake is driven at the bottom of a slope face. From this point,
stakes are placed at desired intervals up the slope face. Once this
initial staking is completed, contour stakes are driven at approximate
6-meter intervals across the slope face along each contour, utilizing a
hand held optical level. Finally, stakes are "eye-balled" in at 0.5
meter intervals along the contour.
The actual willow wattling installation must function as a dynamic pro-
cess. Trenching, placing, staking, and burying of the willows must take
place in rapid succession in order to minimize soil and plant moisture
187
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loss and maximize plant survival. Crew members should start trenching
and preparing the ground, while others finish bundling the wattling and
start placing them in the lowest trench. Once the lowest wattle is
installed, the digging of the next higher trench may be started. This
staggered trenching is important so that as the higher trenches are dug,
sloughed,soil falls into the lower trenches. If this process is oper-
ating properly, all material sloughed from above should land on installed
wattling bundles.
Willows are installed so that approximately one-third of the bundle
extends above the slope grade, enabling it to intercept overland runoff.
For most willow bundles, 3-4 stakes driven through the bundle are
sufficient to hold it in place. An additional stake is driven through
the overlapping ends of adjacent bundles. A total of 3.5 construction
stakes are required for every meter of contour wattling. The end wat-
tling bundle should be angled up the slope to prevent any collected
runoff from flowing around the end. The soil is then replaced and packed
around the base of the wattling bundles. Again, this must be completed
shortly after the willows are installed. The presence of adequate soil
moisture adjacent to the bundles is imperative for plant survival. In
an effort to provide ample soil moisture for willow growth and rooting
at the Rubicon Properties and Northstar projects sites, all wattling
installed at these sites was heavily soaked with irrigation water immedi-
ately after installation. In the case of mid-summer wattling plantings
(July - August 1976) at Rubicon Properties, the willow wattled slopes
Figure VIII-22. Contour willow wattling installation at the
Northstar erosion control project site.
188
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were repeatedly soaked at no greater than one-week intervals throughout
the summer. The rate of willow installation is limited primarily by the
rate at which the trenches are prepared. When the contour wattling
operation is functioning properly, approximately one hundred 2.5 meter
wattling bundles may be stalled by a five-person crew in one day.
Figure VIII-29 depicts a typical wattling installation in progress.
Contour Wattling Cost
By making the necessary arrangements and obtaining a permit from the
U. S. Forest Service, willows may be harvested on Forest Service lands
for the purpose of erosion control. It is therefore assumed that plant
materials cost for willow wattling is negligible. The only substantial
materials cost is for the construction stakes used to hold the wattling
bundles in place. When purchased in large quantities, the unit cost is
about $.25 per stake. Approximately 2,500 meters and 1,500 meters of
willow wattling bundles were installed at the Rubicon Properties and
Northstar project sites, respectively. At Rubicon Properties 238 person-
hours were spent in the harvesting, and transporting 2,000 meters of
willow materials 30 miles to the project site during the summer and fall
.of 1976. In addition, a total of 377 person-hours were spent in the
bundling, staking, and burying of these bundles. The average spacing
between wattling rows was 1.85 meters.
Equipment required for the willow wattling operation consists of a half-
ton pick up truck, a chain saw, and assorted hand tools and safety equip-
ment. Costs for the equipment is assumed to be $4.00 per hour for a
five—person work crew. The willow wattling cost data is summarized as
follows:
$/meter
Materials
Equipment
Labor
TOTAL
$0.88
0.25
5.01
$6.14/meter
The total cost of $6.14 per meter for willow wattling is roughly equiva-
lent to costs cited by Leiser (.46) of $6.56 per meter. The cost summary
shown above is based upon the cost assumptions used in this report as
listed at the beginning of this appendix. Labor is assumed to cost
$16.25 per hour.
Fully 82 percent of the cost of willow wattling is for labor. If less
expensive labor is available contour wattling costs may be drastically
reduced. At the Northstar and Rubicon Properties project sites,
unskilled college students, Youth Conservation Corps workers (YCC) and
California Conservation Corps workers (CCC), were used to install con-
tour wattling. Based on an estimated cost of $5.00 per person-hour for
wages, supervision, transportation, and minimum benefits, contour wat-
tling installed by these groups cost approximately $2.67 per meter
installed.
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5. Other Methods
The methods for the mechanical stabilization of oversteepened slopes
discussed previously in this section require revegetation of the slope
to achieve the highest order of effective erosion control. There are,
however, several other methods of mechanically stabilizing oversteepened
slopes which do not require, nor depend upon, revegetation to effectively
control erosion. The wide variety of products and techniques available
to achieve non-vegetative oriented control are too numerous to mention
in any detail. A few representative techniques will be briefly touched
upon in this section. None of these approaches were demonstrated at
either the Northstar or Rubicon Properties erosion control project sites;
they were excluded by the following selection criteria:
- the judgement that they were aesthetically unpleasing in com-
parison to vegetation, and
— the cost of materials and installation which absolutely pro-
hibited their use as part of this project.
Examples of this "non-revegetative" approach to mechanical stabilization
of oversteepened slopes include gabion revetments, concrete anti-erosion
grid revetments and gunite revetments. A revetment, as used in this
text, means an artificial structure devised to cause earth to stand at a
steeper slope than it would naturally assume.
Gabion Revetments
Wire mesh gabions may be used to form breast walls and retaining struc-
tures at the toe of a steeply eroding slope as discussed in a previous
section. These devices may also be used to completely cover an eroding
slope in the form of a revetment. In order to place rocks in gabion
revetments, extensive heavy equipment such as a loader and/or crane with
a bucket attachment is required. Wire mesh gabion baskets may be obtained
in a variety of thicknesses to form a revetment structure.
Gabion revetment structures do have the advantage of being relatively
easily revegetated. Soil placed in the interstices of the rock fill can
support vegetation. Once the movement of soil from the slope is stabi-
lized by the use of a gabion revetment, the natural invasion of native
plants may be expected to occur much more readily. The porous nature of
the gabion revetment also allows easy passage of seepage water that may
occur naturally on the slope. Because of their great flexibility, gabion
revetments cannot crack or otherwise lose their structural integrity
even if considerable shifting or settling occurs.
Concrete Anti-Erosion Grid Revetments
A variety of these concrete anti-erosion grids are currently available.
One type of concrete grid is precast, slotted, .25 square meter blocks.
The manufacturer indicates that these blocks may be placed on slopes up
to a 1:1 angle. Similar to a gabion revetment, the perforations in the
grids would facilitate the establishment of vegetation. One apparent
190
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TABLE VIII-4'
ESTIMATED REVETMENT COST FOR
STABILIZATION OF'OVERSTEEPENED SLOPES
REVETMENT
Gabion Revetments
Concrete Anti-
erosion Grids
Gunite Revetments
MATERIALS
$12.50
12.84
5.05
UNIT COST ($/SQUARE METER)
EQUIPMENT LABOR TOTAL
$4.16 $11.12 $27.78
11.83 24.67
2.86
2.86
10.76
disadvantage is the absolute inflexibility of the individual blocks. A
slope where the grids are used must be completely level prior to instal-
lation, an added disadvantage of the grids is their high unit weight.
One type of grid weighs 42 kilograms per block. Unlike gabions, which
may be filled by means of heavy equipment, anti-erosion grids must be
placed individually with manual labor. Other applications of this par-
ticular type of product are many and varied. One application which
should receive further evaluation in the Tahoe-Sierra region of California
is their use as pervious paving surfaces for parking lots. Because of
their slotted perforations, concrete anti-erosion grids should be able
to reduce or eliminate storm water runoff from otherwise impervious
surfaces and thereby lessen the need for extensive storm water infiltra-
tion works.
Gunite Revetments
Gunite is sprayed concrete applied directly to a subject by means of an
air jet. A mechanical feeder, mixer, and compressor comprise the prin-
cipal equipment for this method of placement. Gunite can be effectively
pplied to near vertical slopes and is usually applied to a depth of
about 10 centimeters. Disadvantages include gunite's rigid and non-
porous structure. Gunite may be subject to cracking or chipping if any
settlement or shifting occurs. Because of gunite's non-porous nature,
extensive seepage lines or "weep-holes" must be placed on gunited slopes
to prevent the buildup of hydrostatic pressure which could lead to the
failure of the gunite revetment. Use of gunite will increase the amount
of storm runoff from a particular area. If its use leads to extensive
runoff and off-site erosion problems, use of gunite should be discouraged.
Furthermore, objections may be made regarding the use of gunite due to
its unnatural appearance.
Due to the above problems encountered with the use of gunite, its use
should be limited to only special problem areas. One type of problem
for which gunite may be useful is the control of erosion from steep,
191
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near vertical decomposing granite construction cuts. Vegetation is next
to impossible to establish in such locations and the existing decomposing
granitic rock is already highly impervious.
Revetment Costs
The slope treatments mentioned above are considerably more expensive
than revegetative erosion control measures. For this reason alone, use
of revetment structures should be limited to special situations and
extreme problem areas where other methods are unlikely to succeed.
Table VIII-4 summarizes the estimated costs of the above discussed revet-
ment structures. Cost data is derived solely from manufacturers' and/or
contractors' estimates. The actual unit costs may vary depending on
transportation, site accessibility, labor costs, and area covered. The
values given in Table VIII-4 are rough estimates for comparative purposes
only.
F. Permanent Vegetative Erosion Control
Erosion control methods described in this section are treated by this
report as the best approach to the permanent control of erosion from
disturbed areas. Effective revegetation will increase the abstraction
and permeability of the disturbed area and reduce the impact which storm
water runoff may have on down gradient areas. Furthermore, once estab-
lished, vegetation requires a minimum amount of maintenance, particularly
if native plants are able to "reinvade" a previously disturbed area.
Achieving satisfactory establishment of vegetation is dependent on cli-
matic conditions. Unless irrigation is provided, revegetation should
only be conducted in the Tahoe-Sierra region in the fall or preferably
the early spring.
The possible need for "follow-up" plantings and seedings must be acknowl-
edged. In most situations, follow up seedings are relatively inexpensive
(less expensive than providing irrigation) and can easily be provided
for. If a fall seeding does not establish satisfactory growth due to
frost heaving or other causes, additional seedings should be conducted
in the following spring. In all cases, vegetative erosion control in
the Tahoe-Sierra, albeit relatively inexpensive, is a somewhat specula-
tive venture. '
On gentle slopes (2:1 or less), the vegetative techniques described
herein, singly or in various combinations, should be effective in con-
trolling erosion from these disturbed areas. However, on steeper dis-
turbed terrain, or in situations where drainage control is poor, slope
stabilization and proper drainage control prior to revegetation is
essential to successful establishment of plants. At the Northstar and
Rubicon Properties erosion control sites, the use of contour willow
wattling, for example, has more than doubled the survival of other plants.
A wide variety of revegetative techniques are discussed in this section,
ranging in expense from less than $.10 per square meter for seeding and
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mulching to over $2.00 per square meter for native plantings or manual
installation of various mulch nettings and blankets. However, in many
instances, a considerable commitment of funds is required for mechanical
slope stabilization prior to revegetation. The unit erosion control
cost for slopes that require massive slope stabilization in the form of
retaining walls frequently exceed $20.00 per square meter of slope face.
As eroding slopes become steeper and longer9 the vegetative portion of
effective erosion control represents only a small portion of the total
cost.
This section on vegetative erosion control will deal with the following
subject areas:
- willow staking
container and bare root plants
- seed and fertilizer
- seeding and mulching techniques
- fiberglass roving
All of the above planting techniques, with the exception of fiberglass
roving, were used extensively at either the No.rthstar or Rubicon Proper-
ties erosion control project sites. The discussion of seeding and mulch-
ing 'techniques is particularly extensive and includes hydromulching,
straw mulching, straw tackifying, and mulch nets and blankets.
1. Cut Willow'Stakes
Planting a slope with cut willow stake cuttings can be an effective
method of providing a quick, cheap method of revegetating eroding slopes.
Other plants such as dogwood ('Cbrrius) and alder (Alnus) may also be
satisfactory for this purpose but were not tried on these projects.
Willow staking has been conducted with considerable success even on
relatively dry, south facing, exposed slopes. The best results with
willow staking are achieved if the following procedure is rigorously
adhered to.
Willow Staking Procedure
Plant materials are gathered in much the same manner as for the contour
wattling operation. Sources of willow are readily available in the Lake
Tahoe Basin by gaining a use permit for removal from Forest Service
lands. Willow shoots may be cut by either pruning shears or a chain
saw. Small branches should be trimmed from the willow shoots ranging
from 1 to 2.5 centimeters in diameter. The shoots are cut into 15 to 45
centimeter lengths using either a hand axe or a circular saw and marked
with spray paint at their basal ends. The cut length of the willow
stakes is dependent upon the ease with which they may be driven into the
ground. The stakes should be as long as possible, up to 45 centimeters,
with no more than 2-4 centimeters exposed above the slope surface once
they are driven in place. The longer the stake, the better chance it
has for survival.
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Figure VHI-30. New growth on a successfully planted willow stake.
Materials
Equipment
Labor*
- harvesting
- cutting
- installation
TOTAL
TABLE VIII-5
WILLOW S TAKING EQUIVALENT'COST
TIME
EQUIVALENT COST
$/stake
hr/stake
CNo materials other than willows are required.)
.007 .028
.008
.010
.009
.027
.130
.163
.141
.462
*Note: Equivalent labor cost is assumed to be $16.25 per person-hour.
194
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On unconsolidated decomposed granitic soils, willow stakes may be placed
with relative ease at any time. On harder soils with higher clay con-
tent, use of a star drill or other devices may be required to make plant-
ing holes. Due to the very dry summertime conditions in the Sierra
Nevada, willow staking should be conducted in either the early spring or
late fall' to be assured of adequate soil moisture to support growth. In
most instances the rate of successful plant growth from willow staking
appears to be much greater than from willow wattling. As is true with
contour wattling, willow stakes should be cut immediately prior to
installation, and never stored for longer than a 12-hour period unless
they are kept cool and moist. Willow branches for stakes may be stored
up to 7 days if properly stored. A successfully planted willow stake is
pictured in Figure VIII-30.
Willow Staking Cost
Equipment required for the willow staking process includes a half-ton
pick-up truck, chain saw, and assorted hand tools. The cost of this
equipment is assumed to be $4.00 per hour for a five-person work crew.
The willow staking cost data, as performed at Northstar, is presented in
Table VIII-5. Willow stakes were placed at a density of about four per
square meter..
2. Plants
Reestablishment of native plants is generally held to be ideal revegeta-
tive approach for erosion control. Reasons for this include:
1. aesthetically pleasing control method, blending in with the sur-
rounding natural environment
2. lower fertilizer requirements for native species
3. lower water requirements for native, drought tolerant species
Difficulties which are encountered with revegetation using native species
include:
1. plants are not generally available except by advance contracts with
growers
2. plants are relatively expensive due to difficulties of propagation
and cultivation resulting in greater risks to growers
3. poor survival of small seedlings and cuttings when given a minimum
amount of attention and care
4. frequently provide less than adequate ground cover for effective
soil stabilization and erosion control
Considerable work has been recently conducted by the Department of
Environmental Horticulture, University of California, Davis, in
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propagation of native Sierran plants for erosion control and revegeta-
tion. Propagation methods for such plants are covered in detail in
Appendix A.
Plants received at the erosion control project sites came in a variety
of containers:
1. Shrubs — rooted cuttings and seedlings,
- 7.5 cm. peat pots
- 15 cm. and 25 cm. PVC deep conical tubes
- 13 cm. and 25 cm. thin ployethylene book planters
2. Bare root tree seedlings,
- bundles of 50
3. Grass seedlings,
- 7.5 cm. peat pots
The principal plants used as part of this erosion control demonstration
project are as follows (.for a complete listing, refer to Appendix A):
1. Shrubs
a. ArGtostaphylos patula (.greenleaf manzanita)
b. Arctostaphylos nevadensis (pinemat manzanita)
c. Artemesia. trideritata (big sage)
d. Ceanothus prostratus (squaw carpet)
e. Purshia tridentata (bitterbrush)
f. Penstemon newberryi (mountain pride)
g. Various Lupinus species (lupines)
h. Various Salix species (willow)
i. Prunus emarginata (bitter cherry)
3' Atriplex canescens (salt bush)
k. Chrysothamnus hauseosus (rabbitbrush)
2. Bare root tree seedlings
a.
b.
c.
d.
Grass
Pinus jeffreyi (Jeffrey pine)
Pinus lambeftiana (sugar pine)
Abies magnifica (red fir)
Abies concolor (white fir)
a. Various rhizominous wheatgrasses.
Judging from early results, the best success has been achieved by Purshia
tridentata, Artemesia tridentata, Penstemon newberryi, Atriplex canescens,
Pinus jeffreyi, Chrysothamnus nausebsus, and the grass clones.
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Planting Procedure
Once plants have been transported to the erosion control site, they
should be acclimated for approximately 1-2 weeks. During this period,
plants should be watered only when necessary, with a final watering just
before planting. Bare root seedlings should be delivered to the erosion
project site in the early spring and planted as soon as possible. Those
seedlings not used immediately should remain boxed in a cool, dark place
and thoroughly doused with water daily.
At the project site, the actual planting operation requires three or
more people. Two or more individuals are involved with placing the
plants in the ground, while at least one individual is responsible for
supplying each "planter" with plants as needed. On less severely slop-
ing sites, each "planter" may be responsible for providing his/her own
supply of plants. Planting should proceed from the top of the slope to
the bottom at staggered intervals along the contours of the slope face.
This prevents soil disturbed by foot traffic from being sloughed and
deposited on plants lower on the slope. Each "planter" is responsible
for the following planting procedure (see Figure VIII-31):
1. On a loose sloughing slope (such as decomposed granite), dig a hole
just large enough for the root ball of the plant.
On consolidated slopes, the above procedure may be followed, or dig
a shallow bowl shaped excavation and form a slight brim on the
downhill side. An additional excavation large enough to contain
the root Ball of the plant is made in the low point of the bowl,
normal to the surface. The purpose of the bowl is to allow surface
irrigation and to trap rainwater. Care must be taken to remove all
loose soil around the bowl which may erode into the bowl and bury
the plant.
An additional excavation made to the dimension of the plant container
is made in the low point of the bowl normal to the surface.
2. The plant and potting material is removed from the container and
placed in the excavated hole. (In the case of peat pots, the plant
and potting material are not removed. However, any portion of the
peat pot extending above the potting material surface must be
removed. This prevents a loss of soil moisture from around the
roots of the plant via a "wick effect".)
3. The top surface of the root ball should be at or slightly below the
level of the surrounding soil.
4. The native soil is compacted around the plant. Once the plant is
in place, those having basin areas should receive about 2 liters of
water.
In the' case of bare root seedlings, essentially the same procedure is
followed with the exception that the hole in. which the seedling is placed
197
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PROPER PLANTING OF CONTAINER PLANTS
PEAT POT - BREAK OFF RIM OF POT
ABOVE SOIL LINE PRIOR TO 'PLANTING.
DEEP TUBE-TO REMOVE PLANTS, INSERT
CONTAINER AND KNOCK RIM AGAINST A
ROCK OR SHOVEL. PROTECT PLANT FROM
INJURY.
BOOK PLANTERS- PLANTS ARE GENTLY
REMOVED AFTER OPENING THE BOOK.
PLANTERS ARE FRAGILE, BUT REUSEABLE.
PLANTING
TOO SHALLOW
TOP OF ROOTS
MUST BE JUST
BENEATH SOIL
SURFACE.
TAMP FIRMLY.
TOO DEEP
STATE- OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
CONTAINER
PLANTS
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
FIGURE NUMBER
vrn-31 .-
198
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must be sized to accept the full root system. The planter should be
careful not to compress the root system against the central stalks as
soil is replaced around the plant.
Fertilizer is not required when planting the bare root or contained
shrubs. The grasses require about one gram of 16-20-0 fertilizer placed
at the bottom of each hole. Care should be taken to mix fertilizer into
the soil at the bottom of the hole to avoid burning the plants. If
planted early in the spring or fall, the plants should not require con-
tinuous watering. However, greater success can be assured if water is
available when the plant is initially placed in the ground and for subse-
quent watering until the plant is established. Once the root system of
a native drought-tolerant plant is well established (1-2 months),
further artificial watering should not be necessary.
Planting Costs
Plants for erosion control may be obtained from commercial growers if
substantial @g-*l% year) advance notice can be given (see Appendix A).
Native shrubs vary widely in costs. If large quantities (1,000 or
greater) of plant materials in 7.5-centimeter peat pots, or equivalent
size, are ordered in advance, the cost per plant may be as low as $.50
per delivered plant for the more common species. Bare root tree seed-
lings acquired from the California State Division of Forestry plant
nurseries can be obtained for as little as $.05 per plant including
transportation. Although data is not readily available, it is likely
that grass seedlings in 7.5-centimeter peat pots may be obtained for as
little as $.10 per peat pot. For more detailed information on plant
propagation costs refer to Appendix A.
Over 20,000 plants were planted at Rubicon Properties in the fall of
1976 and spring of 1977. Individual planting rates varied from 20 plants
per hour to over 50 plants per hour. With reasonably good conditions
(i.e., moderate slopes and cool weather), sustainable rates of about 40
plants per hour for shallow containers and 30 plants per hour for bare
root trees (large root systems) might be expected.
Equipment required for planting operations involve, at a minimum, a
half-ton pick-up truck and various hand tools. The hourly equipment
cost is about $3.50 per hour for a five-person work crew. Plants at the
Rubicon Properties project site, at an average, were placed 2-4 plants
per square meter. The planting unit cost data is summarized in Table
VIII-6.
3. Seed arid Fertilizer
The ideal objective of revegetative erosion control is to ultimately
produce a vegetative cover which is native and blends naturally with the
surroundings. Most erosion control seed mixtures contain nonnative
grasses with the fertilizer added separately.. Legumes, native shrub,
and wildflower seeds, may also be added. The primary role of the non-
native fertilized grass seeding is to provide a quick, temporary (1-5
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TABLE VIII-6
EQUIVALENT COSTS OF PLANTS FOR EROSION CONTROL
UNIT COST ($/PLANT)
PLANT TYPE MATERIALS EQUIPMENT LABOR* TOTAL
.500 .047 .406 .954
.050 .035 .542 .627
.100 .047 .406 .554
Shrubs
Bare Root Seedlings
Grass Plant Clones
*Note: Equivalent labor cost is assumed to Be $16.25 per person-hour.
years), means to stabilize eroding soil. This allows development of slow
growing, less nutrient-dependent native species, which otherwise would
have been unable to gain a "foothold".
A wide variety of seed and fertilizer is available for erosion control
plantings. The seed and fertilizer used for this erosion control demon-
stration project are shown in Table VIII-7. The individual species
which were chosen for use were based upon the success of previous seed-
ings conducted in the Lake Tahoe-Sierra Nevada environment C46, 53, 54).
Those species listed in Table VIII-7 are described below.
Grasses
*Luna* pubescent wheatgrass CAgropyrdn'trichophorum 'Luna*). 'Luna*
pub'escent wheatgrass shows more seedling vigor than the other grasses
and, except for 'Tegmar* or 'Oahe' intermediate wheatgrasses, has estab-
lished better on droughty or otherwise difficult sites. 'Luna'
rhizomatous and matures early Cat about 60 centimeters).
is
'Tegmar' intermediate wheatgrass CAgropyron iritermedium 'Tegmar').
'Tegmar*" intermediate wheatgrass is slightly inferior to 'Luna1 pubescent
wheatgrass in establishment but superior to other intermediate wheat-
grasses. It could be substituted for 'Luna' pubescent wheatgrass.
'TegmarT intermediate wheatgrass is rhizomatous, stays green longer, and
is shorter than *LunaT.
'Durart hard fescue GFestuca xiviria ^dttrius-ciilal. 'Durar* hard fescue is a
non-»rhizomatous short grass.
"Potomac' orchard grass CDactylis glbmerata'Potomac*),, 'Potomac' orchard"
grass is- a fast growing, non-rhizomatous, short grasX.
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'Manchar' smooth brome (Bromus inermis 'Manchar'). 'Manchar' smooth
Brome, a rhizomatous grass, has deep green foliage and broad brown seed-
heads which add color and contrast to mixtures with the above grasses.
'Lincoln' smooth brome (Bromus inermis 'Lincoln'). 'Lincoln' smooth
brome is rhizomatous, and is similar to 'Manchar' described above.
'Luna' and 'Tegmar' wheatgrasses may be difficult to obtain commercially.
Orders for these species should be placed well in advance. If necessary,
more available rhizomatous substitutes include 'Oahe* intermediate wheatgrass,
'Topar' pubescent wheatgrass, and western wheatgrass. Rhizomatous species
are highly recommended due to their ability to extend and increase the per-
centage of plant coverage from year to year on difficult sites where species
relying solely on seed production face severe limitations.
Other nonrhizomatous, fast growing species such as 'Potomac' orchard grass
provide rapid stabilization of problem sites until other species have an
opportunity to become established.
Grass seed mixture application rates used as part of the erosion control
demonstration project have ranged from 40 to 86 kg/hectare. A rate of 40
kg/hectare should be sufficient if the seed is incorporated into the soil and
then mulched. However, a rate of 80 kg/hectare or higher is recommended if
the seed is placed on the soil surface or applied with the mulch. The "best"
results at the Northstar project site were achieved with a hydromulched plot
which was accidentally seeded at a rate of 260 kg/hectare!
Legumes
'Lutana* cicer milkvetch (Astragulus cicer 'Lutana'). Cicer milkvetch is
a rhizomatous spreading legume which develops slowly but can grow up to
50 centimeters in height.
'Dutch' white clover (Trifolium repens).
low growing rhizomatous legume.
'Dutch' white clover is a
'Cascade' Trefoil (Lotus corniculatus 'Cascade'). 'Cascade' Trefoil
is a bushy legume reaching heights of up to 60 centimeters and produces a
colorful yellow flower.
Legumes provide some nitrogen to other plants, such as the grasses, which
would otherwise require continuous fertilization on the more sterile sites.
In many instances, legumes are difficult to grow at higher elevations and at
dry sites. All legumes planted from seed require inoculation with the proper
Rhizobium bacteria. If legume seeding is specified using a hydraulic system,
the legume seeds should be pellet-inoculated (22).
Legume seed mixture application rates used as part of the erosion control
demonstration project have ranged from 12 to 25 kg/hectare.
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TABLE VIII-7
PERCENTAGE COMPOSITION OF SEED AND FERTILIZER MIXTURES
USED AT THE EROSION CONTROL PROJECT SITES
Grass Seed Mixtures
GRASSES
Luna puBescent wheatgrass
Tegraar intermediate wheatgrass
Durar hard fescue
Potomac orchard grass
Manchar smooth brome
Lincoln smooth Brome
LEGUMES
Lutana cicer milkvetch
Dutch white clover
Cascade trefoil
SHRUBS AND WILDFLOWERS
Artemisia tridentata
Purshia tridentata
Oenotheria hookeri
Linum lewisii
Gilia leptantha
Nemophila maculata
Eschcholzia calif.
FERTILIZERS
16r-20<-0 (fast)
7r-40^6 (slow-pellet)
38-Or-O (slow-pellet)
0-20-0 (fast)
B
D
11 11 16 40
66 56 42 40
17 — 16
33 16 20
6 -_ —
100 100 100 100
Legume Seed Mixtures
A B C D
57
24
19
50
50
67
11
22
50
50
100 100 100 100
ShruB Seed Mixtures
A B C
10
30
*>n
^L. \J
10
i n
JL \J
10
10
100
100
100
100
100
Fertilizer Mixtures
X Y Z
100
45
55
40
60
100
100
100
202
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Shrubs and Wildflowers
'Basin Sagebrush' (Artemesia tridentata). 'Basin Sagebrush' is a common
drought tolerant shrub found in desert and mountainous regions of the
west.
'Bitterbrush1 (Purshia tridentata). 'Bitterbrush' is a drought tolerant
shrub with bright yellow flowers, common to the eastern slope of the
Sierra Nevada range.
'Hooker's Evening Primrose1 (.Oenotheria hookeri) . 'Hooker's' Primrose
is a wildflower with large yellow petal usually found in moist areas
below 2,000 meters elevation.
'Western Blue Flax' (Linus perenne lewisii). 'Western Blue Flax' is
a wildflower with light blue petals, usually found in dry, open exposures
up to 4,000 meter elevations.
'Showy Blue Giliat (Gilia leptantha ssp. purpusii). 'Showy Blue Gilia'
is a wildflower with pinkish violet flowers, usually found in moist
open exposures up to 2,500-meter elevation in the southern Sierra Nevada.
'Fiyespot' (Nemophila maculata). 'Fivespot' is a sprawling wildflower
with white flowers having large purple spots, usually found in moist
areas of the western Sierra Nevada range below 2,500-meter elevations.
'California Poppy' CEschscholzia californica). The 'California Poppy',
the California state flower, is a wildflower with bright orange to yellow
petals, common in open, dry places below 2,500-meter elevations.
Several other species of shrubs and wildflowers native to the Sierra Nevada
range are also available commercially. Sage and bitterbrush were chosen
because of their drought tolerance. The various colorful wildflowers were
chosen more for aesthetic reasons than as a practical means to control ero-
sion. Prior to the erosion control demonstration project, little work has
been done demonstrating the feasibility of establishing these types of plants
at such severe sites as are found within the demonstration project sites. The
California poppy has shown the greatest promise as a colorful additive to
difficult erosion control sites.
Shrub and wildflower mixture application rates used as part of this demonstra-
tion project have ranged from .2 to 4.5 kg/hectare.
Fertilizers
16-20-0. The 16-20-0 fertilizer used was a fast release fertilizer
which dissolves rapidly in water. It has a good balance of nitrogen,
phosphorus, and sulfur. All three are deficient for herbaceous vegeta-
tion in the vicinity of Lake Tahoe C46) .
7-40-6. The 7-40-6 fertilizer used, Mag Amp, was a slow release fer-
tilizer in pellets (approximately one centimeter in diameter) which
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dissolve very slowly in water. The large pellets can clog a hydroseeder
and lead to higher application costs. It contains no sulfur.
38-0-0. The 38-0-0 fertilizer, or urea formaldehyde, was a slow released
fertilizer in pellets Capproximately 0.3 centimeter in diameter) which
is broken down slowly in the soil. It contains only nitrogen.
Q-20-0. The 0-20-0 fertilizer, or single super phosphate, is a fast
release fertilizer, containing phosphorus and sulfur, used to supplement
the urea formaldehyde.
f
There is a considerable degree of controversy surrounding the use of fertil-
izer, particularly within the Lake Tahoe Basin. Overfertilization creates a •
potential for the fertilizer to enter surface waters by means of storm-water
runoff. Fast release fertilizer, such as 16-20-0, is of greatest concern due
to its solubility. The level of fast release fertilizer use, as part of the
erosion control demonstration project, has been held to about 280 kg/hectare
of 16-20-0. The levels of fertilization used at the erosion control demonstra-
tion site contains approximately one-tenth the nitrogen which is normally
applied to a typical golf course in a single season. A rate of 280 kg/hectare
for 16-20-0 is one-half the minimum rate normally recommended for erosion
control seedings elsewhere in California (55).
Even at 280 kg/ha, if a 2.5 centimeters per hour rainstorm were to wash away
all the 16-20-0 fertilizer applied to one hectare, the result would be 250,000
liters of runoff with a nitrogen concentration of approximately 180 mg/1. The
California Regional Water Quality Control Board, Lahontan Region, has estab-
ished a .20 mg/1 total nitrogen water quality objective for Lonely Gulch Creek,
a creek receiving runoff from the Rubicon Properties project site. A discharge
of 250,000 liters of water with a total nitrogen concentration of 180 mg/1
would be a clear violation of this water quality objective. If any more nitro-
gen than 1/1,000 of that applied as fertilizer were to be carried in 2.5 centi-
meters of runoff water, there would probably be a violation of water quality
objectives for Lonely Gulch Creek.
Fortunately, the limited monitoring conducted thus far at the erosion control
project sites has not indicated any increase in nitrogen concentration which
could be attributed to erosion control fertilization, possibly because much of
the fertilizer is bound to the soil particles. Well designed erosion control
measures prevent any significant overland flow which could wash fertilizers
or soil particles into surface waters. Well stabilized soil with incorpor-
ated nutrient materials will not be easily eroded or deposited in surface
water drainages.
On a few plots, slow release fertilizer (7-40-6) was applied at a rate of
280 kg/hectare along with the fast release fertilizer (16-20-0) at 280 kg/
hectare. The success of the slow release fertilizer in sustaining long-term
growth of the seeded plant species is not ascertainable at this time.
In most instances, limiting fertilization to slow release fertilizers would
not provide nutrients to the plant when most needed, immediately after germi-
nation. Use of a slow release fertilizer should be combined with a faster
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release type. If inexpensive labor or equipment is available, the best
approach to fertilization of seeded erosion control sites is to conduct low
level applications of fast release fertilizers on an "as needed" basis. This
is likely to be the least expensive, least polluting, and best plant growth
practice.
High fertilization rates may be detrimental to the growth and development of
native plant species in and around the Tahoe Basin. Many native plant species
have developed abilities to survive in nutrient deficient environments. These
native plants have difficulty competing with artificially fertilized nonnatives.
Figure VXII-32 s-hows an area of a topsoiled roadcut at the Northstar project
site. The native manzanita shrubs (Arctostophylos patula) seen in the photo
developed from seeds contained naturally in the topsoil. The grasses seen in
the right half of the picture are the results of a hydromulched grass seeding
experimental, plot on a portion of the topsoiled area. In the portion of the
topsoiled area which was hydromulched, seeded, and fertilized, there is less
than 50.percent of the manzanita growth which is occurring in the "topsoiled-
only" portion on the left. The picture was taken in 1977, six years after the
topsoiling and four years after the grass seeding.
Seed Placement
Four basic methods for the placement of seed and fertilizer were used as part
of the erosion control demonstration project. These included:
Figure VI5I--32, Competition between artificially seeded plant
materials and native shru&s on a top^soiled slope at Northstar.
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1. "drilling" on a level site by means of a range drill
2. manual application of seed and fertilizer, followed by manual raking
prior to a mulch application
3. hydraulic seeding and fertilization with hydroseeding equipment
prior to an application of mulch
4. application of seed, fertilizer, and mulch conjunctively in a one-
step hydromulching operation
The highest germination percentage and the best results are obtained
when the seeds are covered with soil. This may be achieved on level
surfaces by use'of a range drill, as shown in Figure VIII-33, or a
similar device. On steeper sites, or if a drill is not available,
seeding may be done by manually broadcasting, ;then lightly raked or
Buried by dragging a chain over the seeded area. Grass seeds should
never be covered more than one centimeter, except on decomposed granite
where they may be covered to a depth of 2 to 3 centimeters. Once the
seed is in place, the ground surface should be mulched. Best results
may be expected from this method.
If hydroseeding equipment is available, the seed may be hydraulically
applied to the soil surface in a water slurry with 20 metric tons of
mulch/hectare for visual metering and seed cushioning. An application
of mulch over the hydraulically seeded slope is then required.
yKE!^33, Seed and £e-rt^li^zer placement on a level unvegetated
area By means of a range drill.
206
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If an economical and efficient operation is required, the mulch, seed,
and fertilizer may be hydraulically applied in a one-step operation.
For a more complete discussion of hydroseeding and seed application in
mulch, see the section on hydromulching. Generally poorer results are
obtained using this method due to the fact that a large percentage of
the applied seed is suspended in the mulch and not in contact with the
soil.
The consequences of foot traffic or other disturbances on a seeded
slope is somewhat inconclusive. In some instances, foot traffic on
a seeded slope appears to enhance survival by incorporating the seed
into the soil. In other instances foot traffic on steeper areas, par-
ticularly those with exposed hardpan outcrops, can dislodge the seed and
cause it to be sloughed to the toe of the slope.
Irrigation. Repeated irrigation of a seeded area will enhance seed
germination and plant survival. If irrigation facilities are not avail-
able, seeding should only be conducted in the early spring or late fall
just prior to the appearance of snow. Without a backup irrigation sys-
tem, a seeded slope is at the mercy of the weather. If an irrigation
system is available, the water must be applied very slowly to guard
against erosion induced by runoff. The seedbed must be kept continuously
wet until the seeds sprout.
An irrigation system which could deliver 2.5 centimeters of water to
a 1.0 hectare seeded area once every two weeks at a rate of .5 centi-
meter per hour would cost approximately $3,000 per hectare for instal-
lation. An additional expenditure of approximately $1,000 per month
the installation costs ($1,500) involves materials which would be reuse-
able elsewhere. Assuming that irrigation would be required for two
months Ca total of 10 centimeter water), irrigation cost would total
approximately $5,000 per hectare.
In the Lake Tahoe Basin, early spring seedings benefit from the high
soil moisture remaining for some time after snow pack melt. Seedings
conducted late in the year may suffer from frost heaving, particularly
if a less than average snow pack exposes the seeded slope to repeated
freezing and thawing during portions of the winter. Without instal-
lation of an irrigation system, repeated reseeding of critical areas may
be required. In most instances, reseeding should not be required more
than once. With good weather conditions and good timing neither reseed-
ing nor an irrigation system would be required.
Seeding and Fertilization Costs. Individual varieties of seeds vary
greatly in cost and may fluctuate from season to season and year to year
depending upon market conditions. Costs may range from $1.20 per kg for
Potomac Orchard grass to $3.65 per kg for Durar Hard Fescue. At the
project sites, a wide variety of combinations of various grass seed,
legume seed, and shrub seed mixtures were applied. For the seed unit
cost estimates, various seed mixture unit costs were averaged to arrive
at the following estimated values:
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Grass Seed Mixture
Legume Seed Mixture
Shrub Seed Mixture
$ 2.60/kg
6.00/kg
19.00/kg
Fertilizer costs are estimated as follows:
16-20-0
Mag-Amp
38-0-0
0-20-0
$ -,193/kg
1.203/kg
.638/kg
.180/kg
TABLE VII I- 8
COMPARATIVE LABOR AND EQUIPMENT COSTS FOR VARIOUS DIRECT
SEED AND FERTILIZER APPLICATION TECHNIQUES
(does not include cost of seed, mulch or fertilizer)
DOLLARS/HECTARE
LABOR EQUIPMENT
Applied with wood fiber
hydromulch
Hydroseeding followed by
hydromulching at 2800 kg/ha
Hydroseeding followed by — —
hydromulching at 5600 kg/ha
Hydroseeding before other — —
mulch types
Hand seeding at 'commercial $520/ha $25/ha
rate C$13/hr + 25%)
Hand seeding by county - $320/ha $25/ha
workers rate C$10/hr)
Hand seeding by CCC $160/ha $25/ha
workers C$5/hr)
Seed and fertilizer $130/ha $40/ha
applied with range drill
*Note: These costs derived from CalTrans contracts.
TOTAL
$ 0/ha*
$ 79/ha*
$ 48/ha*
$348/ha*
$645/ha
$345/ha
$185/ha
$170/ha
208
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Comparative unit labor and equipment costs of these various seeding
techniques are shown in Table VIII-8. Costs for seeding utilizing
hydromulching equipment are derived from Figure VIII-35.
The additional labor and equipment cost of simultaneous application of
seed material and fertilizer with the hydromulching process is considered
to be negligible. However, hydroseeding prior to mulching can increase
the unit labor and equipment costs. If hydroseeding is conducted prior
to hydromulching, a moderate increase in unit cost may be expected due
to the additional use of the hydromulching equipment per unit area. If
hydroseeding is conducted prior to a mulching technique other than
hydromulching, the increase in unit cost can be significant due to the
required use of hydromulching equipment which otherwise would not have
been necessary. Hydroseeding is assumed to be conducted by applying
wood fiber mulch at .20 metric tons per hectare (for visual metering and
seed cushioning) and water at 10,000 liters per hectare with the appro-
priate amount of seed and fertilizer. Hand seeding and raking can be
accomplished at a rate of approximately four person-days per hectare.
4. Mulching Techniques
Introduction. Several methods of seeding and mulching are available
for vegetative erosion control. By combining various mulch rates and
techniques, seeding rate and techniques, fertilizing rates and techniques,
and tackifier rates and techniques, many methods with varying costs and
degrees of effectiveness are available for use. Obviously, a project
with time, space, and funding constraints cannot possibly demonstrate
such a wide variety of mulching and seeding techniques. Rather, an
attempt was made to choose those types of methods which, (1) were readily
available for use in and around the Lake Tahoe Basin, (2) appeared to be
relatively inexpensive, and (3) appeared to offer the greatest chance of
successful revegetation of steep, severely eroding sites.
Basically, the seeding and mulching techniques demonstrated as part of
this erosion control demonstration project fall into three general
categories:
a. hydromulch ing
b. straw mulching
c. mulch nets and blankets.
In the following sections, these basic techniques and related variations
are described and discussed, particularly as relating to their cost,
effectiveness, and manner of use at the project demonstration sites.
Cost Estimating Procedures. The cost estimating procedures and assump-
tions listed at the beginning of this section were used in developing
the cost data pertaining to se.eding and mulching techniques. Information
is based upon first-hand experience at the erosion control demonstration
sites, communications with the California Department of Transportation,
and communications with seeding and mulching contractors local to the
Tahoe Basin and vicinity.
209
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5. Wood Fiber Hydro seeding and Hydromulching
Hydroseeding ±s a method of applying seed (and fertilizer) to soil in a
water slurry. Hydromulching, as used in tMs text, refers to the method
of applying wood (cellulose) fiber (with or without seed and fertilizer)
to the soil in a water slurry (see Figure VIII—34). Hydroseeding is an
effective'and a relatively inexpensive means of applying seed to a slope
for revegetation. It requires a minimum labor force, but a fairly large
capital investment in equipment. With rare exceptions, only commercial
enterprises specializing in hydroseeding or hydromulching are available
to conduct such an operation. The cost of hydroseeding equipment covers
a wide spectrum from a few thousand dollars for 250 gallon units up to
$100,000 for self powered 5,000 gallon units. Advantages of hydroseed-
ing include uniform distribution of seed and fertilizer, access to steep
slopes or areas too wet to sustain either pedestrian or heavy equipment
traffic, and, if only commercial labor is available significantly lower
cost than conventional hand seeding. Disadvantages include the necessity
of a paved or otherwise firm surface near or adjacent to the area to be
seeded, a readily available water supply, a high degree of capital commit-
ment, and an inability to place the seed into the soil.
A wide variety of seeds, including grasses, legumes, shrub, and tree
seeds may be used with the hydroseeding process. Large seeds (such as
sugar pine) and extremely fragile seeds should not be used. The inclu-
sion of legume seeds is not recommended unless the inoculant coating is
durable (56). Poor success with legumes in the hydroseeding process
; :?$/yp&$'.; / >,t 7 / -' '
Figure VIII-34. Wood fiber hydromulching with seed and fertilizer
in a one^step operation.
210
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probably due to the extreme dilution of the inoculant when added to
the mulch slurry. Grass, legume, and shrub seeding rates demonstrated
at the project sites varied from 56 to 112 kg per hectare (50 to 100 Ibs
per acre). These rates, or even higher rates, are recommended for use
with the hydromulching process.
The inclusion of a mulch when hydroseeding vastly improves the probability
of successful seed growth and plant development. Generally, the mulch
used with hydroseeding equipment is composed of fine wood fibers which,
when agitated, disperse rapidly in water to form a uniform slurry. Wood
fiber mulch is usually manufactured from aspen or alder wood chips with
dispersing agents and dyes added. Wood fiber mulch manufactured from
recycled waste paper is also available. Although this product is less
expensive and less resource exploitative, other investigators have shown
that it produces a less effective mulch cover (57). Other fibers com-
posed of dairy waste fiber, ground straw, ground newsprint, recycled
office waste, rice hulls, seed screenings, and cubed alfalfa may be
available, but generally do not perform as satisfactorily as virgin
wood fiber. Advantages of wood fiber include:
- formation of a strong, flexible mat which holds the seed and
fertilizer in place until the seed has germinated
insulation of seed and soil from solar radiation
- contains no weed seeds or other foreign seed
uniform application assisted by non-toxic dyes which fade upon
exposure to light
cushioning of seed against damaging action of the mulching
unit's pump
Wood fiber mulch is typically applied at rates ranging from 1,000 - 2,000
kg per hectare. Usually 1,580 kg per hectare is specified. When rates
of about 2,000 kg per hectare or lower were demonstrated as part of this
erosion control project on adverse sites, very poor results were obtained
compared to that achieved with higher mulch rates. On the severely
sloping (2:1.or greater), dry, exposed road cut and fill slopes found
within the demonstration project sites, satisfactory results have been
achieved only with mulching rates above 2,800 kg per hectare (2,500 Ibs
per acre). It appears that even greater success can be achieved with
mulching rates approaching 5,600 kg per hectare (5,000 Ibs per acre).
It should be noted that such high rates are only recommended for the
most severe erosion sites. Lower mulching rates should be sufficient on
lesser (less than 2:1) slopes which are sufficiently moist or shaded.
As is noted later in this report, due to economies of scale, a 100 per-
cent increase in wood fiber mulching rate over a one-hectare area would
normally increase the total cost of the operation only 30 to 40 percent.
Various commercially available chemical additives, both natural and
synthetic, are advertised to hold mulch in place, promote germination,
hold moisture, and reduce soil erodibility. Evidence from previous
investigations (58) indicate that these additives, in most instances, do
not significantly aid plant growth. Polyvinyl acetate (PVA) and styrene
butadiene (SBR) were the only wood fiber mulch additives demonstrated as
211
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part of this project. The chemical additives transformed the flexible
wood fiber mulch covering to a stiff plate-like covering which was sus-
ceptible to frost heaving and cracking. As a result, in most test plots
where such additives were used, there was substantially less seed germ-
ination and growth.
Wood fiber mulch may be purchased with a organic tackifier already con-
tained in the mulch (approximately 3 percent by weight). A substantial
number of plots have been tested using pretreated wood fiber mulch at the
Rubicon erosion control demonstration site. Initial evaluation, however,
indicates that such pretreated mulch produces the same results as
untreated mulch.
Hydromulching Costs
Mulch costs are highly dependent on the quantity of mulch purchased.
It is furthermore assumed that a commercial operation would purchase
wood fiber in 27 metric ton carload lots, which would allow the mulch
to be purchased at the lowest possible price. In addition, it assumed
that such carload prices are F.O.B. the San Francisco Bay area and that
an additional $33.00 per metric ton would be required to transport the
XTOod fiber to the Lake Tahoe area. The unit costs for wood fiber, thus
derived are as follows (.to the nearest dollar) :
a.
b.
c.
d.
Conwed
Conwed 2000 (w/tackifigr additive)
Weyerhauser Silva Fiber
Average for Untreated Mulch
Dollar/Metric Ton*
$200
329
162
181
Up to a 60 percent increase in unit purchase price may be expected if
wood fiber mulch is purchased in 1 ton rather than 30 ton lots.
Unit hydromulching costs used in this report are derived from data
extracted from current CalTrans contracts throughout California. The
CalTrans contract data was available in the form of wood fiber mulch
"in-place" costs for various contracts ranging in size from .14 hectare
to 36.15 hectares. These costs include all materials, labor, and equip-
ment required for the mulch placement, but do not include materials,
equipment, and labor required for fertilizing, seeding, or chemical addi-
tives. CalTrans contracts specify 1.7 metric ton per hectare application
rate for wood fiber mulch. The total cost, area covered, and mulching
rate was used to determine the cost per unit of mulch for each of the
various contracts. This data, after a format adjustment to dollars/
metric ton versus metric tons, is shown in Figure VIII-35.
*Prices as of June 30, 1976
212
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It is assumed,in this report, that the critical factor controlling job
cost is the total amount of mulch applied rather than the total area
covered. Assuming easy accessibility, it should not be significantly
more expensive to cover 10 hectares with 5 metric tons of mulch than it
would to cover 1 hectare with the same total amount. Thus, the cost
data are presented in cost per unit weight rather than cost per unit
area. Unit mulching costs may be readily obtained for a variety of
mulching rates.
Cost data reported elsewhere (41) and obtained through personal communi-
cations with private contractors closely corresponds to the CalTrans
data. Local contractors use as a practical "rule of thumb" that 0.4
hectare (1 acre) mulched at a rate of 1,680 kg per hectare (1,500 Ibs
per acre) should cost $600. This value is within 4 percent of the value
determined from the information in Figure VIII-35 with allowances for
seed and fertilizer costs.
Economies of scale, inherent in most equipment intensive endeavors, are
apparent from the data presented in Figure VIII-35. For example, when
the amount of mulch applied is increased by an order of magnitude from
.68 metric tons to 6.8 metric tons, the unit cost is more than halved
from $882 per metric ton to $392 per metric ton.
HYDROMULCHING COSTS
DOLLARS PER METRIC TON
VS
METRIC TON
MULCH, LABOR, and
EQUIPMENT COSTS
LABOR and
EQUIPMENT ONLY
.4 5 6 7 8 9 10 II
METRIC TONS of WOOD FIBER MULCH
12 13
14 15
Figure VIII-35. Wood fiber hydromulching labor and equipment unit
cost as a function of amount of mulch applied. Based on CalTrans
contracts for first half of 1976.
213
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There may be some questions as to whether or not this data is applicable
to conditions found in and around the Late Tahoe Basin. Unit costs are
partially dependent on the difficulty of application of wood fiber at
the construction site. These difficulties generally derive from three
factors:
a. a readily accessible water supply
b. maneuverability of equipment
c. accessibility to job site
The first factor, water supply, should not be a major difficulty in and
around the Lake Tahoe Basin. Arrangements may be made with the various
water districts to tap the water supply system via fire hydrants in the
towns, villages, developments, and subdivisions throughout the Tahoe
area. Indeed, a majority of erosion problems which may be controlled
through hydromulching exists in the form of oversteepened cut and fill
slopes adjacent to roadways within these urbanized areas. Nevertheless,
the use of hydromulching in more remote areas may require the use of
water trucks, which would significantly increase the unit costs depicted
in Figure VIII-35.
The second factor, maneuverability, may pose significant problems in
steep, switchback, and narrow roadway areas, particularly if the equip-
ment used is trailer-mounted rather than truck-mounted. However, in
most instances, the equipment is likely to be large capacity (greater
than 5,500 liters) truck-mounted units which should be able to negotiate
most paved roadways in mountainous regions, such as those found in the
Lake Tahoe area.
The third factor, accessibility, should not be a problem in the Lake
Tahoe Basin or elsewhere in urbanizing or urbanized areas of California
and Nevada. Several hydromulching contractors are located within a one
to two hour drive from the Lake Tahoe Basin.
The following hydromulching costs per unit area are derived from Figure
VIII-35.
a. 2.8 metric tons/hectare C2,500/lbs/acre) - $967/hectare
b, 5.6 metric tons/hectare ('5,000/lbs/acre) - $l,353/hectare
These unit area costs reflect only the cost of labor, equipment, and
overhead, not the cost of materials (mulch, seed, and fertilizer). The
estimated total cost of hydromulching at three representative applica-
tion rates is included in Table VIII-9.
6. Straw Mulching
Straw is an effective and inexpensive mulch. Straw mulch is generally
applied either by a straw blower (Figure VIII-36) or by manual distri-
bution. Advantages of a straw mulching operation over hydromulching
include:
214
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TABLE VIII- 9
HYDROMULCHING AND ' SEED COSTS
DOLLARS /HECTARE
LABOR & SEED &
EQUIPMENT MULCH FERTILIZER* TOTAL
Mulch
Mulch
Mulch
*Note
at 1680 kg/ha
at 2800 kg/ha
at 5600 kg/ha
:. Grass, legume, and
16-20-0 fertilizer
756 304 400
967 506 400
1,353 1,013 400
shrub seed mixture at 100 kg /ha.
at 280 kg/ha.
1,460
1,873
2,766
- ability to utilize manual labor in difficult spots
lightweight and easily maneuverable equipment
- lower capital investment for equipment
no need for readily accessible water supply
However, unlike wood fiber hydromulch, straw mulch must be held down
by a separate operation. Straw mulch may be incorporated into the
ground by means of a crimper or a modified sheepsfoot roller. The use
of a crimper or a modified sheepsfoot roller is limited to fairly level
or gently sloping terrain. Straw mulch may also be held in place by
the use of chemical tackifiers or nets. These incorporating and tacki-
fying techniques are more fully described in the next section of this
section. Major disadvantages of"straw mulching include:
- separate applications of seed and fertilizer (usually manual)
- high incidence of weed seeds or seeds of foreign plant
materials (use of rice straw significantly reduces the extent
of this problem)
- application radius of straw blowing machine is severely
limited, particularly under windy conditions
- need to incorporate or tackify the straw with soil immediately
after application, and
- higher cleanup costs
- very costly at sites not accessible by straw blowing equipment
Like hydromulching units, straw blowing machines vary greatly in size
and cost. Generally, an operation with experienced personnel and a
large machine can be expected to mulch a large project at a rate of
about 2.0 to 2.5 tons per hour.
215
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Figure VIZX—36. Straw mulch application to fill slope By means of a
straw Blowing machine.
STRAW MULCHING COSTS
DOLLARS PER METRIC TON
VS
METRIC TON
MULCH, LABOR and
EQUIPMENT COSTS
LABOR and
EQUIPMENT COSTS
3456789 10
METRIC TONS OF STRAW MULCH
12 13 14 15
Figure VIXJ.T-37, Straw mulch application laBor and equipment unit
cost as a function of mulch applied. Based on CalTrans contracts
for first half of 1976.
216
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Many different straws are available for use. Straw used as part of
this demonstration project have included: (1) rice straw, C2) Barley
straw, and (3) tall wheatgrass straw. Rice straw was the most difficult
to use, as it was not chopped finely enough and tended to be distributed
from the straw blowing machine in clumps. Rice straw does have the
advantage of not containing seed of drought tolerant, foreign plants
capable of surviving in high altitude mountainous regions of California
and Nevada. Clean barley straw is easy to use if it is not baled too
tightly. Barley straw is likely to contain a significant number of
barley and weed seeds which may interfere and compete with the specified
seeds, although the barley seedlings may provide considerable initial
soil stabilization. Barley, however, is not likely to reproduce at
higher elevations.
The straw tacking operation, described in the next section, should be
conducted immediately after application of the straw, particularly if
applied during windy weather. Untreated straw is very light and can
easily blow away. Loose straw should be kept under control at all
times. Situations can easily develop where loose straw combined with
sediment and other detritus can clog and block drainage ditches, swales,
gutters, drop inlets, and culverts. Cleanup operations must therefore
begin immediately after straw is applied and tacked to an erosion control
site.
Straw Mulching Costs. Straw mulch costs are also highly dependent on
quantity purchased. Straw used for the project ranged from $33.00 per
metric ton for 11 tons of rice straw purchased in 1975 to $25.00 per
metric ton for 4 tons of barley straw purchased in 1976. Throughout
this report the cost of straw is assumed to be $30.00 per metric ton
F.O.B. Sacramento. With assumed transportation costs to Lake Tahoe of
$15.00 per metric ton, the total price of straw for mulching is $45.00
per metric ton.
Straw mulching unit costs used in this report are derived from data
extracted from current CalTrans contracts. The CalTrans contracts give
straw mulch "inplace" costs for areas ranging from .32 to 176.06
hectares. CalTrans specifications require a straw mulch application
rate of 9.0 metric tons per hectare (~4 tons per acre). The cost data
is presented in Figure VIII-37 (upper curve).
The lower curve in Figure VIII-37 depicts the unit labor, equipment,
overhead, and profits of the straw flowing operation only. The costs
of the mulch, $45 per metric ton, and the straw punching operation,
estimated to be one-third of the overall contract price (41, 59), are
not included.
The basic unit area used to compare erosion control costs in this report
is 1 hectare (2.47 acres). It is felt that most contractors equipped
for this operation would be willing to submit a bid .on a project of this
size.
217
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The straw mulching technique using straw blowing equipment is only effec-
tive if the area to be mulched is within 20 to 30 meters of the available
access road or surface. In areas that are unreachable using straw blow-
ing equipment or in situations where inexpensive labor is readily avail-
able, it may be more practical and less costly to use hand labor to spread
the straw mulch. Hand spreading labor and equipment costs become competi-
tive with a commercial straw blowing operation if hourly wages are $5.00
per person-hour. Straw mulching labor and equipment equivalent costs are
summarized as follows:
a. Commercial straw blowing at 4.5
metric ton/hectare
b. Manual straw spreading at 4.5
metric ton/hectare
$ 611/hectare
$l,613/hectare
Manual straw spreading equivalent costs are based upon the assumptions
listed at the beginning of this section, including the assumption that
total labor costs are equivalent to $16.25 per person-hour. County road
crews, on the other hand, could manually spread straw at a cost of $963
per hectare, and CCC workers could manually spread straw for $517 per
hectare. The total estimated costs of straw mulching and seeding, not
including tackifier cost, is included in Table VIII-10.
TABLE VIII-10
STRAW MULCHING AND SEEDING COSTS
Hydroseeded w/blown
straw at 4,500 kg/ha
Hand seeded w/manual
straw at 4,500 kg/ha
LABOR &
EQUIPMENT
960
2,258
DOLLARS/HECTARE
SEED &
MULCH. FERTILIZER*
202
202
400
400
TOTAL**
1,562
2,860
*Note: Grass, legume, and shrub seed mixture at 100 kg/ha.
16-20-0 fertilizer at 280 kg/ha.
**Note: Tackifier costs are not included and should be expected to cost
an additional $l,000/ha.
218
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Hand-spread straw and mechanically blown straw differ in length and con-
tact with the soil. Blown straw pieces are shorter, sometimes split, and
lie down better. Blown straw is generally easier to tack down, although
the longer hand-spread straw may be superior for punching or crimping.
7. Chemical Tackifying Agents
A wide variety of natural and synthetic chemical mulch tackifiers and
stabilizers are available for use. Some of the tackifiers may be
applied directly to soils as a temporary stabilizer.
As discussed in the section on hydromulching, tacking of wood fiber
hydromulch has achieved limited success, particularly in regions prone
to severe frost heaving. On the other hand, straw mulching in areas
which cannot be crimped or punched, requires the use of a tackifying
agent. Asphalt emulsions are commonly used as straw tackifiers. Most
commercial operators find that such asphalt emulsion sprays can be
difficult to use, quite messy, and aesthetically unpleasing when applied
to visible areas. For these reasons, representative samples of other
types of products which can be substituted for asphalt emulsions were
demonstrated as part of this erosion control project. Tackifiers
demonstrated include:
•n
Terra Tack II , a free-flowing powder produced from seaweed
extracts. This material is mixed with water and wood fiber
mulch to form a slurry which is applied as an overspray to a
previously straw mulched site. When mixed properly, it
polymerizes and, upon application, forms an insoluble network
of binding membranes.
•n
- Terra Tack II Super Concentrate, an experimental free-flowing
powder similar to Terra Tack II but which may be applied
simultaneously with the straw mulch at somewhat lower rates.
This material is mixed with water and a small amount of wood
fiber to produce a slurry. This product proved ineffective
and has been removed from the market.
•n
Ecology Controls M-Binder , a free-flowing powder produced
from a plant gum (Plantago insularis). This material has
received limited use as a straw tackifier and was developed
primarily as a wood fiber mulch binder and soil stabilizer.
It is mixed with water and wood fiber to form a slurry which
is applied as an overspray to the previously straw mulched
site.
Styrene butadiene copolymer emulsison (SBR) , a synthetic polymer
in the form of a white, milky translucent liquid which forms
a thin insoluble coating when applied and allowed to dry.
This material is mixed with water, a methyl cellulose
modifier, an anti-foaming agent, and wood fiber mulch to form
a slurry. When applied simultaneously with a straw blowing
219
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operation, the amount of wood fiber mulch should be kept to a
minimum to prevent clogging of the apparatus.
Wood fiber only, which is wood fiber applied as a tackifier
with a hydromulcher at somewhat lower than normal rates. On
experimental plots at the erosion control project sites,
sprayed wood fiber mulch at 800 kg/ha was as effective as any
other tackifier which was used.
TABLE Till- 11
RECOMMENDED STRAW MULCH
TACKIFIER
•n
Terra Tack II
(powder)
Terra Tack IIR~
Super Concentrate
(poxtfder)
Ecology Control
M-Binder (powder)
SBR (Dow XFS
4163-L)
Asphalt
Emulsion
Wood Fiber
SHIPPED
WEIGHT
kg/ha
100
50
150
750
C745 1/ha)
4,400
(4,600 1/ha)
800
TACKIFIER
MODIFIER
kg/ha
(if any)
N/A
N/A
N/A
10.2
N/A
N/A
APPLICATION RATES
WOOD
FIBER
kg/ha
336
75
225
(up to
460)
N/A
800
WATER
liter/ha
14,000
5,340
8,750
4,250
N/A
16,800
SLURRY
liter/ha
14,000
5,340
8,750
5,000
4,400
17,000
The recommended application rates for these materials for steep and/or
difficult erosion control sites are shown in^Table VIII-11. All the
materials demonstrated, except Terra Tack II Super Concentrate, have
been tested by others (60) under controlled conditions and at the rec-
ommended rates have a tacking strength comparable to asphalt emulsion.
Of the materials demonstrated, the powders appear to be the simplest to
use and require considerably lower shipping costs than do liquid tacki-
fiers, such as SBR or asphalt emulsion. Both SBR and asphalt also appear
to require more involved cleanup procedures than do the powders.
Tackifying Costs. The following tackifier materials costs are based upon
manufacturers' quotations, including shipping but not wood fiber mulch
costs (if required):
220
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$Aha*
a.
b.
c.
d.
e.
f.
$6.35
$11.35
$ 4.65
$ .80
$ .20
$ .18
$635
$568
$698
$600
$880
$144
Terra Tack^II
Terra Tank Super Concentrate
M-Binder
SBR
Asphalt Emulsion
Wood Fiber only
* Cost per hectare for tackifier only based upon recommended
application rates. Lower unit costs may be achieved by
purchasing materials in large quantities.
The two basic application methods for mulch tackifiers are: (1) simul-
taneous application with the mulch, and (2) overspray application of
tackifier after the mulch is in place. The overspray tackifier appli-
cation method is usually accomplished using a hydromulching unit. An
asphaltic tackifier is applied with an asphalt rig or simultaneously
with a gear pump provided with most mechanical straw blowers.
It is estimated that the simultaneous tackifier application should only
increase the labor, equipment, and overhead costs of the straw blowing
operation by about 10 percent. This is particularly true if the commer-
cial enterprise is familiar and experienced with the methods involved. A
two-stage application of tackifying agents can substantially increase the
labor, equipment, and overhead cost of the mulching operation. The sepa-
rate, overspray addition of the tackifier necessitates additional hydro-
mulching or spraying equipment and labor not otherwise required. The
cost of overspraying a tackifying agent is assumed in this report to be
equivalent to the "per liter" cost of applying a wood fiber mulch slurry
minus the material cost of the mulch. The wood fiber mulch slurry appli-
cation costs are based upon recent CalTrans contracts and the assumption
that a commercial operation requires 21 liters of water for every kilo-
gram of wood fiber mulch applied (twenty 50 pound bales per 2,500 gallons
water) .
The unit labor, equipment, and overhead costs for tackifier application
via a hydromulching unit are summarized in Figure VIII-38. For example,
application rates for labor, equipment, and overhead cost per unit area
are as follows:
a. 5,000 liters/hectare - $227/hectare
b. 10,000 liters/hectare - $348/hectare
Due to economies of scale, a 100 percent increase in tackifier appli-
cation rate from 5,000 to 10,000 liters per hectare results in only a
53 percent increase in labor, equipment, and overhead costs. The total
estimated materials, equipment, and labor cost required for the instal-
lation of various tackifiers, based on recommended application rates, are
listed in Table VIII-12, assuming a hydromulching unit is used to apply
the tackifier over the straw, as pictured in Figure VTII-39.
221
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STRAW TACKIFIER APPLICATION COSTS
DOLLARS PER METER
VS
METRIC TONS
LABOR and EQUIPMENT
COSTS ONLY
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
METRIC TONS OF APPLIED WATER SLURRY
Figure VIII-38. Chemical taekifier application labor and equipment
unit cost when applied as a water Base slurry with hydromulching
equipment. Based on CalTrans contracts for first half of 1976.
Figure VJIZ~39, Application of a chemical tackifier over straw nlulch
using hydromulching equipment.
222
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ESTIMATED
TACKIFIER
R
Terra Tack II
T>
Terra Tack II -S. C.
•D
M-Binder
SBR
Asphalt Emulsion
Wood Fiber only
TABLE VIII-12
TACKIFIER COST APPLIED
ALL
MATERIALS
$696
$582
$739
$683
$880
$144
OVER STRAW MULCH
' DOLLARS /HECTARE
LABOR &
EQUIPMENT
$426
$236
$321
$227
$720
$600
TOTAL
$1,122
$ 818
$1,060
$ 910
$1,600
$ 744
8. Mulch Nets and Blankets
A variety of mulch nets and blankets are available for placement over
seeded and fertilized areas. These products temporarily stabilize the
soil until the seeded plants have matured. Use of mulch nets and blankets
can be advantageous in that experienced commercial contractors and expen-
sive equipment are not required for their installation. Nonetheless, the
mulch nets and blankets themselves are quite expensive and require a
considerable amount of manual labor to install. As-will be subsequently
shown., the use of mulch nets and blankets becomes economically competitive
in the Lake Tahoe-Sierra Nevada Region only if extremely inexpensive or
volunteer labor is available. In addition there is no evidence at the
demonstration sites to indicate that mulch nets and blankets are partic-
ularly more effective in establishing plant growth or providing temporary
soil stabilization than other, less expensive mulching techniques. A
possible exception would be in the case of extremely sloping terrain
(.steeper than 1%:1).
The mulch nets and blankets demonstrated as part of the erosion control
project are the following:
•D
- Excelsior Blankets, a machine produced mat of curled wood
excelsior which is evenly distributed throughout the blanket.
The top side of each mat is covered with a biodegradable
plastic mesh. The mats are generally produced in rolls with
a coverage of either 67 or 84 square meters each. On slopes,
the excelsior is rolled out from top to bottom with one 15
centimeter "U" shaped staple per square meter, as shown in
223
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Figure VIII-40. Manual application of Excelsior'
seeded and fertilized cut slope.
R
blanket over a
Figure VXII—40. It is not necessary to dig check slots, anchor
ditches, bury the ends of blankets, or provide extensive slope
preparation.
Plastic Netting, a rectangular "mesh of extruded, biodegradable
plastic strands. The netting generally comes rolled on a
cardboard core in widths of 2.3 or 4.6 meters. The total area
covered by a 4.6 meter wide roll is 3,500 square meters. The
area to be covered must be a smooth raked surface, free of
rocks, clumps of plants, or anything else which prevents the
close contact of the net to the surface. The area must then
'be seeded and mulched according to accepted practices and the
plastic netting placed in lengths from the top to the bottom
of the slope, overlapping 5 to 10 centimeters with the adjacent
length. Staples, 15 centimeters in length, are evenly distrib-
uted at approximately one staple per square meter in a diagonal
pattern.
224
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Jute Mesh, a heavy netting of uniform open plain weave, loosely
twisted jute yarn. The jute mesh is furnished in 40 kilogram
rolled strips which cover approximately 80 square meters each.
The area to be covered must be a smooth surface, free of rocks,
clumps of plants, or anything else which would prevent close
contact between the mesh and the ground surface. The area is
then seeded and fertilized according to accepted practices. A
light covering of mulch may also be applied. The jute mesh is
then rolled from the top to the bottom of the slope and held in
place using 15 centimeter "U" shaped staples. The mesh must be
applied loosely without stretching. The upper and lower ends
of the mesh must be buried or otherwise firmly secured. Where
two or more lengths are applied side to side, an overlap o-f at
least 10 centimeters must be made. The staples should be
evenly distributed in a diagonal pattern with approximately
one staple per square meter. A steeply eroding road cut at the
Rubicon Properties erosion control project site treated with
jute netting is shown in Figure VIII-41.
Paper Fabric, a combination of thin paper strips interwoven
with synthetic yarn mesh. Both the paper and synthetic yarn
are degradable. A wide range of yarn-paper durability and
thickness is available depending upon specific site conditions
and the need for slow or rapid degradation of the fabric. The
paper fabric is furnished in widths of 1.5 or 3 meters. The
larger width is folded double and shipped in rolls weighing
VJJI-41. Jute netting applied to a seeded and fertilized slope.
225
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Figure VIII-42. Manual application of paper fabric blanket over a
seeded, fertilized, and straw mulched severely eroding cut slope.
approximately 36 kilograms each and is able to cover approxi-
mately 325 square meters. The area to be covered must be
smooth, free of rocks, clumps of plants, or anything else
which would prevent close contact between the paper fabric and
the ground surface. The area is then seeded and fertilized
according to accepted practices. A light covering of wood
fiber or straw mulch may also be applied to the slope face.
The paper fabric should be loosely applied to the ground sur-
face, with no introduced tension or bridging above the ground
surface. Adjoining strips of paper fabric must be overlapped
10 to 15 centimeters. Staples, "U" shaped, and 15 centimeters
in length are evenly distributed at one staple per square meter
to hold the paper fabric in place. A 10 to 15 centimeter deep
check ditch should be constructed 30 centimeters back from the
slope crown and at the toe of the slope. The top and bottom
edges of the paper fabric should be stapled in these check
slots at 20 to 25 centimeter intervals and buried. Lateral
edges of the covered area should also be heavily stapled and
buried to insure against water channeling or lifting by heavy
winds.
All of the above-mentioned materials appear to perform well as mulch
nets and blankets. Advantages of mulch nets and blankets over other
mulching methods include:
— direct physical attachment of mulch materials to soil surface
— can sustain moderate foot traffic once in place
226
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Figure VIII-430 Penstemon plants sprigged through a slope covered with
paper fabric which helps retain the soil moisture and inhibit erosion.
- after placement, openings may be cut for sprigging plants as
shown in Figure VIII-43
- usually durable and long lasting
*- usually provides some moisture retention
- less subject to foot or vehicle traffic as treatment is more
obvious than hydromulched or straw tacked slope
Disadvantages include:
- extremely high materials cost relative to other mulches
— extremely high manual labor requirement relative to other
mulches
- foot traffic required for installation may dislodge previously
placed seed on steeper slopes
— unsightly and may require eventual removal
•D
Of all the mulch nets and blankets tested, the Excelsior blanket and
jute mesh , appear to provide the best coverage and adherence to the soil
surface. The paper fabric appears effective in retaining soil moisture
even on very dry, exposed slopes. The plastic netting provides an
inexpensive way to apply straw mulch to erosion control sites if straw
blowing equipment is not readily obtainable and low cost manual labor
is available.
227
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INSTALLATION TIMES FOR SELECTED
EROSION CONTROL NETTINGS 8 BLANKETS
KCEL
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2 3 4~ 5 6 7 8 9 10 II 12 13 14 15
DEGREE OF DIFFICULTY
SLOPE LENGTH (METERS) x SLOPE ANGLE (DEGREES)
Figure VIII~44, LaBor requirements for the manual installation of
various erosion control nettings and blankets.
Mulch Net and Blanket Costs. The costs of mulch nets and blankets are
calculated based upon coverage of a one-hectare job site. Since the use
of nets and blankets is relatively uncommon in the Sierra Nevada—Lake
Tahoe area, it is assumed that these materials would not be purchased
in lots larger than that necessary to cover each job. Shipping costs are
dependent upon the location of the nearest distributor and the relative
weight per unit area of the material. The following materials costs are
based upon information provided by various manufacturers and include
estimated shipping costs:
•n
A. Excelsior Blanket
B. Plastic Netting
C. Jute Mesh
D. Paper Fabric
$/hectare
Total
$3,404
$1,293
$5,294
$5,814
In all of the above cases, shipping costs do not exceed 5 percent of the
retail cost of the materials.
The cost estimates of labor required for installation of nets and mulch
blankets varies widely depending on the source. One manufacturer of
228
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jute mesh claims that, with proper installation procedures, jute may be
installed at rates as low as 15 person-days per hectare. On the other
hand, a recent EPA publication (3) indicates installation rates may run
as high as 103 person-days per hectare for steep slopes. The steepness
and length of slopes does affect, to a moderate degree, the amount of
labor required to install these types of materials. Data gathered at the
Rubicon Properties erosion project site demonstrates this. The severely
eroding road cut slopes at Rubicon, where nets and blankets were used,
have slope angles ranging from 31 degrees (1.66:1) to 45 degrees (1:1)
and slope lengths ranging from 4.6 meters to 14.3 meters. For this
range of slope difficulties, the term "degree of difficulty" is used to
empirically describe the slope conditions, which is simply the slope
length multiplied by the tangent of the slope angle. The "degree of
difficulty" is simply a method of correlating the increased manpower
commitments required for the installation of nets and mulch blankets as
the length and steepness of the slope increases. Figure VIII-44 depicts
the person-hours of installation time for the four types of nets or mulch
blankets used as part of the erosion control demonstration project.
Jute netting and paper fabrics appear to have similar manpower require-
ments. Jute weighs considerably more than paper fabic. Thus, jute
requires more effort to spread. Once positioned on the slope, however,
jute has less of a tendency to be disturbed by wind and is easier to
work with and move around on. From experience gained at the project
site, Excelsior blankets require approximately 40 percent more instal-
lation time than either jute or paper fabric. The smaller width of the
excelsior roll necessitates approximately 15 to 20 percent more trips
up and down a slope to place the material. Two advantages of the
excelsior are, (1) as claimed by the manufacturer, the material at the
top and bottom of the slope does not need to be buried, and (2) excelsior
blankets may be formed around slope irregularities such as rocks or clumps.
Plastic netting, over straw, appears to require about 40 percent less
installation time than does jute or paper fabric on steep slopes. This
is due primarily to the extremely light weight of the material and the
larger width (4.6 meters^of the plastic netting rolls. Both the plastic
netting and the Excelsior blanket are almost impossible to use on very
steep slopes. As a result, these two materials were not used on slopes
with a steepness greater than 1%:1.
For a 10-meter slope with a steepness of 1%:1, the labor requirements
and cost comparisons are derived from Figure VIII-44 and depicted in
Table VIII-13.
9. Fiberglass Roving
Fiberglass roving is actually a type of mulch blanket. It was not used
at either the Northstar or Rubicon Properties erosion control project
sites, and is thus treated separately. Fiberglass roving was not used at
the project sites for the following reasons:
229
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TABLE VIII-13
EQUIVALENT EQUIPMENT AND
Excelsior
Plastic Netting
Jute
Paper Fabric
FOR INSTALLATION
PERSON-
DAYS PER
HECTARE
$130.5
60.0
93.5
95.5
*Note: Does not include seed,
LABOR COSTS
OF MULCH NETS ' AND BLANKETS
MATERIALS
$3,404
1,293
5,294
5,814
fertilizer
DOLLARS/HECTARE
EQUIPMENT LABOR
$804 $16,965
370 7,800
576 12,155
588 12,415
or other mulch costs.
TOTAL*
$21,173
9,463
17,449
18,229
- aesthetic and environmental concerns regarding its use
— the close proximity of an extensive experimental
fiberglass roving installation near the Rubicon
Properties erosion control project site (El Dorado
County milepost 22.8 on State Highway 89)
Fiberglass roving is formed from molten glass. It is manufactured-for a
variety of products that utilize fiberglass and commonly is produced in a
coiled package. The roving is fed through a special nozzle connected to
an air compressor. The compressed air propels and separates the strands
of glass fibers, spreading them evenly over the ground surface. A tack
coat of asphalt Cor other tackifier) is applied over the roving to bind
the strands together and to insure adhesion to the soil (61). At the
experimental fiberglass roving site near Rubicon Properties, the area was
seeded with grasses and native shrub seeds and fertilized prior to the
roving application. The application of fiberglass roving is pictured in
Figure VIII—45. Fiberglass roving has also been effectively used by
CalTrans to control erosion in drainage ditches and swales.
Fiberglass roving has the disadvantage of being nonbiodegradable and,
if associated revegetative measures do not succeed, will leave an
unsightly slope covering. Considerable objections have been raised
regarding the use of synthetic or nonbiodegradable materials for
erosion control within the Lake Tahoe Basin. This is particularly true
for materials such as fiberglass roving with its obviously unnatural
appearance.
230
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Figure YIII-^45. Application of fiberglass roving with a
compressed air gun.
HYPOTHETICAL ONE HECTARE ROAD CUT
PAVED ROAD SURFACE
NOTE= NOT DRAWN TO SCALE.
Figure VIII-r46. Hypothetical one hectare steep, eroding, cut slope
adjacent to a road surface.
231
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Roving Costs. CalTrans recommends that fiberglass roving be applied
to a site within 24 hours after normal seeding operations have been
conducted. The fiberglass roving itself should be applied uniformly to
form a random mat of continuous glass fiber at a rate of 0.15 to 0.20
kilogram per square meter. Asphaltic material applied over the roving
should be applied at a rate of 1.10 to 1.60 liters per square meter. It
is recommended that the upgrade end of the roving be buried in a shallow
ditch above the crown of the slope. Total treatment cost for fiberglass
roving, including seed and fertilizer, was estimated by CalTrans to be
about $6,000 per hectare in 1974. Estimated installed cost for fiber-
glass roving as of July 1976 is $8,000 per hectare.
G. Comparative Erosion Control Costs
The preceding pages of this section have described in detail a wide
variety of erosion control measures. Where possible, an individual
breakdown of unit materials, equipment, and labor costs is provided
with each method. The reader should refer to individual methods and
to the assumptions listed at the beginning of this section to determine
how individual cost estimates were developed. Particular attention in
the demonstration project has been paid to the most cost-effective meth-
ods for erosion control on oversteepened slopes in and around the Lake
Tahoe Basin of California. A "hypothetical" eroding cut slope is used
for the purpose of cost comparison. Such a hypothetical 1.0 hectare
eroding cut slope is pictured in Figure VIII-46. The slope has an aver-
age slope length of 10 meters and runs for 1,000 meters adjacent to a
paved roadway. It is further assumed that the cut has an average slope
angle of 1.25:1 and is continually sloughing eroded material into a
poorly constructed drainage structure running along the slope toe. For
all practical purposes, this situation is considered to be typical of the
erosion problems found throughout the Tahoe-Sierra although actual slope
dimensions vary considerably from case to case.
Table VIII-14 summarizes the unit costs and the total costs of selected
erosion control techniques if they were applied to the hypothetical 1.0
hectare road cut. The column entitled "percent labor" refers to.the
percentage of the total unit cost which is devoted to labor costs at
$16.25 per person-hour. Those percentages which are followed by an
asterisk indicate those tasks where a majority, if not all, of the labor
could be performed by unskilled conservation corps workers.
As can be seen in Table VIII-14, erosion control costs vary considerably.
Alternative erosion control techniques vary from a single pass with hydro-
mulching equipment at a cost of $1,800 per hectare to an extensive gabion
revetment structure costing $227,800 per hectare. Neither of these
approaches should be considered appropriate methods for controlling
erosion on this type of slope. Based upon the various methods demon-
strated at the Northstar and Rubicon Properties erosion control project
sites, the best approach would be as follows:
232
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Hypothetical Scenario
1. Construct a curb, gutter and bench system
at the toe of the eroding slope
2. Manual scaling and overhang removal
3. Debris cleanup and removal
4. Three rows of contour willow wattling
5. 100 kg/ha of seed materials covered with
4,500 kg/ha straw mulch and chemical
tackifier treatment
TOTAL
$15,620/1000 meters
9,644/ha
4,086/ha
18,420/3000 meters
2,200/ha
$49,970/ha
It is important to note that all labor costs for the above methods are
assumed to be $16.25 per person-hour. Total erosion control costs may be
reduced significantly if conservation corps workers are used on portions
of the tasks requiring unskilled laborers. For example, if conservation
corps workers costing approximately $5.00 per person—hour were used where
possible to perform nonskill oriented tasks the total cost of the above
erosion control scenario would be reduced from $49,920 per hectare to
$30,387 per hectare. This represents almost a 40 percent cost reduction.
Nevertheless, even if conservation corps workers are used to the fullest
extent, almost 25 percent of the labor required must still be performed
by skilled or semi-skilled laborers using heavy or specialized equipment.
Certain situations will arise when application of the above scenario may
be difficult. The construction of a curb, gutter, and substantial bench
system at the toe of the slope requires commitment of a portion of the
road right-of-way for this purpose. In some instances, this may require
reduction of the required paved road surface or shoulder to less width
than is required by state law or county ordinance. If this is the case,
then either, 1) exceptions must be made to allow for the construction of
a curb, gutter, and bench system, or 2) other alternative stabilization
techniques must be employed. If a rock or gabion breast wall were con-
structed in place of a curb, gutter, and bench system at the edge of the
existing road shoulder, the total cost for implementation of the above
scenario would be almost doubled from $49,970 per hectare to over $93,000
per hectare. Because of the considerable added expense the construction
of major breast wall structures should be avoided wherever possible.
Other substitutions may be made in the above scenario depending upon
the resources available to perform the required tasks. However, no
alternative scenarios are likely to be as cost-effective as the one
listed above for severe, steeply eroding slopes. All of the selected
erosion control methods listed in Table VIII-14 will be effective in
controlling erosion if used in the proper situations.
H. Preliminary Evaluation of'Erosion Control Effectiveness
This erosion control project has resulted in the construction and imple-
mentation of various erosion control demonstration plots at Northstar-
At-Tahoe and Rubicon Properties. These .demonstrations were conducted at
233
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TABLE Till- 14
COMPARATIVE EQUIVALENT UNIT 'COSTS FOR
' SELECTED 'EROSION 'CONTROL METHODS
USED ON OVERSTEEPENED ' SLOPES
MECHANICAL 'STABILIZATION UNIT COST % 'LABOR
Curbs and Dikes $ 15.62/m 50
1.00m Rock Breast Wall 61.16/m 45
0.90m GaBion Breast Wall* 58.61/m 52*
2.70m GaBion Retaining Fall* 190.48/m 52*
Manual Slope Scaling* 42.68/m;: 96*
Cleanup & DeBris Removal* 0.41/m 96*
Contour Wattling* 6.14/m 82*
GaBion Revetments* 27.78/ni2 40*
Concrete Anti-erosion Grids 24.67/m 48
Gunite Revetments 10.76/m 27
REVEGETATION
Willow Staking* $ 0.60/stake 95*
Rooted ShruB Cuttings* 1.36/plant 60*
Bare Root Seedlings* . 63/plant 86*
Seed w/2800 kg/ha Hydromulch .IS/nu 30
Seed w/5600 kg/ha Hydromulch . 27/m^ 30
Seed w/4500 kg/ha Tacked Straw . 22/nu 30
Seed w/Jute* 1.84/m^ 70*
Seed w/Paper FaBric* 1.92/nu 68*
Seed w/Excelsior* 2.16/m 79*
Seed w/Straw & Plastic Net* 1.07/m. 73*
Seed w/FiBerglass Roving . 80/m N/A
* Those tasks where a large portion of the work may
unskilled conservation corps laBorers.
COST PER
HYPOTHETICAL
HECTARE
$ 15,620
61,160
58,610
190,480
9,644
4,086
18,420
277,800
246,700
107,600
$ 24,000
54,400
26,080
1,800
2., 700
2,200
18,400
19,200
21,600
10,700
8,000
Be performed By
Northstar and RuBicon Properties from the summer of 1976 through the
spring of 1977. Prior to 1975, the Soil Conservation Service (SCS) also
established a number of shruB and herBaceous planting demonstration plots
at Northstar in the spring of 1973 and the spring of 1974. In all cases,
the demonstration plots were intended to identify and demonstrate the
effectiveness of techniques which could Be used to control the various
types of slope staBilization and erosion proBlems which were found at
the project sites. In the case of Northstar, only a few scattered ero-
sion proBlems could Be identified. The RuBicon Properties project site,
234
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on the other hand, required extensive erosion control and slope stabili-
zation corrective measures on over 13 percent of the subdivision's land
surface. Complete descriptions of the plots and the various combinations
of demonstrated techniques which were conducted as part of this project
and as part of the previous work by the SCS are given in Appendix B of
this report.
The plots at Northstar and Rubicon Properties demonstrate the wide range
of technologies available to stabilize and revegetate severely eroding
slopes. It is estimated that these various types of "source control"
techniques will be effective in reducing previous erosion and sediment
yield rates by 80 to 90 percent. Any erosion control technology can be
deemed successful, however, only if it withstands the test of time.
Time has not yet enveloped this demonstration project, so only prelimi-
nary observations and comparisons can be made.
Toe Stabilization. Rock walls and gabion baskets seem equally effective
when properly positioned and constructed. The large rocks in walls have
channeled water to low spots between rocks and caused some erosion at
those points. The gabion baskets have received multiple wounds from
snow plows. They are particularly vulnerable to this type of damage,
and ideally should be thoroughly snow staked. Repair of damage has
proven difficult because of rolled asphalt gutters at the base of
baskets. Gabions are also considered very ugly by most people. They
gradually fill with dirt, however, so plant growth in them should be
possible in the future. Willows placed through the gabions into the
backfill during construction at Rubicon Properties are doing well, as
are willow bundles placed behind gabions prior to completion of
Backfilling.
Gutters and dikes are effective when rebuilt to form a bench at the toe
of a steeply eroding slope, and frequently cost less than 25 percent of
•gabion or rock wall construction costs. Gutters and dikes also have
fallen prey to snow plows and other types of heavy equipment and can
only remain effective if protected by snow stakes and careful maintenance.
Willow Wattling. The pattern of growth and survival of willow wattling
at Rubicon Properties points to the benefits of gathering and placing
willow wattling when the plants are dormant or semi-dormant. Willows
gathered in July, August and early September did not survive despite
careful handling and regular irrigation. Willows gathered and placed in
late September, May, and early June, while dormant or semi-dormant,
have produced a profusion of shoots. Even though long term survival is
still a matter of conjecture, correctly installed willow wattling pro-
vides a tremendous degree of mechanical soil stabilization even if the
willow branches eventually die. Willow wattling considerably improves
the opportunity for other types of plants to take root and grow.
Plantings. The Northstar shrub plantings resulted in better survival
than has been the case with other plantings in the Tahoe Basin. This
is probably due to the relatively good soil and gentle slopes which
characterize most of the Northstar Plots. The top performers among the
235
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shrubs include several natives, Chrysothamnus nauseosus, PUrshia
tridentata, Artemisia tridentata, Penstemon newberryi, Atriplex canescens,
and Eriogonum umbellatum and several exotics, Caragana arborescens,
Penstemon strictus,'Salix gracilis, and Salix purpusea.
Seeding. Among the grasses, two wheatgrasses, "Tegmar" and "Luna",
proved outstanding. All herbaceous seeding plots were evaluated in late
July 1977. Grass stands were rated on a relative scale from 1 to 10;
with one indicating no seeding and ten indicating the best stand on the
site. Evaluations were judgmental, rather than quantitative. The over-
all impression of the various treatments on the Rubicon site was that
they were very similar. On the 1-10 scale, the maximum difference
between treatment means was about 2 points. If this trend continues,
then there will be no real differences between treatments, and the most
cost effective methods will be those that are least expensive.
Some small treatment differences have been observed. The higher seeding
rate (86 kg/ha) tends to produce a denser initial grass stand than the
lower seeding rate C41 kg/ha). The additional seed is relatively inex-
pensive and therefore, may be justifiable. The higher wood fiber mulch
rate C5600 kg/ha) produced a slightly better grass stand on the average
than the lower mulch rate (;2800 kg/hal. The additional mulch cost
almost $900 per hectare; thus additional mulch may not be cost effective.
Straw mulched plots produced slightly better initial grass stands on the
average than the hydromulched plots.
Mulch remaining after the first winter and spring was also evaluated in
July 1977. Results, expressed as percentage of plot still covered with
mulch, are as follows;
wood fiber @ 2800 kg/ha
wood fiber @ 5600 kg/ha
straw @ 4500 kg/ha
53%
82%
5 5% A/
The remaining straw mulch coverage for the different tackifiers was as
follows:
wood fiber CL100 kg/ha) as tack
Ecology Control
Dow XFS 4163-L
Terratack II
Terratack II Super Concentrate
70%JB/
50%
70%
50%
40%
Future evaluations will yield more definitive results and possibly reveal
the best method, or methods.
_A/ Average coverage for all straw tackifier treatments.
B/ Wood fiber coverage includes ground covered by the wood fiber tacki^
fier as well as ground covered by straw.
236
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SECTION IX
INSTITUTIONAL PROCEDURES FOR EFFECTIVE EROSION CONTROL
Sufficient regulatory control now exists in California to insure that problems
similar to Rubicon Properties can never develop in the future. The
California State Water Resources Control Board (State Board) and the nine
Regional Water Quality Control Boards (Regional Boards) have regulatory
authority over the water resources of the State (62). As empowered by the
laws of the State of California, one of the regulatory tools available to the
State and Regional Boards is the establishment of waste discharge requirements.
In addition to other types of pollutants, waste has also been defined to
include "waste from construction activities". This has been interpreted in
court to include eroded sediments resulting from improper construction
methods. If waste discharge requirements established for a particular
discharge are violated, then several alternatives are available to a Regional
Board to force a discharger into compliance. Among them are:
A time schedule for compliance with waste discharge requirements
may be ordered by a Regional Board,
A Cease and Desist Order requiring tb_e discharger to comply with
waste discharge requirements may be adopted by a Regional Board,
A Cleanup and Abatement Order-may be issued to the discharger re-
quiring him to cease discharging waste in violation of waste dis-
charge requirements and cleanup any waste discharged to the waters
of the State.
further violation of waste discharge requirements or any of the above orders
may be referred to the Attorney General of the State to collect civil
monitary remedies from the discharger for up to $10,000 per day, or to enjoin
such activities as may be causing violation of waste discharge requirements.
In the case of the operation of wastewater treatment plants in California,
the State and Regional Boards are not allowed to specify which treatment
processes must be used to meet waste discharge requirements. However, unlike
wastewater treatment plants,- California Law (Water Code, Section 13360) permits
the State and Regional Boards to describe specific methods which must be used
to control eroding (or threatening to erode) waste earthen materials. Typical
waste discharge requirements which may be applied by the Regional Board in the
Lake Tahoe vicinity to current and proposed future construction projects
which pose existing or threatened erosion problems are as follows:
237
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A. General Waste Discharge Requirements
. The discharge of treated or untreated domestic sewage, industrial
waste, garbage or other solid wastes, or any other deleterious
material to surface waters is prohibited.
The discharge, attributable to human activities, of solid or liquid
waste materials, including soil, silt, clay, sand, and other organic
and earthen materials, to surface waters is prohibited.
The discharge, attributable to human activities, of solid or liquid
waste materials, including soil, silt, clay, sand, and other organic
and earthen materials, to lands within the highwater rim (Elevation
6229.1 ft. MSL) of Lake Tahoe or within the 100-year flood plain of
any tributary to Lake Tahoe is prohibited.
. The discharge shall not cause a pollution.
Neither the treatment nor the discharge of waste shall cause a
nuisance.
The discharge shall not cause any measurable color, odor, bottom
deposits, floatable materials,, oil, grease, or radionuclides to be
present in any surface waters,
B. Specific Waste Discharge'Requirements
1. Construction Drainage
The transport of suspended sediment by drainage or surface flows
from disturbed areas under construction to adjacent land areas or
surface waters is prohibited.
Adequate erosion control and sediment or surface flow containment
facilities shall be constructed and maintained to prevent discharge
of waste earthen material from disturbed areas under construction.
There shall be no significant modification of existing drainage
ways or existing stream channel geometry which would allow a '
discharge of sediments or eroded materials to adjacent properties
in violation of other provisions of these requirements.
Earthen berms or other sedimentation barriers shall be located
downgradient from construction areas to prevent the discharge of
earthen waste onto adjacent land areas or surface waters.
Rock slope protection aprons shall be placed at the outlet of all
culverts to prevent scour.
238
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All disturbed street surfaces shall be periodically sprinkled
lightly and swept by a mechanical sweeper as necessary to prevent
fine material from being discharged into drainage ways.
The length of the open trench at the end of each working day shall
not exceed 50 feet.
Any damage or break in existing water lines shall be immediately
repaired and measures must be immediately implemented to prevent
erosion or sedimentation into any drainage way.
Water discharged from any sewage or water facilities including water
from testing lines shall be disposed of in such a manner as to not
cause erosion or sedimentation or discharge of waste earthen
materials into any drainage way.
2. Construction Waste
The discharge of surplus or waste material including, but not
limited to, soil, sand, silt, clay, or other earthen materials, to
drainage ways is prohibited.
The placement of waste earthen materials in such a manner as to
allow the discharge of any portion of such materials to adjacent
drainage ways is prohibited.
There shall be no surplus or waste material, including soil, sand,
silt, clay, or other earthen materials, placed in drainage ways.
All loose piles of soil, silt, sand, clay, debris, and other earthen
materials shall be protected in a reasonable manner to eliminate
discharge to waters of the State.
All surplus soil, silt, sand, clay, or other earthen materials shall
be removed from the site after construction and deposited in a loca-
tion so as to eliminate the sedimentation of surface waters.
All rock riprap used for slope protection shall be cleaned of soil
and carefully placed so as not to cause sedimentation or increased
turbidity in surface waters.
Materials used in dams, dikes, and levees used in creek crossings
shall consist of sandbags filled with clean sand or other nonsilting
materials.
At all creek crossings, and whenever the natural bank of the river
is disturbed, or where called for on the construction plans, rock
riprap slopes protection shall be provided for erosion protection
during high flows.
239
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Fresh concrete and cement shall not be allowed to enter surface
waters.
3. Storm Runoff
Effluent discharged from a grease trap/sedimentation basin shall
not appear as surface flow, but must be infiltrated by a subsurface
percolation bed, except for a greater than 1 hour 20-year storm.
A maintenance program shall be established to ensure proper opera-
tion of the grease trap/sedimentation basin and subsurface
percolation bed.
Waste removed from the grease trap/sedimentation basin shall be
disposed of in an approved manner.
Drainage collection, retention, and infiltration facilities shall be
constructed and maintained to prevent transportation of waste from
areas of completed construction.
Surface flows from the subject property shall be controlled so as
to not cause downstream erosion at any point.
Storm runoff from paved areas shall be diverted to percolation
facilities on the project site.
The infiltration trench system shall be installed around the
perimeter of the site and shall be so designed such that any runoff
in excess of the trench storage and percolation capacity is
discharged to a storm drain.
An oil and grease trap shall he installed in the storm drainage
system immediately prior to discharge to the storm drain.
Sheet flow of runoff shall be retained to prevent drainage
concentrations.
Suitably designed, gravel filled infiltration trenches are to be
located under roof drip lines.
Trenches at the edge of driveway and parking areas shall be cleaned
periodically to remove grease and gasoline residues that may
accumulate.
Energy dissipators shall be provided where erosive velocities will
occur.
Cross ditches shall be installed and maintained on slopes where
vegetation does not provide adequate soil stabilization.
240
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4. Disturbed Areas
There shall be no disturbance of natural vegetation or soil
conditions except where erosion control measures can be installed
and operational prior to October 15 of each year.
There shall be no disturbance of natural vegetation or soil condi-
tions between October 15 and May 1 of each year.
Cut and fill slopes which may result from construction on the
subject property shall be designed with slopes not exceeding two
horizontal to one vertical.
All nonconstruction areas shall be protected by barriers or fencing
to prevent disturbance.
Stream alteration areas and stream relocation areas shall be
stabilized by the addition of rock slope protection as necessary,
periods of no flow.
Ephemeral stream relocation areas shall be flared at each downstream
end to conform to existing stream patterns.
5. Revegetation
Disturbed areas shall be adequately restabilized and the
stabilization facilities shall be continually maintained.
All cut and fill slopes, except predominantly rocky areas, shall be
reseeded and/or revegetated with plants indigenous to the area. A
cut and fill slope management program shall be implemented to ensure
that all reseeded areas develop root systems sufficient to prevent
erosion.
6. Effluent Limitations
The discharge from the subject site shall not contain any percep-
tible floating material including, but not limited to solids,
liquids, foams, and scums.
The discharge from the subject site shall not contain oils, greases,
waxes, or other hydrocarbon or petroleum derivative materials that
cause visible film or coating on the surface of the receiving water
or on objects in the receiving water.
The discharge from the subject site shall not contain settleable
substances in concentrations that may result in the deposition of
material in any surface waters.
241
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The discharge from the subject site shall not have a pH value below
7.0 units nor greater than 8.4 units.
The discharge from the subject site shall not contain substances in
concentrations individually, collectively, or cumulatively toxic,
harmful, or deleterious to humans, animals, birds, or aquatic
biota, including, but not limited to, those substances specified in
the California State Drinking Water Standards.
All surface flows generated from the project site which are dis-
charged to surface waters or storm drainage systems shall not
contain constituents in excess of the following limits:
Constituent Units
Total Nitrogen mg/l-N
(Nitrate & Kjeldahl)
Total Phosphate mg/l-P
Turbidity FTU
Suspended Sediment ™S/1
Phenolic Compounds mg/1
C.O.D. mg/1
MBAS mg/1
Apparent Color c.u.
Meanl/
0.25
0.02
3.0
25
Maximum
1.5
0.1
20
80
0.04
10
0.15
5
— Arithmetic mean value of any ten (10) consecutive samples.
If the water quality constituent levels of waters entering or
passing adjacent to the subject property or any work area or waste
producing facility within the subject property from upstream areas
are' of a superior or equal water quality to the numerical standards
above, those waters shall meet the water quality constituent levels
listed above prior to discharge from the property.
Lf the water quality constituent levels entering the subject
property or any work area or waste producing facility within the
subject property exceed the numerical standards specified above,
there shall be no more than a ten percent increase in the down-
stream value as compared to the upstream value.
242
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7. Provisions
The discharger shall comply with the Monitoring and Reporting
Program and requirements established by the Regional Board.
The discharger shall immediately notify the Regional Board by tele-
phone whenever an adverse condition occurs as a result of this
discharge; written confirmation shall follow.
Any proposed material change in the character of the waste, method
of disposal, increase of discharge, or location of discharge shall
be reported to this Regional Board. This shall include all
signifficant soil disturbances and stream channel modifications.
The Regional Board reserves the privilege of changing all or any
portion of the waste discharge requirements upon legal notice
and after opportunity to be heard is given to all concerned parties.
The owner of the property subject to waste discharge requirements
shall be considered to have a continuing responsibility for ensuring
compliance with applicable waste discharge requirements in the
operation or use of the owned property. Any change in the ownership
and/or operation of the property subject to waste discharge require-
ments shall be reported to the Regional Board. Notification of
applicable waste discharge requirements shall be furnished the new
owner(s) and/or operator(s). A copy of such notification shall be
sent to the Regional Board.
Surface waters, as used in this Order, include, but are not limited
to, live streams, either perennial or ephemeral, which flow in
natural or artificial water courses and natural lakes and
artificial impoundments of waters within the State.
C. A Case History
The enforcement of the above waste discharge requirements for ongoing or
future construction activities is relatively straightforward. An entity or
person found to be in violation of waste discharge requirements may be
enjoined, be forced to pay stiff monitary remedies, and/or receive a jail
sentence. In the Lake Tahoe vicinity, the Regional Board is actively engaged
in applying waste discharge requirements of the type listed above to new
construction projects. Coupled with vigorous enforcement, waste discharge
requirements have altered construction activities so that they produce even
less severe erosion and sediment related pollution problems than the low
levels found at Northstar (less than a one fold increase above natural
background levels). Certainly, there will never be future developments which
have such severe erosion and sediment control problem as are found within the
Rubicon Properties Subdivision.
243
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With present and future construction related erosion and sediment problem well
under control, the remaining problem is to control erosion and sediment pollu-
tion generated by past construction activities. Erosion control at Rubicon
Properties is an excellent example of the types of problems which are
encountered in controlling erosion in past developments. The original
developer of Rubicon Properties has long since sold all interest in the
development. Most likely he cannot be held accountable for the poor planning,
construction, and development practices exhibited there. The only potentially
responsible parties are the several hundred hapless individual landowners
within the development and the County. The following chronology of events
is a brief description of the attempts that were made t:o control erosion
problems within Rubicon Properties.
In 1970, the California Regional Water Quality Control Board, Lahontan Region
(Lahontan Regional Board) established waste discharge requirements on the
County and over 200 privately owned parcels within«Rubicon Properties
Subdivision, Unit No. 2 (upper portion) (63). This was the initial formal
attempt to coerce the County and the landowners into correcting the massive
erosion problems that existed there. Replies were received from over 50
percent of the landowners, all of which stated, to the effect, that their
individual holdings were not contributing to the erosion problems. Further-
more, the landowners requested that they no longer be described as
"dischargers". Without lengthy court proceedings, it would have been
difficult cult to prove that they were dischargers and were responsible for
the erosion problems. The County, although remiss in accepting the
Subdivision in the first place, was unable to proceed because of a lack of
funds and knowledge concerning effective erosion control.
By 1971, the Lahontan Regional Board adopted an interim basin water quality
control plan which formally established the following beneficial uses for the
waters of the Lake Tahoe Basin (64):
Domestic supply
Agricultural supply
. Water contact recreation
Nonwater contact recreation
Scientific study
Fresh water habitat
Fish spawning
To protect the beneficial uses, the interim basin furthermore established
several waste discharge prohibitions, including:
. The discharge of solid or liquid materials, including soil, silt,
clay, sand, and other organic and earthen materials, to Lake Tahoe
or any tributary thereto.
The discharge of solid or liquid waste materials, including soil,
silt, clay, sand, and other organic and earthen materials, to lands
244
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below the hlghwater rim of Lake Tahoe or within the 100-year
flood plain of any tributary to Lake Tahoe.
The threatened discharge of solid or liquid waste materials, includ-
ing soil, silt, clay, sand, and other organic and earthen materials,
due to the placement of said materials below the highwater rim of
Lake Tahoe or within the 100-year flood plain of any tributary to
Lake Tahoe.
In 1972, the Lahontan Regional Board proceeded with an intensive water
quality investigation within Rubicon Properties. The purposes of this
investigation were twofold (1) to determine the overall extent of the erosion
problem, and (2) to determine the principle sources of eroded sediment within
the Subdivision. The investigation determined that the roadway cuts and fills
adjacent to. county maintained roadways and extending onto many private
parcels, were primarily responsible for the massive sediment load of Lonely
Gulch Creek. Although unable to quantify the annual sediment load at that
time, the Lahontan Regional Board substantiated the large reduction in insect
species populations and diversity within the Creek, It was concluded that
erosion from-the development was the principle reason for the observed
reductions in aquatic life.
In 1973, the County retained the services of a consultant to determine what
procedures should be employed at Rubicon Properties to correct the erosion
problems (65). In addition, all major erosion problems were identified within
the Lake Tahoe Basin portion of the County and ranked as to degree of severity.
Rubicon Properties, Unit No. 2, was ranked as the number one priority problem.
The total cost of erosion control of all problems within the County was iden-
tified to be $1.5 million. The cost to solve the problems within Rubicon
Properties, Unit No. 2, was estimated at $218,089.
In 1974, The Lahontan Regional Board issued a second set of waste discharge
requirements naming the County as the sole responsible party for the
correction of the erosion problems within Rubicon Properties (66). October 1,
1975, was identified as the date by which all required erosion control work
must be completed. However, arguments were put forward by the County that
insufficient funds existed to correct the problems at Rubicon Properties. Even
though specific erosion control recommendations were made by the consultant,
the County also felt that insufficient knowledge existed to guarantee
success if the proposed control measures were implemented.' As a result, no
enforcement actions were taken by the Lahontan Regional Board and matters
appeared to have reached a state of impasse. Injunctions against the results
of past construction activities are meaningless and civil monetary suits
against public entities, such as the County, are difficult to obtain and
frequently accomplish very little.
In 1975, the Lahontan Regional Board adopted a plan which updated and
replaced the interim basin plan (67). Additional water quality objectives
were "established for Lake Tahoe, including specific objectives for Lonely
245
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Gulch Creek. Also in 1975, the upper portion of Rubicon Properties within
the Lonely Gulch Creek watershed was identified as an erosion and sediment
control site as part of this erosion control project by the State Board.
Until this time, very little had been done to control erosion at Rubicon
Properties beyond normal maintenance activities. However, because
additional funds were available to supplement their resources, the County
readily agreed to assist the State Board in demonstrating a variety of
erosion control techniques. Prior to 1975, the County had invested approxi-
mately $11,500 per year at Rubicon Properties, primarily for cleanup and
maintenance activities. However,, once additional funds were assured from
outside sources, the County expended the equivalent of $65,000 in county
manpower and equipment to-assist the State Board in correcting erosion
problems at Rubicon Properties. This was spent during the 15-month period from
July 1975 through September 1976. The erosion control measures which were
implemented at the Rubicon Properties as a result of this erosion control
project are fully described in Section VI and Appendices A and B.
Summary
Ample controls exist to insure that current and future construction
activities will provide sufficient erosion control. The control of erosion
from past activities, although ample regulatory control exists, requires a
substantial capital investment. For the most part, these capital investments
must be made by public agencies, as exemplified by the situation at Rubicon
Properties. The erosion control project has demonstrated that effective
erosion control does not have to be exorbitantly expensive and, if pre-
control maintenance costs are high, may be amortized in a relatively short
period of time (12.5 years or less in the case of the Rubicon Properties
project site) through local maintenance cost savings. However, the rapidity
at which erosion control problems generated in the past may be corrected can
only be rapidly accelerated if the resources of the directly responsible
local entity are supplimented by assistance from other interested public or
private contributors. The assistance could easily take the form of labor,
equipment, materials, or monitary contributions. As exemplified by the
chronology of events surrounding erosion control at Rubicon Properties,
without a certain degree of outside assistance, remedial erosion control of
past mistakes in rapidly developed areas, such as Lake Tahoe, will be an
extremely time-consuming if not impossible process.
246
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SECTION X
REFERENCES
1. "Sedimentation and Erosion in the Upper Truckee and Truckee and Trout
Creek Watershed, Lake Tahoe, California." Resources Agency, State of
California, July 1969.
2. Goldman, Charles R., "Eutrophication of Lake Tahoe Emphasising Water
Quality," U. S. Environmental Protection Agency, EPA-660/3-74-034,
December 1974.
3. Baker, John A., "Siltation Evaluation Investigation for the Lake Tahoe
Basin," California Regional Water Quality Control Board, Lahontan
Region, June 1976.
4. Debacker, George H., et al, "A Presentation of North Star," Tahoe City,
California, May 21, 1971.
5. "Development Plan Review," Eckbo, Dean, Austin & Williams, inc., San
Francisco, June, 1970.
6. "Logging Road and Protection of Water Quality," Environmental Protection
Agency, PB-243703, March, 1975.
7. "Sediment Yield and Land Treatment," U. S. Department of Agriculture,
September, 1972.
8. "An Investigation of Soil Characteristics and Erosion Rates on California
Forest Lands." Resources Agency, State of California, October, 1976.
9. "A Method for Regulating Timber Harvest and Road Construction Activity
for Water Quality Protection in Northern California." Water Resources
10. Dames and Moore, Thirteen Soils Report for Various Northstar Units,
between March 1971 and March 1972.
11. Eckbo, Dean, Austin & Williams, Nine Environmental Impact Reports for
Various Northstar Units, 1971 and 1972.
12. "Northstar-At-Tahoe Planting and Revegetation Management Program," Eckbo,
Dean, Austin & Williams, San Francisco, August 1971.
247
-------
13. Zinke, Paul J., "Ecologic Review—Northstar-At-Tahoe," 1971.
14. Personal communication with Dick Englehardt, Vice-president, Northstar-
At-Tahoe, June 1977.
15. "Soil Survey: Tahoe Basin Area, California and Nevada," U.S.D.A.,
Washington, B.C., March, 1974.
16. Bailey, Robert G., "Land-Capability Classification of the Lake Tahoe
Basin, California-Nevada, a Guide to Planning," U.S.D.A., 1974.
17. "Ordinance No. 357: An Ordinance to Amend the El Dorado County
Subdivision Ordinance (No. 139) by Adding Provisions Relating to Water
Supply and Distribution Systems, and Specifications for Road Construction,
"El Dorado County, March 30, 1959.
18. "Policy for the Administration of Water Rights in the Lake Tahoe Basin,"
California State Water Resources Control Board, July 15, 1976.
19. "Notice to Water Users in the Lake Tahoe and Truckee River Basins,"
California State Water Resources Control Board, July 15, 1976.
20. Burgy, Robert H. and Allen W. Knight, "The Tahoe Basin Siltation
Monitoring Program, Interim Report," State Water Resources Control Board,
the Resources Agency, State of California, Sacramento, California, 1973.
21. Guy, H. P., "Laboratory Theory and Methods for Sediment Analysis"; U. S.
Geological Survey Techniques Water-Resources Inv., Book 5, Chap. Cl,
p. 58, 1969.
22. "Standard Methods for the Examination of Water and Wastewater," 13th
Edition, American Public Health Association, New York, 1970.
23. Needam, Paul R. and Robert L. Usinger, "Variability in the Macrofauna of
a Single Riffle in Prosser Creek, California, as Indicated by the Surber
Sampler," Hilgardia, Vol. 24, No. 14, pp. 383-409, 1956.
24. Allen, K. R., "The Distribution of Stream Bottom Fauna." Proc. N. Z. Ecol.
Soc. 6, 5-8, 1959.
25. Davis, William E., "The Effects of Physical Degradation on the Benthos
of a Northern California Stream," Masters Thesis Humboldt State College,
Arcata, California, 1966.
26. Cairns, J., Jr. and K. L. Dickson, "A Simple Method for the Biological
Assessment of the Effects of Water Discharges on Aquatic Botton-Dwelling
Organisms." Journal of the Water Pollution Control Federation,, 43(5):
755-772, 1971.
27. Usinger, Robert L., Editor. Aquatic Insects of California. University
of California Press, Berkeley, 1971.
248
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28. Ward, Henry B. and George Whipple, Fresh-Water Biology. John Wiley and
Sons, Inc., New York, 1959.
29. Pennak, Robert W., Fresh-Water Invertebrates of the United States, Ronald
Press Company, New York, 1953.
30. Allen, J. T. and A. W. Knight, "The Use of Benthic Assemblages to Assess
Stream Perturbation Effects: Data Analysis Methods." Tahoe Basin
Siltation Evaluation Program, State Water Resources Control Board,
Sacramento, California, 1974.
31. Egloff, D. A. and W. H. Brake!, "Stream Pollution and a Simplified
Diversity Index." Journal of the Water Pollution Control Federation,
46 (11): 2269-2275, 1973.
32. Sokal, Robert F. and F. James Rohlf, Biometry, W. H. Freeman and Co.,
San Francisco, 1969.
33. Hutcheson, K. "A Test for Comparing Diversities Based on the Shannon
Formula." Journal of Theoretical Biology, 29: 151-154, 1970.
34. "Whittaker, R. H., "Gradient Analysis of Vegetation," Biological Reviews
42:207-264, 1967.
35. "Snow Survey Sampling Guide," U. S. Soil Conservation Service Agr.
Handbook 169, December 1953.
36. Tebo, L. B., Jr.,"Effects of Siltation, Resulting from Improper Logging,
on the Bottom Fauna of a Small Trout Stream in the Southern Appalachians."
Prog. Fish-Cult., Vol. 17, No. 2, pp. 64-70, 1955.
37. Cordone, A. J. and D. W. Kelley, "The Influences of Inorganic Sediment
on the Aquatic Life of Streams." California Fish and Game, 47(2):
189-228, 1961.
38. Marlier, G., "Recherches Hydrobiologiques dans les Rivieres du Congo
Oriental II. Etude Ecologique." Hydrobiologia, 6, 225-64, 1954.
39. Hornuff, L. E., "A Survey of Four Oklahoma Streams with Reference to
Production." Rep. Okla. Fish. Res. Lab. 62, 1-22, 1957.
40. Fitthau, E. J. "Remarks on Limnology of Central-Amazon Rain Forest
Streams." Verh. int. Verein. theor. angew. Limmol. 15, 1092-6, 1964.
41. U. S. Environmental Protection Agency, Office of Water Programs
Operations, Comparative Costs of Erosion and Sediment Control Construction
Activities, July 1973.
42. U. S. Environmental Protection Agency, Office of Research and Monitoring,
Guidelines for Erosion and Sediment Control Planning and Implementation,
August 1972.
249
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43. U. S. Environmental Protection Agency, Office of Air and Water
Programs, Processes, Procedures, and Methods to Control Pollution
Resulting from all Construction Activity, October 1973.
44. U. S. Environmental Protection Agency, Office of Water Planning and
Standards, Methods of Quickly Vegetating Soils of Low Productivity,
Construction Activities, July 1975.
45. State of California, Department of Transportation, Equipment Rental Rates
and General Prevailing Wages Rates, June 1976
46. Leiser, Nussbaum, Kay, Paul, and Thornhill, Revegation of Disturbed Soils
in the Tahoe Basin, California Department of Transportation, June 1974.
47. U. S. Department of Agriculture, U. S. Forest Service, Forest Service
Manual, Title 2500 - Watershed Management, May 1976.
48. Regional Water Quality Control Board, Lahontan Region, Estimation of
Rainfall Excess by Soil Cover Complex Analysis; Infilitration Trench
Design, unpublished staff report by Gerard Thibeault. March 1977.
49. U. S. Department of Agriculture, Soil Conservation Service, National
Engineering Handbook, 1964.
50. Hjedmfelt and Cassidy, Hydrology for Engineers and Planners, Iowa
University Press, Ames, 1975.
51. Peurifoy, R. L., Estimating Construction Costs, McGraw - Hill, New York,
1975.
52. Kraebel, C. J., "Erosion Control on Mountain Roads", U. S. Department of
Agriculture Circular No. 380, March 1936.
53. U. S. Department of Agriculture, Soil Conservation Service, Plant
Materials Study - A Search for Drought Tolerant Plant Materials for
Erosion Control, Revegetation, and Landscaping Along California Highways,
June 1976.
54. Kay, Burgess L.; "Revegetation of Mountain Sites Above 3,000 ft. in
California, Agronomy Progress Report, No. 53 University of California,
Davis, September 1973.
55. Kay, Burgess L.; "Role of Fertilization in Planting of Critical Areas"
Erosion Control Symposium, Proceedings USDA - SCS, U. C. Davis, June
1974.
56. Kay, Burgess L.,' et al, "Pellet Inoculated Legume Seeds are OK in
Hydromulching", Agronomy Progress Report, No. 44, University of California,
Davis, August 1972.
250
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57. Kay, Burgess L.; "New Mulch Materials Tested for Hydroseeding" Agronomy
Progress Report, No. 39; University of California, Davis, July 1972.
58. Kay, Burgess L.; "The Role of Erosion Control Fibers and Chemicals",
Erosion Control Symposium, Proceedings, USDA - SCS, U. C. Davis,
June 1974.
59. Kay, Burgess L.; "Hydroseeding, Straw, and Chemicals for Erosion Control",
Agronomy Progress Report, No. 77, University of California, Davis, June
1976.
60. Kay, Burgess L.; "Tackifiers for Straw Mulch", Agronomy Progress Report,
No. 76 University of California, Davis, April 1976.
61. State of California, Department of Transportation, Fiberglass Roving for
Erosion Control, Highway Study Report, June 1974.
62. "The Porter-Cologne Water Quality Control Act," State of California, 1970.
63. Order No. 6-70-36, "Waste Discharge Requirements for Rubicon Properties
Unit Number 2 Subdivision, El Dorado County," California Regional Water
Quality Control Board, Lahontan Region, October 1, 1970.
64. "Water Quality Control Plan (Interim), North Lahontan, Basin 6A,"
California Regional Water Quality Control Board, Lahontan Region,
June 1971.
65. "Erosion Control and Surface Water Management, Lake Tahoe Portion of El
Dorado County," J. B. Gilbert and Associates, December 1973.
66. Order No. 6-74-87, "Waste Discharge Requirements for El Dorado County
Siltation.and Erosion Correction Priority Areas (Rubicon Properties)
Lake Tahoe Basin," California Regional Water Quality Control Board,
Lahontan Region, August 22, 1974.
67. "Water Quality Control Plan Report, North Lahontan Basin (6A),"
California State Water Resources Control Board, Lahontan Region,
April 1975.
251
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APPENDIX A
PLANT PROPAGATION FOR THE REVEGETATION OF ROAD
CUTS AND FILLS IN THE LAKE TAHOE BASIN
CONTENTS
Pae
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Introduction
Obj actives
Soil Mixes
Containers
Growing Conditions
254
255
256
256
257
Plant Materials - Principal Plants Investigated 257
Plant Materials - Other Species Investigated
Outplantings
Summary
Costs
267
270
273
276
252
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APPENDIX A
TABLES
Number Page
A-l Artemisia tridentata. Survival in 3 soil mixes, 3^
months after transplanting 258
A-2 Atriplex gardneri. Survival in various soil mixes and
container types, 5 months after planting 258
A-3 Penstemon newberryi. Survival in 3 containers and 3 soil
mixes, July and August, 1976 260
A-4 Rooting of Prunus emarginata root suckers under various
conditions 262
A-5 Response of Prunus emarginata seeds to hot and cold
water pre-soaking and three stratification regimes 262
A-6. Response of Prunus emarginata seeds to soaking times and
temperature during stratification, fall 1976 264
A-^7 Survival of Prunus emarginata seedlings in 3 containers,
spring 1977 264
A-8 Purshia tridentata seed response to several pre-germination
treatments, spring 1976 265
A-9 Effect on hormone and cutting diameter on rooting of Salix
lemmonii and S. lasiantra 266
A-10 Salix spp. Comparison of rooting of several species of
Salix as influenced by cutting diameter and hormone
treatment 268
A-ll Inventory of plant materials delivered to Rubicon Properties
Erosion Control Project Site 271
A-12 Total Cost of Rooted Cuttings 277
A-13 Growing Cost Summary—Unit Costs 279
253
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APPENDIX A
Plant Propagation for the
Revegetation of Road Cuts and Fills
in the Lake Tahoe Basin
Department of Environmental Horticulture
University of California, Davis
Andrew T. Leiser, Principal Investigator
for
California 'State Water Resources Control Board
1. Introduction
Highway cuts and fills in the Lake Tahoe Basin often are slow to establish
vegetation cover or do not establish such cover at all. The soils and sub-
soils of this area are subject to extreme erosion when devoid of vegetation
because of the course textured soil types, periods of heavy water run-off,
frost heaving and wind action. This erosion is detrimental to streams and
lakes in the Lake Tahoe Basin, causes costly road maintenance work, endangers
property and people and is aesthetically objectionable.
A 3% year study for the California Department of Transportation (CalTrans)
completed in 1974 has shown that it is possible to revegetate these difficult
sites with combinations of mechanical stabilization and revegetation using
native plant species. The time and financial restraints of this project
were such that only a portion of the potentially useful native plant spectrum
were tested in adequate quantities and several possible techniques of mechani-
cal and vegetative stabilization were either not evaluated or were evaluated
in a limited way. Although much was learned about the propagation, culture
establishment of native plant materials on these difficult sites, the usable
plant spectrum is limited by our present knowledge. Survival and growth of
those species tested in quantity (e.g. Arctostaphylos nevadensis, pine mat
manzanita; Artemisia tridentata, big basin sagebrush; Ceanothus prostratus,
squaw carpet; Purshia tridentata, Antelope brush; and Penstemon newberryi,
mountain pride) might be enhanced by better cultural practices which would,
for example, permit development of better root systems. A number of species
were evaluated in very limited quantities (e.g. Symphoricarpos acutus, creep-
ing snowberry; Lonicera conjugialis, double-fruited honeysuckle; Chryso-
thamnus nauseosus, rabbit brush; Arctostaphylos patula, green leaf manzanita;
Cercocarpus ledifolius, curl leaf mountain mahogany; Rhamnus rubra, Sierra
coffeeberry; and Spiraea densiflora, mountain spiraea) because of limited
254
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resources, difficulty of propagation and growth, or lack of propagating
material (i. e. seeds, cuttings). Many of these show promise of being very
useful if propagation and cultural practices can be solved. A number of other
species which, in their native habitat, show a wide range of adaptation to
microenvironment and inherent ability to stabilize bare soils were not evalu-
ated due to poor seed production during the course of this project or diffi-
culties in propagation or culture. These include Prunus emarginata, bitter
berry; Querus vaccinifolia, huckleberry oak; Nama lobbii, woolly nama;
Castanopsis sempervirens, bush chinquapin; Ceanothus cordulatus, mountain
whitehorn; Lupinus spp., lupine; and Rubus parviflorus, thimbleberry. These
should be studied in great detail in order to effectuate a more thorough
representation of the vegetation in the Tahoe Basin.
'Still other potentially valuable revegetation species were not evaluated due
to time and financial restraints of the project or becaus.e sufficient observa-
tions of their potential were not made in the early portions of this project.
Some examples are Rosa woodsii var. ultramontana, mountain rose; Symphori-
carpos vaccinoides, mountain snowberry; Lonicera caurina, mountain fly honey-
suckle; Lonicera involucrata; Ribes divaricatum var. inerme; Ribes montigenum,
mountain gooseberry; Ribes roezlii, Sierra gooseberry; Ribes cereum, squaw
currant; Ribes viscosissimum, sticky currant; Ribes nevadense, mountain pink
currant; Ceanothus velutinus, snowbrush; Holodiscus microphyllus, littleleaf
cream bush; Amelanchier pallida, Western service-berry; and Amelanchier
pumila, smooth service-berry. The Salix spp. (other than Salix lemmonii,
lemon willow) should be investigated. These should include studies of relative
rootability and performance of several species, if funding permits. Certain
herbaceous genera would also warrant exploration, such as Eriogonum spp. and
Lupinus spp., Lupines.
Additional research on propagation, culture and establishment of methods for
species of proven revegetation potential, of species evaluated only in limited
trials and on species not included in earlier research would provide a plant
spectrum from which to choose the best species for virtually any microsite
in the Lake Tahoe Basin or other similar habitats.
2. Objectives
The objectives were to:
Survey study sites, evaluate physical and microenvironment conditions
and select potentially useful species for revegetation.
Research propagation and cultural practices to produce the required
plant spectrum. Specific studies to be made of seed versus cut-
ting propagation, growing media, depth of containers, irrigation
and nutritional needs (in. the nursery) and timing of propagation.
These studies will provide 10-20,000 plants, depending on level of
funding, for revegetation. Additional plants will be obtained from
the California Division of Forestry.
255
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3. Assist State Water Resources Control Board in planning, restora-
tion and planting which will be done by California Conservation
Corps, County or Water Board personnel.
4. Collect data on growth and survival and monitor overall success
of plantings.
5. Special attention was to be paid to the establishment of greater
vegetation density at the top of highway cuts.
3. Soil Mixes
In an attempt to improve survivability of the plants for this demonstration
project, different soil mixes were used. Standard U.C. mix was used as a
control and comparison for two test mixes. The U.C. mix consists of 1:1:1
ratio of sand, peat and ammoniated redwood sawdust. The other two mixes
used were 1:1 peat-vermiculite and 1:1 peat-basalite. Basalite is a granular
clay material which is a manufacturing by-product. Basalite must be leached
to remove excessive boron before it is incorporated in a planting mix. Both
test mixes had the following nutrients supplied per standard six inch pot;
8g dolomite, 2g oyster shell, 2g superphosphate, 3g potassium nitrate. The
criteria used to determine the desirability of each mix will be the percentage
of plants surviving at the end of the observation period.
4. Containers
Four types of containers were used to compare growth and transplant survival
of several species.
The standard container used for all species unless otherwise noted was a
commerical peat pot^'^) 6.25 cm diameter by 7.5 cm deep.
Two sizes reusable, tapered, deep plastic tubes ^ '^were used. One was
7.5 cm diameter X 23.75 cm deep. The other was 1.9 cm in diameter X 13.75 cm
deep.
"Book" planters^ ' , ribbed plastic folders with 4 (four) planting com-
partments, each 3.75 cm X 3.75 cm X 11.9 cm, were the fourth type of
container. Because of the thin plastic used, these are usually not re-
usable.
1) No endorsement is implied. Commercial names are given for identification
purpose only.
2) Jiffy Pot #425.
3) Manufactured by Crown Zellerbach Corp., Edwood Nursery, Araura, Ore.
4) Hillson's Rootainers, Spencer-Lemaire Ind. Ltd.,. Edmonton, Alberta, Canada
256
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5. Growing Conditions
Greenhouse temperatures were usually 18 C days, 13 C nights but sometimes
greenhouses were used with 21 or 24°C day temperature and 16 or 18°C nights.
Sweatbox conditions for propagation were plastic covered frames with 21°C
bottom heat located in a lathhouse.
Intermittent mist was on a 5 sec. every 2.5 min. (on a greenhouse bench)
with bottom heat (24°C). Both tap water and deionized (DI) water mists
were used. Tap water was used unless DI is specified.
6. Plant Materials
Principal Species Investigated
»-
Plant materials grown in larger quantities are listed alphabetically first.
Species grown in smaller quantities are discussed later.
Agropyron trichophorum ('Luna' pubescent and 'Topar' pubescent wheatgrasses):
Seeds were sown directly in peat pots the first week of April in greenhouses
(18°C day, 13 C nights). Flats were covered with newspaper for about 5 (five)
days until the seeds began to germinate. Plants were ready to plant out
approximately 6 (six) weeks after sowing.
Artemisia caucasica (Caucasica artemisia):
Cuttings were taken from stock plants in June and rooted in small tubes under
mist. One hundred cuttings were stuck in the mixes previously described. The
total rooting after six weeks was 83% (250/300). There was no recorded dif-
ference in rooting between the soil mixes. The rooted cuttings were ready
to plant 10-12 weeks after being stuck.
Artemisia tridentata (Big basin sage):
Seeds were stratified at 2 C for ten days before being sown in flats in the
mist. This seed, which had been in cold storage for three years, germinated
within three weeks. The seedlings were transplanted approximately 5 (five)
weeks after the sowing date to small tubes with the soil mixes listed pre-
viously. The plants were grown in the greenhouse another two months and in
the lathhouse for six weeks before being moved to the planting site. Survival
data are given in Table A-l.
257
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Table A-l. Artemisia tridentata
Survival in 3 soil mixes
Soil Mix
U. C. Mix
Peat-basalite
P ea t-vermiculite
, 3% months after
Numb er
Planted
40
40
40
transplanting .
Survival
# %
36 90.0
39 97.5
38 95.0
Atriplex gardneri (Gardner valley saltbush) :
Seed which had been in cold storage for four years was sown in flats on a
greenhouse bench on 1-27-76. Within a week the first seeds began germinating.
Seedlings were transplanted within a month (2-20-76) of the sowing date to the
containers and in the soil mixes listed previously. After approximately
three months growth in the greenhouse the plants were placed in the lathhouse.
In two months (five months from sowing) the plants were moved to the planting
site. Survival data at that time were given in Table A-2. There were no
consistent differences in survival which could be attributed to container
size or soil mix.
Table A-2. A trip lex gardneri
Survival in various soil mixes and container types, 5 months
after transplanting.
Soil Mix
UC Mix
Peat-basalite
Peat-DG*
UC Mix
Peat-basalite
Peat-DG*
UC Mix
Peat-basalite
Peat-DG*
Container
small tube
small tube
small tube
peat pot
peat pot
peat pot
book
book
book
Numb er
Planted
100
100
100
40
40
40
40
40
40
Survival
# %
92
89
87
38
36
32
38
39
39
92.0
89.0
87.0
95.0
90.0
80.0
95.0
97.5
97.5
*DG = field collected decomposed granite.
258
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Cornus stoloaifera (Creek dogwood):
Cuttings were originally collected in the spring from plants in the field.
These were rooted and used for stock plants.
Succulent tip cuttings from stock plants rooted 100% within two weeks. "Rooted
cuttings grew rapidly in peat pots and were ready to plant out 6-8 weeks
after sticking. ' '.. .
Lupinus spp. (Lupines):
Small lots of lupine seed had been collected in previous years and had been
in cold storage for varying number of years. Most of the seed was not
identified as to species. Hot (73°C) water was poured over the seeds and
they were allowed to soak in the cooling water. Unimbibed seed were separated
and treated as above with boiling water. Still unimbibed seed were separated
and boiled one minute before soaking 24 hours in the cooling water. Imbibed
seeds were sown in flats, covered with newspapers and placed on a greenhouse
bench. Germination began after about five days. At the second leaf stage
the seedlings were transplanted to peat pots. They were moved to the lath-
house after two weeks and outside two weeks later. After about two weeks
outside they were ready to plant.
Considerable additional research on lupine propagation, bacterial inoculation,
direct seeding and transplanting is being done by Mr. David Gilpin as his
master's thesis project. Results of these studies are not yet available.
Penstemon newberryi (Mountain pride):
Dormant cuttings were taken from field grown plants in the late fall and
early winter of 1975-76. The cuttings were dipped in 1000 mg/1 IBA for 1-2
seconds and stuck in vermiculite in outdoor sweat boxes. One flat of cut-
tings that was stuck 12-17-75 had 98% (173/176) rooting after two months.
Of seven flats stuck 1-13-76 to 1-30, 87% (1187/1349) had rooted by 3-22-76.
Most of these cuttings had good top growth and could have been transplanted
at least a month earlier. These rooted cuttings were randomly planted in
the three mixes described previously and in three containers: deep tubes,
small tubes, and 7 cm peat pots. There were nine replications of 13 plants
per treatment in a complete block arrangement. The plants were grown in
the greenhouse two weeks, the lathhouse two weeks and then outside in partial
shade until they were transported to the site. Large, well rooted P. newberryi
cuttings such as these, would reach suitable planting size in about one month
in the small tubes, two months in the deep tubes and about a month and a half
in the peat pots.
After four to five months growth in the containers survival (Table A-3) was
highest in the deep tubes (346/351) next in the small tubes (336/351) and
least in the peat pots (307/351). The plants in the vermiculite peat mix
had the highest survival (335/351), in regular U.C. mix next (330/351)
and the least survival in the basalite peat mixture (324/351). These dif-
ferences are small and probably of no real significance. Survival data one
year after planting should be compared.
259
-------
Table A- 3
. Penstemon newberryi
Survival in 3
containers
and 3
13
soil mixes,
July &
August, 1976
planted/treatment/rep.
MIX
Rep.
1
H 2
S 3
H 4
w -*
ivi ^
5 o
7
8
9
TOTALS
1
en 9
w ^
g 3
H 4
jj 5
s ^
en 7
8
9
TOTALS
1
2
en 3
S 4
5
-------
Four to six weeks after transplanting these first cuttings, additional cut-
tings were taken from them. These softwood (but not succulent) cuttings
were dipped in 1000 ppm IBA for 1-2 seconds and rooted under deionized (DI)
intermittent mist. Three hundred (300) cuttings were rooted in vermiculite
and 300 cuttings were stuck directly in small tubes, 100 of each of the
three mixes previously described. They were left 10 days in DI mist, cycle
2.5 sec. every 2.5 min. and ten days on the hardening off bench. Rooting
was 100% in all cases. The cuttings rooted in vermiculite were then trans-
planted on one of the three previously described mixes in 7.5 cm peat pots.
All cuttings were left in the greenhouse ten days and them moved to the
lathhouse. Thirty days after sticking, roots were protruding from the bottoms
of the small tubes and the root ball held together although the tops were
the sides of the peat pots. After another ten days to two weeks (total time,
six weeks) in the lathhouse the direct stuck plants were ready to plant while
those that were transplanted required another two weeks in the lathhouse
(summer conditions in Davis).
Prunus emarginata (Bitter cherry):
Many propagation techniques have been tried with this species with very
limited success. Dormant hardwood cuttings in the sweatbox and leafy simi-
hard wood cuttings under mist have failed to root. Root cuttings send up
shoots but do not initiate new roots. These shoots were excised from the root
cuttings, dipped in 4000 mg/1 IBA and rooted under mist about 7% (4/60) of the
excised cuttings rooted within three weeks, but four weeks after sticking all
cuttings were dead.
Field collected root suckers have rooted somewhat more successfully. Suckers
were taken (on 4-18-76 at approximately 5000 ft. elevation) before they
emerged from the ground. These were rinsed in 1:9 clorox solution and dipped
in 4000 ppm IBA for 1-2 seconds. They were then stuck (4-23-76) in U.C. mix
in two container sizes, with the top of the cutting just below the soil sur-
face. The containers were placed on a greenhouse bench. In gallon cans there
was no rooting. Cuttings stuck in deep tubes showed, Table D-4, 30% (12/40)
rooting and survival after two months (6-22-76).
Leafy toot suckers (taken 5-17 and 22-76 at approximately 1500 meter elevation)
were dipped (5-31-76) in 4000 mg/1 IBA and stuck in deep tubes up to the former
ground level on the cutting. Cuttings just beginning to show green were held
in the hardening-off mist bench (2.5 sec. every 2.5 min) for two weeks before
being moved to the greenhouse. Five weeks after sticking (7-8-76) they showed
40% (8/20) rooting and survival. Cuttings with more leaves were placed in the
mist bench two weeks and the hardening off mist bench for two weeks before
being moved to the greenhouse. Two months after sticking (7-29-76) they
showed 6% (3/40 and 2/40) rooting and survival. These were limited trials but
show that propagation by root sucker is a definite possibility for this species.
Preliminary research on germination of Prunus emarginata seeds was done in
early 1976. Comparisons were made between hot and cold water pre-soaking
and three stratification regimes: 21oc, constant; 7 C constant and a
fluctuating regime of one month at 3 C and four months at 1 C. The results
are shown in Table A-5.
261
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Table A-4.
Rooting of Prunus emarginata root suckers under various
conditions .
Treatment*
Greenhouse
Greenhouse
Hardening off
2 wk.
Mist 2 wk.
Hardening off
2 wk.
*A11 were dipped in 4000
Container Date Taken No. Rooted
1 gallon 4/19/76 0
Deep tubes 4/19/76 12/40
Deep tubes 5/17 & 22 8/20
Deep tubes 5/17 & 22 3/40
2/40
mg/1 for 1-2 sec. before sticking.
%
0
30
40 f
7.5
^5
Table A-5.
Response
of Prunus emarginata seeds to hot and cold water
pre-soaking and three stratification regimes.
Week
0*
1
2
3
4
5
6
7
Total
Grand Total
Grand totals
Hot Water
Cold Water
Stratification
210C
0
2
5
2
0
3
0
12
24
Stratification
3°-l°C 7°C
11 0
9 2
1 1
1 0
1 0
4 3
3 2
3 2
33 10
67
21°C
46
21°C 3°-l°C 7°C
7 10 10
9 10 10
0 21
1 12
1 0 1
Oil
220
2 2 2 '"
22 27 27
76
3°_l°r 7°r
J ™"J_ U / l_»
60 37
*Germination when removed from stratification.
262
-------
Hot water does not appear to be more effective than cold for soaking the
seeds and temperature during germination appears unimportant although the
experiment was not done in such a way that statistical analysis could be
used on the results.
The higher germination with the fluctuating temperatures was the basis of
further tests in 1976-77.
More work was done on germination of Prunus emarginata seeds in 1976-77.
The seeds have a hard enacarp which may somewhat restrict uptake of water.
They also appear to have an internal dormancy which can be broken by a
period of moist stratification. To try to overcome these factors, seed of
P. emarginata were soaked in deionized water for two or eight days and then
stratified in moist vermiculite for five to five and a half months at four
different temperatures (A and B) constant 7°C (C and D) constant 1°C (E and
F) 7°C for one month and then 1°C for four months or (G and H) 15°C for
one month and then 1°C for four months. These seeds had been in cold storage
for four years. The highest germination of 14% (22/150) was obtained with
an eight-day soak followed by one month stratification at 7°C and four month
stratification at 1°C. The seeds were germinated in the dark at 21°C on
moist filter paper in petri dishes. Radical elongation was counted as
germination. This data is summarized in Table A-6.
The seeds were planted in three different containers. They grew 100% (40/40)
in deep tubes, 90% (54/60) in small tubes and 77% (31/40) in peat pots
(see Table A-7).
Purshia tridentata (Antelope bitterbrush):
Three treatments were tried on small lots of Purshia tridentata seeds. Those
stratified in moist vermiculite at 2°C for 19 days (3-4-76 to 3-23-76) and
germinated under mist had 93% (28/30) germination within two weeks. (Table
A-8). Seeds from the same seed lot which had been soaked 24 hours in Gibber-
ellic acid about 60% (18/30) germinated which was slower and more erratic than
the germination of the stratified seed. These seeds had been in cold storage
for about four years. Freshly purchased seeds treated with 3% thiourea for
five minutes as per seeds of woody plants of the United States, had only 2%
(2/100) germination.
Ribes roezlii (Sierra gooseberry):
Fall collected seeds of this species were stratified in moist vermiculite
at 7°C for three months (10-7-75 to 1-12-76). Half of the seeds were sown
in 1:1 peat/perlite and half in 1:1 perlite/vermiculite. Since the seeds
were very small and mixed with debris they were not counted. After two
weeks in the mist, there were three seedlings in the vermiculite and one in
the peat. Two weeks later there were three more in the peat. None of the
seedlings made any further growth and all died shortly.
In mid-May, 1976, a small number (30) of field collected succulent tip
cuttings were taken. These were dipped in 2000 mg/1 IBA for 1-2 seconds,
stuck in vermiculite, and placed in the mist. There was no rooting. Due
263
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Table A-6. Response of Prunus emarginata seeds to soaking times and
temperature during stratification. Fall, 1976.
Totals for 6 replicates of 25 seeds each.
Treatment
A. 2-day soak-7°C strat
B. 8-day soak-7°C strat
C. 2-day soak-l°C strat
D. 8-day soak-l°C strat
E. 2-day soak-7°C& 1°C strat
F. 8-day soak-7°C& 1°C strat
G. 2-day soak-15°C & 1°C
strat
H. 8-day soak-15°C & 1°C
strat
A. & B. 7°C strat
C. & D. 1°C strat
E. & F. 7°C & 1°C strat
G. & H. 15°C & 1°C strat
Aj C, E & G 2-day soak
No . Germinating
per Week
123456
000000
400000
301200
300100
210000
780222
3 0 0 0.0 2
320202
Summary Totals
400000
601300
990223
620204
811202
B, D, F, & H 8-day soak 17 10 0 5 2 5
GRAND TOTAL 25 11 1 7 2 7
Total
No.
0/150
4/150
6/150
4/150
3/150
21/150
5/150
9/150
4/300
10/300
25/300
14/300
14/600
34/600
53/1200
%
0
2
4
2
2
14
3
6
2
3
8
5
2
7
4
Germination
During
Stratification
%
1
5
2
2
3
7
3
2
Table A-7.
Containers
Peat pots - 2
Small tubes -
Peep tubes - 2
Survival of Prunus emarginata seedlings in 3 containers.
Spring, 1977.
Mean No.
Surviving
replications of 20 each 15.5
3 replication of 20 each 18.0
replications of 20 each 20.0
Sx %
2.1 77
1.0 90
0.0 100
264
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Table A-8. Purshia tridentata seed response to several pre-germination
treatments. Spring 1976.
# Seed Germinated
Treatment
//planted Wk. 1 Wk.2 Wk.3 Wk.4 Wk.5 Final %
Stratified 19 30 25
days @ 2QC
50 mg/1 GA, 24 hrs. 30 5
3% Thiourea 100 1
5 minutes
28 28 28 28 93
9 15 16 18 60
22 222
to the low spreading habit of this species and its ubiquity in dry rocky
places more work should be done toward propagating it.
Ribes viscosissimum (Sticky currant):
Fall collected seeds of this species (tentatively identified as Ribes
viscosissimum) were stratified for five months in moist vermiculite at 7°C.
They were sown on a flat and placed in the mist for two wee~ks. Germination
was fair and six weeks after sowing the seedlings were transplanted to 7.5 cm
peat pots. Tip cuttings taken from the seedlings in early June (four months
after sowing) rooted 100% under mist and grew so rapidly that cuttings could
be made from them within six weeks.
Salix spp. (Varous Willow species):
Dormant cutting material of Salix lemmonii (Lemmon willow) and S. lasiandra
(western block willow) was collected from the field in early December, 1975,
and kept in cold storage until the hardwood cuttings were made. The four-inch
long cuttings were stuck in flats of vermiculite and placed in unheated cold
frames in a lathhouse by mid-January, 1976. Rooted cuttings were transplanted
into deep tubes and peat pots with UC mix within four months of the sticking
date.
Observations were made on the rooting ability as it related to the diameter
of the cuttings and as it was affected by a hormone dip (1000 mg/1 IBA for one
minute). In general, for both species, the large diameter cuttings (1.25 cm
to 1.9 cm) had a higher rooting percentage (see Table A-9) than the medium
(1.0 cm to 1.25 cm) or the small (0.6 cm) diameter cuttings. Cuttings of
both species dipped in the IBA had a lower,rooting percentage than those
not treated with the hormone.
Cutting material of four species, S. rigida, Brittle willow, S. lasiandra,
Western black willow, S. scouleriana, Scouler's willow, S. lemmonii, Lemmon
willow, was collected in mid-December, 1976, from sites at the south end of
the Tahoe Basin. Cuttings were made during the two days following the
265
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Table A-9. Effect of hormone and cutting diameter on rooting of
lemmonii and S. lasiantra.
Salix lemmonii
Cutting Diameter
0.6 cm-small
1.0 cm - 1.25 cm -
medium
1.25 cm - 1.9 cm -
large
Total
Salix lasiandra
Cutting Diameter
0.6 cm - small
1.0 cm - 1.25 cm -
medium
1.25 cm - 1.9 cm - ~
large
Total
No IBA
22/30
29/30
29/30
80/90
No IBA
19/30
28/30
27/30
74/90
HORMONE TREATMENT
% 1000 mg/1 IBA %
73.3 12/30
96.7 16/30
96.7 17/30
88.9 45/90
40.0
53.3
56.7
50.0
HORMONE TREATMENT
% 1000 mg/1 IBA %
63 15/30
93 18/30
90 24/30
82.2 57/90
50
60
80
63.3
Total
34/60
45/60
46/60
Total
34/60
46/60
51/60
Salix
%
56.7
75.0
76.7
%
56.7
76.7
85.0
collection from the field, and stuck on the third day. The cutting diame-
ters, media, and rooting environments were the same as in 1975.
The results did not have the same consistent pattern as in 1975-76 where the
larger diameter cuttings had a higher rooting percentage than the medium or
smaller diameters. Generally, there were higher rooting percentages on cut-
tings not dipped in 1000 mg/1 IBA than those that were given a one minute dip.
S. scouleriana in all treatments had considerably lower percentages of root-
ing. This species was the slowest to root and to make new growth. The new
leaves were infected with insect galls that were treated with Isotox. There
was more noticeable growth after two sprays of Isotox two weeks apart. Well
rooted cuttings (roots 5-10 cm long) were transplanted to containers during
the first week of March (approximately three months after sticking). Trans-
planted cuttings grown in'the lathhouse in deep tubes could fill the container
in 2 to 2% months (= early to mid-May).
Symphoricarpus acutus (Creeping snowberry):
i
In mid-May, 1976 a small number of softwood cuttings were taken from stock
plants of this species. The cuttings were dipped in 2000 mg/1 IBA for 1-2
266
-------
seconds and then stuck in vermlculite. About 95% of the cuttings rooted
within three weeks under mist but all dropped their leaves. When trans-
planted most of the cuttings failed to resprout and all died.
7. Plant Materials
Other Species Investigated
Very limited propagation trials were conducted on a number of other species.
Some of these should be good candidates for revegetation of disturbed sites
and further work is warranted. The trials were limited by both time and
financial constraints and often by the availability of seed or cutting mater-
ial. Brief summaries of these trials follow.
Amelanchier alnifolia (Western serviceberry):
Seeds were stratified at 7 C for three months.
24 plants survived to planting size stock.
Arctostaphylos patula (Greenleaf manzanita):
Of 48 seeds that germinated,
This species has been more difficult to root than A. nevadensis. More work
is needed on both species. Rooting of the latter species has been variable
from year to year and for cuttings from different location. It may be that
variables in microsite (soils, rainfall, etc.) may have a strong influence
on rooting. This hypothesis should be tested by growing stock plants under
controlled conditions of irrigation and fertility.
Atriplex canescens (Four-winged saltbush):
Seeds sown directly in peat pots on February 10, 1977 produced good planting
stock under greenhouse conditions in two months. Plants need cutting back if
held in these conditions more than two months. It is recommended that 5-7
seeds be sown per pot and these be thinned to one seedling per pot at an
early age.
Castanopsis sempervirens (Bush chinquapin):
Viable seed was unobtainable during 1975-1976. Dormant cuttings calloused
heavily but only four plants of over 50 cuttings rooted. This indicated that
it is possible to root the species but better treatments need to be developed.
Cutting back stock plants to force juvenile growth and the use of softwood
cuttings should be investigated.
Ceanothus cordulatus (Mountain whitethorn):
Trials with both seeds and dormant cuttings were essentially unsuccessful
with less than 0.1% success. This species is widespread in California moun-
tains. Additional work with fresh seed from different sources is warranted.
Softwood cuttings should be tried also.
267
-------
Table A-10.
Salix spp. Comparison
Salix as inf
S. rigida:
Treatment*
Replications
1 679
2 977
3 958
4 10 8 10
5 752
6 10 9 10
S. lasiandra:
1
2
3
4
5
6
S. scouleriana:
1
2
3
4
5
6
S. lemmonii:
1
2
3
4
5
6
7
9
8
8
9
8
5
1
2
4
1
1
8
4
7
9
7
9
10
9
6
9
8
10
5
2
6
4
4
4
8
7
9
9
7
7
8
10
7
9
8
10
0
4
3
6
3
4
4
5
6
7
10
9
luenced by
Total
22
23
22
28
14
29
25
28
21
26
25
28
10
7
11
14
8
9
20
16
22
25
24
25
of rooting of several species of
cutting diameter and hormone treatment.
small
medium
large
small
medium
large
small
medium
large
small
medium
large
-IBA %
23/30 76.7
28/30 93.3
29/30 96.7
-IBA %
28/30 93.3
26/30 86.7
28/30 93.3
-IBA %
7/30 23.3
14/30 46.7
9/30 30.0
-IBA %
16/30 53.3
25/30 83.3
25/30 83.3
+IBA %
22/30 73.3
22/30 73.3
14/30 46.7
+IBA %
25/30 83.3
21/30 70.0
25/30 83.3
+IBA %
10/30 33.3
11/30 36.7
8/30 26.7
+IBA %
20/30 66.7
22/30 73.3
24/30 80.0
Treatments
Total Species:
S. rigida
S. lasiandra
S. scouleriana
S. lemmonii
*Treatments: 1.
2.
3.
0.6 cm
0.6 cm
1.0 cm
1000
1
22
25
10
20
dia.
dia.
- 1.
mg/1
2 3
4
23 22 28
28 21 26
7 11 14
16 22 25
+ 1000 mg/1 IBA
, no IBA
25 cm dia. +
IBA
5 6
14 29
25 28
8 9
24 25
4. 1.0 cm - 1.
5. 1.25 cm - 1
1000 mg/1
6. 1.25 cm - 1
25 cm dia., no IBA
.9 cm dia. , +
IBA
.9 cm dia. , no IBA
268
-------
Chrysothamnus nauseosus (Rabbit brush):
This species is easy to grow by direct sowing about ten seeds per pot and
thinning to one or two plants after germination. One problem that must be
recognized is that in some years, early fall frosts when the plant is in
flower, result in a crop of non-viable seed.
Eriogonum unbellatum (Sulphur flower):
Cuttings under mist (March 1977) all rotted. The use of a sweat box should
be tried with this species.
Seeds were sown directly in several sized containers, 3-6 seeds per container
and covered with newspaper. Seed was of poor quality with many hollow (aborted
seeds). Of 574 containers, over 450 had at least one seedling. Seedling
propagation is rapid and good plants can be produced in three to four months.
Holodiscus bousieri (Cream bush):
No cuttings of this plant rooted when taken as dormant cuttings. Softwood
cuttings should be tried in June.
Lonicera conjugialis (Double-flowered honeysuckle):
A limited quantity of seed was available. These were stratified for three
months at 7°C. Of 64 which germinated only 20 survived transplanting and
the subsequent growing period. Cultural conditions (media, container size,
etc.) need more investigations.
Penstemon strictus (Rocky Mountain penstemon):
This penstemon rooted well from cuttings. Other species of penstemon native
to the Sierras should also be tried.
Rhamnus rubra (Sierra coffeeberry) :
Three months stratification at 7 C resulted in good germination. Of 296
seedlings transplanted, 284 survived to transplanting size. This is a good
candidate for revegetation. Cutting propagation of dormant wood was unsuc-
cessful. However, softwood cuttings of this species are being used by
commericial nurseries.
Ribes cereum (Squaw currant):
A limited number of seeds were stratified for four months at 7 C. At the
end of stratification 24 were germinated. Twenty of these survived to plant-
ing size. The remainder of the seeds were sown and an additional 40 plants
resulted.
269
-------
Ribes nevadensis (Sierra currant):
Stratification for six months at 7°C resulted in good germination. A
shorter stratification period (perhaps 3-4 months) probably would be adequate
because nearly 300 seeds had germinated while being stratified. Dormant
cuttings rooted well but survival after transplanting was poor. Softwood
cuttings should be tried.
Rosa woodsii var. ultramontana (Mountain rose):
A small number of s.eeds were stratified for five months at 7 C. Thirty-six
seeds germinated. A cutting propagation trial using dormant wood of two
diameters and several hormone levels (324 cuttings) did not produce any
rooted plants. This is surprising in view of the ease of rooting of most
species of roses. Softwood cuttings should be tried in June or July.
Rubus parviflorus (Thimble b erry):
This species is an invader of highway cuts and talus slides in some parts
of the basin. Limited trials with both softwood and dormant cuttings have not
been very successful. The genus Rubus generally roots well with some species
rooting whenever a tip touches the ground. Because of its potential for
revegetation additional research is warranted. One approach would be the
use of root cuttings.
Sambucus microbotrys (Red elderberry):
This species roots readily from softwood cuttings and no new research was
conducted on the propagation of it.
8. Outplantings
The plant materials were delivered to the site as needed. Planting was done,
for the most part by State Board crews. Because U.C. personnel were not on
site during all planting operations, mapping of plantings was largely the
responsibility of the State Board personnel. Planting locations are summa-
rized in Appendix B.
A large planting of Penstemon newberryi was done by U.C. personnel. This
experiment was to compare field survival of this species which had been grown
in different media and container sizes. Description of the media and container
sizes is at the beginning of this report.
Data was to have been taken in May-June of 1977. Due to the lateness of the
growing season and the covering of many plants by the soil material, valid
counts could not be made prior to the termination date. This species has
the ability to survive some burial and grow through it. This survival data
species which were delivered to' and planted at the Rubicon Properties erosion
control project site is given in Table A-11. Plantings were conducted in the
summer and early fall of 1976 (5,876 plants) and the spring of 1977 (14,484
plants).
270
-------
TABLE A-ll
INVENTORY OF PLANT MATERIALS
DELIVERED TO RUBICON PROPERTIES
EROSION CONTROL PROJECT SITE
Species
Arctostaphylos nevadensis
Artemisia caucasica
Artemisia tridentata
Atriplex gardneri
Ceanothus prostratus
Composite (Purple)
Composite (Yellow)
Cornus stolonifera
Grasses (assorted sp)
Lupinus spp.
Penstemon newberryi
Primus emarginata
Purshia tridentata
Ribes viscosissimum
Symp ho ri carpus acutus
Nama lobbii
Total
Species
Amelanchier alnifolia
Arctostaphylos
nevadensis
Arctostaphylos patula
Artemisia tridentata
Atriplex canes cens
Delivered Summer 1976
7-13 7-27 8-4
8 1
5
31 11 82
490
133
122
14
320 160 420
72 64 77
448 139 761
19
21 21
24
5
1
962 1014 1473
Delivered Spring 1977
Container 5-11 5-23 6-3
book 24 10
gallons 5
peat pots 105
deep tubes 10
gallons 2
peat pots 24
peat pots 400
books 568
small tubes 110
deep tubes 22 35
8-11
31
131
4
64
10
1208
130
31
54
1663
6-20
6
75
8-23
250
12
360
18
124
764
Total by
Container
& Species
34
5
111
10
2
99
400
568
110
57
Total
by
Species
40
255
124
490
264
4
186
36
2108
213
1838
19
73
96
129
1
5876
Total
by
Species
34
5
124
99
1135
271
-------
Table A-ll.
Inventory delivered Spring 1977 (Con't):
Species
Castanopsis sempervirens
Ceanothus cordulatus
Ceanothus prostratus
Chrysothamus nauseosus
Cornus stolonifera
Erigonium umb ellatum
Lonicera conjugialis
Lupinus breweri
Lupinus fulcra tus
Lupinus grayi
Lupinus sellulus
Luna pubescens
Penstemon newberryi
Container 5-11 5-23 6-3
deep tubes 1
books 2
deep tubes
peat pots 120 64
books 156 84 640
small tubes 100
deep tubes 125
gallons 3
peat pots 456 75 125
deep tubes 39
peat pots 126 42
books 175
small tubes 70
peat pots 2
books 20 2
peat pots 36
books
deep tubes
peat pots 36
books
deep tubes
peat pots 37
books
deep tubes
peat pots 37
books
deep tubes
peat pots 1760 380 40
books 672 960 240
peat pots 720 265 53
books 84
small tubes 930 180
large tubes 360 15
Total by
Container
6-20 & Species
1
2
13 13
70 254
800
100
125
3
30 686
39
8 176
175
70
2
22
36
50 50
30 30
36
50 50
40 40
37
50 50
25 25
37
50 50
15 15
2180
1872
1038
100 184
1110
375
Total
by
Species
1
15
1362
686
39
421
24
116
126
112
102
4052
2707
272
-------
Table A-ll.
Inventory delivered Spring 1977 (Con't):
Species
Penstemon stricta
Prunus emarginata
Purshia tridentata
Rhamnus rubia
Ribes cereum
Ribes nevadensis
Ribes roezlii
Ribes viscosissimum
Rosa woods ia
Rubus parviflorus
Salix spp.
Symphoricarpus spp.
Total by date
Container 5-11
peat pots 80
books 92
gallons
peat pots 4
books 8
large tubes 75
gallons 3
peat pots
books
small tubes
large tubes
books 284
books 20
deep tubes
peat pots 3
peat pots 6
deep tubes
gallons
peat pots
peat pots 12
books
deep tubes
books
5117
Total by Total
Container by
5-23 6-3 6-20 & Species Species
88
4
38 ' 135 410
165 450
5
23 26 10
35 73
500
300
100
20
35
5
2 150
7 1
1
1
30
1 1
48
9
65
4508 1378 1681
168
92
4
587
623
80
62
108
500
300
100
304
55
5
155
14
1
1
30
14
48
9
65
264
1352
1008
304
60
155
15
1
30
14
57
65
14484
9. Summary
Advice to project personnel on planning and site preparation was accomplished
in 1976 by several trips to the site by the principal investigator during the
spring and summer. It was not possible to take spring survival data by the
273
-------
termination date of the project because of the unusually late spring. Plants
which were partially buried and some deciduous material could not have been
counted with any degree of validity as late as the week of June 20, 1977.
There is much additional information on procedures and plant materials for
revegetation in the Tahoe Basin in:
"Revegetation of Disturbed Soils in the Tahoe Basin"
Andrew T. Leiser, James J. Nussbaum, Burgess Kay,
Jack Paul, William Thornhill
Final Report, March 1971 - June 1974
CA-DOT-TL-7036-1-75-24
Sponsoring Agency:
California Department of Transportation
Transportation Laboratory, Sacramento, Calif.
Scheduling of plant production is detailed in part under the various plant
species section of the report. The plant species vary in the length of
time required to produce stock suitable for out-planting. Longer growing
time is required to produce adequate root systems in the deeper containers.
A summary of several production schedules with examples of species which
might be grown in each is as follows. Dates given are lead time prior
to planting.
Seed Collection:
Seed Production-Slow Growing Species
Greenhouse Production
Summer-Fall-12-8 mo.
Stratification:
Germination, Transplanting:
Growing-on:
Winter, 8-6 mo.
Late Winter, 6-4 mo.
Spring, 4-2 mo.
Field Production
Summer-Fall, 24-16
mo.
Winter, 16-14 mo.
Late Winter,
14-12 mo.
Spring-Summer,
12-10 mo.
The field production will produce larger plants, 4" to "gallon" can size and
will be higher in cost for the'"gallon"-can size.
Examples: Prunus emarginata, Ribes spp., Penstemon spp., Ceanothus spp. etc.
(the more woody spp. for the most part).
274
-------
Seed Production-Rapid Growing Species
Seed Collection:
Greenhouse Production
Summer-Fall, 12-8 mo.
Field Production
Summer-Fall, 12-8
mo.
Stratification: Non required for most.
Germination: 4-3 mo. 5-4 mo.
Growing on:
3-2 mo.
4-3 mo.
Examples: Grass sp., Atriplex spp., Artemisia spp., Chrysothamum nauseosus,
Eriogonum umbellatum, Purshia tridentata, Lupinus spp. (Herbaceous,
suffrutescent and rapid—growing woody species for the most part).
Cutting Production
Soft-wood Cuttings-Outdoor Stock Plants
May-July, 12-10 mo.
May-Aug., 12-9 mo.
June-Fall and Late Winter-Early Spring
April-through Summer
Take cuttings:
Roo ting:
Growing on:
Finished plants:
Soft-wood Cuttings-Greenhouse Stock Plants
Take cuttings: Jan-March, 6-3 mo.
Growing on: Feb.-June, 5-2 mo.
Finished plants: May through Summer
Examples: Easy to root species, eg. Penstemon, Salix etc.
Take cuttings:
Rooting:
Growing on:
Dormant Cuttings
Sept.-November, 10-7 mo.
Requires 1-4 mo. depending on species
(Greenhouse in colder months)
2-5 mo.
Note: If grown out-of-doors and/or larger plants are
required, one full growing season is required
and lead time becomes 22-19 mo.
275
-------
10. Costs
Production of plants for revegetation involves three basic steps. 1) Seeding
or collecting and preparing cuttings, 2) rooting the cuttings, or germinating
the seed, 3) transplanting the seedlings or rooted cuttings to containers
and growing them to large enough size for outplanted. The following dis-
cussion and tables presents the costs associated with each of these steps.
The final table gives the total cost of producing plants for revegetation.
These cost estimates include some of the many variables which affect plant
production. The factors include difficulty of collecting cuttings, size of
cuttings, percentage rooting, rooting time, type of container and time re-
quired to grow to size.
Seeding
Seed cost per unit is very small. Unit cost includes direct
seeding and thinning to desired number per pot.
Unit Cost
$ 0.03
Collecting and Preparing Cuttings
Cost of collecting cuttings in the Tahoe Basin from Davis, California:
2 man-days @ $8.00/hr.
1% days per diem @ $35.00
Mileage, 500 km. @ 0.9
Supplies: ice, bags, labels
$128.00
52.00
45.00
3.00
$228.00
Number of cutting collected in one trip varies from 5,000 to 10,000 depending
upon ease of collection.
Collection Unit Cost:
High (5,000/trip)
Low (10,000/trip)
Preparing and sticking cuttings
Materials cost: media and pro-rata flats
Preparation Unit cost: Large cuttings @ 100/flat
Small cuttings @ 150/flat
$ 0.045
0.023
0.03
0.015
0.010
Summary of Cutting Collection and Preparation Costs
Low Cost
Cost of collecting cuttings
Cutting preparation
Material large cuttings
Small cutting
TOTAL Large cuttings
Small cuttings
$0.023
0.030
0.015
0.010
0.068
0.063
High Cost
$ 0.045
O.Q30
0.015
0.010
0.090
0.085
276
-------
Rooting Cuttings
The unit cost of rooting a cutting depends on the propagation space required
and the weeks required for adequate rooting.
Costs are based on 35 cm X 55 cm X 8.75 cm flats, prorated for the life of
the flat. One medium, vermiculite (not reusable) is used as an average
cost. Large cuttings @ 100/flat are about 538 cuttings/sq. meter. Small
cuttings @ 150/flat are about 807 cuttings/sq. meter. Figures are given for
two propagation environments, a greenhouse mist requiring four or six weeks
for rooting and a lathhouse sweatbox requiring eight or twelve weeks for
rooting.
Table A-12. Total Cost of Rooted Cuttings ($)
Environment
Rooting Time
Cost of Collecting Cuttings
Greenhouse Mist
4 Weeks
Low | High
6 Weeks
Low | High"
Lathhouse Sweatbox
8 Weeks
Low I High
12 Weeks
Low|High
A. LARGE CUTTINGS
Cost, stock cutting .068 .090 .068 .090
Propagation space/maint. .025 .025 .037 .037
TOTAL: 100% Yield .093 .115 .105 .127
80% Yield .116 .144 .131 .159
60% Yield .155 .192 .175 .212
40% Yield .232 .288 .263 .318
.068 .090 .068 .090
.030 .030 .045 .045
.098 .120 .113 .135
.122 .150 .141 .169
.163 .200 .188 .225
.245 .300 .283 .338
B. SMALL CUTTINGS
Cost, stock cutting .063 .085 .063 .081
Propagation space/maint. .017 .017 .025 .025
TOTAL: 100% Yield .080 .102 .088 .110
80% Yield .100 .128 .110 .138
60% Yield .133 .170 .147 .183
40% Yield .200 .255 .220 .275
.063 .085 .063 .085
.020 .020 .030 .030
.083 .105 .093 .115
.104 .131 .116 .144
.138 .175 .155 .192
.208 .263 .233 .288
Growing Costs
The following are costs associated with transplanting rooted cuttings to con-
tainers, and growing cuttings or seedlings up to a usable size. The following
basic costs are used in the calculations.
277
-------
Greenhouse space and maintenance-
Lathhouse space and maintenance-
Medium (potting mix)
Sand @ $7.85/cubic meter =
Ammonized Redwood Sawdust-
fa $3.50/cubic meter
Peatmoss two bales @ $8.00
Fertilizers
Labor, steam sterilizing
$13.45/sq. meter
8.07/sq. meter
2.00
7.00
16.00
2.00
20.00
2/Mo.
2/Mo.
$47.00
Cost per Cubic Meter $18.81
Containers
Peat Pots
Books^
Large tube
Small tubes
Cost/100 Units
$2.64
3.75
18.75
3.75
Estimated Reuse
No
No
5X
5X
Net
Gost/100 Units
$2.64
3.75
3.75
.75
Total Production Cost
The total cost of producing plants for revegetation can be calculated from
the preceding tables. The total cost of producing direct seeded container
plants can be calculated by adding the seeding cost +_ $.03 per plant to the
growing cost in Table A-13. The total cost of producing plants from cuttings
can be calculated by adding the cost of a rooted cutting from Table A-12 to
the growing cost from Table A-13. Note, however; that large cuttings cannot
be transplanted into the small tubes.
Discussion
In our tests, the 7.5 cm deep peat pots have been used for all species.
Growth is this particular design which is 1.25 cm deeper than the standard
6.25 cm peat pot has been generally good. The greater depth is superior to
the shallow peat pot for the native plant spectrum. Some problems of drying
out are encountered when plants are moved to the field.
Commercial names are given for identification
1. No endorsement is implied.
purposes only.
2. Jiffy Pot #425.
3. Hillson's rootainers, four compartments each, Spencer-Lemaire, Inc.
Ltd., Edmonton, Alberta, Canada.
4. Tubes, large,
small, in block of 100 units.
Crown Zellerbach Corp., (Ed Wood Nursery) Aurora, Oregon.
278
-------
TABLE A-13
Growing Cost Summary - Unit
Container Greenhouse
3 Months | 6 Months
Peat=Pot 1»2 $0.23 $0.41
Books !»3 0.15 0.21
Tube, large !>4 0.26 0.45
Tube, small l>^ 0.04 0.06
Cost
Greenhouse
3 Mo.,
$0
0
0
0
Lath 3 Mo.
.34
.18
.37
.05
Range of Total Production Costs
High Low
Direct seeding
Large cuttings
Small cuttings
$0.07 - $0.48
$0.50 - $0.79
$0.12 - $0.74
The deep tubes require a longer growing period to obtain adequate root systems
than do the peat pots or books. The large tube is more difficult to plant
because of its depth. More work is required on cultural practices with the
1.9 cm tube to determine which species perform well in them. Many cuttings
are too large to transplant into them. They have been very good for
Penstemon newberryi where unrooted cuttings are stuck directly into them and
then rooted.
The books have been very satisfactory. A larger sized book is available for
larger plants. Costs of some larger sized books would be comparable to the
large tube in terms of soil used, growing space etc.
279
-------
APPENDIX B
EROSION CONTROL PLOT DESCRIPTIONS
Number Page
FIGURES
B-l SCS Seedings and Plantings, 1973 - 1974, Northstar 281
B-2 Revegetation Plots, 1975- 1976, Northstar 290
B-3 Herbaceous Seedings and ¥oody Plantings, 1976, Rubicon
Properties 300
B-4 Shrub and Tree Plantings, 1977, Rubicon Properties 318
TABLES
B-l SCS Shrub Plot Descriptions, 1973 - 1974, Northstar 282
B-2 SCS Herbaceous Plot Descriptions, 1973 - 1974, Northstar 286
B-3 Revegetation Plot Descriptions, 1975 - 1976, Northstar . 291
B-4 Herbaceous Seeding and Woody Planting Plot Descriptions,
1976, Rubicon Properties 301
B-5 Plot Description Symbols For Interpretation of Tables
B-3 and B-4 313
B-6 Shrub and Tree Plantings Section Descriptions, 1976,
Rubicon Properties 319
280
-------
HERB-6 ,1973
HERB-
-HERB
12
I POND
HERB-7,1974
LOCATION OF
4 SHRUB PLANTINGS
AND
HERBACIOUS
SEEDINGS
BY THE
SOIL
CONSERVATION
SHRUB-4,1973
HERB-5,1973 SERVICE
AT NORTHSTAR
SPRING
1973, .1974
HERB -8,1974
HERB-I, 1973
HERB-9, 1974
HERB-10,1974
HERB-II, 1974
HERB-4,1973;
SHRUB-3, 1973
SHRUB-2,1973
SHRUB-8, 1974
NOT DRAWN TO SCALE
HIGHWAY 267
SHRUB-7,1974
•SHRUB-1,1973
TRUCKEE—
HERBACIOUS SEEDING RAIL- 45 KG/HECTARE
WOOD FIBER MULCH RATE -1350 KG/HECTARE
16-20-0 FERTILIZER RATE - 560 KG/HECTARE
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
SCS SEEDINGS
AND PLANTINGS
DEMONSTRATION OF EROSION AND
281
-------
TABLE B-l
SOIL CONSERVATION SERVICE TEST SHRUB PLANTING PLOT DESCRIPTIONS
SPRING 1973, 1974 - NORTHSTAR
PLOT NO.
SHRUB 1; South facing cut adjacent to sales office. Planted Spring 1973.
150 Ceanothus prostratus; 30 vertical rows, 5 plants/row, 2 ft.
spacing, 70 survived until 1975, 63 until 1977.
SHRUB 2; Northwest fill facing. Planted Spring 1973.
# Planted
10 Chryso thamnus nauseosus
10 Ceanothus prostratus
10 Ceanothus prostratus
10 Arctostaphylos patula
10 Arctostaphylos uva— ursi
10 Artemisia caucasia
7 Eriogonum umbellatum
10 Penstemon strictus
Survival
1974 1977
(8)
(5)
(4)
(5)
(4)
(1)
(7)
(9)
(8)
(3)
(2)
(1)
(0)
(1)
(6)*
(8)*
Note: Spacing is 1.0 meter, 8 vertical rows. Rows listed left to
right facing slope from Northstar Drive.
SHRUB 3: North facing cut across from Plot No. SH-2. Planted Spring 1973.
# Planted
6 Caragana arborescens
6 Caragana arborescens
7 Myrica pennsylvanica
7 Syringa vulgaris
1974
(6)
(6)
(0)
(4)
1977
(6)
(6)
(0)
(4)
Note: Spacing is 1.5 meter, 2nd and 3rd rows are 2.0 meters apart.
Vertical rows listed from left to right facing fill from road
surface.
SHRUB 4: North facing fill near small creek. Spring 1973.
# Planted
5 Ceanothus prostratus
5 Chrysothamnus nauseosus
5 Chrysothamnus nauseosus
4 Chrysothamnus nauseosus
* Reseeding and spreading profusely
1974 1977
(2)
(3)
(3)
(2)
(1)
(3)
(2)
(2)
282
-------
TABLE B-l continued
SHRUB 4:
# Planted
5 Artemisia' tridentata
5 Artemisia tridentata
5 Artemisia tridentata
3 Caragana arborescens
2 Artemisia tridentata
5 Atriplex canes cens
5 Atriplex canescens
5 Ceanothus cordulatus
4 Ceanothus cordulatus
5 Caragana arborescens
5 Juniperus conferta
5 Kochia prostrata
4 Arctostaphylos patula
5 Penstemon newberryi
5 Penstemon newberryi
5 Purshia tridentata
5 Purshia tridentata
5 Purshia tridentata
2 Purshia tridentata
5 Rhus trilobata
5 Rhus trilobata
4 Rosa woodsii (cut)
5 Rosa wichuriana
5 Salix gracilis
5 Salix purpurea
Note: Spacing 1.22 meter, 28 vertical rows
left facing slope from Northstar Drive.
SHRUB 5: South facing fill near West Martis Creek.
# Planted
10 Ceanothus prostratus
Note: 1.0 meter spacing, 2 vertical rows.
SHRUB 6: Northeast facing cut on Big Springs Drive.
# Planted
6 Ceanothus prostratus
5 Ceanothus prostratus
4 Artemisia tridentata
Survival
1974 1977
(5) (5)
(5) (5)
(4) (3)
(2) (2)
(2) (2)
(2) (1)
(2) (1)
(5) (4)
(3) (4)
(3) (2)
(4) (1)
CD CD
(3) (3)
(5) (3)
(4) (3)
(5) (5)
(5) (5)
(5) (5)
(D CD
(1) (0)
CO) (0)
(4) (3)
(5) (4)
(5) (5)
(5) (5)
Rows listed right to
Spring 1973.
1974 1977
CO) (0)
Spring 1973.
1974 1977
(2) (?)
(2) C?)
(3) (?)
Note: 3 vertical rows, rows 1 and 2 plants are 1.0 meter apart,
row 3 plants are 1.2 meter apart. Rows listed left to right facing
cut from road surface.
283
-------
TABLE B-l (continued)
SHRUB 7: South facing cut near Northstar entrance. Spring 1974.
# Planted
A. 4
3
5
3
7
5
1
B. 4
2
1
3
5
2
C. 5
5
1
2
5
3
3
D. 10
1
3
8
5
2
1
Survival
Artemisia tridentata
Ceonothus velutinus
Chrysothamnus nauseosus
Eriogonum umbellatum
Artemisia tridentata
Penstemon newberryi
Arctostaphylos nevadensis
Penstemon newberryi
Artemisia tridentata
Arctostaphylos nevadensis
Ceanothus cordulatus
Penstemon newberryi
Eriogonum umbellatum
Artemisia tridentata
Penstemon newberryi
Arctostaphylos nevadensis
Ceanothus velutinus
Chrysothamnus nauseousus
Ceanothus velutinus
Ceanothus cordulatus
Penstemon newberryi
Arctostaphytos nevadensis
Erigonum umbellatum
Artemisia tridentata
Ceanothus consulatus
Ceanothus velutinus
Quercus vaccinifolia
Note: Parts A, B, C planted in horizontal rows as
planted at random. See location map.
SHRUB 8: Northwest facing fill adjacent to Northstar Drive.
# Planted
A. 5
5
5
5
5
5
5
Penstemon strictus
Penstemon strictus
Penstemon strictus
Arctostaphylos uva— ursi
Rosa woodsii
Rosa woodsii
Cornus stolonifera
1977
(1)
(0)
(0)
(3)
(2)
(0)
(0)
(0)
(2)
(0)
(0)
(0)
(2)
(0)
(0)
(0)
(0)
(0)
(0)
(0)
(D
(0)
(3)
(2)
(0)
(D
(D
listed. Part D
Spring 1974.
1974 1977
(4)
(4)
(5)
(2)
(4)
(4)
(2)
(D
(D
(4)
(D
(3)
(4)
(2)
284
-------
ABLEB-1 (continued)
HRUB8 (continued):
A.
B.
// Planted
5
5
5
Survival
1974 1977
Cornus stolonifera
Ephedra viridis
Penstemon strictus
5 Atriplex nuttalli
5 Ephedra viridis
5 Ephedra viridis
5 Arctostaphylos uva-ursi
5 Rosa woodsii
5 Eleagnus angustifolia
5 Eleagnus angustifolia
5 Penstemon strictus
5 Penstemon strictus
(1) CD
(2) (0)
(5) (5)
(3)
(2)
(3)
(2)
(4)
(5)
(5)
(0)
(0)
(0)
(2)
(5)
(0)
(0)
(5)
(5)
Note: Parts A and B planted in horizontal rows as listed.
location map.
See
285
-------
TABLE B-2
SOIL CONSERVATION SERVICE TEST HERBACEOUS SEED PLANTING
PLOT DESCRIPTIONS '
SPRING 1973, 1974
PLOT NO.
HERB 1:
HERBACEOUS SEEDING RATE: 45 kg/hectare
WOOD FIBER MULCH RATE: 1,350 kg/hectare
16-20-0 FERTILIZER RATE: 560 kg/hectare
Northwest facing cut on Northstar Drive. Spring 1973.
Subplots A through L left to right in 3.0 meter widths.
Singles |
A. Agropyron trichophorum (Luna pubescent wheatgrass) 100
B. Agropyron intermedium (Tegmar intermediate wheatgrass) 100
C. Agropyron smithii (Western wheatgrass) 100
D. Agropyron cristatum (Fairway crested wheatgrass) 100
E. Poa ampla (Sherman big bluegrass) 100
F. Agrostis tenuis (Highland Colonial bent grass) 100
G. Agropyron riparium (Sodar streambank wheatgrass) 100
H. Festuca ovina duriuscula (Durar hard fescue) 100
Mixtures
I. Sodar streambank wheatgrass 30
Pomar Orchardgrass 30
Durar hard fescue 30
White Dutch clover 10
J. Tegmar intermediate wheatgrass 30
Western wheatgrass 20
Manchar smooth brome 20
Sherman big bluegrass 20
Rambler alfalfa 10
K. Luna pubescent wheatgrass 30
Fairway crested wheatgrass 20
Sherman big bluegrass 20
Latar orchardgrass 20
Cicar Cicer milkvetch 10
L. Fairway crested wheatgrass 20
Pomar orchardgrass 20
Sodar streambank wheatgrass 10
Durar hard fescue 10
286
-------
TABLE B-2 (continued)
HERB 1 (continued):
HERB 2:
HERB 5:
Mixtures
Sherman big bluegrass
Cicar Cicer milkvetch
White Dutch clover
Rambler alfalfa
10
10
10
10
Note: Each single or mixture type planted in 3.0 meter wide plots
left to right facing cut from road surface.
South facing fill adjacent to Northstar Drive and West Martis Creek.
~~Spring 1973.
Same single and mixture application as listed for HERB 1, planted
left to right facing fill slope from road surface. Six meter blank
spacing between single types E and F and mixture types I and J.
HERB 3: Northeast facing cut adjacent to Big Springs Drive. Spring 1973.
Same single and mixture application as listed* for HERB 1, planted
left to right facing cut slope form road surface. Mixture M was
also included at right most end of HERB 3:
M. Purshia tridentata
Atriplex canescens
HERB 4; Southeast facing cut adjacent to Northstar Drive. Spring 1973.
50
50
Fairway crested wheatgrass
Pomar orchardgrass
Sodar streambank wheatgrass
Durar hard fescue
Sherman big bluegrass
Cicar Cicer milkvetch
White Dutch clover
Rambler alfalfa
Northwest facing fill adjacent to Northstar Drive. Spring 1973.
Same mixture application rate as listed for HERB 4.
20
20
10
10
10
10
10
10
287
-------
TABLE B-2 (continued)
HERB 6; East facing cut slope adjacent to parking lot near Big Springs
Drive. Spring 1973.
Cana Reed canarygrass
Luna pubescent wheatgrass
Yellow sweetclover
Cicar Cicer milkvetch
Cascade broadleaf trefoil
7
/o
30
40
10
10
10
HERB 7; Northwest facing cut slope adjacent to'Northstar Drive. Spring 1974
Western wheatgrass
Pomar orchardgrass
Durar hard fescue
Blando brome
Lutana Cicer milkvetch
30
30
20
10
10
HERB 8; Northwest facing cut slope adjacent to Northstar Drive. Spring 1974
Sodar streambank wheatgrass
Pomar orchardgrass
Durar hard fescue
Blando brome
Lutana Cicer milkvetch
White Dutch clover
30
30
20
10
5
5
HERB 9; Northwest facing cut slope adjacent to Northstar Drive. Spring 1974.
Same herbaceous seed mixture as used in HERE 8.
HERB 10; Northwest facing cut slope adjacent to Northstar Drive. Spring 1974.
Luna pubescent wheatgrass
Standard crested wheatgrass
Blando bromegrass
Sherman big bluegrass
Palestine orchardgrass
Lutana Cicer milkvetch
30
10
10
20
20
10
288
-------
TABLE B-2 (continued)
HERB 11; Northwest facing cut slope adjacent to Northstar Drive. Spring 1974.
Tegmar intermediate wheatgrass
Western wheatgrass
Manchar smooth brome
Sherman big bluegrass
Ranger alfalfa
30
20
20
20
10
HERB 12:
HERB 13:
Northeast facing fill slope adjacent to Big Springs Drive. Spring
1974.
Same herbaceous seed mixture as used in HERB 10.
Northeast facing fill slope adjacent to Big Springs Drive. Spring
1974.
Same herbaceous seed mixture as used in HERB 11.
289
-------
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SCALE (meters)
"1 I-
100 150 200
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
HERBACEOUS SEEDING AND WOODY
PLANTINGS, FALL, 1976
AT RUBICON PROPERTIES
DEMONSTRATION OF EROSION AND
SEDIMENT CONTROL TECHNOLOGY
FIQUR E , NUMiER
B-3
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SEE TABLE B-VI
SECTION J
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TABLE B-5
PLOT DESCRIPTION SYMBOLS
Note:
This table identifies the meaning of those symbols used to describe
the plots in columns 1 through 23 of Table B-3 (Northstar Plot
Descriptions) and Table B-4 (Rubicon Properties Plot Descriptions).
A. PLOT DESCRIPTIONS
Column 1.
Plot Identification Number. Corresponds to number in Figure B-3
and Figure B-4.
Column 2. Plot Dimensions
Top - Width, meters
Bottom - Slope length, meters
Column 3. Plot Type and Area
Top, cut or fill
Bottom, area, square meters
Column 4. Plot Slope Angle
Top - Angle of slope before implementation of erosion control,
degrees
Bottom - Angle of slope after erosion control measures, degrees.
"olumn 5. Plot Overhang Description
For the purposes of this table, "Overhang" means all material
above an imaginary 45 degree plane transecting the steepest
uppermost portion of the cuts.
o
Top - Amount of soil in overhang, metersj before erosion control
implemented
Bottom - Estimated amount of soil remaining in overhang after
erosion control implemented.
Column 6. Plot Soil Type (Soil Conservation Service Classification)
MsG - Meeks very stony loamy coarse sand, 30 - 60% slope
DG - Decomposing granite
JTF - Jorge - Tahoma Association, 30 - 50% slopes
H-P - Hardpan layers producing seepage areas
If more than one type is listed, the first is the more prevalent
type.
313
-------
TABLE B-5 (continued)
Column 7. Plot Exposure. The directional exposure of the plot face. N
denotes north, E denotes east, S denotes south, and W denotes
west.
Column 8. Plot Seepage. The percentage of the slope that is affected by
seepage during late spring and early summer.
B. MECHANICAL STABILIZATION
Column 9. Slope Toe Stabilization.
Top-type of toe stabilization.
ROCK - Rockwall of .5 to 1.5 meter diameter boulders
GAB - Rockfilled wire mesh gabion baskets
CURB - Roll curb and gutter
Note: Gutters were constructed at foot of all rockwalls and
gabions. No toe stabilization on fill slopes.
Bottom - height of stabilizing structure
Column 10. Slope Overhang Stabilization.
o
Top - amount of soil removed from overhang (m )
Bottom - percent of total overhang removed.
Column 11. Willow Wattling.
Top - Number of rows of wattling
Bottom - Total length of wattling in meters.
C. PLANTS
Column 12. Number of Each Type of Plant
Column 13. Transplant Type
GRS - Container grown grass seedlings
SHRB - Container grown shrubs. Unless otherwise indicated, all
shrubs were obtained from the Dept. of Env. Horticulture,
U. C. Davis.
(HO) - Plants obtained locally
TRS - Bare root trees purchased from the California State
Division of Forestry.
314
-------
TABLE B-5 (continued)
D. PLOT SEEDING
Column 14. Grass Seeding Hate, kg/ha.
Column 15. Legume Seeding Rate, kg/ha.
Column 16. Shrub Seeding Rate, kg/ha.
Letters A-E in Columns 15-17 indicate seed mixtures as follows. The top one-
quarter of all plots at Rubicon Properties was hand seeded with grass mixture
C at a rate of approximately 50 kg/ha after application of final mulch or
PERCENTAGE COMPOSITION OF SEED AND FERTILIZER MIXTURES
USED AT THE EROSION CONTROL PROJECT SITES
GRASSES
Luna pubescent wheatgrass
Tegmar intermediate wheatgrass
Durar hard fescue
Potomac orchard grass
Manchar smooth brome
Lincoln smooth brome
LEGUMES
Lutana cicer milkvetch
Dutch white clover
Cascade trefoil
Grass Seed Mixtures
A B C D E
11
66
17
11
56
—
33
16
42
16
16
40
40
—
20
25
25
12
25
— — 10 — 13
100 100 100 100 100
Legume Seed Mixtures
ABC D E
57 50 67
24 50 11
19 — 22
50
50 100
100 100 100 100 100
315
-------
TABLE B-5 (continued)
SHRUBS AMD WILDFLOWERS
Artemisia tridentata
Purshia tridentata
Oenotheria hookeri
Linum lewis ii
Gilia leptantha
Nemophila maculata
Eschcholzia calif.
Eriogonum umbellatum
Shrub Seed Mixtures
A B C D
10 100 100
30 — —
20 -- --
10
10 —
10
10 — ~
10
10
30
60
100 100 100 100
Column 17. Wood Fiber Mulch.
Top - Type of mulch and method of seed application.
I - Weyerhauser "Silva-Fiber"R
II - Conwed Hydro MulchR
III - Conwed Hydro Mulch "2000"R
1 - Seed in mulch
2 - Hydroseeded, then mulched
3 - Hand seeded and raked in, then mulched
Bottom - Rate of mulch application, kg/ha
Column 18. Straw Mulch.
Top - Type of straw applied
DAVIS - Barley straw
PMC - Tall wheatgrass
BOTH - PMC in upper part of plot. DAVIS in lower part,
RICE - Rice straw
WHEAT - Wheat straw
Note: Seed hand cast and hand raked on all straw plots.
Bottom - Rate of straw application, kg/ha
Column 19. Straw Tack.
Top - Type of straw tack applied
SSEC - Sta-Soil Ecology Control
TT II - Terra Tack IIR
TTSC - Terra Tack IIR, super concentrate
316
-------
TABLE B-5 (continued)
Column 19. (continued)
WF - Woodfiber
PVA - Polyvinyl acetate (used to tack wood fiber
mulch only)
DOW - DOW Chemical USA XFS - 4163 L mulch binder
(1,2,3,X) applied as indicated below:
DOW MULCH BINDER APPLICATION RATES
DOW 1
DOW 2
DOW 3
DOW X
Note:
Water
kg/ha
4.25
4.25
4.25
8.50
Latex
kg/ha
.77
.77
.77
1.54
Modifier
kg/ha
10.2
10.2
10.2
20.4
Wood Fiber
kg/ha
230
460
460
DOW XFS - 4163 L mulch binder is a form of Styreme
butadiene (SBR).
Bottom - Straw tack application rate, kg/ha
Column 20. Other Materials Used to Stabilize Seeded Slopes
EXCEL - ExcelsiorR netting
CONWED - ConwedR plastic netting
HG • - Hold-GroR netting
JUTE - Jute netting
E. FERTILIZER
Column 21. Type of Fertilizer Applied.
16-20—0 - Commercial fertilizer
M-A - Mag-Amp 7-40-6 slow release
U-F - Urea formaldehyde 38-0-0 slow release
Column 22. Rate of Fertilizer Application, kg/ha
317
-------
LEGEND
PROJECT SITE
SHRUB a TREE
• f PLANTING SECTIONS
SPRING, 1977.
STATE OF CALIFORNIA
STATE WATER RESOURCES CONTROL BOARD
SHRUB AND TREE PLANTINGS
SPRING, 1977
AT RUBICON PROPERTIES
SCALE (METERS)
i 1 1 1
100 150 200 250 300
318
-------
TABLE B-6
RUBICON PROPERTIES SHRUB PLANTING SECTION
DESCRIPTION - MAY, JUNE 1977
Section A:
Section B;
Section C:
Section D:
Section E:
East facing cut slope adjacent to Rubicon Glen Drive. Planted
6/3/77.
&
160 Atriplex canescens
160 Ceanothus prostratus
120 Rhamnus rubra
120 Penstemom strictus
Note: Spacing is variable. Planted as listed above right
to left facing slope from road surface. Propagated in various
containers. Fertilized with various fertilizer treatments.
North and west facing cut slope adjacent to Rubicon Glen Drive.
2-3 rows of wattling at south end of section. Planted 6/23/77.
600 +_ willow stakes driven in at random over entire plot.
East and west facing cut slopes adjacent to Rubicon Glen Drive.
Planted 6/3/77.
350 Abies concolor, Abies magnifica, Pinus jeffreyi (bare root)
various pines and firs (bare root)
280 Penstemon newberryi
50 Erigonum umbellatum
440 Agropyron trichophorum "Luna" (peat pots)
80 Atriplex canescens
Note: Above planted at random within Section C.
East to north facing cut slope adjacent to Rubicon Glen Drive
and Lonely Gulch Creek. Planted 5/24/77 and 6/3/77.
120 Agropyron trichophorum "Luna" (peat pots)
80 Penstemon newberryi
160 Chrysothanmus nauseousus
+300 Willow stakes
Note: Above planted at random within Section D.
Northwest facing cut slope adjacent to Rubicon Glen Drive and
Lonely Gulch Creek. One and two tier gabion breastwall con-
structed behind curb and gutter at slope toe. Slope scaled,
overhangs removed with three to four rows of willow wattling.
Planted 6/2/77.
319
-------
TABLE B-6 (continued)
Section E (continued):
Section F:
Section G:
Section H:
100 Pinus jeffreyi
280 Agropyron trichophorum "Luna" (peat pots and books)
Note: Jeffrey pines planted in fertilizer test plots.
Abandoned dirt road adjacent to Lonely Gulch Creek. Planted
5/11, 12, 13, 24/77.
500 Pinus jeffreyi (bare root)
275 Pinus lambertiana (bare root)
120 Purshia tridentata (books)
120 Ceanothus prostratus (books)
120 Chrysothamnus nauseosus (peat pots)
20 Cornus stolonifera (deep tubes)
40 Penstemon strictus (peat pots)
40 jlymphoricarpos sp. (peat pots)
40 Prunus emarginata (peat pots)
20 Penstemon newberryi (deep tubes)
Above planted in fertilizer test plots and container compari-
son plots.
160 Agropyron trichophorum "Luna" (peat pots)
213 Penstemon newberryi
603 Prunus emarginata
55 Penstemon strictus
60 Atriplex canescens
40 Lupinus sp.
60 Rhamnus rubra
90 Ribes sp.
68 Ceanothus prostratus
16 Cornus stolohifera
15 Eriogonum umbellatum
48 Salix sp.
Planted in blocks by species.
Severe north facing cut slope adjacent to Lower Lakeview Drive
Two and three tier gabion retaining wall constructed behind
curb and gutter at slope toe. Slope extensively scaled and
overhangs removed with four to six rows of contour willow
wattling. Planted 6/3/77.
66 various Lupinus species
400 Agropyron trichophorum "Luna" (peat pots)
80 Penstemon newberryi
320
-------
TABLE B-6 (continued)
Section H (continued):
Section I
Note: Lupinus species planted with various fertilizer treat-
ments. Other plants at random. Partially replanted on 6/20
with +200 "Luna" and Penstemon newberryi.
Cleared lot above Section H adjacent to North Lakeview Drive.
Planted 5/24/77.
120 Agropyron trichophorum "Luna" (peat pots)
240 Atriplex canescens (book planters)
150 Abies concolor (bare root)
Note: "Luna" and Atriplex planted in fertilizer test plots.
Section J: Severe east facing cut slope at corner of Lakeview and Manzanit
Drives. Two and three tier gabion retaining wall constructed
behind curb and gutter at slope toe on southerly two-thirds of
this section. Planted 6/1, 3/77.
140 Eriogonum umbellatum
100 Pinus labertiana. and Pinus jeffreyi (bare root)
80 Atriplex canescens
40 Chrysothamnus nauseousus
Note: Erigonum on northerly 15 meters of section with various
fertilizer treatments.
East facing cut slope adjacent to Upper Lakeview Drive.
Planted 5/24/77.
250 Penstemon newberryi (small tubes north end)
280 Agropyron trichophorum "Luna" (south end)
North facing cut slope adjacent to Forest Drive. Four rows of
contour willow wattling. Entire slope extensively scaled with
overhang removed. Curb and gutter reconstructed at slope toe.
390 Penstemon newberryi
280 Agropyron trichophorum "Luna"
240 Chrysothamnus nauseousus
75 various Abies species
400 willow (Salix) stakes
200 Atriplex canescens
Note: Above planted in fertilizer and container test plots.
Section K:
Section L:
321
-------
TABLE B-6 (continued)
Section M:
Section N:
Section 0:
Section P:
North facing cut slope at the end of Forest Drive. Overhang
removed and 3-4 rows of contour wattling placed at 2 meter
intervals.
80 Penstemon newberryi
52 Chrysothamnus nauseosus
42 Purnus emarginata
123 Atriplex canescens
67 Ceanothus prostratus
10 Symphoricarpos sp.
60 Purshia tridentata
21 Rhamnus rubra
22 Arctostaphylos patula
Plants listed above planted at random below wattled cut and on
adjacent cuts.
250 Penstemon newberryi
160 Ceanothus prostratus
280 Purshia tridentata
180 Chrysothamnus nauseosus
Plants listed above planted in fertilizer test plots on wat-
tled cut.
Abandoned dirt road from Highland Drive. Water bar and grass
seeding conducted in fall 1976. Planted 6/1/77.
400 Agropyron trichophorum "Luna"
Note: "Luna" in peat pots placed southerly portion adjacent to
Highland Drive.
Northwest facing fill slope adjacent to Highland Drive. Plante
6/1/77.
250 Pinus lambertiana and P. jeffreyi (bare root)
Northwest facing cut slope adjacent to Highland Drive. Four
rows of willow wattling on southerly portion. Planted 5/27/77.
360 Agropyron trichophorum "Luna" (book planters)
125 Pinus jeffreyi (bare root)
125 Pinus lambertiana (bare root)
Note: "Luna" on northerly portion of section and Pinus spp
planted in fertilizer test plots.
322
-------
TABLE B-6 (continued)
Section Q:
Section R:
East and west facing cut slopes adjacent to dirt road leading
to water storage tank from Highland Drive. Planted 6/1/77.
250 Pinus lambertiana and P. jeffreyi (bare root)
North facing gentle slope with a portion of cut and a portion
of an old road. Planted 6/15/77.
240 Prunus emarginata
280 Purshia tridentata
160 Ceanothus prostratus
These planted in fertilizer test plots.
Area adjacent to test plots planted with +_ 400 container grown
grasses and shrubs.
323
-------
Number
APPENDIX C
WATER QUALITY AND ENVIRONMENTAL MONITORING DATA
TABLES
C-l Water Stored as Snow for each 105 Meter (500 Feet)
Contour Internal at Northstar .............. 328
G-2 Suspended Sediment Sampling Site Locations in West
Martis Creek Watershed 329
C-3 Summarized Suspended Sediment Data Collected at North-
' star, October 1974 through September 1976 333
C-4 Suspended Sediment Site Locations in Lonely Gulch Creek
Watershed .,,,,., 336
G-5 , Summarized Suspended Sediment Data Collected at Rubicon
Properties, October 1972 through September 1976 337
C—6 Standing Crop Estimates of Benthic Macroinvertibrates
listed by Family for West Martis Creek for all Stations
Sampled during 1974, 1975, and 1976 339
C-7 Standing Crop Estimates of Benthic Macroinvertibrates
listed by Family for Lonely Gulch Creek for all Stations
Sampled during 1975 and 1976 345
C-8 Summarized Monthly Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 1, West
Martis Creek 347
C-9 Summarized Monthly Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 2, West
Martis Creek 349
C-10 Summarized Monthly Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 3, West
Martis Creek 351
324
-------
Number
C-ll
C-12
C-13
Summarized Monthly Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 4, Unnamed
Tributary to Martis Creek
Summarized Monthly .Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 5, Lonely
Gulch Creek
Summarized Monthly Flows and Suspended Sediment Loads
Projected by Water Quality Model for Gage No. 6, Lonely
Gulch Creek
Page
353
354
358
325
-------
APPENDIX C
WATER QUALITY AND'ENVIRONMENTAL MONITORING DATA
INTRODUCTION
The material in Appendix C is a more extensive presentation of much of the
hydrologic and water quality data which is only briefly referred to Section
VII of the main report. Included on the following pages are the following
Tables:
Table C-l: Water Stored as Snow for each 105 Meter (500 Feet) Contour
Interval at Northstar. Presented is a summarization of the
water content of snow pack measurements taken at six sampling
sites at Northstar during 1975 and 1976. The original data
at each site is assumed to be representative of conditions
found in succeeding 150 meter contour intervals from the
lowest elevation of the Northstar development to the top of
Mt. Pluto. Estimate of total water content of snow pack at each
sampling date is also included.
Table C-2: Suspended Sediment Sampling Site Locations in West Martis
Creek Watershed. Presented is a brief description of
suspended sediment sampling stations located in the West Martis
Creek (Northstar) watershed. Included is description of
drainage area above sampling site listing types of
disturbances, if any.
Table C-3: Summarized Suspended Sediment Data Collected at Northstar
October 1974 through September 1976. Presented is a
summarization of the suspended sediment samples collected at
Northstar at each sampling site for each runoff type:
Lowflow, Stage I Snowmelt, Stage II Snowmelt, and Rainfall. A
total of 571 samples were collected and analyzed.
Table C-4: Suspended Sediment Sampling Site Locations in Lonely Gulch
Creek Watershed. Presented is brief description of
suspended sediment sampling stations located in the Lonely
Gulch Creek (Rubicon Properties) Watershed.
326
-------
Table C-5:
Table C-6:
Table 0-7:
Table C-8:
(through
Table C-13:)
Summarized Suspended Sediment Data Collected at Lonely Gulch
Creek (Rubicon Properties) October, 1972 through September.
1976. Presented is a summarization of the suspended
sediment samples collected at Norths tar at each sampling site
for each runoff type: Lowflow, Stage I Snowmelt, Stage II
Snowmelt, and Rainfall. A total of 301 samples were collected
and analyzed.
Standing Crop Estimates (number of individuals/m2) of Benthic
Macroinvertebrates listed by Family for West Martis Creek
(Northstar) for all Stations Sampled during 1974, 1975 and
1976' Summarized data for nine sampling stations in West
Martis Creek.
Same as above for four stations in Lonely Gulch Creek
(Rubicon Properties) during 1975 and 1976.
Summarized Monthly Flows arid Suspended Sediment Loads
Projected by Water Quality Models. Based upon
suspended sediment concentration vs. streamflow relationships,
and continuous streamflow records at four West Martis Creek
and two Lonely Gulch Creek gaging stations. Estimated
suspended sediment loads for the four different runoff types
during each month of record, at each gage is presented.
327
-------
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328
-------
TABLE C-2
SUSPENDED SEDIMENT SAMPLING SITE LOCATIONS IN
WEST MARTIS CREEK WATERSHED
Site !• Gage No. 1. Stevens gage above 1.22 meter rectangular weir.
Located near the Big Springs day lodge on the west fork, West Martis Creek.
Drainage area above this point is 294 hectares and extends to the summit of
Mount Pluto at an elevation of 2620 meters. Approximately 113 acres of fores
land have been cleared for ski trails. Flow over this weir is principally
overland flow as spring water is collected via an underground collection
system above this point. Groundwater collected by this system is transported
either to the water treatment plant or through a bypass mechanism to the
V-notch weir (Site 5).
Site 2. Gage No. 2. Stevens gage above a 90° V-notch weir. Located
on east fork of West Martis Creek above the confluence with the west fork.
The drainage area .above this point is 471 hectares. A 2.0 x 105 cubic meter
storage reservoir is located 2.4 kilometers above this sampling site. All
surface runoff is collected by this reservoir which only briefly overflows
in the spring time of some years. A groundwater collection system is
located above this reservoir. A bypass valve spills excess water to the
east fork about one-third of a mile below the reservoir. Extremely low
flows have been observed in the east fork at this point due to the
limitation of bypass flow from the groundwater collection system when the
treatment plant is on.
Site 3. Gage No. 3. Stevens gage above a 1.8.3 meter retangular weir.
located on West Martis Creek below a bridge approximately one-eighth
mile north, of th.e golf course club Louse. Samples taken above bridge
crossing the creek. Drainage area above this point is 1308 hectares. The
majority of the Northstar development is above this point.
'ite 4. Gage No. 4. Stevens gage above 1.22 meter retangular weir.
Located on unnamed tributary to Martis Creek. Drainage area' above this
point is 220 hectares. Meadow, pasture, and timber areas are located
above this sampling point.
ite 5. 'V-notch weir. Sixty degree V-notch weir located 1.22 meters
east of Gage No. 1. Flow consists of overflow from the Big Springs
groundwater collection system. Flows have been seen to range from
approximately 30 liters/sec when the treatment plant is not functioning
to as low as 2.25 liters/sec when the treatment plant is on.
ite 6. Village Culvert. 1.22 meter CMP draining Northstar Village
and parking area. Discharging to the west fork of West Martis Creek
about 100 meters NE of the village center. The total draining to the
329
-------
ABLE C-2 - continued
sriLllage culvert is 80 hectares. 70 hectares or 88 percent of the total
rea does not include any man-made disturbances. The lower 10 hectares
f the drainage contains 0.6 hectare of paved roadway, 2.0 hectare of
aved parking area, 0.2 hectare of structures, 0.4 hectare of unrevege-
ated oversteepened cut slopes. These structures, paved roadways,
arking lots, and cut slope surfaces drain directly to drop inlets and
ubsequently to the Village Culvert.
ite 7. West Fork of West Martis Creek just above the discharge point
f the Village Culvert.
ite 8.
Trapezoidal weir with staff gauge on the west fork of West
artis Creek above the contours with the East Fork. The total drainage
area above the T-weir is 560 hectares including the ski area and village
center.
jite 9. Overflow or bypass valve from the Sawmill Flat groundwater
collection system on the east fork of West Martis Creek at the point
rhere Big Springs Road crosses the creek.
Site 10. East Fork of West Martis directly above Big Springs Road.
lurface drainage is apparent at this point only when there is substantial
overflow from the reservoir.
Site 11. Drainage from unpaved dirt road into East Fork of West Martis
Creek.
Site 12. East fork of West Martis Creek below Big Springs Road and the
sawmill valve.
Site 13. Rock lined drainage ditch from Unit 1-B discharging to West
lartis Creek about. 60 meters below the confluence of the east and west
forks. The Unit 1-B drainage area is 4.1 hectare. This drainage area
has 0.75 hectare of paved surface area and 0.4 hectare of condominiums.
Hence, approximately 28 percent of this drainage basin is covered with
impervious surfaces.
Site 14.
^^ J.-T. A drop inlet collecting drainage from the upper reaches of
the parking lot across Norths tar Drive from the village. The drop
inlet is located at the north end of the parking lot near Big Springs
Drive. The entire drainage area is 7.7 hectates. The total paved
parking lot surface draining to this drop inlet is 0.6 hectare.' Cut
slopes adjacent to the parking lot area are approximately .22 hectare.
Site 15. A drop inlet collecting drainage from the middle bay of the
parking lot across Northstar Drive from the village. Total area of
330
-------
TABLE C-2 - continued
this drainage is approximately 0.80 hectare. Paved surface area is 0 4
hectare and cut slope surface area is 0.1 hectare. Drainage to this
drop inlet eventually flows to the village culvert and subsequently to
the west fork of West Martis Creek.
S*te 16.- A drop inlet collecting drainage from the southwest corner of
the_uPPer reach of the parking lot. Total surface area of this drainage
basin is 9.3 hectare. Ninety-nine percent of this drainage area is
nnf?ed> Cut sl°Pe area at the lower-reach of this drainage basin
is 0.06 hectare; 'paved surface adjacent to the cut surface is 0.08
hectare.
, 17' Discharge of drainage ditch to the west side of West Martis
Creek about 30 meters south of the Northstar Drive. Total area of this
drainage is 108 hectare. The only direct discharge from a disturbed
area to this drainage ditch is from Site 14. The Goldbend Condominium
units of Unit 1-C are also located within this drainage basin, however
any discharge from disturbed areas is spread over undisturbed land
Site 18.
West Martis Creek directly ahove Site 17 discharge point.
S:Lte 19- Sampling point is at the end of the culvert under Northstar
Drrve above confluence with rock lined drainage ditch approximately 100
meters west of West Martis Creek. Drainage is surface flow from waste
water treatment plant site.
Slte 20- Sampling point in rock lined drainage ditch above Site 19.
?,1' DrainaSe from Unit 1~A at discharge point to each side of
ftrfrt -V- +- •? 1-1 r^t~r*.~1- -2 J_ _ 1 -»T .-.
TT . -,, -, ~ —~~—C?1- f V/J.J.J.I- i~\j CCH-1JL O_LUfcI U-L
West Martis Creek just above Northstar Drive. Total drainage area is
1.5 hectares. Paved surface area which contributes to the majority of
the runoff from this unit is about .26 hectare.
Site 22- West Martis Creek about 30 meters below Northstar Drive.
Site 23. Small unnamed creek about 300 meters east of West Martis
Creek just above Northstar Drive.
Site 24- Small unnamed creek about 1,000 meters east of West Martis
Creek just below Northstar Drive.
S.ite 25- Small unnamed creek about 120 meters of West Martis Creek
just north of Basque Street
i
Site 2.6-/ West Martis Creek just north of Basque Street.
331
-------
TABLE C-2 - continued
Site 27. West Fork of West Martis Creek about 10 meters above the
bridge from the village parking lot to the recreation complex.
Site 28. Overland drainage from condominium unit and concentrated
across fill slope which forms the ski run at the bottom of the
transport lift. Drainage is to the west fork of West Martis Creek at
the recreation complex bridge. The total area of this drainage is
approximately 10.5 hectares. Fill area comprising the ski run-out
area at the bottom of the transport lift about 1.2 hectare. Impervi-
ous paved parking lot and street surface areas from which flow is
concentrated across the ski run has an areal extent of 0.5 hectare.
Site 29. Middle Martis Creek above confluence with Martis Creek.
Site 30. West Martis Creek just above confluence with Martis Creek.
Site 31. Martis Creek just above confluence with West Martis Creek.
332
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TABLE C-4
SUSPENDED SEDIMENT SAMPLING SITE LOCATIONS IN
LONELY GULCH CREEK WATERSHED
Site 32 - Above a small reservoir on Lonely Gulch Creek and above all
development.
Site 33 - Located 200 meters below Site 32 and just below the small
domestic water supply reservoir. It was located upstream of all
disturbances and drainages from Rubicon Properties Subdivision.
Gage No. 5 flow recorder located here.
Site 34 - Approximately 130 meters downstream of Site 33 at Rubicon Glen
Drive and below a third major drainage swale draining the
subdivision.
Site 35 - Located 170 meters below Site 34 and immediately above Highway 89
and below a fourth major drainage swale.
Site 36 - Located 800 meters below Site 35 at Gage No. 6 flow recorder and
below the majority of Rubicon Properties Subdivision development.
Site 37 - In Lake Tahoe ,at the mouth of Lonely Gulch Creek and about 180
meters downstream of Site 36.
Site 38 - Brook Street Culvert No. 1 carrying surface drainage from Forest
View Drive.
Site 39 - Drainage ditch at lower end of Highland Drive.
Site 40 - Drainage ditch at lower end of Highview Drive.
Site 41 - Brook Street Culvert No. 2 carrying surface drainage from Highland
and Highview Drives.
Site 42 - Brook Street Culvert No. 3 carrying drainage from Upper Lakeview
Drive.
Site 43 - Brook Street Culvert No. 4 carrying drainage from Upper Lakeview
Drive.
Site 44 - Upper Scenic drainage ditch carrying surface drainage from North
Lakeview, South Lakeview, Manzanita and Upper Scenic Drives.
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APPENDIX D .
SOURCES OF ESOSION CONTROL
PRODUCTS AND SERVICES
Included in this appendix are lists of numerous commercial sources for erosion
control plants, seeds, products and services which were used as part of the
erosion control demonstration project or may be suitable for use in the Lake
Tahoe Basin of California and surrounding areas. The lists are not complete
and do not constitute a guarantee of reliability or quality of product or
service. The California State Water Resources Control Board does not endorse
any supplies or providers of services. No discrimination is intended by
omission.
I. Plants and Seeds
Parts A, B, C, D, and E are listings of the various grasses, legumes.
flowers, shrubs and trees, respectively, which were used as part
wild-
he
erosion'control demonstration project. Numerical designations following
each plant species refers to the numerical listing of plant and seed
suppliers contained in Part F.
A. Grasses
1. Agropyron intermedium (intermediate wheatgrass)
. Greenar - 1, 2, 3, 17
. Oahe - 1, 2, 3, 8, 14, 15, 16, 17
. Tegmar - 27, 35
. No variety given - 7, 12, 13, 18, 28, 31, 34
2. Agropyron trichophorum (pubescent wheatgrass)
Luna
- 1, 2, 3, 7, 8, 14, 15, 18, 24, 28, 31, 34, 35
Topar - 1, 2, 3, 13, 17, 18, 24, 35
. No variety given - 8, 12, 13, 28
Bromus enermis (smooth brome)
. Manchar -7,8, 13, 14, 17, 18, 24, 28
. Lincoln - 8, 12, 14, 17, 18, 24, 28, 33
Dactylis glomerata (orchard grass)
. Potomac - 1, 2, 3, 7, 8, 13, 15, 17, 18, 24, 31, 33, 35
362
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5. Festuca ovina (hard fescue)
. Durar - 1, 2, 3, 7, 8, 13, 15, 17, 18, 24, 31, 33, 35
B. Legumes
1. Astragalus cicer (Cicer milkvetch)
. Lutana - 2, 8, 13, 16, 28, 34
2. Lotus corniculatus (Birds foot trefoil)
. Broadleaf - 1, 2, 3, 10, 12, 13, 14, 15, 17, 18, 31, 33
3. Lupinus Spp. (lupines)
. 1, 3, 6, 9, 10, 19, 21, 22, 25, 26, 30, 31
4. Trifolium repens (white dutch clover)
. 1, 3, 7, 8, 13, 17, 18, 24, 31, 33
C. Wildflowers
!• Eschscholzia calif. (California poppy)
. 1, 3, 9, 10, 21, 22, 25, 30, 31, 36
2. Gilia leptantha (showy blue gilia)
. 1, 3, 9, 10, 22, 25, 30, 31
3. Linum perenne lewisii (western blue flax)
. 1, 3, 9, 10, 22, 25, 30, 31
4. Nemophila maculata (fivespot)
. 1, 3, 9, 10, 22, 25, 30, 31
5. Oenothera hookeri (hooker's evening primrose)
. 1, 3, 9, 10, 22, 25, 30, 31
6. Wild flower seed mixtures
. 1, 3, 9, 10, 21, 22, 25, 30, 31
363
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D. Woody Shrubs
1. Amelanchier alnifolia (service berry)
. 11, 19, 25
2. Arctostaphylos nevadensis (pinemat manzanita)
. 11, 22, 25, 26, 30, 34
3. Arctostaphylos patula (greenleaf manzanita)
. 11, 19, 22, 25, 26, 30, 34
4. Artemisia tridentata (basin sagebrush)
. 3, 5, 11, 21, 22, 25, 26, 30, 31, 36
5. Atriplex canescens (fourwing saltbush)
. 2, 3, 5, 19, 21, 22, 25, 28, 30, 31, 33
. 6. Atriplex gardneri (Gardner's saltbush)
not commercially available
7. Castanopsis sempervirens (bush chinquapin)
. 11
8. Ceanothus cordulatus (snowbush)
. 11, 19, 25, 30
9. Ceanothus prostratus (squaw carpet)
. 11, 19, 22, 25, 26, 29, 34, 36
10. Chrysothamus nauseosus (common rabbitbush)
. 11, 19, 22, 25, 26, 28, 30
11. Cornus stolonifera (dogwood)
. 11, 19, 25
12. Eriogonum umbellatum (sulfur flower buckwheat)
. 3, 19, 22, 25, 26, 30, 31, 36
364
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13. Lonicera conj ugalis (double honeysuckle)
. 11, 25
14. Nama lobbii (wooly nama)
not commercially available
15. Penstemon newberryi (mountain pride)
. 11, 20, 26, 29, 34, 36
16. Penstemon strictus (Rocky Mountain penstemon)
. not commercially available in California
17. Prunus emarginata (bittercherry)
. 11
18. Purshia tridentata (bitter brush)
. 3, 11, 19, 25, 26, 28, 30, 34
19. Rhamnus rubra (Sierra Coffeeberry)
. no commercially "available
20. Ribes spp. (Currant, gooseberry)
. 11, 19, 25, 34
21. Rosa woodsia (Wood's rose)
. 11, 19
22. Rubus parviflorus (thimbleberry)
. 11, 19
23. Salix spp. (willow)
. 11
24. Symphoricarpos spp. (snowberry)
. 11, 19, 25, 34
365
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E. Trees
1. Abies magnifica (red fir)
. 3, 4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
2. Abies concolor (white fir)
. 3, 4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
3. Calocedrus decurrens (incense cedar)
. 3, 4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
4. Juniperus occidentalis (western juniper)
. 3,,4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
5. Pinus jeffreyi (Jeffrey pine)
. 3, 4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
6. Pinus lambertiana (sugar pine)
. 3, 4, 9, 10, 11, 18, 19, 24, 25, 30, 31, 32, 34, 36
F. Plant and Seed Suppliers
The suppliers are listed in alphabetical order with numerical
designations as referred to in preceeding parts A, B, C, D, and E.
1. Albright & Company, 3613 Brook St., Lafayette, CA 94549
(213) 442-3330
2. Arkansas Valley Seeds, Box 270, Rocy Ford, CO 81067
(303) 254-7469
3. Berger & Plate Co., 1 California St., San Francisco, CA 94104
(415) 445-1553
4. California Division of Forestry Nursery, 5800 Chiles Rd.,
Davia, CA 95616 (916) 753-2441
5. Carter, Roy, P. 0. Box 4006, Sylmar, CA 91342 '(213) 367-5811
6. Coates,'Leonard Nurseries, Inc., 400 Casserly Rd.,
Watsonville, CA 95076 (408) 724-0651
7. Curtis & Curtis, Inc., Star Rt., Box 8A, Clovis, New Mexico
88101 (505) 762-4759
8. Eisenman Seed Co., Fairfield, Montana 59436 (406) 467-2521
366
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9. Environmental Seed Producers, Inc., P. 0. Box 5904, El Monte
CA 91734 (213) 442-3330
10. Ferry-Morse Seed Co., Box 100, Mountain View, CA 94042
(415) 967-6973
11. Forest Farm, 990 Tetherow Rd., Williams, OR 97544
(503) 846-6963
12. Germain's, Inc., P. 0. Box 12447, Fresno, CA 93777
(209) 233-8823
13. Jacklin Seed Co., 8803 E. SpragueAve., Spokane, WA 99206
(509) 926-6241
14. Mile-High Seed Co., Box 1988, Grand Junction, CO 81501
(303) 242-3122
15. Miller Seed Co., P. 0. Box 81823, Lincoln, Nebraska 68501
(402) 432-1232
16. Montana Seeds, Inc., Rt. 3, Conrad, Montana 59425
(406) 278-5547
17. North Coast Seed Co., P. 0. Box 12185, Portland, OR 97212
(503) 288-5281
18. Northrup King & Co., P. 0. Box 12123, Fresno, CA 93776
(209) 237-4731
19. Northplan Seed Producers, Box 9107, Moscow, Idaho 83843
(208) 882-8040
20. Cutwater, Harry, P. 0. Box 13709, South Lake Tahoe, CA 95702
(916) 544-5160
21. Payne, Theodore Foundation, 10459 Tuxford St., Sun Valley,
CA 91352 (213) 768-1802
22. Pecoff Bros., Nursery and Seed, Rt. 5 Box 215R, Escondido, CA
92025 (714) 744-3120
23. Perry's Plants, Inc. 19362 Walnut Drive, La Puente, CA
91745 (213) 964-1285
24. Ramsey Seed, Inc., P. 0. Box 352, 260 S. Main, Manteca, CA
95336 (209) 823-1721
25. Robin Clyde, P. 0.- Box 2091, Castro Valley, CA 94546 (415)
581-3467
367
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26. Saratoga Horticultural Foundation, P. 0. Box 308, Saratoga,
CA 95070 (408) 867-3214
27. Sasaki & Sasaki's Farm, Rt. 1, Box 173-B, Weiser, ID 83672
(208) 549-2434
28. Sharp Bros. Seed Co., Healy, Kansas 67850 (316) 398-2231
29. Siskiyou Rare Plant Nursery, 522 Franquette St., Medford, OR
97501 (503) 772-6050
30. S & S Seeds, 382 Arboleda Rd., Santa Barbara, CA 93110
(805) 967-6927
31. Stover Seed Co., 598 Mateo St., Los Angeles, CA 90013
(213) 626-9668
32. Tahoe Tree Company, P. 0. Box 488, Tahoe City, CA 95730
(916) 583-3911
33. Valley Seed Co., P. 0. Box 1110, Phoenix, AZ 85001
(602) 956-4656
34. Wapumne Native Plant Nursery, 8305 Cedar Crest Way,
Sacramento, CA 95826 (916) 383-5154
35. Winterfeld, Delbert F., Box 97, Swan Valley, Idaho 83449
(208) 483-2248
36. Yerba Buena Nursery, 19500 Skyline Blvd., Woodside, CA 94062
(415) 851-1668
II. Erosion Control Products
The following is a partial list of erosion control products and manufacturers.
The list is not complete and does not constitute a guarantee of reliability
or quality of service or product. This list is not meant to endorse any
product, and no discrimination is intended by omission. Products and
manufacturers listed below are those which were:
•
. used as part of the demonstration project,
. similar to product used, or
. mentioned elsewhere in this report.
A. Wood Fiber Mulch
Silva-Fiber Mulch
Weyerhaeuser Co.
Tacoma, WA
(206) 924-2345
Conwed & Conwed 2000
Conwed Corp.
St. Paul, MN
(612) 222-3033
368
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Necco Fiber
National Erosion Control Co.
Cotati, CA
(707) 795-9210
B., Straw and Mulch Tackifiers
Ecology Controls M-Binder
Ecology Controls
No. Hollywood, CA
(213) 877-7645
Dow XFS-4163-L
Dow Chemical, USA
Midland, MI
(517) 636-2086
C. Mulch Nets and Blankets
Excelsior
American Excelsior Co.
Sheboygan, WI
(414) 458-4333
.Conwed Netting
Conwed Corp.
St. Paul, MV
(612) 222-3033
D. Fiber Glass Roving
Glassroot
Pittsburg Plate Glass Co.
Pittsburg, PA
(412) 434-3131
E. Gabions
Bekaert Gabions
Terra-Aqua Conservation
Reno, NV
(702) 329-6262
Terra Tack II
Grass Growers, Inc.
Plainfield, NV
(201) 755-0923
Petroset Soil Binder
Phillips Chemical Co.
Bartlesville, OK
(918) 661-6600
Jute Netting
Ludlow Textiles
Needham Heights, MA
(617) 444-4900
Hold-Gro
Gulf States Paper'
Tuscaloosa, AL
(810) 729-5831
Landglas
Owens-Corning Fiberglass
Toledo, OH
(419) 248-8000
Maccaferri Gabions
Bellevue, WA
(206) 455-4567
Erosion Control Contractors
The following is a partial list of erosion control contractors who have
hydromulching and/or mechanical straw mulching capability in northern
California and northern Nevada. The list is not complete and does not
constitute a guarantee of reliability of quality or service. This list
is not meant to endorse any contractor, and no discrimination is intended
369
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by omission. Generally, other local landscape or nursery contractors are
also available to perform other erosion control activities besides hydro-
mulching or mechanical straw mulching.
A. Northern California
Cagwin and Dorward
San Rafael
(415) 454-3122
Valley Crest Landscaping, Inc.
Hayward
(415) 489-1179
Bibens
Modesto
(209) 545-1621
Coberly-Plumb
Visalia
(209) 732-2216
Enterprise Gardens
Redding
(916) 243-7170
North State Nursery
Ukiah
(707) 462-0553
Selby Soil Erosion Control
Vacaville
(707) 448-1664
B. Northern Nevada
P & S Hardware
Reno
(707) 329-1392
Angelo Pecorilla
Carson City
(702) 883-1119
Contra Costa Landscaping
Martinez
(415) 229-1060
Sunshine Landscapes
San Rafael
(415) 924-2844
Cal-Kirk
Eureka
(707) 822-1168
Econo-Garden
Oakland
(415) 638-4161
Gary Justice
San Ramon
(415) 837-2787
Sci-Soil
Tulare
(209) 586-0117
Howe Landscape
Reno
(702) 358-2888
Unrue Turf Farm
Minden
(702) 782-3146
370
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APPENDIX E
GLOSSARY
abundance, species (richness): A measure of the variety of biologic species
present in a community.
angle of internal friction: The maximum slope that an unconsolidated soil
may assume.
angle of repose: The angle between the horizontal and the maximum slope that
an unconsolidated soil material assumes through natural'processes.
annual plant: A plant that normally lives for one year or less.
aspect: The direction that a slope faces.
asphaltic concrete (A - C): Asphalt and aggregate construction material for
roadway pavement, shoulders, and dikes.
bed load: The sediment that moves by sliding, rolling, or bounding on or
very near the stream bed.
bench: Gently sloping stable area at the toe of a steeper slope.
benthic: Of or pertaining to the bottom of streams, rivers, lakes, or oceans.
berm: ^A raised and elongated area of earth for erosion control intended to
direct the flow of water or suspended sediment.
breast wall: A short retaining wall used for stabilizing the toe of eroding
cut slopes.
Caltrans: California Department of Transportation; the branch of California
State government responsible for the construction and maintenance of
state and federal highways within California.
check dam: A small dam constructed in a gully or watercourse to decrease the
streamflow velocity, minimize channel scour, and promote deposition of
sediment.
contour: The shape of a land surface as expressed by contour lines.
371
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contour line: (a) An imaginary line on the surface of the earth connecting
points of the same elevation; (b) A line drawn on a map connecting points
of the same elevation.
crown: The uppermost edge or edges of a slope.
cut and fill: A process of earth moving by excavating part of an area and
using the excavated material for adjacent embankments or fill areas.
deposition: The lying down of material because of reduction of carrying
capacity.
detritus: In aquatic biology, disintegrated or fragmented organic matter
which is carried to and deposited in a stream, river, lake, or ocean.
diversity (species): A measure of the relationship between the number of
species and the total population of a biologic community; considered to
be a very sensitive biological index of environmental change.
drill seeding: Planting seed with a mechanical device which places the seed
at variable depths into the soil in relatively narrow rows, generally
less than one foot apart.
drop-inlet (D.I.): A structure for collecting surface drainage which has
been directed to it, and dropping the collected drainage water to an
underground conduit.
eco-system: A community of organisms, its interrelationships, and the
surroundings in which they live.
ecology: The interrelationship of organisms with other organisms and their
environment.
equivalent cost: The cost of labor intensive erosion control techniques if
conducted by skilled landscape laborers with a total labor cost of
$16.25 per person-hour.
erosion: Detachment and movement of soil or rock by water, wind, ice, or
gravity.
erosion hazard (rating): A rating system for determining the Degree which
land disturbance would increase erosion rate from a particular area.
evenness, species: A measure of the equality of apportionment of individuals
in a biologic community to various species present.
fertilizer: Any organic or inorganic material of natural.or synthetic origin
which is added to a soil to supply certain elements essential to the
growth of plants.
372
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fertilizer grade: The guaranteed minimum analysis, in percent of the major
plant nutrient elements contained in a,fertilizer material. A 16-20-0
fertilizer refers to the percentage, by weight, of N - P?0 - K 0,
respectively. 5 *•
gabions: Rock filled, heavily galvinized wire mesh baskets used for the con-
struction of breast walls, retaining walls, revetments, and groins.
grade: (a) The slope of a road, channel, or natural ground surface; (b) The
finished surface of a canal bed, roadbed, top of embankment, or bottom
of excavation; any surface prepared for the support of constructipn;
(c) To finish the surface of a canal bed, roadbed, top of embankment,
or bottom of excavation.
gradient: The rate of regular or graded ascent or descent.
ground cover: Herbaceous vegetation and low-growing woody plants that form an
earth cover.
grubbing: The process of removing roots, stumps, and low-growing vegetation.
gully erosion: The erosion process whereby water accumulates in narrow
channels and, over short periods, removes the soil from this narrow
area to considerable depths, ranging from 30 to 60 centimeters to as
much as 170 to 250 centimeters.
hardpan: A hardened subsurface soil layer caused by cementation of soil
particles with organic matter or with materials such as silica,
sesquioxides, or calcium carbonate.
herbaceous: Vegetation that is nonwoody.
hydromulching: The mechanical application of a natural or synthetic mulch to
a soil surface.
hydroseeding: The mechanical application of plant seeds to a soil surface in
a water slurry, with or without fibrous mulch.
imperveous, impermeable: A material or device which is incapable of being
penetrated or passed through by moisture or water.
indicator species: Specific organisms whose individual populations may be
analyzed to determine the degree of stress on an entire ecosystem.
indigenous: Produced, growing, or living naturally in a particular region or
environment.
infiltration: The flow of a liquid into a substance, such as soil, through
pores or other openings; connoting flow into a soil in contradistinction
to "percolation" which connotes flow through a porous substance.
373
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innoculation: The process of adding cultures of symbiotic microorganisms to
legume seed to enhance atmospheric nitrogen fixation.
Lahontan Regional Board:
Region.
Regional Water Quality Control Board, Lahontan
Lake Tahoe Basin: The 1,310 square kilometer watershed of Lake Tahoe (eleva-
tion 1,898 meters) in the Sierra Nevada Mountains of California and
Nevada.
legume: A member of the plant family, Leguminosae, the fruit of which is
usually a pod that opens along two sutures when ripe, leaves are alter-
nate, have stipules, and are usually compound. Includes many valuable
food and forage species such as peas, beans, peanuts, clovers, alfalfas,
and vetches. Practically all legumes are nitrogen fixing plants.
Lonely Gulch Creek: A small creek draining a 237 hectare watershed on the
west side of the Lake Tahoe Basin in California; the stream which flows
through the Rubicon Properties development.
macroinvertibrates: Invertibrate animals generally larger than .5 millemeters
which inhabit stream bottoms or are attached to stones or other objects
in a stream.
mulch: Natural or artificial material used to provide more desirable moisture
and temperature relationships for plant growth.
native plants or species: A plant or species that is a part of an area's
original flora or fauna.
natural (background) level: The natural concentration of potential pollutants
in the environment which would occur without the presence of man's
activities.
Northstar-at-Tahoe: A well-planned and constructed 1,036 hectare all-year
residental and recreational development in the West Martis Creek water-
shed north of the Lake Tahoe Basin in California.
overhang: The verticle, near verticle, or overhanging top section of a heav-
ily eroded cut slope, usually retained by root systems of plants surviv-
ing above the cut slope.
parent material (soils): The unconsolidated, relatively unweathered mineral
or organic matter,from which the surface soils have developed.
percolation (soil water): The downward movement of water through soil, espe-
cially the downward flow of water in saturated or nearly saturated soil
at hydraulic gradients of the order of 1.0 or less.
374
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perennial plant: A plant that normally lives three or more years.
permeability: The capacity for transmitting a fluid.
perveous, permeable: Having the capability of being penetrated or passed
through by moisture or water.
Porter-Cologne Water Quality Control Act: California state law enacted in
1970 which'established the State Water Resources Control Board and estab-
lished procedures, including the collection of monitory remedies, for
maintaining high quality waters within the State.
profile, soil: A verticle section of the soil through all its horizons and
extending into the parent material.
rainfall intensity: The rate at which rain is falling at any given instant,
expressed in centimeters/hour.
retaining walls: Structure used to support and retain soil at an angle
steeper than the angle of internal friction to provide a gently sloping
soil surface above the structure.
Regional Water Quality Control Board, Lahontan Region (Regional Board):
A branch of California State Government, headed by a nine member board,
responsible for water quality control, subject to review by the State
Board, within all watersheds to the east of the crest of the Sierra
Nevada Mountains in California.
revetment: A facing of stone or other material, either permanent or
temporary, placed upon a highly erodible, oversteepened slope to protect
it from erosion.
rhizomatous: Having a root-like stem under or along the ground which sends
out roots from its lower surface and leafy shoots from its upper surface.
riffle: A shallow portion of a stream with rapid turbulent flow.
right-of-way: Right of passage, as over another's property; a route that is
lawful to use; a strip of land acquired for transport or utility
construction.
rill erosion: An erosion process in which numerous small channels of only
several centimeters in depth are formed.
rip rap: Broken rock, cobbles, or boulders placed on earth surfaces, such as
the face of an oversteepened slope, for protection against erosion.
rounding, slope: The modeling or contouring of roadside and oversteepened
slopes to provide a curvilinear transition between several planes; e.g.,
tops, bottoms, and ends of cuts and fills.
375
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Rubicon Properties subdivision (Unit No. 2): An extremely poorly planned and
constructed subdivision development on the west side of the Lake Tahoe
Basin in California.
runoff: That portion of the precipitation on a drainage area that is dis-
charged from the area in swails and stream channels. Types include sur-
face runoff, groundwater runoff, or seepage.
scaling (slope): The process of reworking eroding cut and fill slopes to
eliminate unstable conditions and prepare a surface suitable for the
establishment of vegetation.
scarify: To abrade, scratch, or modify the surface; for example, to scratch
the impervious seed coat of hard seed or to break the surface of the soil
with a narrow bladed implement.
scour: The wearing away of channel substrate on stream beds.
sediment: Solid material, both mineral and organic, that is in suspension, is
being transported, or has been moved from its site of origin by air,
water, ice, or gravity.
sediment load: The quantity of sediment, measured in dry weight or by volume,
transported through a stream cross section in a given time; sediment load
consists of both suspended load and bed load.
sedimentation: The natural geologic or man-made process which includes
erosion, transportation, and deposition of solid particles by wind,
water, ice, or gravity.
seepage: Water escaping through or emerging from the ground along an exten-
sive line or surface as contrasted with a spring where the water emerges
from a localized spot.
settling basin: An enlargement in the channel of a stream or dammed area
to permit' the settling of debris carried in suspension.
slope: The degree of deviation of a surface from the horizontal, usually
expressed in a ratio, percent, or degrees, such as Ug:l (horizontal to
vertical), 67 percent, or 34 degrees, respectively.
slough: Come off; fall away.
sprigging: The planting of a portion of the stem and/or root of a plant.
State Board: State Water Resources Control Board, California.
State Water Resources Control .Board, California (State Board): A branch of
California State Government, headed by a five member board, responsible
for water rights, water quality, and water pollution control within the
State.
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standing crop: In aquatic biology, an estimate of the number of individuals
per unit area in a community.
stilling basin: An open structure or excavation above a flow measuring
device, such as a weir, to reduce the kinetic energy of the flowing
water.
straw blowing: The application of straw mulch to a soil surface by means of a
mechanical blower.
stream environment zone: Riparian area adjacent to streams containing sensi-
tive vegetation and animal life.
subsoil: The stratum of material beneath the surface soil.
substrate: The bottom or benthic medium which biologic organisms inhabit.
swale: A hollow or depression. "
tackifier: A chemical agent used to bind mulch fibers together.
tacking: The process of binding mulch fibers together by the addition of a
sprayed chemical compound.
toe: The lower edge or edges of a slope.
tolerant (plants): Capable of growth and survival under competitive or
adverse conditions.
topsoil: The upper layer of soil containing organic matter and usually suited
for plant survival and growth. On a construction site, the topsoil
should be saved for topsoiling.
topsoiling: The practice of replacing temporarily removed topsoil at a con-
struction site once construction activities have been completed.
transpiration: The process by which water vapor is released to the atmosphere
by the foliage or other parts of a living plant.
turbidity: An expression of the optical property of water which causes light
to be scattered or absorbed due to the presence of suspended matter.
waste, construction: Excess sediment, earth, rocks, vegetation, or other
materials resulting from roadway, residential, commercial, or other
building construction.
water bars: Artificial barriers to divert surface runoff from erodible
surfaces and to prevent accumulation of drainage water.
wattling, contour: Bundles of live, rooting plant species placed as partially
buried "cables" across an eroding slope at regular contour intervals and
supported at the lower side by stakes.
377
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weathering: All physical, chemical, and biological changes produced in rocks
at or near the earth's surface.
weir: An obstruction placed in a stream or channel diverting the water
through a prepared aperture for measuring the rate of flow.
West Martis Creek: A small stream draining a 1,308 hectare watershed in the
Truckee River watershed north of the Lake Tahoe Basin in California; the
stream which flows through the Northstar-at-Tahoe development.
378
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APPENDIX F
CONVERSION FACTORS^/
Various conversion factors are included in this appendix for the convenience
of the user of this report in calculating areas, rates, and volumes.
Conversion factors are generally shown for four significant digits suitable
for field use with a slide rule. For office calculations, more precise
conversion factors of five or more significant digits may be needed in some
ins tances.
To Convert
UNITS AND EQUIVALENTS
Conversion Factors
Into
Multiply By
acre
acre-ft
Cac-ft)
hectare
sq feet Csq ft)
sq meters Csq m)
sq miles (sq mi)
cu ft
cu yds
gallons Cgal)
cu meters (cu m)
tons (short)
0.4047
43,560.0
4,047.0
1.562 x 10~3
43,560.0
1,613.0
325,850.0
1,234.0
1,359.0
Celsius or
Centigrade (C)
centimeters (cm)
cubic centimeters
(cc)
Fahrenheit (F)
feet (ft)
inches (in)
meters (m)
millimeters (mm)
cu ft
1.8C + 32
0.03281
0.3937
0.01
10.0
3.531 x 10 5
I/ National Engineering Handbook, Chapter 10, Section 3, Soil
Conservation Service, USDA, April 1971.
379
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To Convert
cubic feet
(cu ft)
cubic feet of
water
cubic feet/
sec (cfs)
cu ft/sec/sq
mi (csm)
cubic ft/sec
(cfs)
cfs-days
cubic inches
(cu in)
cubic meters
(cu m)
cubic yards
(cu yd)
Into
cu in
U.S. gallons
(U.S. gal)
liters (1)
U.S. pints
U.S. quarts
cu cms (cc)
cu in
cu meters (cu m)
cu yards (cu yd)
U.S. gallons
(U.S. gal)
liters (1)
pounds (Ibs)
kgs/sq cm
kgs/sq meter
(kgs/sq m)
pounds/sq ft
(psf)
pounds/sq in.
(psi)
acre-ft per day
(ac-ft/d)
acre-ft per year
(ac-ft/yr)
million gal's/
day (mgd)
liters/sec (I/sec)
cu m/sec
liters/sec/sq km
(1/sec/sq km)
g aliens /min (gpm)
cu ft
cu cms (cc)
cu f t
cu ft
U.S. gallons
(U.S. gal)
cubic yards (cu yd)
cu cms (cc)
Multiply By
0.06102
,-4
2.642 x 10
0.001
2.113 x 10~3
1.057 x 10~3
28,320.0
1,728.0
0.02832
0.03704
7.481
28.32
62.43
0.03048
304.8
62.43
0.4335
1.984
724.0
0.6463
28.32
0.02832
0.0915
448.8
86,400.0
16.39
5.787 x 10~4
35.32
264.2
0.7645
7.646 x 105
380
-------
APPENDIX F
CONVERSION FACTORS^/
Various conversion factors are included in this appendix for the convenience
of the user of this report in calculating areas, rates, and volumes.
Conversion factors are generally shown for four significant digits suitable
for field use with a slide rule. For office calculations, more precise
conversion factors of five or more significant digits may be needed in some
ins tances.
To Convert
UNITS AND EQUIVALENTS
Conversion Factors
Iii to
Multiply By
acre
acre-ft
Cac-ft)
hectare
sq feet (sq ft)
sq meters Csq m)
sq miles (sq mi)
cu ft
cu yds
gallons (gal)
cu meters (cu m)
tons (short)
0.4047
43,560.0
4,047.0
1.562 x 10'
43,560.0
1,613.0
325,850.0
1,234.0
1,359.0
,-3
Celsius or
Centigrade (C)
centimeters (cm)
cubic centimeters
(cc)
Fahrenheit (F)
feet (ft)
inches (in)
meters (m)
millimeters (mm)
cu ft
1.8C + 32
0.03281
0.3937
0.01
10.0
3.531 x 10~5
_!/ National Engineering Handbook, Chapter 10, Section 3, Soil
Conservation Service, USDA, April 1971.
379
-------
To Convert
cubic feet,
(cu ft)
cubic feet of
water
cubic feet/
sec (cfs)
cu ft/sec/sq
mi (csm)
cubic ft/sec
(cfs)
cfs-days
cubic inches
(cu in)
cubic meters
(cu m)
cubic yards
(cu yd)
Into
cu in
U.S. gallons
(U.S. gal)
liters (1)
U.S. pints
U.S. quarts
cu cms (cc)
cu in
cu meters (cu m)
cu yards (cu yd)
U.S. gallons
(U.S. gal)
liters (1)
pounds (Ibs)
kgs/sq cm
kgs/sq meter
Ckgs/sq m)
pounds/sq ft
(Psf)
pounds/sq in.
(psi)
acre-ft per day
(ac-ft/d)
acre-ft per year
(ac-ft/yr)
million gal's/
day (mgd)
liters/sec (I/sec)
cu m/sec
liters/sec/sq km
(1/sec/sq km)
g aliens /min (gpm)
cu ft
cu cms (cc)
cu f t
cu ft
U.S. gallons
(U.S. gal)
cubic yards (cu yd)
cu cms (.cc)
Multiply By
0.06102
,-4
2.642 x 10
0.001
2.113 x 10~3
1.057 x 10~3
28,320.0
1,728.0
0.02832
0.03704
7.481
' 28.32
62.43
0.03048
304.8
62.43
0.4335
1.984
724.0
0.6463
28.32
0.02832
0.0915
448.8
86,400.0
16.39
5.787 x 10~4
35.32
264.2
0.7645
7.646 x 105
380
-------
To Convert
Into
Multiply By
days
deg F
cu ft
cu meters (cu m)
U.S. gallons
(U.S. gal)
aere-ft
D
second (sec)
deg C (Centi-
grade or
Celsius)
27.0
0.7646
202.0
6.19 x
86,400.0
(F° - 32).5556
Fahrenheit (F)
feet (ft)
feet/min (fpm)
feet/sec (fps)
gal CU.S.)
gallons of water
(gal of wtr)
gallons/min
(gpm)
gallons/acre
(gal/A)
Centigrade (C)
centimeters
(cm)
kilometers
(km)
meters (m)
miles (mi)
cms/sec (.cps)
feet/sec (.fps)
kms/hour (km/hr)
miles/hour (mi/hr)
meters/min (m/min)
miles/hour (mph)
km/hour Ckm/hr)
G
cubic cms (cc)
cubic feet (.cu ft)
cubic inches
(cu in)
gallons Br. Imp.
(gal Br. Imp .)
liters (1)
pounds of water
(Ibs of wtr)
cu ft/sec Ccfs)
liters/sec (I/sec)
cu ft/hr
liters/hectare
(1/ha)
(F° - 32). 5556
30.48
3.048 x 10'
0.3048
1.894 x 10'
0.5080
0.01667
0.01829
0.01136
18.29
0.6818
1.097
3,785.0
0.1337
231.0
0.8327
3.785
8.3453
2.228 x 10
0.06308
8.0208
9.353
r4
,-4
r3
381
-------
To Convert
Into
Multiply By
grams (g)
gram of water
(g of wtr)
hectares (ha)
hours (hr)
pounds (Ibs)
cu cm of water
(cc of wtr)
H
acres
sq feet (sq ft)
days
weeks (wk)
2.205 x 10~3
1.0 (at 4°C)
2.471
1.076 x 10
0.04167
5.952 x 10'
—3
inches (in)
inches
(watershed)
kilograms (kg)
kilograms/hectare
(kgs/ha)
kilograms/sec
(kg/sec)
kilometers (km)
centimeters (cm)
cu ft/sec/sq mi
(csm)
K
pounds, (lh)
avoirdupois
tons, short (T)
pounds/acre
(Ibs/A)
ton (short)/
year (T/yr)
miles (mi)
2.540
13.584
2.205
1.102 x 10'
0.8921
34,786.0
0.6214
,-3
liters (1)
liters/sec (I/sec)
liters/sec/
sq km (I/sec/sq km)
liters/hectare
(1/ha)
meters On)
cubic cm (cc)
gallons U.S.
(gal U.S.)
cubic foot/sec
(cu ft/sec)
cubic ft/sec/sq
mi (csm)
gallons/acre
(gal/A)
M
yards (yd)
feet (ft)
inches (in)
1,000.0
0.2642
0.0353
10.93
0.1069
1.094
3.281
39.37
382
-------
To Convert
meters (m)
miles (U.S.
stat) (mi)
miles/hour (mph)
mi 11 igr ams /1 i te r
(mg/1) •
milliliters (ml)
millimeters (mm)
million gallons/
day (mgd)
minutes (min) (angles)
ounces (oz)
ounces/gallon
(U.S.)
(oz/gal-U.S.)
Into
miles (stat)
(mi stat)
kilometers (km)
)
feet/sec (fps)
parts/million (ppm)
liters (1)
inches (in)
microns (u)
cu ft/sec (cfs)
acre-ft/day
cu m/min
degrees (deg)
0
grams (g)
pounds (Ibs)
gms/liter Cgm/1)
Multiply By
6.214 x 10~4
1.609
1.467
1.000*
0.001
0.03937
1 x 103
1.547
3.069
2.629
0.01667
28.35
0.0625
7.489
parts per million
(ppm)
pounds (Ibs)
pounds of .water
(Ibs of wtr)
pounds of water/min
(Ibs of wtr/min)
milligrams per
liter (mg/1)
grains
grams (g)
kilograms (kg)
ounces (oz)
tons** (T)
cubic feet (cu ft)
cubic inches (cu in)
gallons (gal)
cu ft/sec (cfs)
1.000*
7,000.0
453.6
0.4536
16.00
0.0005
0.01602
27.68
0.1198
2.670 x 10~4
*
**
True within one percent when the concentration is less than 10 000
Throughout this report, tons means metric tons (2,205 Ibs) unless
otherwise indicated as tons (short) or tons (long).
383
-------
To Convert
pounds/cu foot
(pcf)
pounds/cu in
(pel)
pounds/gallon
(U.S.)
pounds/acre
(Ibs/A)
rods
Into
grams/cu cm (g/cc)
kgs/cu meter
(kg/cu m)
pounds /cu in (pci)
gms/cu cm (g/cc)
gins/liter (g/1)
kilograms/hectare
(kgs/ha)
R
feet (ft)
miles (mi)
Multiply By
0.01602
16.02
5.787 x 10"
27.68
119.8
1.121
16.50
3.125 x 10
,-3
sq centimeters
(sq cm)
square feet
(sq ft)
square inches
(sq in)
sq kilometers
(sq km)
square meters
(sq m)
square miles
(sq mi)
square yards
(sq yd)
tons* (long) (T)
square inches 0.1550
(sq in)
acres (ac)
sq cms
sq miles (sq
sq ft
acres (ac)
square feet (sq ft)
square kms (sq km)
square meters (sq m)
square yards (sq yd)
square feet (sq ft)
square meters (sq m)
T
pounds (Ibs) 2,240.0
2.296 x 10
6.452
0.3861
10.76
640.0
27.88 x 106
2.590
2.590 x 10*
3.098 x 10fc
9.0
0.8361
,-5
* Throughout this report, tons means metric tons (2,205 Ibs) unless
otherwise indicated as tons (short) or tons (long).
384
-------
To Convert
tons* (metric) (T)
tons* (metric)/
sq km
(T(met)/sq km)
tons* (short)
tons (short) /
sq mi
watershed in
watershed inches
Into
kilograms (kg)
tons (short) (T)
pounds (Ibs)
tons (short)/
sq mi
kilograms (kgs)
pounds (Ibs)
tons (long)
tons (metric)
tons (metric)/
sq km
tons (short)/acre
W
acre-ft/sq mi
acre-ft (total)
Multiply By
1,000.0
1.102
2,205.0
2.854
907.2
2,000.0
0.8929
0.9078
0.350
.-3
1.5625 x 10
53.33
53.33 x drainage
area (in sq mi)
years (yr)
seconds (sec)
31.5576 x 106
^Throughout this report, tons means metric tons (2,205 Ibs) unless
otherwxse indicated as tons (short) or tons (long).
385
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-78-208
3. RECIPIENT'S ACCESSION-NO.
, TITLE AND SUBTITLE
DEMONSTRATION OF EROSION AND SEDIMENT CONTROL
TECHNOLOGY - Lake Tahoe Region of California
. REPORT DATE
December 1978 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Charles A. White
Alvin L. Franks
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
California State Water Resources Control Board
Division of Planning and Research
Sacramento, California 95801
10. PROGRAM ELEMENT NO.
1BC611; SOS #2; Task 17
11.XHNXK3C U.S. GOVERNMENT PRINTING OFfICE: 1979-657-060/1568
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