HomeMy WebLinkAboutCT 11-04; Quarry Creek; Hydromodification Screening; 2012-10-03HYDROMODIFICATION SCREENING
FOR
QUARRY CREEK
(C.T. 11-04)
October 3, 2012
Wayne W.'thang, MS^M>46548
ChanoSsnMlIM®
Civil Engineering« Hydrology ° Hydraulics - Sedimentation
P.O. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760
1
o
I. '>g^ \€
Q
i mm
I wm
-TABLE OF CONTENTS -
Introduction 1
Domain of Analysis 3
Initial Desktop Analysis 5
Field Screening 6
Conclusion 11
Figures 12
APPENDICES
A. SCCWRP Initial Desktop Analysis
B. SCCWRP Field Screening Data
MAP POCKET
Study Area Exhibit
INTRODUCTION
The County of San Diego's March 2011, Final Hydromodification Management Plan, and
January 8, 2011, Standard Urban Stormwater Mitigation Plan (SUSMP) outline low flow
thresholds for hydromodification analyses. The thresholds are based on a percentage of the pre-
project 2-year flow (Q2), i.e., 0.1 Q2 (low), O.3Q2 (medium), or O.5Q2 (high). A threshold of O.IQ2
represents a downstream receiving conveyance system with a high susceptibility to erosion. This
is the default value used for hydromodification analyses and will result in the most conservative
(greatest) on-site facility sizing. A threshold of O.3Q2 or O.5Q2 represents downstream receiving
conveyance systems with a medium or low susceptibility to erosion, respectively. In order to
qualify for a medium or low susceptibility rating, a project must perform a channel screening
analysis based on a "hydromodification screening tool" procedure developed by the Southem
Califomia Coastal Water Research Project (SCCWRP). The SCCWRP results are compared with
the critical shear stress calculator results from the County of San Diego's BMP Sizing Calculator
to establish the appropriate susceptibility threshold of low, medium, or high.
PAanc
OCEAN
VICINITY MAP
NO SCALE
Vicinity Map
This report provides hydromodification screening analyses for McMillin Land Development's
(McMillin) Quarry Creek project (C.T. 11-04) being designed by Project Design Consultants
(PDC). The project is located south of Haymar Drive and west of College Boulevard in the cities
of Carlsbad and Oceanside, Califomia (see the Vicinity Map above as well as the Study Area
Exhibit in the map pocket). A portion of the project will be within Hanson Aggregates Pacific
Southwest Inc.'s (Hanson) South Coast Materials Quarry. Reclamation of the Hanson site was
recendy approved by the Cities of Carlsbad (SUP 07-03 and Drawing No. 470-5A) and
Oceanside (RMA-1-2001 Revision 05 and Drawing No. 011-0002). The McMillin project will
not proceed until Hanson's reclamation grading is complete. Hanson's reclamation grading will
result in channelization of Buena Vista Creek within their site. The channelization will create a
vegetated trapezoidal channel with a 150-foot bottom width, 2.5 to 1 side slopes, a terrace along
each channel bank, and seven riprap drop stmctures. The pre-reclamation longitudinal channel
slope was hydraulically steep, which resulted in erosive flow velocities. In order to reduce the
100-year flow velocities below the non-erosive threshold of 6 feet per second (fps) as much as
possible, the seven drop stmctures were used to reduce the longitudinal slope. This resulted in a
hydraulically stable channel. Since the drop stmctures and channel were designed to be stable in
accordance with established engineering criteria, long-term stability can be assumed for the
purposes of this report. The drop stmctures and channel constmction was complete in September
2012.
Surface mnoff from McMillin's proposed project and tributary off-site areas will be collected by
a series of on-site storm drain systems (see Study Area Exhibit). The storm drain systems will
have eight discharge locations. Five of the discharge locations will be directly into the Buena
Vista Creek channel being constmcted by the Hanson project (into Reaches 5 and 6 on the Study
Area Exhibit). Buena Vista Creek flows in a westerly direction and bisects the easterly portion of
the site. The sixth storm drain discharge location will be into an existing minor, natural drainage
course approximately mid-way along the southerly development area (into Reach 7 on the Study
Area Exhibit). This drainage course will be referred to herein as the Middle Tributary and flows
a short distance to the north and confluences into Buena Vista Creek. The final two discharge
locations will be into an unnamed natural tributary canyon to Buena Vista Creek (into Reach 8
on the Study Area Exhibit). The canyon is just beyond the westerly edge of the southerly
development area and flows in a northwesterly direction into Buena Vista Creek. This tributary
will be identified herein as the West Tributary.
The SCCWRP screening tool requires both office and field work to establish the vertical and
lateral susceptibility of a downstream receiving channel to erosion. The vertical and lateral
assessments are performed independently of each other although the lateral results can be
affected by the vertical rating. A screening analysis was performed to assess the low flow
threshold for each point of compliance. A point of compliance exists at the project's storm drain
outlets. Each point of compliance establishes a location for which a channel screening analysis
must be performed.
The initial step in performing the SCCWRP screening analysis is to establish the domain of
analysis and the study reaches within the domain. This is followed by office and field
components of the screening tool along with the associated analyses and results. The following
sections cover these procedures in sequence.
DOMAIN OF ANALYSIS
SCCWRP defines an upstream and downstream domain of analysis, which establish the required
study limits. The Quarry Creek project discharges into three watercourses: Buena Vista Creek,
the minor drainage course near the middle of the southerly development area (Middle Tributary),
and the unnamed tributary canyon just west of the southerly development area (West Tributary).
Separate upstream and downstream domain of analyses must be established within each of these
three watercourses. The County of San Diego's HMP specifies the downstream domain of
analysis based on the SCCWRP criteria. The HMP indicates that the downstream domain is the
first point where one of these is reached:
• at least one reach downstream of the first grade control point
• tidal backwater/lentic waterbody
• equal order tributary
• accumulation of 50 percent drainage area for stream systems or 100 percent drainage area
for urban conveyance systems (storm drains, hardened channels, etc.)
The upstream limit is defined as:
• proceed upstream for 20 channel top widths or to the first grade control point, whichever
comes first. Identify hard points that can check headward migration and evidence of
active headcutting.
SCCWRP defines the maximum spatial unit, or reach (a reach is circa 20 channel widths), for
assigning a susceptibility rating within the domain of analysis to be 200 meters (656 feet). If the
domain of analysis is greater than 200 meters, the study area should be subdivided into smaller
reaches of less than 200 meters for analysis. Most of the units in the HMP's SCCWRP analysis
are metric. Metric units are used in this report only where given so in the HMP. Otherwise
English units are used.
Downstream Domain of Analysis
A separate downstream domain of analysis for the three watercourses (Buena Vista Creek,
Middle Tributary, and West Tributary) in the study area has been determined by assessing and
comparing the four bullet items above for each point of compliance (i.e., the storm drain
discharge locations). There are five discharge locations directly into Buena Vista Creek (see the
Study Area Exhibit). The easterly-most is identified on the Study Area Exhibit as point of
compliance 1 (POC 1). The middle two discharge locations are at essentially the same point
along the creek, so these are identified as POC 2. Similarly, the westerly two discharge locations
are at essentially the same point along the creek and are identified as POC 3. The storm drain
discharge location into the Middle Tributary is POC 4. There are two storm drain discharge
locations into the West Tributary. The discharge locations are in proximity to each other and the
physical and vegetative conditions in the West Tributary are similar, so both discharge locations
were considered to be POC 5.
Per the first bullet item above, the first permanent grade control below POC 1 and 2 will be the
closest downstream riprap drop stmcture within Buena Vista Creek constmcted by the Hanson
project. For POC 1 and 2, a drop stmcture exists within 70 feet. For POC 3, 4, and 5 the first
permanent grade control is a concrete-lined trapezoidal channel approximately 250 feet upstream
of El Camino Real (see Study Area Exhibit).
The second bullet item is the tidal backwater or lentic (standing or still water such as ponds,
pools, marshes, lakes, etc.) waterbody location. The closest waterbody that meets this criteria is
Buena Vista Lagoon. Buena Vista Lagoon is downstream of all the permanent grade controls, so
the second bullet item will not govem.
The final two bullet items are related to the tributary drainage area. According to a June 23,
1994, Hydrologic Study for Buena Vista Creek Basin, by Hunsaker & Associates San Diego, Inc.
the Buena Vista Creek tributary drainage areas at College Boulevard, El Camino Real, and the
Pacific Ocean are 13.35, 17.33, 21.55 square miles, respectively (see Appendix A). POC 1
through 3 outlet into Buena Vista Creek between College Boulevard and El Camino Real. Based
on the Hunsaker areas, the 50 percent or equal order (100 percent) tributary will not govem for
POC 1 through 3 because they occur in the Pacific Ocean. The project hydrology study by PDC
shows that the tributary area to POC 4 is 107.4 acres (see Appendix A). Based on this, an equal
order tributary below POC 4 exists where the Middle Tributary confluences with Buena Vista
Creek since the Buena Vista Creek watershed is much larger than the POC watershed. In
addition, a drainage basin delineation determined that the tributary area to the West Tributary is
0.48 square miles (see the Watershed Delineation exhibit in Appendix A). From this, an equal
area tributary below POC 5 exists where the West Tributary confluences with Buena Vista
Creek.
Based on the above information, the following are the downstream domain of analysis locations
for POC 1 through 5. For POC 1 and 2, the downstream domain of analysis location is one reach
(200 meters) below the nearest downstream drop stmcture constmcted by the Hanson project.
This location will be within Hanson's Buena Vista Creek channel. For POC 3, the downstream
domain of analysis location is one reach below the upstream end of the concrete trapezoidal
channel near El Camino Real. This location will land within the concrete channel because the
channel is longer than a reach. For POC 4, the downstream domain of analysis location is where
the Middle Tributary confluences with Buena Vista Creek. For POC 5, the downstream domain
of analysis location is where the West Tributary confluences with Buena Vista Creek.
Upstream Domain of Analysis
For POC 1 through 3, a permanent drop stmcture (or grade control) exists immediately upstream
of each storm drain discharge point. Therefore, the adjacent drop stmcture establishes the
upstream domain of analysis location for POC 1 through 3. For POC 4, the Middle Tributary
does not extend upstream of POC 4, so the upstream domain of analysis location will be at POC
4. For POC 5, a grade control does not exist upstream of the storm drain outlets. Therefore, the
upstream domain of analysis location is based on 20 channel top widths upstream of the upper
storm drain outlet. The average top width upstream of POC 5 is approximately 20 feet from the
topographic mapping, so the upstream domain of analysis location is 400 feet upstream of the
upper pipe outlet.
Study Reaches within Domain of Analysis
The Buena Vista Creek and West Tributary domain of analysis extend over relatively long
distances. The entire domain of analysis along Buena Vista Creek covers over 9,000 feet, while
the entire domain of analysis along the West Tributary covers over 3,200 feet. The domain of
analysis for these two streams was subdivided into study reaches with similar characteristics (see
Study Area Exhibit). Buena Vista Creek contains six study reaches (Reach 1 through 6) and the
West Tributary contains two study reaches (Reach 8 and 9).
Each study reach other than 5, 7, and 9 is longer than the 656 feet maximum reach length
specified by SCCWRP. Review of topographic mapping, aerial photographs, and field conditions
reveals that the physical (channel geometry and longitudinal slope), vegetative, hydraulic, and
soil conditions within each longer reach are relatively uniform. Subdividing the reaches into
smaller subreaches of less than 656 feet will not yield significantiy varying results within a
reach. Although the screening tool was applied across the entire length of each reach, the results
will be similar for shorter subreaches within each reach.
INITIAL DESKTOP ANALYSIS
After the domain of analysis is established, SCCWRP requires an "initial desktop analysis" that
involves office work. The initial desktop analysis establishes the watershed area, mean annual
precipitation, valley slope, and valley width. These terms are defined in Form 1, which is
included in Appendix A. SCCWRP recommends the use of National Elevation Data (NED) to
determine the watershed area, valley slope, and valley width. The NED data is similar to USGS
mapping. Therefore, USGS quadrangle mapping was used to establish the watershed area, where
needed. For this report, 2-foot contour interval topographic mapping by PDC was available
covering the entire study reaches of Buena Vista Creek, the Middle Tributary, and the West
Tributary. The PDC mapping is more detailed than NED/USGS topography, so it was used to
determine the valley slope and valley width.
The watershed areas tributary to Buena Vista Creek, the Middle Tributary, and the West
Tributary were determined from different sources. For Buena Vista Creek, the June 23, 1994,
Hydrologic Study for Buena Vista Creek Basin, by Hunsaker & Associates San Diego, Inc.
provides tributary watershed areas at College Boulevard and El Camino Real (see Appendix A),
which bracket the upstream and downstream ends of the study area, respectively. The watershed
areas are 17.33 and 13.35 square miles, respectively. The tributary areas to Reaches 1 through 6
were determined by interpolating the Hunsaker values based on the location of the downstream
end of each reach between College Boulevard and El Camino Real. Table 1 summarizes the
tributary areas.
For the Middle Tributary, the watershed area (107.4 acres or 0.17 square miles) was obtained
from PDC's hydrologic analysis (see PDCs work map in Appendix A). This represents the post-
project area that will drain to the Middle Tributary. For the West Tributary, the watershed area
extends over a relatively large area. Consequently, the USGS mapping was used to delineate the
area in accordance with SCCWRP. A "Watershed Delineation" exhibit is included in the
Appendix A and shows the drainage areas tributary to Reach 8 and 9 in the West Tributary.
The mean annual precipitation was obtained from the County of San Diego's BMP Sizing
Calculator and is 13.3 inches (see Appendix A).
The valley slopes of Reaches 1 through 9 were determined from the PDC's 2-foot contour
interval topographic mapping. The valley slope is the longitudinal slope ofthe channel bed along
the flow line, so it is determined by dividing the elevation difference within a reach by the flow
path.
The valley width is the bottom width of the stream channel. The average valley width within
each reach was estimated from PDC's topographic mapping, field observations, and review of
aerial photographs. The average valley slope and valley width for each reach are summarized in
Table 1.
Reach Tributary Area,
sq. mi.
Valley Slope,
m/m
Valley Width,
m
1 17.33 0.0067 30.5
2 16.75 0.0022 7.0
3 16.43 0.0074 15.0
4 14.91 0.0071 10.0
5 14.50 0.0076 5.0
6 14.28 0.0014 45.0
7 0.17 0.0659 2.5
8 0.48 0.0156 18.0
9 0.32 0.0138 3.0
Table 1. Summary of Valley Slope and Valley Width
The Table 1 values were input to a spreadsheet to calculate the simulated peak flow, screening
index, and valley width index outlined in Form 1. The input data and results are tabulated in
Appendix A. This completes the initial desktop analysis.
FIELD SCREENING
After the initial desktop analysis is complete, a field assessment must be performed. The field
assessment is used to establish a natural channel's vertical and lateral susceptibility to erosion.
SCCWRP states that although they are admittedly linked, vertical and lateral susceptibility are
assessed separately for several reasons. First, vertical and lateral responses are primarily
controlled by different types of resistance, which, when assessed separately, may improve ease
of use and lead to increased repeatability compared to an integrated, cross-dimensional
assessment. Second, the mechanistic differences between vertical and lateral responses point to
different modeling tools and potentially different management strategies. Having separate
screening ratings may better direct users and managers to the most appropriate tools for
subsequent analyses.
The field screening tool uses combinations of decision trees and checklists. Decision trees are
typically used when a question can be answered fairly definitively and/or quantitatively (e.g., dso
< 16 mm). Checklists are used where answers are relatively qualitative (e.g., the condition of a
grade control). Low, medium, high, and very high ratings are applied separately to the vertical
and lateral analyses. When the vertical and lateral analyses retum divergent values, the most
conservative value shall be selected as the flow threshold for the hydromodification analyses.
Vertical Stability
The purpose of the vertical stability decision tree (Figure 6-4 in the County of San Diego HMP)
is to assess the state of the channel bed with a particular focus on the risk of incision (i.e., down
cutting). The decision tree is included in Figure 28. The first step is to assess the channel bed
resistance. There are three categories defined as follows:
1. Labile Bed - sand-dominated bed, little resistant substrate.
2. Transitional/Intermediate Bed - bed typically characterized by gravel/small cobble.
Intermediate level of resistance of the substrate and uncertain potential for armoring.
3. Threshold Bed (Coarse/Armored Bed) - armored with large cobbles or larger bed
material or highly-resistant bed substrate (i.e., bedrock).
Figures 21 through 27 show photographs of the bed material within Buena Vista Creek, the
Middle Tributary, and the West Tributary. A gravelometer is included in the photographs for
reference. Each square on the gravelometer indicates grain size in millimeters (the squares range
from 2 mm to 180 mm). Based on the photographs and site investigation, the bed material and
resistance is generally within the transitional/intermediate bed category. There was no evidence
of a threshold bed condition. The figures show that the grain size is fairiy large in the upstream
reach of Buena Vista Creek and decreases in the downstream direction. Even the smaller grain
sizes are rather gravelly. In the Middle Tributary, the grain size is typically in the gravel range.
In the West Tributary, there are gravel sized particles, but a larger population of smaller grain
sizes.
The figures show dense vegetation throughout the natural portion of Buena Vista Creek and the
West Tributary. The vegetation consists of a variety of mature grasses, shmbs, and trees.
Vegetation prevents bed incision because its root stmcture binds soil and because the
aboveground vegetative growth will reduce flow velocities. Table 5-13 from the County of San
Diego's Drainage Design Manual outlines maximum permissible velocities for various channel
linings (Table 5-13 is included in Appendix B). Maximum permissible velocity is defined in the
manual as the velocity below which a channel section will remain stable, i.e., not erode. Table 5-
13 indicates that a fully-lined channel with unreinforced vegetation has a maximum permissible
velocity of 5 feet per second (fps). Due to the dense cover and mature vegetation, the permissible
velocity when erosion can begin is likely greater than 5 Q)S in most of the natural stream areas.
Table 5-13 indicates that 5 fps is equivalent to an unvegetated channel containing cobbles (grain
size from 64 to 256 mm) and shingles (rounded cobbles). In comparison, coarse gravel (19 to 75
mm) has a maximum permissible velocity of 4 fps. Based on this information, the uniformly
vegetated natural streams within Buena Vista Creek and the West Tributary have an equivalent
grain size of at least 64 mm.
In addition to the material size, there are several factors that establish the erodibility of a channel
such as the flow rate (i.e., size of the tributary area), grade controls, channel slope, vegetative
cover, channel planform, etc. The Introduction of the SCCWRP Hydromodification Screening
Tools: Field Manual identifies several of these factors. When multiple factors influence
erodibility, it is appropriate to perform the more detailed SCCWRP analysis, which is to analyze
a channel according to SCCWRP's transitional/intermediate bed procedure. This requires the
most rigorous steps and will generate the appropriate results given the range of factors that
define erodibility. Dr. Eric Stein from SCCWRP, who co-authored the Hydromodification
Screening Tools: Field Manual in the Final Hydromodification Management Plan (HMP),
indicated that it would be appropriate to analyze channels with multiple factors that impact
erodibility using the transitional/intermediate bed procedure. Consequently, this procedure was
used to produce more accurate results.
Transitional/intermediate beds cover a wide susceptibility/potential response range and need to
be assessed in greater detail to develop a weight of evidence for the appropriate screening rating.
The three primary risk factors used to assess vertical susceptibility for channels with
transitional/intermediate bed materials are:
1. Armoring potential - three states (Checklist 1)
2. Grade control - three states (Checklist 2)
3. Proximity to regionally-calibrated incision/braiding threshold (Mobility Index Threshold
- Probability Diagram)
These three risk factors are assessed using checklists and a diagram (see Appendix B), and the
results of each are combined to provide a final vertical susceptibility rating for the
intermediate/transitional bed-material group. Each checklist and diagram contains a Category A,
B, or C rating. Category A is the most resistant to vertical changes while Category C is the most
susceptible.
Checklist 1 determines armoring potential of the channel bed. The channel bed along all of the
reaches is within Category B, which represents intermediate bed material within unknown
armoring potential due to a surface veneer (and/or vegetation). The soil was probed and
penetration was relatively difficult through the underlying layer. As seen in the figures, all the
channel bed areas either contain a gravel layer and/or dense vegetation.
Checklist 2 determines grade control characteristics of the channel bed. This is based on the
spacing of the grade controls. Reach 6 below POC 1 and POC 2 encompasses the Hanson
channel, which contains multiple grade controls (see Figures 1 through 4), so this area falls
within Category A on Checklist 2. Portions of Reach 7 have eroded to bedrock (see Figures 15
and 16), so this area also falls within Category A on Checklist 2. In all of these reaches, the grade
control spacing meets the threshold in Category A.
SCCWRP states that grade controls can be natural. Examples are vegetation or confluences with
a larger waterbody. As verified during the site investigation, each of the remaining reaches (1
through 5, 8, and 9) contains dense, mature vegetation (see the figures). The plant roots and
fallen tree tmnks serve as a natural grade control. The spacing of these is much closer than the 50
meters identified in the checklist. Further evidence of the effectiveness of the natural grade
controls is the absence of headcutting and mass wasting (large vertical erosion of a channel
bank). Based on this information, each remaining reach is within Category A on Checklist 2.
The Mobility Index Threshold is a probability diagram that depicts the risk of incising or
braiding based on the potential stream power of the valley relative to the median particle
diameter. The threshold is based on regional data from Dr. Howard Chang of Chang Consultants
and others. The probability diagram is based on dso as well as the Screening Index determined in
the initial desktop analysis (see Appendix A), dso is derived from a pebble count in which a
minimum of 100 particles are obtained along transects at the site. SCCRWP states that if fines
less than '/2-inch thick are at a sample point, it is appropriate to sample the coarser bviried
substrate. The dso value is the particle size in which 50 percent ofthe particles are smaller and 50
percent are larger.
Pebble counts were performed within Buena Vista Creek, the Middle Tributary, and the West
Tributary. The results are included in Appendix B. Pebble counts were combined for Reaches 1
to 5 and for Reach 8 and 9 because the bed material sizes within these reaches are relatively
uniform. The results show a dso of 16 millimeters for Reaches 1 to 5, 32 mm for Reach 6, 32
mm for Reach 7, and 8 mm for Reaches 8 and 9. The screening index for the associated reaches
are tabulated in Appendix A. For Reaches 1 to 5 as well as 8 and 9, the greatest screening index
value was used because this will generate the greatest erosion susceptibility. Plotting the dso and
screening index values on the Mobility Index Threshold diagram shows that all of the reaches
have a less than 50 percent probability of incising or braiding, which falls within Category A.
The overall vertical rating is determined from the Checklist 1, Checklist 2, and Mobility Index
Threshold results. The scoring is based on the following values:
Category A = 3, Category B = 6, Category C = 9
The vertical rating score is based on these values and the equation:
Vertical Rating = [(armoring x grade control)"^ x screening index score]"^
= [(6x3)"^x3]"^
= 3.6
Since the vertical rating is less than 4.5, each reach has a low threshold for vertical susceptibility.
Lateral Stability
The purpose of the lateral decision tree (Figure 6-5 from County of San Diego HMP included in
Figure 29) is to assess the state of the channel banks with a focus on the risk of widening.
Channels can widen from either bank failure or through fluvial processes such as chute cutoffs,
avulsions, and braiding. Widening through fluvial avulsions/active braiding is a relatively
straightforward observation. If braiding is not already occurring, the next logical step is to assess
the condition of the banks. Banks fail through a variety of mechanisms; however, one of the most
important distinctions is whether they fail in mass (as many particles) or by fluvial detachment of
individual particles. Although much research is dedicated to the combined effects of weakening,
fluvial erosion, and mass failure, SCCWRP found it valuable to segregate bank types based on
the inference of the dominant failure mechanism (as the management approach may vary based
on the dominant failure mechanism). A decision tree (Form 4 in Appendix B) is used in
conducting the lateral susceptibility assessment. Definitions and photographic examples are also
provided below for terms used in the lateral susceptibility assessment.
The first step in the decision tree is to determine if lateral adjustments are occurring. The
adjustments can take the form of extensive mass wasting (greater than 50 percent of the banks
are exhibiting planar, slab, or rotational failures and/or scalloping, undermining, and/or tension
cracks). The adjustments can also involve extensive fluvial erosion (significant and frequent
bank cuts on over 50 percent of the banks). The banks are intact in the photographs included in
the figures. The relatively uniform, dense vegetative cover on many of the banks is evidence of
the absence of large lateral adjustments. Neither lateral mass wasting nor extensive lateral fluvial
erosion was evident within any of the reaches during a field investigation. Reach 7 was the only
portion of the entire study area that exhibited bank erosion. However, the erosion is not
associated with lateral changes, but with historic vertical changes. The bottom of Reach 7 has
reached bedrock, so fUture vertical changes will be limited.
The next step in the Form 4 decision tree is to assess the consolidation of the bank material. The
banks were moderate to well-consolidated. This determination was made because the banks were
difficult to penetrate with a probe. In addition, the banks showed limited evidence of cmmbling
and were composed of well-packed particles (see figures).
Form 6 (see Appendix B) is used to assess the probability of mass wasting. Form 6 identifies a
10, 50, and 90 percent probability based on the bank angle and bank height. From the 2-foot
contour topographic mapping and site investigation, the bank angle in Reaches 1 through 6, 8
and 9 are at a 2 to 1 (horizontal to vertical) slope (26.6 degrees) or less. Form 6 shows that the
probably of mass wasting and bank failure has less than 10 percent risk for a 26.6 degree bank
angle or less regardless of the bank height.
The bank slope on Reach 7 is approximately 1:1 or 45 degrees. The 10-year flow in Reach 7
from Form 1 in Appendix A is 28 cubic feet per second. A normal depth analysis was performed
(see Appendix B), which shows that the 10-year flow depth in Reach 7 will be approximately 0.5
feet. This represents the bank height subject to erosion by flows. Plotting this flow depth versus
the 45 degree bank angle on Form 6, shows that the probability of mass wasting in Reach 7 is
less than 10 percent.
10
The final two steps in the Form 4 decision tree are based on the braiding risk determined from
the vertical rating as well as the Valley Width Index (VWI) calculated in Appendix A. If the
vertical rating is high, the braiding risk is considered to be greater than 50 percent. Excessive
braiding can lead to lateral bank failure. For all of the reaches the vertical rating is low, so the
braiding risk is less than 50 percent. There was no evidence of braiding in the field. Furthermore,
a VWI greater than 2 represents channels unconfined by bedrock or hillslope and, hence, subject
to lateral migration. The VWI calculations in the spreadsheet in Appendix A show that the VWI
for each reach is less than 2.
From the above steps, the lateral susceptibility rating is low (red circles are included on the Form
4: Lateral Susceptibility Field Sheet decision tree in Appendix B showing the decision path).
CONCLUSION
The SCCWRP channel screening tools were used to assess the downstream channel
susceptibility for McMillin Land Development's Quarry Creek project. The project mnoff will
be collected by Buena Vista Creek, a Middle Tributary to Buena Vista Creek, and a West
Tributary to Buena Vista Creek. Each of these watercourses is natural, so has a susceptibility to
erosion. The project mnoff will discharge into the watercourses at various storm drain outfalls,
which are the points of compliance. A downstream channel assessment was performed for each
point of compliance. The results indicate a low threshold for vertical and lateral susceptibilities
for all of the study reaches. This is consistent with the field conditions because the majority of
the downstream watercourses are either engineered channels or densely vegetated channels
exhibiting limited evidence of erosion.
The HMP requires that these results be compared with the critical stress calculator results
incorporated in the County of San Diego's BMP Sizing Calculator. The BMP Sizing Calculator
critical stress results are included in Appendix B for the reaches immediately below each point of
compliance (Reach 5, 6, 7, and 8). The critical stress results retumed a low threshold. Therefore,
the SCCWRP analyses and critical stress calculator demonstrate that the entire project can be
designed assuming a low susceptibility to erosion, i.e., O.5Q2.
11
Figure 1. Upper End of Buena Vista Creek Study Area near POC 1 and 2
Figure 2. Looking Downstream at Hanson Cliannel from Upper End of Buena Vista Creek
12
Figure 3. Looking Downstream Within Hanson Channel
Figure 4. Looking Upstream at Hanson Channel
13
Figure 5. Looking Downstream of the Hanson Channel at Buena Vista Creek
Figure 6. Rocks and Gravel in Buena Vista Creek Channel Bed Downstream of Hanson Channel
14
Figure 7. Dense Vegetation at Edge of Buena Vista Creek Adjacent to Access Road
Figure 8. Dense Vegetation in Buena Vista Creek Looking Upstream
from East End of Westerly Segment of Haymar Drive
15
Figure 9. Looking Upstream at Buena Vista Creek within Driving Range
Figure 10. Looking Downstream at Buena Vista Creek from Haymar Drive Bridge
16
Figure 11. Gravel Bed under Haymar Drive Bridge over Buena Vista Creek
M
Figure 12. Looking Downstream along Buena Vista Creek towards El Camino Real
17
Figure 13. Concrete-Lined Trapezoidal Channel near El Camino Real (vegetation growth on concrete)
Figure 14. Gravel on Buena Vista Creek Channel Bed near El Camino Real
18
Figure 15. Bedrock at Upper End of Middle Tributary
Figure 16. Looking North along Middle Tributary towards Buena Vista Creek
19
Figure 17. Looking East towards Confluence of Buena Vista Creek and West Tributary
y
Figure 18. Looking Upstream along Densely Vegetated West Tributary
20
Figure 19. Looking Downstream along Densely Vegetated West Tributary
Figure 20. Vegetation within West Tributary Floodplain
21
Figure 21. Channel Bed Material within Hanson Channel of Buena Vista Creek
Figure 22. Channel Bed Material near East End of Westerly Segment of Haymar Drive
22
Figure 23. Channel Bed Material near Haymar Drive Bridge over Buena Vista Creek
Figure 24. Channel Bed Material at Upstream End of Buena Vista Creek Concrete Trapezoidal Channel
23
Figure 25. Channel Bed Material at Downstream End of Concrete Trapezoidal Channel
Figure 26. Channel Bed Material at Middle Tributary
24
Figure 27. Channel Bed Material at East Tributary
25
Figure
6-2
LABILE BED
• Sand-dom mated
• <1^ < 16 mm
• % surface sand > 2S%
• Loo&ely-pac^
1 CHANNEL BED RESISTANCE \
INTERMEDIATE BED
' Moderaiety-to loosely-
packed cobble / gravel
> Hardpan of uncertain
depth, -extent arodUfity
1 COARSE/ARMQRFD BED
• cly, > 128 mm
• Boulder / large cobWe
• tighlly-packed
• <5% sand
• Continuous bedrock
• Conbnuous concrete
EXAMINE RISK FACTORS
• grade control
• armoring potenha!
• proximity lo incision threshold
go td bed erodibility
checklists and incision
diagram check list
Fll out SCCWRP sconr^g
cnieria to determine if tbe
receiving channel has a HIGH.
MEDIUM, or LOW susceptibiity
Figure 6-4. SCCWRP Vertical Susceptibility
Figure 28. SCCWRP Vertical Channel Susceptibility Matrix
26
• Fuly *irored i ttsdwcd Dank
• Ha evidercB o' chule
rorraatwn / avulEnns
• Fuly eQririned, ditecOy
cotvi«cfcKl lohilsKJaL yw-l
>
VES
<AP£. LATERAL \
PkDJUSTWENTS >
OOCORRING? y
ves
NO
None, ar ftj^nl CFil|f ltnt«sd to t>«rxlB ana cor^tnclcfi*
MASSVi-ASTINGOR
EXlENSrVE FLUVIAL
EROSlQN OR CHUTE
CUTCf F FIDRMATKJN
MED Hlfift
\W » 2
Go»a
l>9dsion
AU. BANK fil HAT A
C0t4SOLIDATED Pcorty cr urcmsaldateil
8imK haighl
reh tty ar>ala
1 BarA neifihl
>lO%lD9Sbc
tt»t. <0f ansJ*
AND UWI > 2
riM stent loa,(t
> 64 ffltn
I I
uncoTBoldahid
ANDVW
1
Fln«
uixoriHldaled
At«) VWI > 2
b)pfr«lii'4ly to
bfaidrng
Figure 6-5. Lateral Channel Susceptibility
Figure 29. SCCWRP Lateral Channel Susceptibility Matrix
27
APPENDIX A
SCCWRP INITIAL DESKTOP ANALYSIS
FORM 1: INITIAL DESKTOP ANALYSIS
Complete all shaded sections.
IF required at multiple locations, circle one of the following site types:
Applicant Site / Upstream Extent / Downstream Extent
Location: Latitude: 33.1784 Longitude: -117.3036
Description (river name, crossing streets, etc.): Buena Vista Creek, Middle Tributary
to Buena Vista Creek, West Tributary to Buena Vista Creek
GIS Parameters: The international System of Units (SI) is used throughout the assessment as the field
standard and for consistency with the broader scientific community. However, as the singular exception, US
Customary units are used for contributing drainage area (A) and mean annual precipitation (P) to apply regional flow
equations after the USGS. See SCCWRP Technical Report 607 for example measurements and "Screening Tool
Data Entry.xls" for automated calculations.
Form 1 Table 1. Initial desktop analysis in GIS.
Symbol Variable Description and Source Value •shed ) rties 1 units) A Area
(mi')
Contributing drainage area to screening location via published
Hydrologic Unit Codes (HUCs) and/or < 30 m National Elevation Data
(NED), USGS seamless server Watei prop€ (EnqlisI P Mean annual
precipitation
(in)
Area-weighted annual precipitation via USGS delineated polygons using
records from 1900 to 1960 (which was more significant in hydrologic
models than polygons delineated from shorter record lengths)
See attached
Form 1 table lerties its) Sv Valley slope
(m/m)
Valley slope at site via NED, measured over a relatively homogenous
valley segment as dictated by hillslope configuration, tributary
confluences, etc., over a distance of up to --500 m or 10% of the main-
channel length from site to drainage divide
on next page
for calculated
values for each
rfianh. Site prop (SI un Wv Valley width
(m)
Valley bottom width at site between natural valley walls as dictated by
clear breaks in hillslope on NED raster, irrespective of potential
armoring from floodplain encroachment, levees, etc. (imprecise
measurements have negligible effect on rating in wide valleys where
VWI is » 2, as defined in lateral decision tree)
Form 1 TabI e 2. SImplif ied peak flo w, screening index, and valley width index. Values for this
table should be calculated in the sequence shown in this table, using values from Form 1 Table 1.
Symbol Dependent Variable Equation Required Units Value
QiOcfs
Qio
10-yr peak flow (ft^/s)
10-yr peak flow (m^/s)
Qiocfs= 18.2*A°^'*P°''
Qio = 0.0283 * Qiocfs
A (mi^)
P(in)
Qiocfs (ft'/s)
See attached
Form 1 table
INDEX
Wref
10-yr screening index (m^ %° ^)
Reference width (m)
INDEX = Sv*Qio°^
Wref = 6.99 * Qio
Sv (m/m)
Qio (m^/s)
Qio (m^/s)
on next page
for calculated
values for each
VWI Valley width index (m/m) VWI = Wv/Wref Wv(m)
Wref (m)
reach.
(Sheet 1 of1)
B-3
SCCWRP FORM 1 ANALYSES
Area Mean Annual Precip. Valley Slope Valley Width 10-Year Flow 10-Year Flow
Reach A, sq. mi. P, inches Sv, m/m Wv, m QlOcfs, cfs QIO, cms
1 17.33 13.3 0.0067 30.5 1597 45.2
2 16.75 13.3 0.0022 7.0 1550 43.9
3 16.43 13.3 0.0074 15.0 1524 43.1
4 14.91 13.3 0.0071 10.0 1400 39.6
5 14.50 13.3 0.0076 5.0 1367 38.7
6 14.28 13.3 0.0014 45.0 1349 38.2
7 0.17 13.3 0.0659 2.5 28 0.8
8 0.48 13.3 0.0156 18.0 70 2.0
9 0.32 13.3 0.0138 3.0 50 1.4
10-Year Screening Index Reference Width Valley Width Index
Reach INDEX Wref, m VWI, m/m
1 0.045 37.1 0.82
2 0.015 36.6 0.19
3 0.049 36.4 0.41
4 0.045 35.0 0.29
5 0.047 34.7 0.14
6 0.009 34.5 1.31
7 0.059 6.3 0.39
8 0.022 9.5 1.90
9 0.016 8.1 0.37
Notes:
The areas for Reach 1 through 6 were determined from a Hunsaker study.
The area for Reach 7 was determined from PDC's Quarry Creek hydrology study.
The area for Reach 8 and 9 was determined from the Watershed Delineation exhibit in this appendix.
The mean annual precipitation was obtained from the County of San Diego's BIVIP Calculator in this appendix.
The valley slope was determined from the elevations and flow lengths from the Study Area Exhibit.
The valley width was estimated from the topographic mapping on the Study Area Exhibit and a site investigation.
The 10-year flow, screening index, reference width, and valley width index are calculated from the equations on Form 1 {see Appendix A).
Hunsaker & Associates San Diego, Inc.
Planning • Engineering'Surveying • GPS
THE FOLLOWING THREE SHEETS
PROVIDE THE BUENA VISTA CREEK
WATERSHED AREAS AT COLLEGE BLVD.
AND EL CAMINO REAL
HYDROLOGIC STUDY
FOR
BUENA VISTA CREEK BASIN
1 P
V
'1
Prepared for:
The City of
Oceanside, California
Prepared by:
L
HUNSAKER & ASSOCIATES SAN DIEGO, INC.
10179 Huennekens Street
San Diego, CA 92121
(619) 558-4500
Mark A. Brencick
R.C.E. No. 48153, Exp. 06/30/96
W.O. No. 1509-1
Date: June 23,1994
MB.kk msword\k:\l 509\a02.doc
wo 1309-1
10179 Huennekens Street • San Diego. CA 92121 • ('619J 558-4500 • FAX: (619) 558-1414
Offices: San Diego • Irvine' Riivrsicle/San liermirciino
Dai id Ilanunar • lack l lill
BUENA VISTA CREEK BASIN
HYDROLOGIC STUDY
CITY OF OCEANSIDE
June 23, 1994
III Summary Of Results
The results from the HEC-1 run were as follows:
Subbasin Location 100 Year Runoff from
H&A Report (CFS)
100 Year Runoff from
Willdan Report (CFS)
lA Brengle Terrace Park Detention
Basin 1028 *
IB West of Vista City Hall in
Buena Vista Creek 1932 3960
2A South Santa Fe Road 3025
2B Monte Vista Detention Basin 181
20 Confluenced with Subbasin 2A 4703 •
2D Melrose Avenue 6906 8570
3 College Avenue 10306 •
4 El Camino Real 12802 12790
5 Buena Vista Lagoon 13027 13030
6 Pacific Ocean 14167 *
* Indicates there was not a corresponding analysis point in the Willdan Report.
In the higher reaches of the Buena Vista Creek Basin, the H&A results were considerably lower
then the Willdan results. This may be due to the fact that the H&A report considered the two
detention basins to be operational and functioning. However, as the runoff travels down the
Basin, the Willdan results and the H&A results become increasingly closer - the flow entering the
Buena Vista Lagoon at the bottom of the Basin is essentially the same.
L 4
MBrkk mswoni\k:\l 509\a02.doc
wo 1309-1
ma
OPERATION
ROUTED TO
HYDROGRAPH AT
HYOROGRAPH AT
HYDROGRAPH AT
ROUTED TO
HYDROGRAPH AT
2 COMBINED AT
HYDROGRAPH AT
HYDROGRAPH AT
HYOROGRAPH AT
HYDROGRAPH AT
HYDROGRAPH AT
STATION
HYOROGRAPH AT SUB1A
ROUTE
SUB IB
SUB2A
SUB2B
ROUTE
SU82C
COMB
SUB 2D
SUB 3
SUB i.
SUB 5
SUB 6
6906.
12802.
RUNOFF SUMMARY
FLOW IN CUBIC FEET PER SECOND
TIME IN HOURS, AREA IN SQUARE MILES
PEAK TIME OF
FLOW PEAK
2572. 1.33
1028. 2.25
1932. 1.17
3025. 1.17
1266. 1.08
181. 2.50
1678. 1.17
6703. 1.17
1.17
10306. 1.33
1.62
13027. 1.50
K167. 1.50
AVERAGE FLOW FOR MAXIMUM PERIOD
6-HOUR 26-HOUR 72-HOUR
665.
666.
697.
869.
168.
152.
377.
1266.
1590.
2181.
2698.
2896.
3217.
339.
339.
508.
633.
123.
122.
289.
923.
1176.
1609.
1988.
2133.
2372.
339.
339.
508.
633.
123.
122.
289.
923.
1176.
1609.
1988.
2133.
2372.
BASIN
AREA
2.66
2.66
3.98
6.97
.95
.95
2.32
7.29
9.35
13.35
17.33
18.96
21.55
MAXIMUM
STAGE
637.56
TIME OF
MAX STAGE
2.25
493.56 2.50
3e>
-rP^CMAfORK MAP COVERmq R^ACH,?
OTE: L' / I M
JHE AREA DISCI^Ai](i5INGi)f
[^-THE?CO MmNE ARE A^lf"
ID /GO GN^TInli^TOttpWi
/ (S^.SfACREsV ^.RACftES
I
V aMv^ '\X..,
iy
Process from Point/Station 646.000 to Point/Station 632.000
*•** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 102.500{Ft.)
Downstream point/station elevation = 93.000(Ft.)
Pipe length = 851.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 207.422(CFS)
Nearest computed pipe diameter = 54.00(In.)
Calculated individual pipe flow = 207.422(CFS)
Normal flow depth in pipe = 44.16(In.)
Flow top width inside pipe = 41.70 (In.)
Critical Depth = 48 . 98 (In.)
Pipe flow velocity = 14.89(Ft/s)
Travel time through pipe = 0.95 min.
Time of concentration (TC) = 9.87 min.
End of co.mpu tat ions, total study area = 80.780 (Ac.)
PDC RATIONAL METHOD RESULTS FOR
BASIN 600 WHICH OUTLETS INTO REACH 7
Subarea runoff = 3.153(CFS)
Total initial stream area = 1.740(Ac.)
+ + + -I--I- + 4--F-I- + -1--I--H-h + + + -f-h++ + + + + + + + + + ++ + + + + + + + + + + + + + + + + + + + + +
Process from Point/Station 787.000 to Point/Station 788.000
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 1.740(Ac.)
Runoff from this stream = 3.153(CFS)
Time of concentration = 11.68 min.
Rainfall intensity = 4.419(In/Kr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Kr)
1 87.775 7.82 5.728
2 3.153 11.68 4.419
Qrcax(l) =
1.000 * 1.000 *• 87.775) +
1.000 * 0.669 * 3.153) + = 89.884
Qmax(2) =
0.772 * 1.000 * 87.775) +
1.000 * 1.000 * 3.153) + = 70.872
Total of 2 streams to confluence:
Flow rates before confluence point:
87.775 3.153
Maximum flow rates at confluence using above data:
89.884 70.872
Area of streams before confluence:
24.900 1.740
Results of confluence:
Total flow rate = 89.884(CFS)
Time of concentration = 7.815 min.
Effective stream area after confluence = 26.640(Ac.)
End of computations, total study area = 26.640 (Ac,
PDC RATIONAL METHOD RESULTS FOR
BASIN 700 WHICH OUTLETS INTO REACH 7
NOTE:
THIS EXHIBIT SHOWS THE DRAINAGE
AREAS TRIBUTARY TO REACHES 8
AND 9 ASSOCIATED WITH POINT OF
COMPLIANCE 5.
GRAPHIC SCALE
0 2000
1 INCH = 2,000 FEET
WATERSHED DELINEATION
BUENA VISTA CREEK WEST TRIBUTARY
^esultVlew
Define Drainage Basins Quarry Creek at Buena Vista
Basin: ^
Creek
Project QUARRY CREEK
Manage Your Basins
Create a new Basin by clicking the New button and scroll down to view
entry. Alternatively, select an existing Basin from table and view
properties below. Click Edit button to change Basin properties then
press Save to commit changes.
Name
Quarry Creek at Buena Vista Creek
Description: Quarry Creek
Design Goal: Treatment + Flow Control
Rainfall Basin: Oceansidt
Point of Compliance: Buena Vista Creek + Tributaries
Project Basin Area (ac): 8500.00
Mean Annual Precipition (in): 13.3
APPENDIX B
SCCWRP FIELD SCREENING DATA
Ciiapter 5. Open Channels
Table 5-13 Maximum Permissible Velocities for Lined and Unlined Channels
Material or Lining Maximum Permissible
Average Velocity* (ft/sec)
Natural and Improved Unlined Channels
Fine Sand, Colloidal 1.50
Sandy Loam, Noncolloidal 1.75
Silt Loam, Noncolloidal 2.00
Alluvial Silts, Noncolloidal 2.00
Ordinary Firm Loam 2.50
Volcanic Ash 2.50
Stiff Clay, Very Colloidal 3.75
Alluvial Silts. Collodal 3.75
Shales And Hardpans 6.00
Fine Gravel 2.50
Graded Loam To Cobbles When Noncolloidal 3.75
Giaded Sills Tu Cobbles When Culluidal 4.00
Coarse Gravel, Noncolloidal 4.00
Cobble And Shingtes.... .^^IV.:ST:^T::^I:I. 5.00
Sandy Silt 2.00
Silty Clay 2.50
Clay 6.00
Poor Sedimentary Rock 10.0
Fully-Lined Channels
Unreinforced Vegetation 5.0
Reinforced Turf 10.0
Loose Riprap per Table 5-2
Grouted Riprap 25.0
Gabions 15.0
Soil Cement 15.0
Concrete 35.0
* Maximum pemiissible velocity listed here is basic guideline; higher design velocities may be used, provided appropriate
technical documentation from manufacturer
San Diego County Drainage Design Manual Page 5-43
July 2005
Form 3 Support Materials
Form 3 Checklists 1 and 2, along with information recording in Form 3 Table 1,
are intended to support the decisions pathways illustrated in
Form 3 Overall Vertical Rating for Intermediate/Transitional Bed.
Form 3 Checklist 1: Armoring Potential
A A mix of coarse gravels and cobbles that are tightly packed with <5%
surface material of diameter <2 mm
B Intermediate to A and C or hardpan of unknown resistance, spatial extent
(longitudinal and depth), or unknown armoring potential due to surface
veneer covering gravel or coarser layer encountered with probe
C Gravels/cobbles that are loosely packed or >25% surface material of
diameter <2 mm
least resistant
- >• Form 3 Figure 2. Armoring potential photographic supplement for assessing intermediate beds
(16 < dso < 128 mm) to be used in conjunction with Form 3 Checklist 1.
(Sheet 2 of 4)
This sheet applies to Reaches 1 through 9
B-7
X
Form 3 Checklist 2: Grade Control
A Grade control is present with spacing <50 m or 2/Sv m
• No evidence of failure/ineffectiveness, e.g., no headcutting (>30 cm), no
active mass wasting (analyst cannot say grade control sufficient if mass-
wasting checklist indicates presence of bank failure), no exposed bridge
pilings, no culverts/structures undermined
• Hard points in serviceable condition at decadal time scale, e.g., no apparent
undermining, flanking, failing grout
• If geologic grade control, rock should be resistant igneous and/or
metamorphic; For sedimentary/hardpan to be classified as 'grade control', it
should be of demonstrable strength as indicated by field testing such as
hammer test/borings and/or inspected by appropriate stakeholder
B Intermediate to A and C - artificial or geologic grade control present but
spaced 2/Sv m to 4/Sv m or potential evidence of failure or hardpan of
uncertain resistance
Grade control absent, spaced >100 m or >4/Sv m,
of ineffectiveness
or clear evidence
[ GRADEC ONTROL
most resislarA^^,..,^^''''''''''''''''^ least resistant
Form 3 Figure 3. Grade-control (condition) photographic supplement for assessing intermediate
beds (16 < dso < 128 mm) to be used in conjunction with Form 3 Checklist 2.
(Sheet 3 of 4)
This sheet applies to Reaches 1 through 9
B-8
Regionally-Calibrated Screening Index Threshold for Incising/Braiding
For transitional bed channels (dso between 16 and 128 mm) or labile beds (channel not incised
past critical bank height), use Form 3 Figure 3 to determine Screening Index Score and complete
Form 3 Table 1.
<f^ach 8-91 ^
Q Q-\ '• Reach 6 * ^
0.001
100 dso (miTi)
• Stable X Braided + Incising
10% risk 50% risk 90% risk
GIS-derived: 10-yr flow & valley slope
Field-derived: 65Q (100-pebble count)
128 0.145
c
.2 96 0.125 Coo 16 mm 80 0.114 .ogislic Regr 16 mm 64 0.101 .ogislic Regr Al 48
32
0.087
0.070
16 0.049
8 0.031 Stic Reg LUliJ 4 0.026 Stic Reg to 2 0.022
1 O)
0
V 1 0.018
1 ..J
0.5 0.015
Form 3 Figure 4. Probability of incising/braiding based on logistic regression of Screening Index
and dso to be used in conjunction with Form 3 Table 1.
Form 3 Table 1. Values for Screening Index Threshold (probability of incising/braiding) to be used
in conjunction with Form 3 Figure 4 (above) to complete Form 3 Overall Vertical Rating for
Intermediate/Transitional Bed (below).. Screening Index Score: A = <50% probability of incision
for current Q10, valley slope, and dso; B = Hardpan/dso indeterminate; and C = >50% probability of
incising/braiding for current do, valley slope, and dso-
dso (mm)
From Form 2
S/Qio° ' (m^ V-=)
From Form 1
Is'')
50% risi< of incising/braiding
from table in Form 3 Figure 3 above
Screening Index Score
(A. B, C)
Overall Vertical Rating for Intermediate/Transitional Bed
Calculate the overall Vertical Rating for Transitional Bed channels using the formula below.
Numeric values for responses to Form 3 Checklists and Table 1 as follows: A = 3, B = 6, C = 9.
Vertical Rating = ^[(y/armoring * grade control ) * screening index score]
Vertical Susceptibility based on Vertical Rating: <4.5 = LOW; 4.5 to 7 = MEDIUM; and >7 = HIGH.
(Sheet 4 of 4)
B-9
PEBBLE COUNT
n Reach 1 to 5 diameter, mm Reach 6 diameter, mm Reach 7 diameter, mm Reach 8 and 9 dh
1 2 5.5 2 2
2 2 5.5 2 2
3 2 5.5 2.8 2
4 2 8 2.8 2
5 2.8 8 2.8 2
6 2.8 8 2.8 2
7 2.8 8 4 2
8 2.8 8 4 2
9 2.8 8 4 2.8
10 2.8 8 5.6 2.8
11 4 8 5.6 2.8
12 4 8 5.6 2.8
13 4 11 5.6 2.8
14 4 11 5.6 2.8
15 4 11 5.6 2.8
16 4 11 5.6 2.8
17 4 11 8 4
18 4 11 8 4
19 5.6 11 8 4
20 5.6 16 8 4
21 5.6 16 8 4
22 5.6 16 11 4
23 5.6 16 11 4
24 5.6 16 11 4
25 5.6 16 11 4
26 5.6 16 11 4
27 5.6 22.6 11 4
28 5.6 22.6 11 5.6
29 5.6 22.6 11 5.6
30 8 22.6 11 5.6
31 8 22.6 11 5.6
32 8 22.6 16 5.6
33 8 22.6 16 5.6
34 8 22,6 16 5.6
35 8 22.6 16 5.6
36 8 22.6 16 5.6
37 8 22.6 16 5.6
38 8 22.6 16 5.6
39 11 22.6 22.6 5.6
40 11 22.6 22.6 5.6
41 11 22.6 22.6 5.6
42 11 22.6 22.6 5.6
43 11 22.6 22.6 5.6
44 11 22.6 22.6 8
45 11 32 22.6 8
46 11 32 22.6 8
47 11 32 22.6 8
48 16 32 22.6 8
49 16 32 22.6 8
50 16 32 32 8
51 16 32 32 8
52 16 32 32 8
53 16 32 32 8
54 16 32 32 8
55 16 32 32 8
56 16 32 32 8
57 16 32 32 8
58 16 32 32 8
59 16 45 32 8
D50
PEBBLE COUNT
# Reach 1 to 5 diameter, mm Reach 6 diameter, mm Reach 7 diameter, mm Reach 8 and 9 dia
60 16 45 32 8
61 16 45 32 8
62 16 45 32 8
63 16 45 32 8
64 16 45 32 8
65 16 45 32 8
66 16 45 32 8
67 16 45 32 11
68 16 45 32 11
69 16 45 32 11
70 16 45 32 11
71 16 45 32 11
72 16 45 32 11
73 16 45 32 11
74 16 45 32 11
75 22.6 45 32 11
76 22.6 45 32 11
77 22.6 45 32 11
78 22.6 45 32 11
79 22.6 45 32 11
80 22.6 45 45 16
81 22.6 64 45 16
82 22.6 64 45 16
83 22.6 64 45 16
84 22.6 64 45 16
85 22.6 64 45 16
86 22.6 64 45 16
87 22.6 64 45 16
88 22.6 64 45 16
89 22.6 64 45 16
90 22.6 64 45 16
91 22.6 64 45 16
92 22.6 90 45 16
93 22.6 90 45 22.6
94 22.6 90 64 22.6
95 22.6 90 64 22.6
96 22.6 90 64 22.6
97 32 90 64 22.6
98 32 90 90 32
99 32 90 90 32
100 45 90 90 32
FORM 4: LATERAL SUSCEPTIBILTY FIELD SHEET
Circle appropriate nodes/pathway for proposed site
OR use sequence of questions provided in Form 5.
(Sheet 1 of 1)
This sheet applies to Reaches 1 through 9
B-10
FORM 6: PROBABILITY OF MASS WASTING BANK FAILURE
If mass wasting is not currently extensive and the banks are moderately- to well-consolidated, measure
bank height and angle at several locations (i.e., at least three locations that capture the range of
conditions present in the study reach) to estimate representative values for the reach. Use Form 6 Figure
1 below to determine if risk of bank failure is >10% and complete Form 6 Table 1. Support your results
with photographs that include a protractor/rod/tape/person for scale.
Bank Angle Bank Height Corresponding Bank Height for
(degrees) (m) 10% Risk of Mass Wasting (m)
(from Field) (from Field) (from Form 6 Figure 1 below)
Bank Failure Risk
(<10% Risk)
(>10%Risk)
Left Bank
Right Bank
probability of mass wasting
in moderately/well consolidated banks
50% Risk 90% Risk X Unstable
I o
cP §
Reach 7
o
^ O 00 0
O 00 0
^ oQ>Q?o
i ^ 1 r
30 40
oo
1 J 1 J_
50 60 70
Bank Angle (degrees)
Oo ^
90
30 7.6
35 4.7
40 3.7
45 2.1
50 1.5
55 1.1
60 0.85
65 0.66
70 0.52
80 0.34
90 0.24
Bank height and angle
schematic
Form 6 Figure 1. Probability Mass Wasting diagram. Bank Angle:Height/% Risk table, and
Band Height:Angle schematic.
(Sheet 1 of 1)
Probability is less than 10% for the existing bank angles (2:1 = 26.6 degrees) in Reaches 1-6 and 8-9.
See attached normal depth analysis for bank height in Reach 7 during 10-year flow of 28 cfs.
B-12
Worksheet for Trapezoidal Channel - Reach 7
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.030
Channel Slope 0.06590 ft/ft
Left Side Slope 1.00 ft/ft (H:V)
Right Side Slope 1.00 ft/ft (H:V)
Bottom Width 8.00 ft
Discharge 28.00 ft'/s
Results
Normal Depth 0.46 ft
Flow Area 3.92 ft^
Wetted Perimeter 9.31 ft
Hydraulic Radius 0.42 ft
Top Width 8.93 ft
Critical Depth 0.70 ft
Critical Slope 0.01640 ft/ft
Velocity 7.14 ft/s
Velocity Head 0.79 ft
Specific Energy 1.26 ft
Froude Number 1.90
Flow Type Supercritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 ft
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 fl
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ft/s
Normal Depth 0.46 ft
Critical Depth 0.70 ft
Channel Slope 0.06590 ft/ft
12/19/2011 4:35:13 PM
Bentley Systems, Inc. Haestad Methods ScflaWte^htwWaster V8i (SELECTseries 1) [08.11.01.03]
27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2
esult View
Define Drainage Basins
CRITICAL STRESS CALCULATOR - REACH 5
Quarry Creek at Buena Vista Basin: Creek Project QUARRY CREEK
J L POC J
Vlanage Your Point of Compliance (POC)
\nalyze the receiving water at the 'Point of Compliance' by completing
his form. Click Edit and enter the appropriate fields, then click the
Jpdate button to calculate the critical flow and low-flow threshold
:ondition. Finally, click Save to commit the changes.
Cancel Save Update
Channel Susceptibility: L
Low Flow Threshold: 0.5Q2
Channel Assessed: Yes
Watershed Area (ac): 9280.00
Vertical Susceptibility: Low (Vertical)
Lateral Susceptibility: Low (Lateral)
Material: Vegetation
Roughness: iO.100
Channel Top Width (ft): j36.0
Channel Bottom Width (ft): 16.0
Channel Height (ft): 5.0
Channel Slope: p.008|
Large Viev/
esult View
Define Drainage Basins
CRITICAL STRESS CALCULATOR RESULTS - REACH 6
Quarry Creek at Buena Vista
Basin: Creek Project QUARRY CREEK
Vlanage Your Point of Compliance (POC)
\nalyze the receiving water at the 'Point of Compliance' by completing
his form. Click Edit and enter the appropriate fields, then click the
Jpdate button to calculate the critical flow and low-flow threshold
:ondition. Finally, click Save to commit the changes.
Cancel Update
Channel Susceptibility:
Low Flow Threshold: I0.5Q2
Channel Assessed: Yes Vertical Susceptibility: Low (Vertical)
Watershed Area (ac): 9138.00 Lateral Susceptibility: Low (Lateral)
Material: Vegetation
Roughness: 0.100
Channel Top Width (ft): 170.0
Channel Bottom Width (ft): 150.0
Channel Height (ft): 5.0
Channel Slope: 10.001
Large View
lesult View CRITICAL STRESS CALCULATOR RESULTS - REACH 7
Define Drainage Basins Basin; Quarry Creek at Buena Vista
Creek Project: QUARRY CREEK
POC
L^J L—
Manage Your Point of Compliance (POC)
Analyze the receiving water at the 'Point of Compliance' by completing
this form. Click Edit and enter the appropriate fields, then click the
Update button to calculate the critical flow and low-flow threshold
condition. Finally, click Save to commit the changes.
Cancel Save Update
Channel Susceptibility: L
Low Flow Threshold: I0.5Q2
Channel Assessed: Yes
Watershed Area (ac): 107.40
Vertical Susceptibility: Low (Vertical)
Lateral Susceptibility: Low (Lateral)
Material: Medium gravel
Roughness: 0.026
Channel Top Width (ft): 16.0
Channel Bottom Width (ft): 8.0
Channel Height (ft): 2.0
Channel Slope: 0.066
Large View
esult View CRITICAL STRESS CALCULATOR RESULTS - REACH 8
Define Drainage Basins Basin: Quarry Creek at Buena Vista
Creek Project QUARRY CREEK
J u
Vlanage Your Point of Compliance (POC)
\nalyze the receiving water at the 'Point of Compliance' by completing
his form. Click Edit and enter the appropriate fields, then click the
Jpdate button to calculate the critical flow and low-flow threshold
:ondition. Finally, click Save to commit the changes.
Cancel Save Update
Channel Susceptibility:
Low Flow Threshold: 0.5Q2
Channel Assessed: Yes
Watershed Area (ac): 307.2
Vertical Susceptibility: Low (Vertical)
Lateral Susceptibility: Low (Lateral)
Material: Vegetation
Roughness: 0.100
Channel Top Width (ft): 80
Channel Bottom Width (ft): 60
Channel Height (ft): 5
Channel Slope: 0.016
La roe View