CA_FLAP_SR89(2)_MeeksBayBikeTrail_DrainageReport_v2.pdf

D R A I N A G E R E P O R T

CA FLAP SR-89 (2) - Meeks Bay Bike Path

Prepared for

Central Federal Lands - Highway Division

May 2017

III

Contents Section Page

Acronyms and Abbreviations .............................................................................................................. v

Project Overview ........................................................................................................................... 1-1

1.1 Introduction ..................................................................................................................... 1-1

1.2 Project Description .......................................................................................................... 1-1

Project Background ........................................................................................................................ 2-2

2.1 Existing Drainage Facility Summary ................................................................................. 2-2

2.2 Floodplains ....................................................................................................................... 2-2

2.3 Field Review and Major Design Revisions ........................................................................ 2-2

2.4 Regulatory Requirements ................................................................................................ 2-3

Hydrology ...................................................................................................................................... 3-1

3.1 General ............................................................................................................................. 3-1

3.2 Methods and Recurrence Intervals.................................................................................. 3-1

3.3 Basin Characteristics ........................................................................................................ 3-1

3.4 Precipitation ..................................................................................................................... 3-2

3.5 Debris and Bulking Potential ............................................................................................ 3-2

3.6 Travel Time and Time of Concentration .......................................................................... 3-3

Hydraulics ...................................................................................................................................... 4-1

4.1 General ............................................................................................................................. 4-1

Stormwater Quality........................................................................................................................ 5-1

5.1 General ............................................................................................................................. 5-1

5.2 Water Quality Treatment Option and Sizing ................................................................... 5-1

5.3 Stormwater Mitigation Report ........................................................................................ 5-1

References ..................................................................................................................................... 6-1

Appendixes

A Location Map B Hydrology C Hydraulics D Stormwater Quality E References

V

Acronyms and Abbreviations BMP Best Management Practice

CFLHD Central Federal Lands Highway Division cfs cubic feet per second

CP concrete pipe

CSP corrugated steel pipe

DSN Drainage System Number

FEMA Federal Emergency Management Agency

FHWA Federal Highway Administration

GIS Geographic Information Systems

HDM Highway Design Manual

MEAT Modified Environment as Treatment

NEAT Natural Environment as Treatment

No. Number

NOAA National Oceanic and Atmospheric Administration

NRCS Natural Resources Conservation Service

NWS National Weather Service

PDT Project Development Team

PPDG Project Planning and Design Guide

Project CA FLAP SR-89(2) Meeks Bay Bike Path

RCP Reinforced Concrete Pipe

Regional Board Lahontan Regional Water Quality Control Board

SEZ stream environmental zone

SR State Route

TMDL Total Maximum Daily Load

TRPA Tahoe Regional Planning Agency

TST Traction Sand Traps

USACE U.S. Army Corps of Engineers

USGS United States Geological Survey

WQF Water Quality Flow

WQV Water Quality Volume

WSEL Water Surface Elevation

SECTION 1

1-1

Project Overview

1.1 Introduction

This drainage report summarizes the proposed hydrologic and hydraulic design conditions for the 0.7-mile long Class 1 Bike Path commencing near the southern boundary of the Sugar Pine Point State Park and extending southward to the Meeks Bay Resort & Marina. The project is located ten miles south of Tahoe City, California on the west shore of Lake Tahoe in the community of Meeks Bay in El Dorado County, California. Figure 1 in Appendix A provides the project location map.

1.2 Project Description

The Federal Highway Administration – Central Federal Lands Highway Division (FHWA-CFLHD), in coordination with the United States Forest Service (USFS), California Department of Transportation (Caltrans), Tahoe City Public Utilities District (TCPUD) and Tahoe Transportation District (TTD), propose to construct an extension of the west shore bike trail system that currently extends from Sugar Pine Point State Park to Dollar Hill in Tahoe City and the resort area of Squaw Valley located in Olympic Valley, California in a manner that is consistent with goals, policies and actions set forth in the 2010 Lake Tahoe Bicycle and Pedestrian Plan (BPP). In addition, the proposed Project will link two major activity centers on the west shore of Lake Tahoe; Sugar Pine Point State Park and the Meeks Bay Resort.

Currently, the west shore trail system terminates at Sugar Pine Point State Park which requires bicyclist and pedestrians to share right-of-way (ROW) with auto traffic or terminate their trip altogether prior to reaching Meeks Bay Resort.

The project will construct a Class 1 Bike Path with a paved width of 10 feet. The proposed bike path generally maintains a northeast inclination adjacent to SR 89. The project includes four crossings of private driveways and one crossing of a culvert. The portion of the project within Caltrans right-of-way includes a bike/pedestrian bridge and geosynthetic reinforced retaining walls along the majority of its length. Post construction water quality treatment is proposed for the portion of SR 89 that drains to the stream environment zone near the bridge crossing. The portion of the project within USFS land will have traditional cut/fill slope grading with appropriate soil stabilization BMPs. Figure 2 in Appendix A provides the Proposed Bike Trail Layout.

Water quality is a major priority in the environmentally sensitive Lake Tahoe Basin. With the exception of the portion of the project crossing the stream environment zone, the project area has been identified as either Natural Environment as Treatment (NEAT) or Modified Environment as Treatment (MEAT) areas by Caltrans. A NEAT designation indicates that no additional improvements are necessary to sufficiently treat runoff with the existing vegetation in the area. A MEAT designation indicates that minor modifications are required to adequately address storm water runoff (e.g. minor grading and promotion of sheet flow). Therefore, sheet flow of the runoff has been chosen as the primary treatment method in the project area.

SECTION 2

2-2

Project Background

2.1 Existing Drainage Facility Summary

Topography across the Project area generally consists of an established vegetated forest and slopes from west to east, toward Lake Tahoe. The roadway embankment extends some 20 to 40-feet (horizontally) from the edge of the highway shoulder.

The entire Project area resides within the Meeks Creek Watershed (Tahoe Regional Planning Agency Watershed 55), which is a Priority 1 Watershed for Best Management Practices (BMP) retrofit. The most significant drainage course through the Project area is located near the north end of the Project, near the intersection of Northridge Drive and SR 89. This un-named ephemeral drainage course includes a 48-inch diameter culvert that extends under SR 89, from the west side of SR 89 to the east side, toward Lake Tahoe.

For most of the highway area that is within the Project area, highway runoff is dispersed as sheet flow along the road shoulder and into the adjacent forest. Near the intersection of Northridge Drive and SR 89, there is an overside drain that carries highway runoff from a low spot on the east side of SR 89 down a steep slope to the discharge end of the above-mentioned 48-inch culvert.

Lake Tahoe is included in the Clean Water Act Section 303d list for threatened or impaired waters and great care must be taken to avoid discharge of contaminated runoff to Lake Tahoe or any of its tributaries. To the extent feasible, existing drainage shall be maintained in proper functioning order throughout construction or until proposed infrastructure is in place and functioning as designed.

2.2 Floodplains

Regulatory floodplains are delineated on the effective Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map 32005C0025G (effective date of January 19, 2010). This project resides entirely within the stated FIRM panel which is not printed due to consisting entirely of Zone A, all open water.

2.3 Field Review and Major Design Revisions

Tahoe Transportation District’s (TTD) previous consultant submitted a 95% design package on July 3, 2014, including plans, specification, estimate, and technical memorandum. The following is a summary of the significant changes that have occurred since the previous submittal to incorporate the review comments regarding bike path alignment refinements, drainage design, water quality design, erosion control, retaining wall refinement, and CFLHD CADD standard requirements.

The bike path alignment has been updated based on the locations identified during the September 17, 2014 field walk in order to avoid conflict with the existing wood wall, rock outcrops, large trees, and the existing sanitary sewer force main. In addition, the bike path alignment has been shifted closer to the SR 89 near Drum Road and Driveways #2 and #3 in order to improve the cross slope of the bike path at the driveway crossings.

Within USFS property, various locations have been graded with 1:20 uphill fill slopes to promote sheet flow across the bike path and avoid concentrating storm water runoff. A graded ditch has been added at the switchback curve to convey storm water runoff through the double cut section and discharge via a riprap lined outfall to the toe of the adjacent fill slope. Within Caltrans ROW, runoff from SR 89 will be allowed to sheet flow off the roadway and across the bike path into adjacent vegetated forest land per

SECTION 2 – PROJECT BACKGROUND

2-3

Caltrans NEAT and MEAT standards, instead of into an infiltration trench. A 3-foot wide riprap band is proposed between SR 89 and the bike path to capture traction sand, prevent scour and erosion of the roadside shoulder, and reduce sheet flow velocities without concentrating the runoff. Between Driveway #2 and #3, a swale was added along the east side of the proposed bike path to collect runoff from the path and adjacent regrading of an earthen berm on private property. This swale flows north to a pipe inlet sand trap and discharges to a riprap pad. Near the intersection with Northridge Drive, curb and gutter with a storm drain system have been added along the east side of SR 89 to collect and convey highway stormwater into drainage inlet sand traps prior to entering the stream environment zone (SEZ).

2.4 Regulatory Requirements

A number of agencies will be directly and indirectly involved in the design review through various permitting processes. Due to construction within the Truckee River and impacts to wetlands, the following are the agencies that will be involved:

• Caltrans District 3 – will provide review of the drainage report for compliance with their highway design manual.

• CFLHD – will provide review of the drainage report for compliance to their design and construction requirements.

• Regional Board, Lahontan Region – The Regional Board will not require a Water Quality Certification (Section 401) to certify that the project will not exceed water quality standards.

Construction of the project will also require coverage under the General Permit for Discharges of Storm Water Associated with Construction Activity Board Order No. R6T-2016-0010 NPDES No. CAG616002.

• Tahoe Regional Planning Agency (TRPA) - TRPA is actively involved by providing input on trail design and stormwater treatment strategies for the project. Specifically, TRPA regulates:

development within a stream environmental zone (SEZ), tree removal, impervious surface coverage, and a soil hydrologic analysis in areas where infiltration facilities are proposed to ensure there is 1-foot separation between the invert of the infiltration facility and the seasonally high groundwater elevation. Soil hydrologic information was obtained from project geotechnical boring samples.

• U.S. Army Corps of Engineers (USACE) – A 404 Permit will not be required as the project will not impact jurisdictional wetlands.

• USDA Forest Service– A special use permit will be required to complete any work that occurs within the limits of the Forest Service property.

http://www.waterboards.ca.gov/water_issues/programs/stormwater/constpermits.shtml

SECTION 3

3-1

Hydrology

3.1 General

This section provides an overview of the input parameters, calculations, and peak flow results for both the proposed drainage system networks and proposed roadside channels. The offsite and onsite watershed hydrology has been analyzed using methods outlined in the Caltrans Highway Design Manual (HDM) (Reference 1).

3.2 Methods and Recurrence Intervals

Rational Method hydrologic calculations were performed to determine the surface runoff tributary to the proposed drainage system. Rational Method runoff coefficients given in Figure 819.2A and Table 819.2B of the HDM were used to calculate a weighted composite runoff coefficient for each tributary area. The undeveloped portion of each tributary area was assigned a pervious runoff coefficient using the method described in Figure 819.2A.

For this method, each undeveloped portion of a drainage tributary area was matched with four different basin characteristics of relief, soil infiltration, vegetal cover, and surface storage. The relief or slope of the undeveloped surface was determined by using existing and proposed topographic elevation data.

The soil infiltration characteristic was determined by matching the existing hydrologic soil group with the soil infiltration classifications found in Figure 819.2A. For the project area the existing soils were mapped by the Web Soil Survey (WSS) Soil Data (Reference 3) as hydrologic soil group A, and were characterized as high infiltration or well drained soils. WSS Soil Data is provided in Appendix E. Vegetal cover for each tributary area was determined from aerial imagery of each basin. The last basin characteristic of surface storage was also determined by using aerial imagery and field visit photography.

Tributary areas with impervious surfaces such as paved roadways and pathways were assigned a runoff coefficient of 0.95. The pervious runoff coefficient and pervious area was used with the impervious runoff coefficient and impervious area of each tributary area to calculate a weighted composite runoff coefficient. This weighted composite runoff coefficient was used with the Rational Method formula to generate a peak flow for each tributary area.

The hydrologic calculations for the proposed drainage systems were evaluated with the 25-year storm event in accordance with the HDM Table 831.3 for highways with the design speed limit of over 45 miles per hour. For onsite facilities that collect and convey offsite and onsite runoff, a combined 25-year peak flow was computed. The spread and depth of flow along the shoulders has been designed to carry the runoff from the 25-year storm event without encroaching into the travelled way or overtopping the curb. Culverts have been designed to carry the 10-year storm event without the HGL rising above the soffit of the culvert, and for the 100-year storm event, the hydraulic grade line does not rise above the elevation of the inlet grate and/or cause objectionable backwater. See Appendix B for hydrologic calculations and Appendix C for Hydraulic calculations for the 10, 25 and 100-year storm events.

3.3 Basin Characteristics

The proposed drainage basins contributing runoff to the bike path improvements along with a detailed summary of hydrology calculations for each area are presented in Appendix B. Drainage basin boundaries were delineated using a combination of proposed improvement contour data and existing topographic project data including an InRoads digital terrain model. Existing drainage basins have been

SECTION 3

3-2 delineated on the Drainage Basin Boundaries Map provided in Appendix B, however, hydrologic calculations have only been provided for basins contributing runoff to the bike path improvements.

Proposed drainage facilities are separated into drainage networks that are identified with a Drainage System No. (DSN). Each drainage network is labeled on the Drainage Basin Boundaries Map, provided in Appendix B, and referenced in this report. In addition to the Drainage System No., each proposed structure also has a structure identification number also referred to as Structure ID. The Structure ID is comprised of the contributing basin ID plus a letter to identify its upstream order in the system.

Proposed downstream pipes from proposed structures have been labeled similar to its upstream structure.

North of the Driveway #4, cut slopes prevent runoff from sheet flowing. A ditch is proposed along the right side of the bike path north of the driveway to capture runoff from the highway and bike path before it encroaches onto the private property. The ditch will collect and convey stormwater south to a storm drain system (DSN 1) consisting of sand trap inlets with infiltration bottoms and pipes that discharge onto rock slope protection outside of the SEZ to promote infiltration.

Water quality improvements have been incorporated to treat SR 89 stormwater runoff into the Project area. With the exception of the portion of project crossing a SEZ, the project area has been identified as a MEAT area by Caltrans. Therefore, sheet flow of the runoff has been chosen as the primary treatment method in the project area. South of the bike bridge, a 3-foot wide band will be constructed between SR 89 and the bike path in areas receiving sheet flow runoff to capture traction sand, prevent scour and erosion of the roadside shoulder, and reduce sheet flow velocities without concentrating the runoff.

Within the US Forest Service portion of the project, a graded ditch is proposed along the right side of the bike path, from Station 19+74 to 23+88. The ditch collects and conveys stormwater from the forest and bike path and dissipates onto a riprap outfall.

From Station 8+20 to 9+40, drainage along the west side of the bike path will be graded to drain away from the path.

The Project does not include any significant alterations to the existing drainage patterns throughout the Project area. In general, existing drainage patterns are maintained via sheet flow across the bike path to existing concentration points. In areas with minor flow concentration adjacent to the path, riprap will be installed to dissipate flow.

3.4 Precipitation

National Oceanic and Atmospheric Administration (NOAA) Atlas 14 (Reference 4) data were used to determine point precipitation and intensity duration frequency curves. This data is included in Appendix E.

3.5 Debris and Bulking Potential

The debris and bulking potential, or likelihood of large volume stormwater runoff to entrain large volumes of sediment, increases the volume and rates of runoff within watersheds and causes the capacity of facilities, designed for clear-water flow, to be exceeded in large storm events. The facilities throughout the project site do not have a history of lack of conveyance due to large amounts of debris and there are no major reports of flooding areas. The upstream areas draining to the project area have no recent history of large-scale burns and do not have a large sediment supply. Any sediment clogging proposed facilities appears to be from traction sand. This has been addressed through the incorporation of sand traps and water quality structures, which have been sized to collect traction sand applied to highway watersheds. The application of a bulking factor is typically appropriate for areas where very

SECTION 3 – HYDROLOGY

3-3 high sediment generation is anticipated. All runoff contains some portion of entrained sediment, but for most typical hydrologic analyses it is neglected. In the case of the Tahoe Basin, standard hydrologic analysis is very imprecise (and typically conservative) due to the ability of forested areas to absorb and attenuate runoff below established runoff coefficients. The volume of the limited sediment generated, falls within the accuracy of the standard methods to predict runoff. Because the runoff reaching the project area is predominantly highway flows with relatively small sediment generation potential, bulking potential was neglected in the sizing of any proposed systems for the project.

3.6 Travel Time and Time of Concentration

The proposed time of concentrations for the hydrology basin boundaries were calculated according to the HDM, Section 816.6. The time of concentration was broken into segments of sheet flow, shallow concentrated flow, and channel flow for the maximum flow length through a watershed. The maximum flow length and slope were determined from the most hydraulically distant point of the watershed to the concentration point using existing and proposed topography. Sheet flow and concentrated shallow flow travel times were determined with the equations and parameters outlined in the HDM. Channel velocities/travel times were determined using the Manning’s Equation with slopes determined by offsite or onsite topography (depending upon the location of the channel) and roughness factors and depths determined by HDM Table 866.3A and proposed topography. Maximum lengths of approximately 100-feet for unpaved areas and 300-feet for paved areas were used for sheet flow segments. Flow was considered shallow concentrated from the end of the sheet flow to the outflow location unless there is an established creek or stream evident on the topography. A minimum time of concentration of 5 minutes was used as recommended in the HDM. Where tributary areas consisted of mostly pervious surfaces, a minimum time of concentration of 10 minutes was used. Time of concentration calculations have been included in Appendix B, for basins contributing flow to proposed drainage facilities.

SECTION 4

4-1

Hydraulics

4.1 General

The 25-year design storm with InRoads Storm and Sanitary was used to size and design the storm drain pipe networks, culverts, and ditches throughout the project per HDM Table 831.3. System capacity was designed to keep the hydraulic grade line (HGL) at least one foot below the rim elevation of drainage structures for the 25-year storm event. The 25-year design storm with Bentley Flowmaster was used to evaluate the storm drain inlet capacity and spread calculations based on methods described in FHWA Hydraulic Engineering Circular 22 (Reference 2). A 50% clogging factor was used for grate inlets, as outlined in the HDM. Inlet locations and roadway improvements were made to keep the 25-year storm event spread within the roadway shoulder and out of the traveled way.

All proposed roadway inlets are depressed 1 ¼ -inches to avoid catching the blade of snow plows.

Proposed inlets are grate inlets. Type 24-12X grates were also selected for the roadway inlets to increase interception capacity.

Ditch capacity calculations with a 25-year design storm were performed with Bentley Flowmaster.

Riprap aprons are located at the outlets of the storm drain pipe network and ditches following CFL standards. The following hydraulic calculations have been included in Appendix C:

• 25-year hydraulic summary for the proposed storm drain system with pipe HGLs, generated by InRoads Storm and Sanitary

• Inlet capacity and spread calculations for the 25-year design storm using Bentley Flowmaster

• Ditch hydraulic and lining summary

SECTION 5

5-1

Stormwater Quality

5.1 General

CH2M reviewed the Caltrans PPDG for Stormwater Quality, the NEAT Study, and TRPA’s Code of Ordinances to determine storm water related requirements for the project. The project incorporates BMPs for design pollution prevention, permanent treatment, temporary construction site, and maintenance to control the water quality discharge of storm water. Treatment BMPs are designed to handle the discharge from impervious surfaces generated by the 20-year, 1-hour storm (1 inch of rainfall in the Lake Tahoe Basin). The treatment strategy relies upon use of proposed BMPs including: Riprap and traction sand traps (TST).

5.2 Water Quality Treatment Option and Sizing

While the technical discussions regarding specific treatment strategies are outside of the scope of the drainage study, the sizing of approved treatment applications was performed as part of this study. The project location incurs snow throughout the winter months. Caltrans will apply traction sand or other roadway abrasives to increase driver safety during those times. This sand will collect along the roadway until a snow melt or rain event washes the sand off the roadway. One of the primary objectives of the Stormwater Quality portion of this project is to capture the sand before it is allowed to discharge into nearby creeks or streams that flow to Lake Tahoe. Below is a description of the selected BMPs and their functions:

TST: TSTs capture traction sand before it discharges into storm drain systems which ultimately drain to Lake Tahoe. TSTs will be used at all catch basin locations, where feasible, on the project. For this project, the Traction Sand Trap, Pipe Inlet – CSP Type and concrete inlet Type G1 will be used. These TST types also have the benefit of infiltration through the weep holes on the bottom of the catch basin.

The method for trapping sand is a function of the contributing tributary area being directed to the catchment facility and the sand application rate. Other factors include the effectiveness of sweeping removal and the expected number of sand trap cleanings per year. Sand application rates were provided by Caltrans (John Schnoor, Tahoe City Maintenance) and were used for the preliminary sizing of sand trap facilities. The calculations for the sizing of the proposed sand trapping facilities are shown on the table in Appendix D. The sizing calculations utilized the watershed areas determined under the onsite hydrology section and the provided sand application rates.

Riprap: South of the bike bridge, a 3-foot wide riprap band of Class 5 riprap will be constructed between SR 89 and the bike path in areas receiving sheet flow runoff to capture traction sand, prevent scour and erosion of the roadside shoulder, and reduce sheet flow velocities without concentrating the runoff.

Class 5 riprap was selected based on its larger size and weight as requested by Caltrans District Maintenance to reduce the potential of sucking up the riprap with their vactor trucks.

5.3 Stormwater Mitigation Report

A Stormwater Mitigation Report has been prepared for the project. The report incorporates the rationale for the selection of BMPs for design pollution prevention, permanent treatment, temporary construction site, and maintenance to control the discharge of storm water. The SWDR also documents design considerations, environmental concerns, and Caltrans regional and local requirements for the project.

6-1

References

1. Caltrans Highway Design Manual (HDM) 2015

2. FHWA Hydraulic Engineering Circular 22 (Urban Drainage Design Manual, 2001)

3. Web Soil Survey (WSS) Soil Data produced by the National Cooperative Soil Survey

4. National Oceanic and Atmospheric Administration (NOAA) Atlas 14 Precipitation Data

Appendix A Location Maps

U S

-5

S R

-89

U S

-5 s Project

Location Map

0 3 6 9 121.5

Miles

Project Location

Figure 1

S R

-89

STATE

CA

PROJECT

CA FLAP SR 89 (1)

5+

20+00

400'200'0

Scale in Feet

Lake Tahoe 5+

E 7097521.64

N 2146489.32

Begin Bike Path

CA FLAP SR89(1)

5+25.85

Begin Project

E 7098521.38

N 2149071.34

End Bike Path

CA FLAP SR89(1)

42+58.00

End Project

Potential Staging Area

Potential Storage Area

Limits of Construction

LAYOUT

BIKE TRAIL

PROPOSED

FIGURE 2

CA

STATE PROJECT

CA FLAP SR89(2)

NF-1417

Marina Resort and Meeks Bay

South Lake Tahoe

18 miles to

SR89

Drum Rd #2

Drum Rd #3

Driveway Sugar Pine

B ik e P a th

E x istin g

Tahoe City

10 miles to

Drum Rd #1

Appendix B Hydrology

5+

20+00

400'200'0

Scale in Feet

20+00

5+

Tahoe City

10 miles to

B ik e P a th

E x istin g

CA

STATE PROJECT

CA FLAP SR89(2)

BOUNDARIES MAP

DRAINAGE BASIN

FIGURE 3

SR89

LEGEND

MBBT15

Proposed storm drain network

Time of concentration flow path

Proposed Basin Boundary

Basin Boundary ID

MBBT10MBBT11

MBBT15

MBBT16

MBBT22

MBBT21

MBBT23

MBBT24

MBBT20

MBBT19

MBBT18

MBBT17

MBBT14

MBBT13

MBBT12

MBBT09

MBBT08

MBBT06

MBBT05

MBBT04

MBBT03

MBBT02

MBBT01

MBBT07

MBBTOFF

SP039573

Callout

DSN 1

SP039573

Callout

DSN 2

SP039573

Callout

DSN 3

SP039573

Callout

DSN 4

SP039573

Text Box

DSN 1

SP039573

Typewritten Text Drainage System Number

Meeks Bay Bike Trail Project - Proposed 10-year Hydrology Summary

Drainage System No.

Tributary Area

ID

Relief Descrip-tion (HDM Figure 819.2A)

Relief Runoff

Coefficient, C1

Soil Infiltration

Descrip-tion (HDM

Figure 819.2A)

Soil Infiltration

Runoff Coefficient, C2

Vegetal Cover

Descrip-tion (HDM

Figure 819.2A)

Vegetal Cover Runoff

Coefficient, C3

Surface Storage Descrip-tion (HDM Figure 819.2A)

Surface Storage Runoff

Coefficient, C4

Pervious Runoff

Coefficient, C

Pervious Tributary

Area (acres)

Impervious Runoff

Coefficient, C

Impervious Tributary

Area (acres)

Frequency Factor, Cf

Basin Weighted

Runoff Coefficient, C

Time of Concen-tration, Tc

(min)

Rainfall Intensity (in/hr)

Total Tributary

Area (acres)

Rational Method Runoff

(cfs)

Bypass or Flow

From Up-stream (cfs)

Total Flow to

Structure (cfs)

Assigned Structure to

Receive Flow

1 MBBT01 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.02 0.95 0.06 1.0 0.79 5 3.05 0.08 0.19 0.00 0.19 MBBT01-B

1 MBBT02 0.00 0.00 0.95 0.07 1.0 0.95 5 3.05 0.07 0.19 0.00 0.19 MBBT03-A

1 MBBT03 0.00 0.00 0.95 0.05 1.0 0.95 5 3.05 0.05 0.14 0.19 0.33 MBBT03-A

1 MBBT04 0.00 0.00 0.95 0.05 1.0 0.95 5 3.05 0.05 0.16 0.03 0.19 MBBT04-A

1 MBBT05 0.00 0.00 0.95 0.12 1.0 0.95 5 3.05 0.12 0.35 0.02 0.37 MBBT05-A

2 MBBT07 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.07 0.95 0.04 1.0 0.59 5 3.05 0.11 0.20 0.00 0.20 MBBT07-A 3 MBBT11 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.10 0.95 0.05 1.0 0.60 5 3.05 0.15 0.28 0.00 0.28 MBBT11-A 3 MBBT12 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.54 0.95 0.20 1.0 0.60 5 3.05 0.75 1.37 0.28 1.65 MBBT11-A 4 MBBT20 Hilly 0.24 Normal 0.07 Good 0.07 Negligible 0.11 0.49 0.11 0.95 0.00 1.0 0.49 5 3.05 0.11 0.16 0.00 0.16 MBBT20-A

4 MBBT21 0.00 0.00 0.95 0.17 1.0 0.95 5 3.05 0.17 0.49 0.16 0.65 MBBT20-A

4 MBBT22 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.08 0.95 0.00 1.0 0.40 5 3.05 0.08 0.10 0.65 0.75 MBBT20-A 4 MBBT23 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.17 0.95 0.06 1.0 0.60 5 3.05 0.23 0.42 0.75 1.17 MBBT20-A

Meeks Bay Bike Trail Project - Proposed 25-year Hydrology Summary

System No.

Tributary Area

ID

Relief Descrip-tion (HDM Figure 819.2A)

Relief Runoff

Coefficient, C1

Soil Infiltration

Descrip-tion (HDM

Figure 819.2A)

Soil Infiltration

Runoff Coefficient, C2

Vegetal Cover

Descrip-tion (HDM

Figure 819.2A)

Vegetal Cover Runoff

Coefficient, C3

Surface Storage Descrip-tion (HDM Figure 819.2A)

Surface Storage Runoff

Coefficient, C4

Pervious Runoff

Coefficient, C

Pervious Tributary

Area (acres)

Impervious Runoff

Coefficient, C

Impervious Tributary

Area (acres)

Frequency Factor, Cf

Basin Weighted

Runoff Coefficient, C

Time of Concen-tration, Tc

(min)

Rainfall Intensity (in/hr)

Total Tributary

Area (acres)

Rational Method Runoff

(cfs)

Bypass or Flow

From Up-stream (cfs)

Total Flow to

Structure (cfs)

Assigned Structure to

Receive Flow

1 MBBT01 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.02 0.95 0.06 1.1 0.87 5 3.97 0.08 0.28 0.00 0.28 MBBT01-B

1 MBBT02 0.00 0.00 0.95 0.07 1.1 1.00 5 3.97 0.07 0.26 0.00 0.26 MBBT03-A

1 MBBT03 0.00 0.00 0.95 0.05 1.1 1.00 5 3.97 0.05 0.19 0.26 0.45 MBBT03-A

1 MBBT04 0.00 0.00 0.95 0.05 1.1 1.00 5 3.97 0.05 0.21 0.06 0.27 MBBT04-A

1 MBBT05 0.00 0.00 0.95 0.12 1.1 1.00 5 3.97 0.12 0.48 0.03 0.51 MBBT05-A

2 MBBT07 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.07 0.95 0.04 1.1 0.65 5 3.97 0.11 0.28 0.00 0.28 MBBT07-A 3 MBBT11 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.10 0.95 0.05 1.1 0.67 5 3.97 0.15 0.40 0.00 0.40 MBBT11-A 3 MBBT12 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.54 0.95 0.20 1.1 0.66 5 3.97 0.75 1.96 0.40 2.36 MBBT11-A 4 MBBT20 Hilly 0.24 Normal 0.07 Good 0.07 Negligible 0.11 0.49 0.11 0.95 0.00 1.1 0.54 5 3.97 0.11 0.23 0.00 0.23 MBBT20-A

4 MBBT21 0.00 0.00 0.95 0.17 1.1 1.00 5 3.97 0.17 0.67 0.23 0.90 MBBT20-A

4 MBBT22 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.08 0.95 0.00 1.1 0.44 5 3.97 0.08 0.15 0.90 1.04 MBBT20-A 4 MBBT23 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.17 0.95 0.06 1.1 0.66 5 3.97 0.23 0.60 1.04 1.65 MBBT20-A

Meeks Bay Bike Trail Project - Proposed 100-year Hydrology Summary

System No.

Tributary Area

ID

Relief Descrip-tion (HDM Figure 819.2A)

Relief Runoff

Coefficient, C1

Soil Infiltration

Descrip-tion (HDM

Figure 819.2A)

Soil Infiltration

Runoff Coefficient, C2

Vegetal Cover

Descrip-tion (HDM

Figure 819.2A)

Vegetal Cover Runoff

Coefficient, C3

Surface Storage Descrip-tion (HDM Figure 819.2A)

Surface Storage Runoff

Coefficient, C4

Pervious Runoff

Coefficient, C

Pervious Tributary

Area (acres)

Impervious Runoff

Coefficient, C

Impervious Tributary

Area (acres)

Frequency Factor, Cf

Basin Weighted

Runoff Coefficient, C

Time of Concen-tration, Tc

(min)

Rainfall Intensity (in/hr)

Total Tributary

Area (acres)

Rational Method Runoff

(cfs)

Bypass or Flow

From Up-stream (cfs)

Total Flow to

Structure (cfs)

Assigned Structure to

Receive Flow

1 MBBT01 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.02 0.95 0.06 1.25 0.99 5 5.99 0.08 0.48 0.00 0.48 MBBT01-B

1 MBBT02 0.00 0.00 0.95 0.07 1.25 1.00 5 5.99 0.07 0.39 0.00 0.39 MBBT03-A

1 MBBT03 0.00 0.00 0.95 0.05 1.25 1.00 5 5.99 0.05 0.29 0.39 0.68 MBBT03-A

1 MBBT04 0.00 0.00 0.95 0.05 1.25 1.00 5 5.99 0.05 0.32 0.03 0.35 MBBT04-A

1 MBBT05 0.00 0.00 0.95 0.12 1.25 1.00 5 5.99 0.12 0.72 0.02 0.74 MBBT05-A

2 MBBT07 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.07 0.95 0.04 1.25 0.74 5 5.99 0.11 0.49 0.00 0.49 MBBT07-A 3 MBBT11 Rolling 0.17 Normal 0.07 Good 0.07 Negligible 0.11 0.42 0.10 0.95 0.05 1.25 0.76 5 5.99 0.15 0.68 0.00 0.68 MBBT11-A 3 MBBT12 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.54 0.95 0.20 1.25 0.75 5 5.99 0.75 3.36 0.68 4.04 MBBT11-A 4 MBBT20 Hilly 0.24 Normal 0.07 Good 0.07 Negligible 0.11 0.49 0.11 0.95 0.00 1.25 0.61 5 5.99 0.11 0.39 0.00 0.39 MBBT20-A

4 MBBT21 0.00 0.00 0.95 0.17 1.25 1.00 5 5.99 0.17 1.00 0.39 1.40 MBBT20-A

4 MBBT22 Rolling 0.17 Normal 0.07 Good 0.07 Low 0.09 0.40 0.08 0.95 0.00 1.25 0.50 5 5.99 0.08 0.25 1.40 1.65 MBBT20-A 4 MBBT23 Hilly 0.24 Normal 0.07 Good 0.07 Low 0.09 0.47 0.17 0.95 0.06 1.25 0.75 5 5.99 0.23 1.04 1.65 2.69 MBBT20-A

Meeks Bay Bike Trail Project - MBBT01

Flow Length L = 44 ft Flow Length L = 44 ft Flow Length L = 56 ft Reach Start Elevation Elev= 6,332.1 ft Reach Start Elevation Elev= 6,328.4 ft Reach Start Elevation Elev= 6,327.5 ft Reach End Elevation Elev= 6,328.4 ft Reach End Elevation Elev= 6,327.5 ft Reach End Elevation Elev= 6,324.5 ft Land Slope So = 0.0832 ft/ft Land Slope So = 0.0198 ft/ft Land Slope So = 0.0544 ft/ft Manning's roughness n = 0.025 Manning's roughness n = 0.04 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.152 Channel side slope (z:1 => H:V) z = 2 Travel Time tt = 0.74 min. Average velocity = (3.28)kSo

0.5 vx = 0.70 ft/s Channel base width b = 0 ft Travel Time tt = 1.04 min. Channel depth y = 0.60 ft

Cross-sectional area A = 0.71 ft2

Wetted Perimiter Pw = 2.67 ft Hydraulic radius Rh = 0.27 ft Velocity vx = 3.60 ft/s Travel Time tt = 0.26 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Time of Concentration = 2 minutes

Reach 1 - Sheet Flow Segment Reach 2 - Shallow Concentrated Flow Segment Reach 3 - Open Channel Flow Segment

= 4.05.0

8.0

)(007.060

SP

nLtt

)3600( x t v

Lt t v

Lt t v

Lt 60 t v t v t v t v

Lt

1/19/2017

Meeks Bay Bike Trail Project - MBBT02

Flow Length L = 76 ft Flow Length L = 30 ft Reach Start Elevation Elev= 6,329.3 ft Reach Start Elevation Elev= 6,323.9 ft Reach End Elevation Elev= 6,323.9 ft Reach End Elevation Elev= 6,322.5 ft Land Slope So = 0.0701 ft/ft Land Slope So = 0.0466 ft/ft Manning's roughness n = 0.017 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.62 Travel Time tt = 0.88 min. Average velocity = (3.28)kSo

0.5 vx = 4.39 ft/s Travel Time tt = 0.12 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Time of Concentration = 1 minutes

Reach 2 - Shallow Concentrated Flow SegmentReach 1 - Sheet Flow Segment

)(007.060

SP

nLtt t v t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT07

Flow Length L = 8 ft Flow Length L = 14 ft Flow Length L = 113 ft Reach Start Elevation Elev= 6,321.2 ft Reach Start Elevation Elev= 6,320.8 ft Reach Start Elevation Elev= 6,320.4 ft Reach End Elevation Elev= 6,320.8 ft Reach End Elevation Elev= 6,320.4 ft Reach End Elevation Elev= 6,319.6 ft Land Slope So = 0.0517 ft/ft Land Slope So = 0.0280 ft/ft Land Slope So = 0.0070 ft/ft Manning's roughness n = 0.025 Manning's roughness n = 0.04 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.62 Channel side slope (z:1 => H:V) z = 6 Travel Time tt = 0.23 min. Average velocity = (3.28)kSo

0.5 vx = 3.40 ft/s Channel base width b = 0 ft Travel Time tt = 0.07 min. Channel depth y = 0.50 ft

Cross-sectional area A = 1.50 ft2

Wetted Perimiter Pw = 6.08 ft Hydraulic radius Rh = 0.25 ft Velocity vx = 1.22 ft/s Travel Time tt = 1.53 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Reach 1 - Sheet Flow Segment Reach 2 - Shallow Concentrated Flow Segment Reach 3 - Open Channel Flow Segment

)(007.060

SP

nLtt t v

Lt t v

Lt t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT11

Flow Length L = 12 ft Flow Length L = 35 ft Reach Start Elevation Elev= 6,310.4 ft Reach Start Elevation Elev= 6,309.6 ft Reach End Elevation Elev= 6,309.6 ft Reach End Elevation Elev= 6,306.9 ft Land Slope So = 0.0658 ft/ft Land Slope So = 0.0789 ft/ft Manning's roughness n = 0.017 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.076 Travel Time tt = 0.21 min. Average velocity = (3.28)kSo

0.5 vx = 0.70 ft/s Travel Time tt = 0.83 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Time of Concentration = 1 minutes

Reach 1 - Sheet Flow Segment Reach 2 - Shallow Concentrated Flow Segment

)(007.060

SP

nLtt t v t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT12

Flow Length L = 30 ft Flow Length L = 42 ft Flow Length L = 394 ft Reach Start Elevation Elev= 6,306.2 ft Reach Start Elevation Elev= 6,304.0 ft Reach Start Elevation Elev= 6,301.3 ft Reach End Elevation Elev= 6,304.0 ft Reach End Elevation Elev= 6,301.3 ft Reach End Elevation Elev= 6,282.7 ft Land Slope So = 0.0750 ft/ft Land Slope So = 0.0635 ft/ft Land Slope So = 0.0472 ft/ft Manning's roughness n = 0.040 Manning's roughness n = 0.04 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.62 Channel side slope (z:1 => H:V) z = 6 Travel Time tt = 0.81 min. Average velocity = (3.28)kSo

0.5 vx = 5.12 ft/s Channel base width b = 0 ft Travel Time tt = 0.14 min. Channel depth y = 0.50 ft

Cross-sectional area A = 1.50 ft2

Wetted Perimiter Pw = 6.08 ft Hydraulic radius Rh = 0.25 ft Velocity vx = 3.17 ft/s Travel Time tt = 2.07 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Time of Concentration = 3 minutes

Reach 1 - Sheet Flow Segment Reach 2 - Shallow Concentrated Flow Segment Reach 3 - Open Channel Flow Segment

)(007.060

SP

nLtt t v

Lt t v

Lt t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT20

Flow Length L = 75 ft Flow Length L = 71 ft Reach Start Elevation Elev= 6,272.2 ft Reach Start Elevation Elev= 6,252.5 ft Reach End Elevation Elev= 6,252.5 ft Reach End Elevation Elev= 6,247.8 ft Land Slope So = 0.2624 ft/ft Land Slope So = 0.0670 ft/ft Manning's roughness n = 0.040 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.076 Travel Time tt = 1.02 min. Average velocity = (3.28)kSo

0.5 vx = 0.65 ft/s Travel Time tt = 1.83 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

)(007.060

SP

nLtt t v t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT21

Flow Length L = 49 ft Flow Length L = 158 ft Reach Start Elevation Elev= 6,278.6 ft Reach Start Elevation Elev= 6,275.1 ft Reach End Elevation Elev= 6,275.1 ft Reach End Elevation Elev= 6,264.8 ft Land Slope So = 0.0735 ft/ft Land Slope So = 0.0651 ft/ft Manning's roughness n = 0.017 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.152 Travel Time tt = 0.61 min. Average velocity = (3.28)kSo

0.5 vx = 1.27 ft/s Travel Time tt = 2.06 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

)(007.060

SP

nLtt t v t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT22

Flow Length L = 100 ft Flow Length L = 254 ft Reach Start Elevation Elev= 6,288.3 ft Reach Start Elevation Elev= 6,281.3 ft Reach End Elevation Elev= 6,281.3 ft Reach End Elevation Elev= 6,264.8 ft Land Slope So = 0.0702 ft/ft Land Slope So = 0.0648 ft/ft Manning's roughness n = 0.020 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.152 Travel Time tt = 1.25 min. Average velocity = (3.28)kSo

0.5 vx = 1.27 ft/s Travel Time tt = 3.34 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Time of Concentration = 5 minutes

)(007.060

SP

nLtt t v t v t v t v t v t v

Meeks Bay Bike Trail Project - MBBT23

Flow Length L = 55 ft Flow Length L = 95 ft Flow Length L = 62 ft Reach Start Elevation Elev= 6,265.8 ft Reach Start Elevation Elev= 6,262.0 ft Reach Start Elevation Elev= 6,244.7 ft Reach End Elevation Elev= 6,262.0 ft Reach End Elevation Elev= 6,244.7 ft Reach End Elevation Elev= 6,242.9 ft Land Slope So = 0.0691 ft/ft Land Slope So = 0.1822 ft/ft Land Slope So = 0.0294 ft/ft Manning's roughness n = 0.017 Manning's roughness n = 0.04 2-yr, 24-hr rainfall depth P = 2.87 in. Intercept Coefficient k = 0.076 Channel side slope (z:1 => H:V) z = 2 Travel Time tt = 0.68 min. Average velocity = (3.28)kSo

0.5 vx = 1.06 ft/s Channel base width b = 0 ft Travel Time tt = 1.49 min. Channel depth y = 1.00 ft

Cross-sectional area A = 2.00 ft2

Wetted Perimiter Pw = 4.47 ft Hydraulic radius Rh = 0.45 ft Velocity vx = 3.73 ft/s Travel Time tt = 0.28 min.

k = 0.62 for pavement k = 0.152 = bare ground k = 0.076 = forest

Reach 1 - Sheet Flow Segment Reach 2 - Shallow Concentrated Flow Segment Reach 3 - Open Channel Flow Segment

)(007.060

SP

nLtt t v

Lt t v

Lt t v t v t v t v t v

Appendix C Hydraulics

Meeks Bay Bike Trail Project - Proposed 25-year Pipe Summary

System No. Pipe ID

Pipe Size (in)

Slope

Pipe Roughness

Total Flow (cfs)

Velocity (ft/s)

Entrance

HGL

(ft)

Exit HGL (ft)

Rim Elevation

(ft)

1 MBBT01-C 18 5.50 0.013 0.25 4.50 6321.41 6315.36 6325.20

1 MBBT03-B 18 5.99 0.013 0.69 6.24 6315.31 6311.15 6319.24

1 MBBT04-B 18 5.35 0.013 0.89 6.52 6311.07 6309.40 6314.97

1 MBBT05-B 18 0.51 0.013 1.35 0.76 6309.40 6309.25 6311.29

Truckee River Project - Proposed 25-year Hydraulic Summary

System No. Structure ID Structure Location Grate Type

Surface Longitu-dinal Slope

Surface Cross Slope

Left Ditch Side

Slope

Right Ditch Side

Slope

Manning's Roughness Coefficient

(HEC-22,

Table 4-3)

Catch Basin Grate

Length (ft)

Catch Basin Grate Width

(ft)

Curb Opening

Width (ft)

Curb & Gutter Cross Slope

Gutter Width

(ft)

Clogging Percent-age

Allow-able

Spread (ft)

Calc-ulated Spread

(ft)

Allowable Depth

(in)

Flow depth

(in)

Bypass To

Down-stream

(cfs)

Bypass To Location

1 MBBT01-B Ditch Sag 36R NA NA 50.00 50.00 NA 2.00 2.00 NA NA NA 50 NA NA 6 3 NA NA

1 MBBT03-A On Grade 24-12X 5.53 11.21 NA NA 0.017 3.00 2.00 NA 11.21 3.00 50 4 1.4 6 2 0.06 MBBT04-A 1 MBBT04-A On Grade 24-12X 6.70 13.33 NA NA 0.017 3.00 2.00 NA 13.33 3.00 50 4 1.0 6 2 0.03 MBBT05-A 1 MBBT05-A Roadside Sag 24-12X NA 8.72 NA NA 0.017 6.00 2.00 NA 8.72 3.00 50 4 2.6 6 3 NA NA 2 MBBT07-A Ditch Sag 36R NA NA 16.67 50.00 0.040 2.00 2.00 NA NA NA 50 NA NA 6 3 NA NA

Meeks Bay Bike Trail Project - Proposed Ditch Summary 25-year Storm

Description Design Point Station Discharge (cfs)

Surface Longitu-dinal Slope

Left Side

Slope

Right Side

Slope

Bottom Width

(ft)

Manning's Roughness Coefficient

Ditch Depth

(ft)

Normal Depth

(ft)

Velocity (ft/s)

Northern Right Trailside Ditch 41+12 0.28 5.44 50 50 0 0.040 0.67 0.26 2.07

Right Trailside Ditch 33+80 0.28 0.70 17 50 0 0.040 0.50 0.29 0.84

Trailside "S" Ditch 19+85 2.36 4.72 17 17 0 0.040 0.50 0.38 2.66

Southern Left Trailside Ditch 8+20 1.65 2.94 50 50 0 0.040 1.25 0.57 2.56

CH2MHILL Ditch Summary Calculations.xlsx 1/19/2017

Appendix D Stormwater Quality

TR 5/25/2017 1 of 1 03\2A940\Design\Sand Trap\MeeksBay_Sand_Vault_Storage English units

TRACTION SAND TRAP SIZING 4-ED-89, PM 25.4/25.7

EA 03-3F6201

Volume = Total volume of traction sand that must be stored (ft3) = (SxRxLxE)/F

S = Estimated volume of sand applied (ft3) Var R = A reduction factor to account for sand recovered by roadway sweeping 0.6

Use 0.6<R<1.0 L = A factor to account for other miscellaneous losses/accumulations 0.8

Use 0.8<L<1.0 (0.8 used to account for unrecoverable (blown) snow) E = 1 F = Number of times trap will be cleaned per season 1

Vault Station

Post Mile

Dir of Flow

Sanded Length

Applied Rate

Grade K1 K2 K3 K4

Ktot

(4.0 max)

Sand Applied

S

Reduction Factor

Sand Collected

10-Yr Flow

WQV

(Impervious Area X 1")

Use L= 8ft Min in 4ft

Increments Notes ln-ft ft3/ft % ft3 R*L*E/F ft3 ft3/s ft3 W D Radius Lmin ft 32+50 Crest v 134 0.194 0.50 0.5 1.0 1.0 0.5 0.3 7 0.48 3.1 0.2 145

33+84 1.5 0.6 Use TST Pipe Inlet - 36" CSP inlet with 2.5' sump, storage volume =17.7 cubic feet.

38+43 Crest v 0 0.194 0.50 0.5 1.0 1.0 0.5 0.3 0 0.48 0.0 0.0 0

38+43 1.5 0.0 Use TST Pipe Inlet - 36" CSP inlet with 3.0' sump, storage volume =21.2 cubic feet.

37+80 Crest v 160 0.194 0.50 0.5 1.0 1.0 0.5 0.3 8 0.48 3.7 0.2 218

38+60 2 2.5 1.0 Use TST Inlet - CIP Type with G1 inlet with 2.5' sump.

G1 dimensions = 2.00' x 2.94'. 2.94' > 1.0' from calculation.

39+30 Crest v 132 0.194 0.50 0.5 1.0 1.0 0.5 0.3 6 0.48 3.1 0.2 218

38+64 2 2.5 0.8 Use TST Inlet - CIP Type with G1 inlet with 2.5' sump.

G1 dimensions = 2.00' x 2.94'. 2.94' > 0.8' from calculation.

40+00 Crest v 140 0.194 5.00 1.5 1.0 1.0 0.5 0.8 20 0.48 9.8 0.2 182

39+30 2 2.5 2.5 Use TST Inlet - CIP Type with G1 inlet with 2.5' sump.

G1 dimensions = 2.00' x 2.94'. 2.94' > 2.5' from calculation.

41+10 Crest v 110 0.194 5.00 1.5 1.0 1.0 0.5 0.8 16 0.48 7.7 0.3 436

40+00 2 2.5 2.0 Use TST Inlet - CIP Type with G1 inlet with 2.5' sump.

G1 dimensions = 2.00' x 2.94'. 2.94' > 2.0' from calculation.

42+10 Crest v 100 0.194 5.00 1.5 1.0 1.0 0.5 0.8 15 0.48 7.0 0.2 218

41+10 1.5 1.3 Use TST Pipe Inlet - 36" CSP inlet with 3.0' sump, storage volume =21.2 cubic feet.

Total 72

Application Rate (provided by John Schnoor, Caltrans Tahoe City) = 1,500 tons of sand per year for 12.2 centerline miles of Hwy Placer 89) =

1500 ton 2000# ft3 ln-mi

24.4 ln-mi ton 120# 5280ft

K1 = Factor for Grade: K2 = Snow Shadow Effect: K3 = Shade/Curve Effect: K4 = Other Factors:

K1 = 0.5 for 0% - 2% K1 =1.5 for 5% K2 = 1.3 for PM 0.8 to 4.0 K3 = 1.5 for Curves in Shade Offsite Sand Contribution: Erodible Slope or Sanded Public Road Connections or

K1 = 0.75 for 3% K1 = 2.0 for 6% K2 = 1.0 for PM 4.0 to 7.6 K3 = 0.8 for Tangents in Sun

K1 = 1.0 for 4% K1 = 3.0 for 7% K2 = 0.7 for PM 7.6 to 11.0 K3 = 1.0 for Other Sections

Sand Applied (S) = Sanded Length x Application Rate x Ktot Sand Collected = S x R x L x E / F

Note: For "Single" locations, consider Pipe Inlet Sand Trap first.

= 0.19

Estimated recovery efficiency (Use E = 1.0 ) ft3 sand ft road

Sections with cut slopes (K>1.0) or fill slopes (K<1.0) on both sides (Use K4 = 0.5 for 1 lane each direction, both sides in fill)

"L" includes 30% Safety Factor

D = depth of sand or water, not depth of Vault. Vault floor elev. = pipe flowline elev. - 6 in (or vault roof elev - 12 in) - D.

Sand Vault Storage Dimensions ft

X X X

Appendix E References

HIGHWAY DESIGN MANUAL 810-19

July 1, 2015

Figure 819.2A

Runoff Coefficients for Undeveloped Areas Watershed Types

Extreme High Normal Low

Relief .28 -.35

Steep, rugged terrain with average slopes above 30%

.20 -.28

Hilly, with average slopes of 10 to 30%

.14 -.20

Rolling, with average slopes of 5 to 10%

.08 -.14

Relatively flat land, with average slopes of 0 to 5%

Soil Infiltration

.12 -.16

No effective soil cover, either rock or thin soil mantle of negligible infiltration capacity

.08 -.12

Slow to take up water, clay or shallow loam soils of low infiltration capacity, imperfectly or poorly drained

.06 -.08

Normal; well drained light or medium textured soils, sandy loams, silt and silt loams

.04 -.06

High; deep sand or other soil that takes up water readily, very light well drained soils

Vegetal Cover

.12 -.16

No effective plant cover, bare or very sparse cover

.08 -.12

Poor to fair; clean cultivation crops, or poor natural cover, less than 20% of drainage area over good cover

.06 -.08

Fair to good;

about 50% of area in good grassland or woodland, not more than 50% of area in cultivated crops

.04 -.06

Good to excellent;

about 90% of drainage area in good grassland, woodland or equivalent cover

Surface Storage

.10 -.12

Negligible surface depression few and shallow;

drainageways steep and small, no marshes

.08 -.10

Low; well defined system of small drainageways; no ponds or marshes

.06…