Attachment 11 - Hydraulics Memo.pdf

From: Hiciano, Wendy (FHWA) To: Kirtley, Yanina (FHWA); Santaliz, Francisco (FHWA) Cc: Wright, Rachel (FHWA); Dorose, Basha (FHWA); Lyons, Canisha (FHWA); Colon-Torres, Enid (FHWA) Subject: RE: MD NP CHOH 235(2), 242(1), etc. Items needed from hydraulics Date: Friday, August 16, 2024 11:46:26 AM Attachments: OUTLET CHANNEL WITH CULVERT AND BERM PLAN-Design SurvFt.pdf

Good morning Team, I have completed adding the additional modifications for the proposed culvert and currently working on updating the final memo, but in the meantime, please see a summary of the changes below:

Pipe Length: The calculations were revised and updated in the HY-8 software to determine the changes implicated by increasing the length of the pipe. The pipe length was updated from 23 lnft to 34 lnft. This new proposed length allows for the top of the driving surface to accommodate a vehicle and provides additional space for pedestrian and cyclist safety with a slope of 4:1 (H:V). The recommended 4:1 (H:V) slope will not require pedestrian safety rails, based on the information provided and confirmed with Safety. The driving surface proposed is a width of 12 ft, which is more than the required 8ft minimum.

Pipe Material: The initial proposed pipe was evaluated for Reinforced Concrete Pipe (RCP) material. The analysis was updated to reflect changes from RCP material to the preferred High-Density Polyethylene (HDPE) material by the National Park Service.

Pipe Alignment: The pipe alignment was modified to provide minimal skew between the pipe and the headwall.

I have attached the modified layout of the pipe to represent the changes made and I am including Enid in this email, in case there are any additional changes required for pedestrian and cyclists safety.

Basha – even though I confirmed the elevations and stations with you, please let me know if I missed any other information.

Please let me know if you have any questions or additional suggestions.

Thank you, Wendy Hiciano Hydraulic Engineer Team Leader Eastern Federal Lands Highway Division 22001 Loudoun County Parkway Building E-2, Suite 200 Ashburn, Virginia 20147

Phone: 703-404-6218 Mobile: 787-503-3986 Email: wendy.hiciano@dot.gov

From: Kirtley, Yanina (FHWA) <Yanina.Kirtley@dot.gov> Sent: Tuesday, August 6, 2024 1:19 PM mailto:wendy.hiciano@dot.gov mailto:Yanina.Kirtley@dot.gov mailto:francisco.santaliz@dot.gov mailto:rachel.wright@dot.gov mailto:basha.dorose@dot.gov mailto:canisha.lyons@dot.gov mailto:enid.colon-torres@dot.gov mailto:wendy.hiciano@dot.gov

359.80'

INV

359.34'

INV

34.0 LF @ 1.3%

60" CL. 3 HDPE

(MD 354.01)

TYPE C HEADWALL

12'

GRADE

PROPOSED

TOP ELEV = 369.20'

CULVERT PROFILE

Q 50-YR (DESIGN) = 142.4 CFS

EXISTING GROUND

POTOMAC RIVER

S T

A

.1

.2

HEADWALL UPSTREAM ELEVATION

MD CLASS II

W/ FILTER FABRIC

CL 3 RIPRA 24" THICK FP-14

HDPE

60" Ø

2'

STA 3+15.12

HEADWALL DOWNSTREAM ELEVATION

CL 3 RIPRA 24" THICK (FP-14)

HDPE

60" Ø

2'

STA 3+49.21

50-YR WSE = 365.47'

100-YR WSE = 366.80'

C L

.6

50-YR OUTLET V = 9.95 FPS

50-YR TAILWATER V = 5.76 FPS

50-YR OUTLET/TAILWATER WSE = 362.76'

CL 3 RIPRAP 24" THICK (FP-14)

CL 3 RIPRAP 24" THICK (FP-14)

N.T.S.

Page 1 of 7 EFL-FM-HWY-04(01)

U.S. Department Of Transportation Federal Highway Administration

Subject: Design Final Technical Memorandum Project CHOH 235(2) 242(1) ETC Engineered Channel at Four Locks Boat Ramp Access (Starliper Road)

Date: April 10, 2024

From: Wendy Hiciano Hydraulics Team Leader

Reply to Attn of:

HFPM-15

To: Libby O’Brien, Highway Design Branch Chief Scott Whittemore, Technical Services Branch Chief

BACKGROUND

General Site and Drainage Pattern Description Starliper Road provides access to the Four Locks boat ramp, crossing under the C&O Canal Towpath thru an historic 112-foot long, 12-foot span x 10-foot rise arch shaped tunnel from Four Locks Road to the Four Locks boat ramp and parking lot on the Potomac River. The tunnel is located approximately 2.0 river miles upstream of Dam 5 in Washington County, MD at the historic community of Four Locks, between Lock 48 and 49. Both tunnel portals are terminated with stone masonry unit (SMU) headwalls with wingwalls. The northwest (upstream) tunnel portal receives approximately 262.4 acres of offsite drainage area covered primarily by a mixture of pasture and woods, and localized pavement drainage from Starliper Road. The drainage enters the tunnel via a natural swale on the right-hand side (looking downstream) of the tunnel portal where it conveys along and across a deteriorated concrete floor surface to the left-hand side of the southeast (downstream) tunnel portal. The downstream tunnel portal is in a sump configuration for the entire contributing drainage area. The head of the outfall channel functions as a shallow saddle point within the sump that allows it to drain to the Potomac River.

Tunnel Floor Deficiencies The longitudinal tunnel floor profile is very flat, with only about 0.8 feet of drop over its 112-foot length, from a floor elevation of 364.5 at the upstream portal to an elevation of 363.7 at the downstream portal. The deteriorated tunnel floor, coupled with the flat longitudinal slope results in ponding water within the tunnel proper. The poorly drained conditions contribute to deterioration of the tunnel floor, excessive sedimentation, driver discomfort from mud splash and spray, and potential unsafe conditions when ponded water freezes.

Channel and Apron Deficiencies When the runoff depression storage on the tunnel floor fills up, runoff exits the tunnel onto a deteriorated concrete apron adjacent to the head of an existing outfall channel where excessive sediment has accumulated, effectively blocking the flow from entering the outfall channel, resulting in excessive ponding on the concrete apron and Starliper Road pavement surface. Grassy vegetation has taken root on the accumulated sediment between the left wingwall and edge of the concrete apron, further impeding positive drainage. The outfall channel is approximately 400 feet long that conveys flow through four (4) horizontal bends to the Potomac River, with one (1) of the bends having a severely short radius of approximately 34 feet. There is only about

4.4 feet of available drop over the length of the channel, from 363.4 at the head of the channel between the left wingwall and concrete apron at the southeast tunnel portal, to the channel outlet at elevation 359.0 near the

Memorandum surveyed ordinary high water (OHM) elevation of the Potomac River. The channel has a discontinuous and varied profile and cross section due to vegetative overgrowth, sedimentation, and moderately scour damaged bottom and side slopes, resulting in poor hydraulic performance in maintaining positive drainage. There is a treated wood pedestrian (PED) bridge supported on pier post foundations that spans the channel approximately 75 feet upstream of the channel outfall. The PED bridge provides access from the Four Locks boat ramp parking lot to a grassy picnic area on the north side of the channel. The PED bridge appears to be pinned to, and supported by sloped 8x posts, presumably bearing on formed concrete piers, and appears to have 4x stringers connected to 4x floor beams, pinned to the top of the posts, with 2x decking.

Work Description and Primary Project Elements Project work includes improvements to address the surface water drainage deficiencies at the tunnel, concrete apron at the downstream tunnel portal, and the outfall channel.

DESIGN CRITERIA, APPROACH AND METHODOLOGY

Criteria Design criteria was based on PDDM Chapter 7 for channels (10-Year design return period) and sump culverts (50-year design return period). HW/D ratios for 48 inches and smaller diameters or span pipes were limited to 1.5, and 1.2 for diameters or spans larger than 48 inches.

Approach and Methodology Hydrology was based on USGS StreamStats (Appendix 1). The contributing drainage area (DA) straddles 2 hydrologic regions with vastly different runoff potential: the Piedmont/Blueridge Rural and the Appalachian Plateau. The hydrology was weighted by area proportion as outlined in “Application of Hydrologic Methods in Maryland”, 3rd Edition, PDF page 38, September 2010 by MD SHA, and resulting in the following discharges:

HYDROLOGIC REGION DISCHARGES

RETURN

PERIOD

(YR)

PIEDMONT /

BLUERIDGE

RURAL

DISCHARGE (CFS)

APPALACHIAN

PLATEAU

DISCHARGE (CFS)

AREA

WEIGHTED

DISCHARGE

(CFS)

2 28.5 22.1 24.3 10 100.0 50.9 67.9 25 170.0 70.7 105.0 50 245.0 88.2 142.4 100 345.0 109.0 190.5

FHWA Hydraulic Toolbox ™ Ver 5.2.0.0 was used to evaluate the proposed outfall channel between Sta 0+00 to 4+00. The proposed lined trapezoidal prismatic channel with a 1.0% grade will replace the existing vegetatively overgrown, sediment filled and scour damaged, non-uniform channel. The proposed channel section was evaluated to balance stability with self-cleaning velocity, resulting in a 2-foot wide bottom with 2:1 (H:V) side slopes. A variety of adequate channel bottom widths and lining combinations were evaluated and quantified and are provided in the Channel Analysis Summary Worksheet and Channel Lining Quantities Summary Worksheet in Appendix 2, with supporting Hydraulic Toolbox channel and lining analysis computations provided in Appendix 3.

Pipe hydraulic evaluation was performed with FHWA HY-8 ® Ver. 7.80.0.2 (Appendix 3).

ANALYSIS AND DESIGN WITH RECOMMENDATIONS

Tunnel Floor Hydraulics staff recommends reconstructing or resurfacing the deteriorated tunnel floor to provide a smooth continuous concrete surface that will restore positive drainage thru the tunnel to the concrete apron at the downstream tunnel portal. An inverted crown floor cross section is recommended, which will convey drainage down the centerline of the tunnel floor, away from vehicle wheel paths to reduce driver discomfort.

Should an inverted crown not be preferred, it is still highly recommended that the tunnel floor be reconstructed or resurfaced to match the current drainage pattern as previously described, albeit more efficiently and without ponding.

During the Plan-In-Hands (PIH) field site meeting inverted crown was determined to not be feasible for the site and NPS and EFLHD personnel determined the best option to move forward is to reconstruct the tunnel floor with a 3% cross slope and installing a new culvert concrete curb to convey drainage to the proposed outlet channel.

Concrete Aprons The concrete aprons at both portals will have to be reconstructed to provide a transition from and to the normal existing pavement section point of tie-in, to the proposed tunnel floor inverted crown section. There is limited available drop along the tunnel floor, but a 1.0% longitudinal slope may be feasible with proper grading configuration of the portal concrete aprons and precision construction stakeout.

The current proposed grading of the downstream tunnel portal concrete apron ties-into the existing tunnel floor slab, which will have to be modified to match a tunnel floor inverted crown section should that approach move forward.

Extension of Concrete Aprons Hydraulics also recommends that both concrete aprons be reconfigured to extend to the tips of the SMU wingwalls and graded to properly drain all corners of wingwall’s base. An added benefit is this will eliminate the small grassy areas between the wingwalls and the pavement which act like a debris and sediment trap and will not have to be mowed. A continuous concrete apron between the wingwalls will also improve the appearance and provide maintenance crews a hardened surface to “shovel down to” for sediment removal.

Concrete Apron Dimensional Constraints Proper configuration and grading of the concrete apron is critical in conveying drainage from the tunnel floor to the head of the outfall channel, as previously described. Drainage will continue to pond between the left wingwall and edge of pavement of Starliper road if a smooth concrete surface and proper grade transitions are not provided between the tunnel floor and the head of the outfall channel. The available space to increase vertical relief for positive drainage entry into the head of the outfall channel from the concrete apron is restricted due to the left SMW wingwall and existing edge of pavement of Starliper Road. A smooth, accurately graded concrete apron will partially mitigate for the lack of available space for channel grading and increasing vertical relief.

Concrete Apron Matching Existing Tunnel Floor Hydraulics has provided a grading plan for the concrete apron at the downstream tunnel portal to facilitate conveyance of floor tunnel drainage into the head of the proposed outfall channel. The plan ties into the existing tunnel floor grades and provides for a concrete lined broad transverse swale that drains all corners of the wingwalls and collects tunnel floor drainage and turns it into the head of the outfall channel. The concrete apron is extended about 8.5 feet into the head of the outfall channel to facilitate higher speed, shallower flows where because of the dimensional grading pinch point between the left wingwall and Starliper Road edge of pavement, the channel has not yet reached its proposed full capacity depth of 3 feet.

Concrete Apron Matching Tunnel Floor Inverted Crown As mentioned previously, if an inverted crown section is provided for the tunnel floor, the concrete apron grading must be modified to match the inverted crown. An additional grading plan for the upstream portal concrete apron must be generated as described earlier. Final grading of both concrete aprons should be checked by HD for vehicle tunnel headroom clearances and bumper dragging and should account for boat trailering.

Outfall Channel Proposed Section Hydraulics recommends a trapezoidal channel section with a 2-foot bottom width, 2:1 side slopes at a 1.0% longitudinal slope. The relatively narrow channel bottom will help maintain self-scouring velocities and thus reduce sedimentation while maintaining channel stability with proper lining types and will minimize the disturbed area. Other channel width and lining type combinations were evaluated, but given the presence of bends in the channel, lining types were relatively insensitive to bottom widths at the bends, so increasing the channel bottom width had limited impact in reducing lining requirements and associated cost.

Outfall Channel Soils Underlying channel soils, and classification as non-cohesive or cohesive soil types has an impact on the lining types to resist shear stress and subsequent scour. Given the location of the channel within the Potomac River floodplain, Hydraulics was inclined to assume silty/sandy cohesionless soils. However further soils investigation using NRCS Web Soil Survey indicates Bigpool silt loam (Bp soil symbol) predominates the project’s outfall channel location, with a CL Unified textural classification. At average anticipated channel excavation depths of 24-48 inches, the Soil Survey indicates a plasticity index (PI) of 14.1 and a void ratio e of

0.50. These parameters fall within the bounds of a cohesive soil, thus the original soil type assumption was changed to cohesive soils with the aforementioned physical properties, and the channel lining analysis was refined.

Outfall Channel Straight Segments The lining evaluation for the straight segments of the outfall channel indicate mixed grass turf in “good” condition with a minimum mowing height of 4 inches is sufficient for a stable channel. Turf-type linings can provide adequate shear resistance if certain turf quality parameters are met. Those qualities can be difficult to meet due to the variability and difficulty of controlling the amount of shade and sunlight, soil content, properties and amendments for the establishment turf, moisture content and rainfall, turf maintenance and mowing practices, frequency of inundation from the Potomac River, and maintenance clearing of understory brush and vegetation. The following turf establishment and maintenance requirements should be met to provide adequate channel scour protection:

1. Establishment of “good” or better turf type quality through tight contract document controls that hold contractor responsible (thru retainage) for establishment of a durable turf type lining for the anticipated amount of shade, soil characteristics and rainfall.

2. This will require detailed specs on the seed mix, soil testing and proper addition of amendments, broadcast method and temporary RECP, watering during droughts/dry season, tree, brush, and vegetation clearing requirements to establish proper sunlight, fertilizer requirements, etc.

3. The turf must also be perpetually maintained no shorter than 4 inches high and maintained in good or better condition.

4. Temporary vegetative stabilization measures require "Wildlife" friendly RECP with Min 2.0 lb/sf shear resistance per ASTM D6460.

Outfall Channel Bends There are four (4) horizontal bends in the channel that required additional scour evaluation due to increased scour from the associated momentum change. The lining evaluation for the channel bend segments require riprap lining of various size, from Class 1 (D50 = 6 inch) to Class 2 (D50 = 9 inch). The riprap lining class, location, and quantities are shown on the applicable worksheets in Appendix 2. It should be noted that Hydraulic Toolbox indicated a riprap lining was required on the 200-foot radius bend at the upstream end of the channel from Sta 0+24.19 to 0+50.10. Given the combination of a longer radius and shorter arc length of the bend, Hydraulics believes Hydraulic Toolbox is overestimating the need for a riprap liner, thus only turf grass is proposed at this bend.

Outfall Channel Self-Cleaning Velocity As mentioned previously, self-cleaning velocities for the 2-year discharge were checked as shown in Appendix 2’s Channel Analysis Summary Worksheet. A 2-year minimum velocity was checked to meet a minimum target of 2.5 fps. This target was not met at two (2) of the three (3) remaining bend locations where riprap is needed to meet channel scour shear stability requirements. The increased roughness associated with the riprap resulted in slower velocities at the two (2) bends. However, channel stability was chosen as the more critical parameter to maintain in the channel design, and the slower velocities in the two (2) bends was viewed as an acceptable design compromise.

PED Bridge Impacts and Modifications Due to the amount of excavation to construct the new outfall channel, and the potential of the excavation exposing the PED bridge pier post foundation, the PED bridge may need to be removed from the pier post foundation, set aside temporarily so the pier post foundation can be reconstructed to proper depths relative to proposed grades. The PED bridge could then be reset onto the reconstructed foundation.

PED Bridge Alternative As an alternative to the modifications to the PED bridge, Hydraulic staff suggested an alternative channel modification to replace the PED bridge with an embankment crossing over the channel, with an integral 60-inch RCP culvert to convey tunnel flows thru the embankment. Consequently, an alternative modified plan showing the embankment grading and the culvert were generated for consideration by NPS. In addition to pedestrian access, the embankment will provide maintenance vehicle access from the Four Locks boat ramp parking lot and access road to the grassy picnic area on the north side of the channel. The plan shows a level embankment top for simplicity, with additional fill placement at the north embankment approach at the grassy picnic area to provide a maximum 10% approach grade. The embankment top could be modified to provide a uniform grade to lessen the north approach grade should the embankment approach be moved forward to final design. Spoil material from excavation of the proposed outfall channel will need to be tested for suitability for constructing the embankment. Although RCP is preferred for its durability, resistance to buoyant uplift and drag forces, hoop strength during backfill placement and compactive effort, and lesser reliance on backfill material envelope qualities, other pipe materials such as HDPE is acceptable, with concurrence from EFL Construction and NPS staff.

The pedestrian bridge alternative was the selected alternative. It is recommended to replace the existing pedestrian bridge with a 60-inch HDPE.

Pipe Diversion Alternative (found not feasible) Ideally, drainage entering the tunnel at the upstream (northwest) portal should be diverted thru and under the tunnel to prevent the previously described ponding issues on the tunnel floor and at the downstream tunnel portal concrete apron. This could be accomplished with a storm drain system composed of an upstream collection structure (headwall or inlet) to intercept both the offsite and localized pavement drainage, and pipe it under the tunnel floor to a convenient daylight somewhere along the outfall channel. This alternative was evaluated early on in the design process and found not to be feasible due to the limited available drop thru the project reach given the required pipe size and cover depth requirements. Consequently, the only feasible approach is to improve the surface conveyance of drainage thru the tunnel to the outfall channel, and on to the Potomac River outfall as proposed herein.

River Sedimentation Problem Potomac River sourced sedimentation during the recessionary limb of the longer lagged Potomac River hydrograph after the shorter lagged contributing drainage area hydrograph flows approach zero will always be problematic regarding outfall channel sedimentation and keeping it clean.

Summary of Recommendations and Selected Alternatives:

The following is a summary of all changes made and alternatives selected during the PIH meeting, on March 4, 2024.

• Tunnel Floor: Reconstruct tunnel floor with a 3% cross slope and install concrete curb.

• Pedestrian Bridge: It is recommended to replace the existing pedestrian bridge with a 60-inch HDPE.

• Outfall Channel Bends: Install riprap lining Class 3 (D50 = 12 inch. MD Riprap Class 2 equivalent).

Approved:

Libby O’Brien, Highway Design Branch Chief _____________________

Scott Whittemore, Technical Services Branch Chief ______________________

APPENDICES

• APPENDIX 1 - USGS Stream Stats Analysis Output

• APPENDIX 2 - Channel Analysis Summary and Channel Lining Quantities Summary Worksheets

• APPENDIX 3 – Hydraulic Computation Output o FHWA Hydraulic Toolbox ™ Output (Channel Analysis) o FHWA HY-8 ™ Output

• APPENDIX 4 – Outfall Channel Plan

• APPENDIX 5 – Outfall Channel with Culvert and Embankment in Lieu of PED Bridge Plan

• APPENDIX 6 – Culvert at Embankment Profile and Elevations

• APPENDIX 7 –Field Photos

APPENDIX 1 – USGS Stream Stats Analysis Output

StreamStats Report

Collapse All

Basin Characteristics

Parameter Code Parameter Description Value Unit

BSLDEM10ff Mean basin slope computed from 10 m DEM in feet per foot 0.0746 foot per foot

DRNAREA Area that drains to a point on a stream 0.41 square miles

FOREST Percentage of area covered by forest 55.3 percent

FOREST_MD Percent forest from Maryland 2010 land-use data 66.7 percent

IMPERV Percentage of impervious area 0.92 percent

LC11DEV Percentage of developed (urban) land from NLCD 2011 classes 21-24 1.88 percent

LC11IMP Average percentage of impervious area determined from NLCD 2011 impervious dataset

0.0683 percent

LIME Percentage of area of limestone geology 99.9 percent

PRECIP Mean Annual Precipitation 40.4 inches

SOILCorD Percentage of area of Hydrologic Soil Type C or D from SSURGO 23.8 percent

SSURGOA Percentage of area of Hydrologic Soil Type A from SSURGO 0 percent

STATSGOA Percentage of area of Hydrologic Soil Type A from STATSGO 0 percent

STATSGOD Percentage of area of Hydrologic Soil Type D from STATSGO 0 percent

Region ID: MD Workspace ID: MD20230824183441915000 Clicked Point (Latitude, Longitude): 39.61653, -77.94776 Time: 2023-08-24 14:35:16 -0400

Peak-Flow Statistics

Peak-Flow Statistics Parameters [34.5 Percent (0.142 square miles) Peak Piedmont and BlueRidge Rural 2010

AHMMD]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.41 square miles 0.11 820

LIME Percent Limestone 99.9 percent 0 81.7

FOREST_MD Percent forest from MD 2010 land use 66.7 percent 2.7 100

Peak-Flow Statistics Parameters [65.5 Percent (0.269 square miles) Peak Appalachian Plateau 2010 AHMMD]

Parameter Code Parameter Name Value Units Min Limit Max Limit

DRNAREA Drainage Area 0.41 square miles 0.52 293.7

BSLDEM10ff Mean Basin Slope from 10m DEM ft per ft 0.0746 foot per foot 0.06632 0.22653

Peak-Flow Statistics Disclaimers [34.5 Percent (0.142 square miles) Peak Piedmont and BlueRidge Rural 2010

AHMMD]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors.

Peak-Flow Statistics Flow Report [34.5 Percent (0.142 square miles) Peak Piedmont and BlueRidge Rural 2010

AHMMD]

Statistic Value Unit

80-percent AEP flood 14.3 ft^3/s

66.7-percent AEP flood 21.1 ft^3/s

50-percent AEP flood 28.5 ft^3/s

20-percent AEP flood 63 ft^3/s

10-percent AEP flood 100 ft^3/s

4-percent AEP flood 170 ft^3/s

2-percent AEP flood 245 ft^3/s

1-percent AEP flood 345 ft^3/s

0.5-percent AEP flood 477 ft^3/s

0.2-percent AEP flood 717 ft^3/s

Peak-Flow Statistics Disclaimers [65.5 Percent (0.269 square miles) Peak Appalachian Plateau 2010 AHMMD]

One or more of the parameters is outside the suggested range. Estimates were extrapolated with unknown errors.

Peak-Flow Statistics Flow Report [65.5 Percent (0.269 square miles) Peak Appalachian Plateau 2010 AHMMD]

Statistic Value Unit

80-percent AEP flood 14.3 ft^3/s

66.7-percent AEP flood 18 ft^3/s

50-percent AEP flood 22.1 ft^3/s

20-percent AEP flood 38 ft^3/s

10-percent AEP flood 50.9 ft^3/s

Statistic Value Unit

4-percent AEP flood 70.7 ft^3/s

2-percent AEP flood 88.2 ft^3/s

1-percent AEP flood 109 ft^3/s

0.5-percent AEP flood 132 ft^3/s

0.2-percent AEP flood 169 ft^3/s

Peak-Flow Statistics Flow Report [Area-Averaged]

Statistic Value Unit

80-percent AEP flood 14.3 ft^3/s

66.7-percent AEP flood 19.1 ft^3/s

50-percent AEP flood 24.3 ft^3/s

20-percent AEP flood 46.6 ft^3/s

10-percent AEP flood 67.8 ft^3/s

4-percent AEP flood 105 ft^3/s

2-percent AEP flood 142 ft^3/s

1-percent AEP flood 190 ft^3/s

0.5-percent AEP flood 251 ft^3/s

0.2-percent AEP flood 358 ft^3/s

Peak-Flow Statistics Citations

Thomas, Jr., W.O. and Moglen, G.E.,2010, An Update of Regional Regression Equations for Maryland, Appendix 3 in Application of Hydrologic Methods in Maryland, Third Edition, September 2010: Maryland State Highway Administration and Maryland Department of the Environment, 38 p.

(http://gishydro.eng.umd.edu/HydroPanel/hydrology_panel_report_3rd_edition_final.pdf)

USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological

Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

USGS Software Disclaimer: This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S.

Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

USGS Product Names Disclaimer: Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Application Version: 4.16.1

StreamStats Services Version: 1.2.22

NSS Services Version: 2.2.1 http://gishydro.eng.umd.edu/HydroPanel/hydrology_panel_report_3rd_edition_final.pdf

APPENDIX 2 - Channel Analysis Summary and Channel Lining Quantities Summary Worksheets

PROJECT: CHOH 235(2) 242(1) ETC BIGPOOL (Bp) CL SOILS COHESSIVE W/ PI=14 and e = 0.50

LOCATION FOUR LOCKS BOAT RAMP ACCESS TUNNEL

DATE: 18-Oct-23

CONDITION: PROPOSED

COMPUTED: BLM

CHANNEL

BOTTOM

WIDTH (FT)

STRAIGHT

SECTION LINING

TYPE

BEND LINING TYPE

(200 FT RADIUS)

BEND LINING TYPE

(79.6 FT RADIUS)

BEND LINING TYPE (34.2

FT RADIUS)

BEND LINING TYPE

(116.3 FT RADIUS) REMARKS

TURF GRASS

(GOOD AT 0.33')

TURF GRASS (GOOD

AT 0.33')

CLASS 2 (D50 = 9 IN) CLASS 2 (D50 = 9 IN) CLASS 1 (D50 = 6 IN)

For Temporary Stabilization Measures, Requires "Wildlife" Friendly RECP with Min 2.0 lb/sf shear resistance per ASTM D6460.

TURF GRASS

(GOOD AT 0.33')

TURF GRASS (GOOD

AT 0.33')

CLASS 2 (D50 = 9 IN) CLASS 2 (D50 = 9 IN) CLASS 1 (D50 = 6 IN)

TURF GRASS

(GOOD AT 0.33')

TURF GRASS (GOOD

AT 0.33')

CLASS 1 (D50 = 6 IN) CLASS 2 (D50 = 9 IN) CLASS 1 (D50 = 6 IN)

TURF GRASS

(GOOD AT 0.33')

TURF GRASS (GOOD

AT 0.33')

CLASS 1 (D50 = 6 IN) CLASS 2 (D50 = 9 IN) D50 = 4 IN ROCK

TURF GRASS

(GOOD AT 0.33')

TURF GRASS (GOOD

AT 0.33')

CLASS 1 (D50 = 6 IN) CLASS 2 (D50 = 9 IN) D50 = 4 IN ROCK

CHANNEL

BOTTOM

WIDTH (FT)

STRAIGHT

SECTION FLOW

DEPTH (FT)

STRAIGHT SECTION

FLOW VELOCITY

(FPS)

BEND 200 FT

RADIUS FLOW

DEPTH (FT)

BEND 200 FT RADIUS

FLOW VELOCITY (FPS)

BEND 79.6 FT

RADIUS FLOW

DEPTH (FT)

BEND 79.6 FT RADIUS FLOW

VELOCITY (FPS)

BEND 34.2 FT

RADIUS FLOW

DEPTH (FT)

BEND 34.2 FT RADIUS

FLOW VELOCITY (FPS)

BEND 116.3 FT

RADIUS FLOW

DEPTH (FT)

BEND 116.3 FT

RADIUS FLOW

VELOCITY (FPS)

2 2.07 5.36 2.76 3.28 2.98 2.86 2.98 2.86 2.76 3.28 3 1.88 5.33 2.57 3.26 2.79 2.84 2.79 2.84 2.57 3.26 4 1.73 5.27 2.22 3.63 2.39 3.23 2.61 2.82 2.39 3.23 5 1.59 5.20 2.07 3.59 2.24 3.19 2.46 2.79 2.09 3.54 6 1.48 5.12 1.94 3.53 2.11 3.14 2.32 2.75 1.94 3.53

CHANNEL

BOTTOM

WIDTH (FT)

STRAIGHT

SECTION FLOW

VELOCITY (FPS)

BEND 200 FT

RADIUS FLOW

VELOCITY (FPS)

BEND 79.6 FT

RADIUS FLOW

VELOCITY (FPS)

BEND 34.2 FT RADIUS

FLOW VELOCITY (FPS)

BEND 116.3 FT

RADIUS FLOW

VELOCITY (FPS)

2 4.12 2.53 2.21 2.21 2.53 3 4.06 2.50 2.18 2.18 2.50 4 3.97 2.76 2.45 2.15 2.45 5 3.87 2.69 2.40 2.11 2.66 6 2.93 2.63 2.35 2.06 2.63

CLASS D50 (IN) D50 (MM) CLASS WEIGHT50 (LBS) SPECIFIC GRAVITY DENSITY (LBS/CF) SPHERE VOLUME50 (CF) D50 (IN) D50 (MM)

1 6 152.4 MD CL 0 10 2.64 164.74 0.0607 5.85 148.6

2 9 228.6 MD CL I 40 2.64 164.74 0.2428 9.29 235.9

3 12 304.8 MD CL II 200 2.64 164.74 1.2141 15.88 403.4

4 15 381.0 MD CL III 600 2.64 164.74 3.6422 22.91 581.8

5 18 457.2

6 21 533.4

7 24 609.6 NO. D LOWER (IN) D UPPER (IN) D50 (IN) D50 (MM)

8 27 685.8 1 2.0 4.0 3.00 76.20 9 30 762.0 2 2.0 3.0 2.50 63.50 10 33 838.2

MDSHA RIPRAP WEIGHT50 TO D50 CONVERSIONEFL RIPRAP D50 SIZES

AASHTO M 43 STONE SIZE

CHANNEL ANALYSIS SUMMARY

DESIGN CRITERIA

10-YEAR DESIGN CAPACITY DISCHARGE = 67.9 CFS

10-YEAR DESIGN CAPACITY DISCHARGE = 67.9 CFS

SELF CLEANING VELOCITY CHECK - 2-YEAR DISCHARGE = 24.3 CFS

PROJECT: CHOH 235(2) 242(1) ETC

LOCATION FOUR LOCKS BOAT RAMP ACCESS TUNNEL

DATE: 18-Oct-23

CONDITION: PROPOSED

COMPUTED: BLM

LINING LIMITS AND QUANTITIES FOR 2 FT WIDE CHANNEL (EXTEND LINING 3 FEET VERTICALLY)

STA

BEGINNING STA END DISTANCE (FT) LINING TYPE LINING AREA (SF)

LINING

VOLUME (CF) LINING TONNAGE (TON)

0+12.33 1+16.09 103.760

TURF GRASS W/

TYPE 2B

1599.98 n/a n/a

1+16.09 1+63.38 47.290 CLASS 2 (D50 = 9 IN) 729.21 1093.82 67.00

1+63.38 2+46.97 83.590

TURF GRASS W/

TYPE 2B

1288.96 n/a n/a

2+46.97 3+33.92 86.950 CLASS 2 (D50 = 9 IN) 1340.77 2011.15 123.00

3+33.92 4+00.00 66.080 CLASS 1 (D50 = 6 IN) 1018.95 1018.95 62.00

CHANNEL LINING QUANTITIES SUMMARY

APPENDIX 3 – Hydraulic Computation Output

• FHWA Hydraulic Toolbox ™ Output (Channel Analysis)

• FHWA HY-8 ™ Output

Hydraulic Analysis Report

Project Data Project Title:

Designer:

Project Date: Thursday, August 31, 2023

Project Units: U.S. Customary Units

Notes:

Channel Analysis: 2 FT BOTTOM STRAIGHT Notes:

Input Parameters Channel Type: Trapezoidal

Side Slope 1 (Z1): 2.0000 ft/ft

Side Slope 2 (Z2): 2.0000 ft/ft

Channel Width 2.00 ft

Longitudinal Slope: 0.0100 ft/ft

Manning's n: 0.0389

Flow 67.9000 cfs

Result Parameters Depth 2.3182 ft

Area of Flow 15.3845 ft^2

Wetted Perimeter 12.3673 ft

Hydraulic Radius 1.2440 ft

Average Velocity 4.4135 ft/s

Top Width 11.2728 ft

Froude Number: 0.6658

Critical Depth 1.9122 ft

Critical Velocity 6.0964 ft/s

Critical Slope: 0.0237 ft/ft

Critical Top Width 9.65 ft

Calculated Max Shear Stress 1.4466 lb/ft^2

Calculated Avg Shear Stress 0.7762 lb/ft^2

Channel Lining Analysis: 2 FT BOTTOM STRAIGHT Notes:

Lining Input Parameters Channel Lining Type: Vegetation

Specific Weight of Water: 62.4 lb/ft^3

Height of Vegetation: 0.333 ft

Vegetation Condition is good

Growth Form of Vegetation is mixed

Cf: 0.75

See HEC-15, Table 4.5 (default: 0.75 for Good cover factor and Mixed growth form) soil is cohesive

Soil Class is CL: Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

Plasticity Index: 14

Void Ratio: 0.5

C1: 1.07

C2: 14.3

C3: 47.7

C4: 1.48

C5: -0.57

C6: 0.0001

Safety Factor: 1

Lining Results Cn: 0.165205

Permissible Soil Shear Stress: 0.0653493 lb/ft^2

Mean Boundary Shear Stress: 0.776235 lb/ft^2

Maximum Shear Stress on the Channel Bottom: 1.44656 lb/ft^2

Manning's n: 0.0389409

Soil Grain Roughness: 0.016

Effective Shear Stress: 0.0610527 lb/ft^2

Permissible Shear Stress on Vegetation: 1.54836 lb/ft^2

This value is compared with the maximum shear stress times the safety factor to determine lining stability

This value is compared with the maximum shear stress times the safety factor to determine lining stability

Channel bottom is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM STRAIGHT

Channel Analysis: 2 FT BOTTOM 200' RADIUS BEND Notes:

Input Parameters Channel Type: Trapezoidal

Side Slope 1 (Z1): 2.0000 ft/ft

Side Slope 2 (Z2): 2.0000 ft/ft

Channel Width 2.00 ft

Longitudinal Slope: 0.0100 ft/ft

Manning's n: 0.0580

Flow 67.9000 cfs

Result Parameters Depth 2.7582 ft

Area of Flow 20.7317 ft^2

Wetted Perimeter 14.3350 ft

Hydraulic Radius 1.4462 ft

Average Velocity 3.2752 ft/s

Top Width 13.0328 ft

Froude Number: 0.4576

Critical Depth 1.9123 ft

Critical Velocity 6.0962 ft/s

Critical Slope: 0.0527 ft/ft

Critical Top Width 9.65 ft

Calculated Max Shear Stress 1.7211 lb/ft^2

Calculated Avg Shear Stress 0.9024 lb/ft^2

Channel Lining Analysis: 2 FT BOTTOM 200' RADIUS BEND Notes:

Lining Input Parameters Channel Lining Type: Riprap, Cobble, or Gravel

D50: 152.40 mm

Riprap Specific Weight: 165 lb/ft^3

Water Specific Weight: 62.4 lb/ft^3

Riprap Shape is Angular

Safety Factor: 1

Calculated Safety Factor: 1.00016

Lining Results Angle of Repose: 41.15 degrees

Relative Flow Depth: 3.18147 ft

Manning's n method: Blodgett

Manning's n: 0.058022

Channel Bottom Shear Results V*: 0.942412

Reynold's Number: 38718.7

Shield's Parameter: 0.047

Shear stress on channel bottom: 1.72112 lb/ft^2

Permissible shear stress for channel bottom: 2.4111 lb/ft^2

Channel bottom is stable

Stable D50: 108.805 mm

Channel Side Shear Results

K1: 0.802

K2: 0.733562

Kb: 1.05

Shear stress on side of channel: 1.72112 lb/ft^2

Permissible shear stress for side of channel: 1.76869 lb/ft^2

Stable Side D50: 0.390274 lb/ft^2

Side of channel is stable

Channel Bend Shear Results Curvature Radius: 200 ft

No further correction will occur once R/T > 10

Shear stress on bottom of channel in bend: 1.80717 lb/ft^2

Bottom of bend of the channel is stable

Length of Protection beyond PT: 15.9038 ft

Additional Freeboard required because of Superelevation: 0.0217255 ft

Channel Bend Side Shear Results

Shear stress on side of channel in bend: 1.44935 lb/ft^2

The side of the bend of the channel is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM 200' RADIUS BEND

Channel Analysis: 2 FT BOTTOM 79.6' RADIUS BEND Notes:

Input Parameters Channel Type: Trapezoidal

Side Slope 1 (Z1): 2.0000 ft/ft

Side Slope 2 (Z2): 2.0000 ft/ft

Channel Width 2.00 ft

Longitudinal Slope: 0.0100 ft/ft

Manning's n: 0.0696

Flow 67.9000 cfs

Result Parameters Depth 2.9822 ft

Area of Flow 23.7517 ft^2

Wetted Perimeter 15.3369 ft

Hydraulic Radius 1.5487 ft

Average Velocity 2.8587 ft/s

Top Width 13.9289 ft

Froude Number: 0.3858

Critical Depth 1.9123 ft

Critical Velocity 6.0961 ft/s

Critical Slope: 0.0758 ft/ft

Critical Top Width 9.65 ft

Calculated Max Shear Stress 1.8609 lb/ft^2

Calculated Avg Shear Stress 0.9664 lb/ft^2

Channel Lining Analysis: 2 FT BOTTOM 79.6' RADIUS BEND Notes:

Lining Input Parameters Channel Lining Type: Riprap, Cobble, or Gravel

D50: 228.60 mm

Riprap Specific Weight: 165 lb/ft^3

Water Specific Weight: 62.4 lb/ft^3

Riprap Shape is Angular

Safety Factor: 1

Calculated Safety Factor: 1.06388

Lining Results Angle of Repose: 41.7 degrees

Relative Flow Depth: 2.27362 ft

Manning's n method: Blodgett

Manning's n: 0.0695816

Channel Bottom Shear Results V*: 0.979936

Reynold's Number: 60390.5

Shield's Parameter: 0.0601264

Shear stress on channel bottom: 1.86091 lb/ft^2

Permissible shear stress for channel bottom: 4.62672 lb/ft^2

Channel bottom is stable

Stable D50: 97.8178 mm

Channel Side Shear Results

K1: 0.802

K2: 0.740307

Kb: 1.44117

Shear stress on side of channel: 1.86091 lb/ft^2

Permissible shear stress for side of channel: 3.4252 lb/ft^2

Stable Side D50: 0.347668 lb/ft^2

Side of channel is stable

Channel Bend Shear Results Curvature Radius: 79.6 ft

No further correction will occur once R/T > 10

Shear stress on bottom of channel in bend: 2.68188 lb/ft^2

Bottom of bend of the channel is stable

Length of Protection beyond PT: 14.364 ft

Additional Freeboard required because of Superelevation: 0.0444475 ft

Channel Bend Side Shear Results

Shear stress on side of channel in bend: 2.15087 lb/ft^2

The side of the bend of the channel is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM 79.6' RADIUS BEND

Channel Analysis: 2 FT BOTTOM 34.2' RADIUS BEND Notes:

Input Parameters Channel Type: Trapezoidal

Side Slope 1 (Z1): 2.0000 ft/ft

Side Slope 2 (Z2): 2.0000 ft/ft

Channel Width 2.00 ft

Longitudinal Slope: 0.0100 ft/ft

Manning's n: 0.0696

Flow 67.9000 cfs

Result Parameters Depth 2.9822 ft

Area of Flow 23.7517 ft^2

Wetted Perimeter 15.3369 ft

Hydraulic Radius 1.5487 ft

Average Velocity 2.8587 ft/s

Top Width 13.9289 ft

Froude Number: 0.3858

Critical Depth 1.9123 ft

Critical Velocity 6.0961 ft/s

Critical Slope: 0.0758 ft/ft

Critical Top Width 9.65 ft

Calculated Max Shear Stress 1.8609 lb/ft^2

Calculated Avg Shear Stress 0.9664 lb/ft^2

Channel Lining Analysis: 2 FT BOTTOM 34.2' RADIUS BEND Notes:

Lining Input Parameters Channel Lining Type: Riprap, Cobble, or Gravel

D50: 228.60 mm

Riprap Specific Weight: 165 lb/ft^3

Water Specific Weight: 62.4 lb/ft^3

Riprap Shape is Angular

Safety Factor: 1

Calculated Safety Factor: 1.06388

Lining Results Angle of Repose: 41.7 degrees

Relative Flow Depth: 2.27362 ft

Manning's n method: Blodgett

Manning's n: 0.0695816

Channel Bottom Shear Results V*: 0.979936

Reynold's Number: 60390.5

Shield's Parameter: 0.0601264

Shear stress on channel bottom: 1.86091 lb/ft^2

Permissible shear stress for channel bottom: 4.62672 lb/ft^2

Channel bottom is stable

Stable D50: 97.8178 mm

Channel Side Shear Results

K1: 0.802

K2: 0.740307

Kb: 1.91821

Shear stress on side of channel: 1.86091 lb/ft^2

Permissible shear stress for side of channel: 3.4252 lb/ft^2

Stable Side D50: 0.347668 lb/ft^2

Side of channel is stable

Channel Bend Shear Results Curvature Radius: 34.2 ft

No further correction will occur once R/T > 10

Shear stress on bottom of channel in bend: 3.56961 lb/ft^2

Bottom of bend of the channel is stable

Length of Protection beyond PT: 14.364 ft

Additional Freeboard required because of Superelevation: 0.103451 ft

Channel Bend Side Shear Results

Shear stress on side of channel in bend: 2.86283 lb/ft^2

The side of the bend of the channel is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM 34.2' RADIUS BEND

Channel Analysis: 2 FT BOTTOM 116.3' RADIUS BEND Notes:

Input Parameters Channel Type: Trapezoidal

Side Slope 1 (Z1): 2.0000 ft/ft

Side Slope 2 (Z2): 2.0000 ft/ft

Channel Width 2.00 ft

Longitudinal Slope: 0.0100 ft/ft

Manning's n: 0.0580

Flow 67.9000 cfs

Result Parameters Depth 2.7582 ft

Area of Flow 20.7317 ft^2

Wetted Perimeter 14.3350 ft

Hydraulic Radius 1.4462 ft

Average Velocity 3.2752 ft/s

Top Width 13.0328 ft

Froude Number: 0.4576

Critical Depth 1.9123 ft

Critical Velocity 6.0962 ft/s

Critical Slope: 0.0527 ft/ft

Critical Top Width 9.65 ft

Calculated Max Shear Stress 1.7211 lb/ft^2

Calculated Avg Shear Stress 0.9024 lb/ft^2

Channel Lining Analysis: 2 FT BOTTOM 116.3' RADIUS BEND Notes:

Lining Input Parameters Channel Lining Type: Riprap, Cobble, or Gravel

D50: 152.40 mm

Riprap Specific Weight: 165 lb/ft^3

Water Specific Weight: 62.4 lb/ft^3

Riprap Shape is Angular

Safety Factor: 1

Calculated Safety Factor: 1.00016

Lining Results Angle of Repose: 41.15 degrees

Relative Flow Depth: 3.18147 ft

Manning's n method: Blodgett

Manning's n: 0.058022

Channel Bottom Shear Results V*: 0.942412

Reynold's Number: 38718.7

Shield's Parameter: 0.047

Shear stress on channel bottom: 1.72112 lb/ft^2

Permissible shear stress for channel bottom: 2.4111 lb/ft^2

Channel bottom is stable

Stable D50: 108.805 mm

Channel Side Shear Results

K1: 0.802

K2: 0.733562

Kb: 1.12304

Shear stress on side of channel: 1.72112 lb/ft^2

Permissible shear stress for side of channel: 1.76869 lb/ft^2

Stable Side D50: 0.390274 lb/ft^2

Side of channel is stable

Channel Bend Shear Results Curvature Radius: 116.3 ft

No further correction will occur once R/T > 10

Shear stress on bottom of channel in bend: 1.93288 lb/ft^2

Bottom of bend of the channel is stable

Length of Protection beyond PT: 15.9038 ft

Additional Freeboard required because of Superelevation: 0.0373612 ft

Channel Bend Side Shear Results

Shear stress on side of channel in bend: 1.55017 lb/ft^2

The side of the bend of the channel is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM 116.3' RADIUS BEND

Channel Lining Analysis: 2 FT BOTTOM 116.3' RADIUS BEND WITH CL 3 Notes:

Lining Input Parameters Channel Lining Type: Riprap, Cobble, or Gravel

D50: 304.80 mm

Riprap Specific Weight: 165 lb/ft^3

Water Specific Weight: 62.4 lb/ft^3

Riprap Shape is Angular

Safety Factor: 1

Calculated Safety Factor: 1.13476

Lining Results Angle of Repose: 41.7 degrees

Relative Flow Depth: 1.80311 ft

Manning's n method: Blodgett

Manning's n: 0.0805376

Channel Bottom Shear Results V*: 1.011

Reynold's Number: 83072.8

Shield's Parameter: 0.0747281

Shear stress on channel bottom: 1.98074 lb/ft^2

Permissible shear stress for channel bottom: 7.6671 lb/ft^2

Channel bottom is stable

Stable D50: 89.3541 mm

Channel Side Shear Results

K1: 0.802

K2: 0.740307

Kb: 1.207

Shear stress on side of channel: 1.98074 lb/ft^2

Permissible shear stress for side of channel: 5.67601 lb/ft^2

Stable Side D50: 0.317586 lb/ft^2

Side of channel is stable

Channel Bend Shear Results Curvature Radius: 116.3 ft

No further correction will occur once R/T > 10

Shear stress on bottom of channel in bend: 2.39076 lb/ft^2

Bottom of bend of the channel is stable

Length of Protection beyond PT: 13.2326 ft

Additional Freeboard required because of Superelevation: 0.0257857 ft

Channel Bend Side Shear Results

Shear stress on side of channel in bend: 1.91739 lb/ft^2

The side of the bend of the channel is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM 116.3' RADIUS BEND

Channel Lining Analysis: 2 FT BOTTOM STRAIGHT temp lining Notes:

Lining Input Parameters Channel Lining Type: Rolled Erosion Control Product

Shear Stress on RECP that results in 0.5 in of erosion: 2 lb/ft^2

See https://highways.dot.gov/federal-lands/specs refer to FLH FP 14, Table 713-3 or 713-4 to get this value

Manning's n value input as user-supplied n

RECP is an open weave textile

Manning's n: 0.025

Manning's n range: 0.022-0.028

Specific Weight of Water: 62.4 lb/ft^3 soil is cohesive

Soil Class is CL: Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

Plasticity Index: 14

Void Ratio: 0.5

C1: 1.07

C2: 14.3

C3: 47.7

C4: 1.42

C5: -0.61

C6: 0.0001

Safety Factor: 1

Lining Results Permissible Soil Shear Stress: 0.0568925 lb/ft^2

Mean Boundary Shear Stress: 0.655971 lb/ft^2

Maximum Shear Stress on the Channel Bottom: 1.18749 lb/ft^2

Effective Shear Stress: 0.0505664 lb/ft^2

Permissible Shear Stress on RECP: 1.27787 lb/ft^2

This value is compared with the maximum shear stress times the safety factor to determine lining stability

This value is compared with the maximum shear stress times the safety factor to determine lining stability

Channel bottom is stable

Channel Lining Stability Results 2

The channel is stable

Channel Summary Name of Selected Channel: 2 FT BOTTOM STRAIGHT

HY-8 Culvert Analysis Report Crossing Discharge Data Discharge Selection Method: Specify Minimum, Design, and Maximum Flow

Minimum Flow: 24.30 cfs

Design Flow: 142.40 cfs

Maximum Flow: 190.50 cfs

Table 1 - Summary of Culvert Flows at Crossing: CHANNEL PIPE THRU BERM Headwater Elevation (ft)

Total Discharge (cfs)

60 INCH RCP

Discharge (cfs)

Roadway Discharge (cfs)

Iterations

361.70 24.30 24.30 0.00 1

362.29 40.92 40.92 0.00 1

362.88 57.54 57.54 0.00 1

363.39 74.16 74.16 0.00 1

363.86 90.78 90.78 0.00 1

364.31 107.40 107.40 0.00 1

364.76 124.02 124.02 0.00 1

365.29 142.40 142.40 0.00 1

365.74 157.26 157.26 0.00 1

366.29 173.88 173.88 0.00 1

366.90 190.50 190.50 0.00 1

368.00 217.39 217.39 0.00 Overtopping

Rating Curve Plot for Crossing: CHANNEL PIPE THRU BERM

Culvert Data: 60 INCH RCP

Table 1 - Culvert Summary Table: 60 INCH RCP Total Disch arge (cfs)

Culve rt Disch arge (cfs)

Head water Elevat ion (ft)

Inle t Cont rol Dep th (ft)

Outl et Cont rol Dep th (ft)

Fl ow Ty pe

Nor mal Dep th (ft)

Criti cal Dep th (ft)

Out let De pth (ft)

Tailw ater Dept h (ft)

Outl et Velo city (ft/s

Tailw ater Veloc ity (ft/s)

24.30 cfs

24.30 cfs

361.70 1.86 1.19

1- S2 n

0.99 1.36 1.1

1.39 7.37 3.68

40.92 cfs

40.92 cfs

362.29 2.45 1.66

1- S2 n

1.29 1.79 1.4

1.76 8.30 4.20

57.54 cfs

57.54 cfs

362.88 3.04 2.11

1- S2 n

1.53 2.13 1.8

2.05 9.00 4.58

74.16 cfs

74.16 cfs

363.39 3.55 2.55

1- S2 n

1.75 2.43 2.0

2.30 9.59 4.89

90.78 cfs

90.78 cfs

363.86 4.02 2.99

1- S2 n

1.95 2.71 2.3

2.51 10.1

5.14

107.4 0 cfs

107.4 0 cfs

364.31 4.47 3.45

1- S2 n

2.14 2.95 2.5

2.70 10.5

5.37

124.0 2 cfs

124.0 2 cfs

364.76 4.92 3.92

1- S2 n

2.32 3.18 2.7

2.88 11.0

5.56

142.4 0 cfs

142.4 0 cfs

365.29 5.45 4.47

5- S2 n

2.51 3.42 3.0

3.05 11.5

5.76

157.2 6 cfs

157.2 6 cfs

365.74 5.90 4.93

5- S2 n

2.67 3.60 3.1

3.18 11.8

5.91

173.8 8 cfs

173.8 8 cfs

366.29 6.45 6.07

5- S2 n

2.84 3.78 3.3

3.32 12.3

6.06

190.5 0 cfs

190.5 0 cfs

366.90 7.06 6.54

5- S2 n

3.01 3.95 3.5

3.45 12.7

6.20

Culvert Barrel Data Culvert Barrel Type Straight Culvert

Inlet Elevation (invert): 359.84 ft, Outlet Elevation (invert): 359.61 ft

Culvert Length: 23.10 ft, Culvert Slope: 0.0100

Culvert Performance Curve Plot: 60 INCH RCP

Water Surface Profile Plot for Culvert: 60 INCH RCP

Site Data - 60 INCH RCP Site Data Option: Culvert Invert Data

Inlet Station: 0.00 ft

Inlet Elevation: 359.84 ft

Outlet Station: 23.10 ft

Outlet Elevation: 359.61 ft

Number of Barrels: 1

Culvert Data Summary - 60 INCH RCP Barrel Shape: Circular

Barrel Diameter: 5.00 ft

Barrel Material: Concrete

Embedment: 0.00 in

Barrel Manning's n: 0.0120

Culvert Type: Straight

Inlet Configuration: Square Edge with Headwall (Ke=0.5)

Inlet Depression: None

Tailwater Data for Crossing: CHANNEL PIPE THRU BERM

Table 2 - Downstream Channel Rating Curve (Crossing: CHANNEL PIPE THRU BERM) Flow (cfs) Water

Surface Elev (ft)

Velocity (ft/s)

Depth (ft) Shear (psf) Froude Number

24.30 361.00 1.39 3.68 0.86 0.69

40.92 361.37 1.76 4.20 1.10 0.71

57.54 361.66 2.05 4.58 1.28 0.73

74.16 361.91 2.30 4.89 1.43 0.74

90.78 362.12 2.51 5.14 1.57 0.75

107.40 362.31 2.70 5.37 1.69 0.76

124.02 362.49 2.88 5.56 1.79 0.76

142.40 362.66 3.05 5.76 1.90 0.77

157.26 362.79 3.18 5.91 1.99 0.77

173.88 362.93 3.32 6.06 2.07 0.78

190.50 363.06 3.45 6.20 2.15 0.78

Tailwater Channel Data - CHANNEL PIPE THRU BERM Tailwater Channel Option: Trapezoidal Channel

Bottom Width: 2.00 ft

Side Slope (H:V): 2.00 (_:1)

Channel Slope: 0.0100

Channel Manning's n: 0.0350

Channel Invert Elevation: 359.61 ft

Roadway Data for Crossing: CHANNEL PIPE THRU BERM Roadway Profile Shape: Constant Roadway Elevation

Crest Length: 36.26 ft

Crest Elevation: 368.00 ft

Roadway Surface: Gravel

Roadway Top Width: 12.00 ft

APPENDIX 4 – Outfall Channel Plan

NATIONAL HISTORIC PARK

C&O CANAL

P O

T O

M A

C R I V

E R

EX

363.65

EX & PR

366.15

%8.5

EX & PR

364.84

364.12 PR

EX & PR

364.49

EX & PR

364.20

EX & PR

363.69

EX & PR

363.71

EX & PR

364.00

363.00 PR

363.38 EX

EX & PR

364.42

EX & PR

364.18

363.08 PR

364.67 EX

364.69 EX

364.53 EX

364.49 EX

363.52 PR

.1

R

1+

1+75

2+00

1+

2+25

2+

LOD (0.36199226 AC)

3 FEET MINIMUM

EXTEND VERTICALLY

TURF LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 2 RIPRAP LINING

3 FEET MINIMUM

EXTEND VERTICALLY

TURF LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 2 RIPRAP LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 2 RIPRAP LINING

360.20'

ELEV.

OHWM

S T

A R

L I P

E R R

O A

D

E L E

V .9

ELEV. 378.79'

S T O

N E H

E A

D W

A L L

R O

C K W

A L L

R O

C K W

A L L

G A

B

IO

N W

A L L

B E

N C

H

W F

W O

O D

E N B

R

ID

G E

EFL - Hydraulics (WH) Text Box

CL RIPRAP LINING

EXTEND VERTICALLY

3 FEET MINIMUM

EFL - Hydraulics (WH) Text Box

CL RIPRAP LINING

EXTEND VERTICALLY

3 FEET MINIMUM

EFL - Hydraulics (WH) Text Box

CL RIPRAP LINING

EXTEND VERTICALLY

3 FEET MINIMUM

APPENDIX 5 – Outfall Channel with Culvert and Embankment in Lieu of PED Bridge Plan

NATIONAL HISTORIC PARK

C&O CANAL

P O

T O

M A

C R I V

E R

EX

363.65

EX & PR

366.15

%8.5

EX & PR

364.84

364.12 PR

EX & PR

364.49

EX & PR

364.20

EX & PR

363.69

EX & PR

363.71

EX & PR

364.00

363.00 PR

363.38 EX

EX & PR

364.42

EX & PR

364.18

363.08 PR

364.67 EX

364.69 EX

364.53 EX

364.49 EX

363.52 PR

.1

R

1+

1+75

2+00

1+

2+25

2+

LOD (0.37793024 AC)

(MD 354.01)

TYPE C HEADWAL

(MD 354.01)

TYPE C HEADWAL

60" CL. 3 RCP 23.1 LF

3 FEET MINIMUM

EXTEND VERTICALLY

TURF LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 2 RIPRAP LINING

3 FEET MINIMUM

EXTEND VERTICALLY

TURF LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 2 RIPRAP LINING

3 FEET MINIMUM

EXTEND VERTICALLY

CL 3 RIPRAP LINING

360.20'

ELEV.

OHWM

S T

A R

L I P

E R R

O A

D

E L E

V .9

ELEV. 378.79'

S T O

N…