Hydraulics_Report.pdf

DRAFT

HYDRAULIC EVALUATIONS

AND

RECOMMENDATION

REPORT

(Phase III – Intermediate PS&E)

BLUE RIDGE PARKWAY

WATAUGA COUNTY

NORTH CAROLINA

Project:

PRA-BLRI 2F24

Prepared for:

NATIONAL PARK SERVICE

AND

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL

LANDS HIGHWAY DIVISION

October 2014

HYDRAULIC EVALUATION

AND

RECOMMENDATION REPORT

WATAUGA COUNTY

NORTH CAROLINA

PROJECT: PRA-BLRI 2F24

Table of Contents

Description Page No.

1.0 Introduction 1

2.0 Findings of the Culvert Survey 1

3.0 Paved Waterway 4

4.0 Hydraulic Analysis of Existing Drainage Systems 5

5.0 Photographs of Typical Conditions 7

Appendix A Culvert Survey and Evaluation Form

Appendix B Paved Waterways and Ditch Evaluation Form

Appendix C Hydrologic and Hydraulic Calculations

Exhibit 1 Drainage Area Map i

HYDRAULIC EVALUATION

AND

RECOMMENDATION REPORT

WATAUGA COUNTY, NORTH CAROLINA

PROJECT PRA-BLRI 2F24

1.0 Introduction

A hydraulic investigation of Blue Ridge Parkway Section 2F24 located in Watauga

County, North Carolina, was conducted in order to verify the condition and hydraulic adequacy of each hydraulic structure and waterway within the project limits, to recommend rehabilitation work if necessary, and, where required, to recommend the construction of new drainage structures. This report will include the findings of the field investigations, photographs of typical and unique drainage problems, and the culvert and paved waterway and ditch field evaluation forms.

At the beginning of the project, the Blue Ridge Parkway Section 2F24 starts at the Blue

Ridge Parkway Bridge over County Road 1509 at approximately Milepost (MP) 283 and extends to MP 291.9, in the vicinity of the Blue Ridge Parkway Bridge over Route 321.

Within the project limits, the Blue Ridge Parkway traverses stream valleys and steep

Mountain slopes sections alternating between forest and pasture including Boone and

Aho Gap. At some locations such as the end of MP 288, the Blue Ridge Parkway is located nearby the ridge line with no or small drainage areas and with infrequently located drainage structures. At other locations, the Blue Ridge Parkway is within a valley adjacent to Sandpit and Goshen Branch

A field survey was made from MP 283 to MP 292 to check the conditions of culverts and ditches. The culvert survey included an examination of the condition of each headwall, drop inlet, pipe and box culvert, and inlet and outlet channel. The ditch survey collected data on where vegetated and paved waterways should be replaced, overlaid, or added.

The proposed locations of rubble paved waterways below rock cuts were also identified.

HDR Engineering conducted a field survey from March 20 th through March 24 th

, 2014.

Photographs of drainage structures including problems encountered are located in Section

4.0.

2.0 Findings of the Culvert Survey

The field survey found several hydraulic structures within the project limits that require major reconstruction. Per visual observations, no hydraulic structures were found hydraulically inadequate based on the lack of evidence of overtopping and with discussions with the local National Parks Services (NPS) personnel. Numerous hydraulic structures throughout the project area have problems as described in the following list:

Inadequate connections between pipe sections (pipe separation).

Loose pipe sections at culvert outlets.

Concrete pipes with scoured pipe bottoms.

Buried pipe outfalls.

Erosion problems at the outlet and outfall channels.

Erosion problems around headwalls.

Headwalls with loose or missing stones.

Collapsed headwalls.

Headwalls with missing connections between the pipe.

Pipes filled in with varying amounts of sediment.

Spalling concrete on drop inlet top slabs.

Box Culverts with scoured bottoms and exposed reinforcement, infiltration and local spalling.

Box culvert with collapsed ceiling section at the outlet interface.

Difficult access for maintenance and rehabilitation construction activities.

One of the most common and serious problems identified in our field survey is full or partially clogged pipes with sediment and loose pipe sections at culvert outlets. Due to the steep mountain slopes with steep pipe grades, the last sections of pipe have separated from the rest of the culvert. Loose pipe sections generally occur where the last pipe section projects out of the fill slope without a headwall. Loose pipe sections at the outlet were also found where serious outfall channel erosion has occurred. At one location at

MP 291, Station 3+95, the separated pipe sections have created a sinkhole within the embankment approximately 10 feet from the edge of the travel lane that could be a public safety hazard. Approximately, a quarter of the 79 culverts evaluated had loose pipe sections at the outlet. In most cases, it is recommended to reset the loose pipe sections and to secure the last pipe section with riprap. The riprap will prevent stream erosion and the stones placed against the pipe bottom will help anchor the last pipe section.

In several locations, the outlet is far below the parkway mainline elevation in deep fill with difficult access. In these areas, when the loose pipe sections at the outlet were covered by stones and the fill slope and the pipe appeared to be stable, resetting of the loose pipe sections was not recommended. An example of this case is located at MP 283, Station 52+17 the culvert consists of a 2 feet by 2 feet box culvert at the bottom of a 7.5 feet drop down shaft at the inlet end with the pipe section changing to a corrugated metal pipe at the last 20 feet at the outlet end. The corrugated pipe section has failed, based on observed collapsed section and with section with a rusted out bottom. It would be desirable to replace the failed pipe section; however, the outlet is deep below the

Parkway and access is extremely difficult. Furthermore, the fill on top of the collapsed pipe section consist of rock fill. Further evaluation of the constructability of any rehabilitation measures at the outfall would be required.

In a very few cases, the bottom of the concrete culvert had exposed aggregate along the invert of the culvert indicating scouring action located along a steep slope. Due to the amount of cover over the culvert, it is difficult to excavate and replace or reline the existing culvert. At MP 283, Station 42+80 scouring of the box culvert bottom with exposed rebar was observed at the outlet end. At MP 287, Station 28+50, approximately

2-inches of the box culvert bottom has scoured out. Relining the box culvert should be evaluated based on constructability since access is difficult at both locations.

Pipe outfalls were also frequently obstructed by debris and sediment deposits at the outfall channel which resulted in partial or significant pipe blockage at the outfall. In such cases, sediment was also frequently observed to be inside the pipe reducing the conveyance capacity. At approximately twenty-three (23) locations, the pipe contained sediment inside. Pipe cleaning and excavation of outfall channel and placing erosion control matting or a riprap apron was recommended for those cases. At some locations with deep fill sections, the outlet of the culvert could not be located due to either the presence of thick brush or that the outlet of the culvert was buried by fill material during or after construction of the embankment.

Another problem is erosion at the outfall of some culverts. Many of the pipe outfalls are on steep rock mountain slopes and rock fill areas. However, there were several locations where channel erosion and drops of up to approximately eight-feet (8) deep have developed due to steep outfall channels, erosive channel materials and high discharge velocities. These locations typically have existing headwalls that were at risk from undermining and separated pipe culvert end sections. Suggested solutions for these locations generally include repair of the outlet to the original condition by resetting loose pipe sections, replacing fill, and armoring the outfall channels with riprap. At one location within the Boone Gap overlook area, (MP 285, Station 31+90) an approximate

6- feet deep headcut has formed with caving action threatening to undermine the stone headwall. At this location a drop structure consisting of stair stepped gabions or imbricated riprap stone is recommended. For smaller pipe sizes, less than 36-inches, and for situations with a moderate degree of outfall channel erosion, loose riprap Class 3 has been specified. For larger pipe sizes, box culverts and for seriously eroded outfall channels, loose riprap Class 4 has been specified.

Many of the stone headwalls found in this section were found to require rehabilitation measures. Numerous stone headwalls had one or more loose stones and/or missing grout between some of the stones. In such cases, it is only necessary to remove and reset the loose stones and recondition the structure by placing grout between the stones. For example, at MP 288, Station 12+00, the ceiling of the box culvert at the interface with the outlet stone headwall has collapsed creating a sinkhole and potential public safety hazard.

At MP 283, Station 20+60 erosion has caused undermining below the headwall with the result that the bottom stones became loose and that left (Southbound) side of the foundation collapsed. The headwall is shown in Photo 20, Section 5.5 An unusual structure is located at MP 283, Station 52+17 where a stone headwall is part of an approximately 7 feet deep vertical concrete drop structure connected to a 2 feet by 2 feet concrete box culvert. The drop structure, which is in good condition, is shown in Photo

Number 14 in Section 5.4

At several locations throughout the project, the headwalls consist of stacked stones placed on top of each other without any mortar placed between the stones. The stacked stone headwall sometimes consisted of curved wingwalls. Some of these types of stone headwalls had problems consisting of loose or knocked over stones. Rehabilitation measures generally consist of replacing or resetting the loose stones.

Most of the 44 drop inlets consist of the FHWA EFLHD Type 4B with the opening facing the roadway. The drop inlets within Section 2F24 were generally in good condition. A few drop inlets had local spalling on the top slab or had deteriorated top slabs that needed replacement.

At the overlooks within the project limits, drainage is through sheet flow with no drainage structures required. Therefore there are no drainage rehabilitation recommendations for the overlook areas/

Detailed descriptions of the culvert conditions and recommended rehabilitation can be found in Appendix A.

3.0 Paved Waterways

The existing paved waterways in this project corridor consist exclusively of asphalt-paved ditches located alongside cut sections of the Blue Ridge Parkway. The condition of the asphalt ditches ranges from fair to good. Many of the paved ditches were silted in with several inches of soil on top of the pavement. Observations include pavement wear, cracking, some heaving and raveling of the asphalt, and vegetative infiltration and overgrowth.

A few ditches with significant cracking and heaving were recommended for replacement.

The remainder will be cleaned and overlaid with a 2-inch asphalt layer unless the grade between ditch and roadway is such that the ditch elevation requires greater adjustment.

Where erosion or rutting is observed in vegetated ditches, new paved waterways or riprap channels are recommended. Eroded gullies at the end of the paved ditches were found at a few locations such as MP 283, Station 07+65 and at other locations noted in the Paved

Ditch Evaluation Forms. At one location a 6-inch clay underdrain pipe outlets within the paved waterway. It is recommended in this section that the underdrain pipe be extended to the end of the cut slope and to remove the underlain outlets within the asphalt paved waterway.

Per the Scoping Report, rubble paved water waterway ditches where recommended at locations where existing paved waterways were located below rock faces. No rubble paved waterways were proposed in existing grass lined ditches below rock faces if they were in good condition. Detailed descriptions of the ditch conditions and recommended rehabilitation can be found in Appendix B.

4.0 Hydrologic and Hydraulic Analysis of Existing Drainage

Culverts

A hydrologic and hydraulic analysis was performed to determine the hydraulic adequacy of the existing culverts per the FHWA 2008 Project Development and Design manual (PDDM) criteria. Since the Blue Ridge Parkway is considered a Low Standard Road with a design speed of 50 MPH and a current ADT (2013) less than 500, the culverts were analyzed for the 25-year event with peak flows calculated using the rational equations for drainage areas less than 200 acres and USGS regression equation (per USGS WRI 4207) for drainage areas greater than 200 acres. Drainage areas for each culvert were developed based on USGS quad maps. For the Rational Method rainfall intensity values were obtain from IDF curves per the 1999 North Carolina Division of Highways “Guidelines for Drainage Studies and Hydraulic Design”. North Carolina uses a minimum 10 minute time of concentration which was used for small drainage basins. For land use conditions with predominantly forested areas in steeply sloping terrain with some pasture lands, a project wide C value of 0.35 was used for the rational equations.

A spreadsheet was developed to calculate peak flow rates and perform inlet and outlet control elevations based on published equations in Appendix A, Table 9 of the FHWA HDS No. 5 “Hydraulic Design of Highway Culverts” . Refer to Appendix C for the hydrologic and hydraulic calculations

The results of the hydraulic analysis indicate that of the 79 culvert structures, only two had a Headwater over Depth (HW/D) ratio of 1.5 for the 25-year event. The remaining 77 culverts had HW/D and therefore meet the criteria in the PDDM. The survey included the pipe inverts and pipe lengths; however, the shoulder elevation was not surveyed.

The inlets with a HW/D greater than 1.5 are at MP 287, Station 46+65 and MP 288, Station 09+60. They both consist of 18-inch pipes with drainage areas greater 18.8 and

13.5 acres respectively. Even though the two had a HW/D greater than 1.5, the actual headwater depth for both structures is less than 4 feet and overtopping most likely does not occur. Both culverts have inlets at the upstream side and the headwater is most likely contained inside. However since the pipe at MP 288, Station 9+60 is across a side road and need extensive rehabilitation measures including extending the pipe and placing a new headwall at the inlet, the recommendation is made to replace the 18-inch pipe with a 24-inch pipe which will result in a HW/D less than 1.5.

For erosion control and energy dissipation at culvert outfalls, a nomographs from the Virginia Department of Transportation Manual was used for sizing the riprap. The nomograph relates the size of riprap to the exit velocity. Due to the varying pipes slopes throughout the project ranging from flat to very steep, subsequent exit velocities ranged from 5.2 feet per second to 27 feet per second. Riprap classes were determined based on current FHWA gradations. Using the nomograph for the exit velocity the size of riprap, riprap classes at the outfalls ranged from Class 2 riprap to Class 9. Since the steepest channel was often located in existing rocky slopes, and due to difficulty of placing large diameter stones in areas with difficult access, Class 5 riprap was used as the maximum stone size.

5.0 Photographs of Typical Conditions

5.1 Drop Inlets

Photo 1:

Drop inlet in good condition.

However the top slap was usualy covered by soil and vegetation. Also some debris such as leaves and sediment was noted to be inside the structure. No rehabilitation work is required.

Photo 2:

Reverse drop inlet in good condition. Some debris was noted to be inside the structure. No rehabilitation work is required.

Photo 3:

Many drop inlets within section 2F24 are generally covered with soil and vegetation with some chipping that has occurred over the years. Recommend to repair inlet top slab with epoxy mortar.

Photo 4:

Drop inlet with spalling of the concrete top slab and exposed rebar. Recommend to replace the top slab section.

Photo 5:

Outfall Pipe from Drop inlet close to roadway located at MP 288, Station 9+60. Due to the close proximately with existing pavement, it has been recommended to add additional pipe length and build a new stone masonry headwall.

5.2 Box Culverts

Photo 6:

Box culverts within section 2F24 are generally located within live streams and have scoured out bottom slabs.

This box culvert is located at MP287, station 43+40.

Recommend to place concrete lining on the culvert bottom.

Photo 7:

Double Box Culvert at MP 286, Station 43+00, cobble stones have deposited on one of the box culvert bottom slabs which has rock side interior walls and concrete ceiling and exterior walls.

Photo 8:

At the outlet end of box culvert at MP 285, Station 51+50, efflorescence has formed across the concrete ceiling at most box culvert openings throughout section 2F24. Future periodic inspections are recommended.

Photo 9:

Example of box culvert outfall with a 2-foot drop from the bottom of the headwall to the channel bottom located at MP 287, Station 8+90.

Recommend placing rip rap apron at bottom of the drop below the invert of the opening.

5.3 Pipe Separation

Photo 10:

At MP 290, Station 28+30 the last pipe section is completely separated.

Recommend removing last section of pipe and installing new stone masonry headwall.

Photo 11:

Example of pipe separation at the outlet end. Photo shown is at MP 291, Station 3+95, the last two sections were separated and caused a sink hole to form above. Resetting of the last two pipe sections and placing fill in the sink hole are recommended in this case.

Photo 12:

Example of pipe separation between pipe joint and headwall. Reconditioning of the drainage structure is

5.4 Pipe Relining

Photo 13:

Example of pipe with exposed aggregate. This is located at MP 287, Station 20+70 where the entire length of pipe displays exposed aggregate at bottom. Consider to re-line the entire length of pipe.

Photo 14:

At MP 283, Station 52+17 the last 20 feet of pipe material transitions from box culvert to CMP. The CMP pipe section is severely corroded.

Consider relining CMP pipe section.

5.5 Stone Headwalls

Photo 15:

Example of stone headwall with loose stones.

Photo 16:

Example of stacked stone headwall with no mortar.

Photo 17:

Example of stone headwall that has collapsed requiring to be rebuilt.

Photo 18:

Stone headwall at the inlet of the double box culvert at MP 286, Station 43+00 is in good condition. Note the natural rocky channel bottom typical for the double box culverts in Section 2F24.

Photo 19:

Stone head wall at the outfall of the culvert at MP 287, Station 28+50 with 2-inch scour invert and 8-inch drop from outlet to channel.

Recommendations include to reline invert of box culvert and chink and grout bottom of headwall.

Photo 20:

Stone headwall with damaged foundation caused by undermining at the pipe outfall into an eroded channel along a steep mountain side at MP 283, Station 20+60.

Note the tree growth on top of headwall. Recommend repairing the headwall foundation and placing a riprap apron.

Photos 21 & 22:

MP 288, Station 12+00. At the outfall interface of the box culvert and the stone headwall the concrete ceiling has collapsed with exposed rebar creating a sink hole at the top. This situation is within several feet from the edge of the roadway.

Recommend repairing the concrete ceiling and filling in sink hole.

MP 288, Station 12+00.

Sinkholes formed at the separation and collapsed ceiling of the box culvert headwall connection

5.6 Culverts Projecting

Photo 23:

Example of projecting outlet with partially filled in pipes.

Photo 24:

In many cases, projecting pipe outlets are located at the bottom of the rock fill.

Photo 25:

Example of projecting outlet where a new stone masonry headwall has been

Photo 26:

There were several cases where pipe separation occurred at the outfall within a rock embankment, however the projecting pipe and surrounding stones on top of the pipe are stable and therefore no rehabilitation measures are recommended.

5.7 Paved Waterways

Photo 27:

Asphalt paved ditch in good condition.

Photo 28:

Asphalt paved ditch with some cracking and vegetation growing in the channel.

Photo 29:

Asphalt paved ditch with a thick layer of vegetation growing within the channel.

Photo 30:

Diverging flume typical at intersections and ramps.

This one located at Aho Gap.

Photo 31:

Paved ditch with underdrain outfall.

Photo 32:

Eroded gully at the end of a paved ditch.

5.8 Non-Paved Waterways

Photo 33:

Eroded gully at outfall channel located at MP 285, Station 31+90 where the channel is several feet lower than headwall. Note the heavy debris and fallen trees at the headwall.

Recommendations include placing riprap at the apron and constructing a gabion or imbricated riprap drop structure to prevent future erosion.

Photo 34:

Example of an eroded outfall channel. Recommend placing either riprap or erosion control matting.

Photo 35:

Example of a rocky outfall channel from a box culvert in good condition.

Photo 36:

Example of outfall channel without positive drainage causing pipe to be half filled with sediment. Recommend cleaning the pipe, excavate the outfall channel for positive drainage, and to recondition ditch and line it with erosion control matting.

Appendix A

Culvert Survey and Evaluation Forms

Appendix B

Paved Waterways and Ditch Evaluation Forms

Appendix C

Hydrologic and Hydraulic Calculations

APPENDIX C

SHEET 8 OF 8

CHART C 200.9

Blue Rigde Parkway - 2F24

Location Designer ZAS MP - 283 Date: 4/8/2014 Station 27+50 Checker: JMB

Date: 5/21/2014 Drainage Area 11.25 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3370.0 feet Low Elevation 3325.0 feet n= 0.4 L= 300 ft So = 0.15 ft/ft P2-24 = 3 inches

Tol 0.40 hours Tol = 24 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

454 3325 3270 55 0.121 N 5.62 1.3

1.3

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 25.2 minutes Tc 0.4 hours Lag 0.25 hours

Shallow Concentrated Flow

Channel Flow

Elevation

MP - 283 Date: 4/8/2014 Station 42+80 Checker: JMB

Date: 5/21/2014 Drainage Area 8.87 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3610.0 feet Low Elevation 3540.0 feet n= 0.4 L= 300 ft So = 0.233333 ft/ft P2-24 = 3 inches

Tol 0.33 hours Tol = 20 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

661 3540 3380 160 0.242 N 7.94 1.4

1.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 21.4 minutes Tc 0.4 hours Lag 0.21 hours

Shallow Concentrated Flow

Elevation

Channel Flow

MP - 284 Date: 4/8/2014 Station 5+25 Checker: JMB

Date: 5/21/2013 Drainage Area 10.78 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3610.0 feet Low Elevation 3545.0 feet n= 0.4 L= 300 ft So = 0.216667 ft/ft P2-24 = 3 inches

Tol 0.34 hours Tol = 21 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

514 3545 3470 75 0.146 N 6.16 1.4

1.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 22.0 minutes Tc 0.4 hours Lag 0.22 hours

Shallow Concentrated Flow

Elevation

MP - 285 Date: 4/8/2014 Station 0+50 Checker: JMB

Date: 5/21/2014 Drainage Area 120.09 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3610.0 feet Low Elevation 3570.0 feet n= 0.4 L= 300 ft So = 0.133333 ft/ft P2-24 = 3 inches

Tol 0.42 hours Tol = 25 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

887 3570 3360 210 0.237 N 7.85 1.9

1.9

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

3364 3360 3265 0.028 5 1.5 1.0 0.05 5.1 11.0

11.0

Tc 37.9 minutes Tc 0.6 hours Lag 0.38 hours

Shallow Concentrated Flow

Elevation

MP - 285 Date: 4/8/2014 Station 11+90 Checker: JMB

Date: 5/21/2014 Drainage Area 7.39 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3285.0 feet Low Elevation 3270.0 feet n= 0.4 L= 300 ft So = 0.05 ft/ft P2-24 = 3 inches

Tol 0.62 hours Tol = 37 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

719 3270 3260 10 0.014 N 1.90 6.3

6.3

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 43.3 minutes Tc 0.7 hours Lag 0.43 hours

Shallow Concentrated Flow

Elevation

MP - 285 Date: 4/8/2014 Station 44+50 Checker: JMB

Date: 5/27/2014 Drainage Area 6.25 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3260.0 feet Low Elevation 3240.0 feet n= 0.4 L= 300 ft So = 0.066667 ft/ft P2-24 = 3 inches

Tol 0.55 hours Tol = 33 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

350 3240 3230 10 0.029 N 2.73 2.1

2.1

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 35.1 minutes Tc 0.6 hours Lag 0.35 hours

Shallow Concentrated Flow

Elevation

MP - 286 Date: 4/8/2014 Station 1+90 Checker: JMB

Date: 5/27/2014 Drainage Area 7.34 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3495.0 feet Low Elevation 3436.0 feet n= 0.4 L= 300 ft So = 0.196667 ft/ft P2-24 = 3 inches

Tol 0.36 hours Tol = 21 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

779 3436 3236 200 0.257 N 8.18 1.6

1.6

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 23.0 minutes Tc 0.4 hours Lag 0.23 hours

Shallow Concentrated Flow

Elevation

MP - 286 Date: 4/8/2014 Station 7+90 Checker: JMB

Date: 5/27/2014 Drainage Area 15.38 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3490.0 feet Low Elevation 3403.0 feet n= 0.4 L= 300 ft So = 0.29 ft/ft P2-24 = 3 inches

Tol 0.31 hours Tol = 18 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

697 3403 3240 163 0.234 N 7.80 1.5

1.5

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 19.8 minutes Tc 0.3 hours Lag 0.20 hours

Shallow Concentrated Flow

Elevation

MP - 286 Date: 4/17/2014 Station 34+55 Checker: JMB

Date: 5/27/2014 Drainage Area 5.47 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3730.0 feet Low Elevation 3675.0 feet n= 0.4 L= 300 ft So = 0.183333 ft/ft P2-24 = 3 inches

Tol 0.37 hours Tol = 22 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

747 3675 3400 275 0.368 N 9.79 1.3

1.3

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 23.3 minutes Tc 0.4 hours Lag 0.23 hours

Shallow Concentrated Flow

Elevation

MP - 287 Date: 4/17/2014 Station 18+55 Checker: JMB

Date: 5/27/2014 Drainage Area 7.59 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3770.0 feet Low Elevation 3735.0 feet n= 0.4 L= 300 ft So = 0.116667 ft/ft P2-24 = 3 inches

Tol 0.44 hours Tol = 26 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

673 3735 3560 175 0.260 N 8.23 1.4

1.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 27.7 minutes Tc 0.5 hours Lag 0.28 hours

Shallow Concentrated Flow

Elevation

MP - 287 Date: 4/17/2014 Station 20+70 Checker: JMB

Date: 5/27/2014 Drainage Area 12.3 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3770.0 feet Low Elevation 3735.0 feet n= 0.4 L= 300 ft So = 0.116667 ft/ft P2-24 = 3 inches

Tol 0.44 hours Tol = 26 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

718 3735 3570 165 0.230 N 7.73 1.5

1.5

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 27.9 minutes Tc 0.5 hours Lag 0.28 hours

Shallow Concentrated Flow

Elevation

MP - 287 Date: 4/17/2014 Station 28+50 Checker: JMB

Date: 5/27/2014 Drainage Area 132.64 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 4050.0 feet Low Elevation 4005.0 feet n= 0.4 L= 300 ft So = 0.15 ft/ft P2-24 = 3 inches

Tol 0.40 hours Tol = 24 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

2043 4005 3685 320 0.157 N 6.39 5.3

5.3

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

1387 3685 3630 0.040 10 1.5 1.2 0.055 6.0 3.9

3.9

Tc 33.1 minutes Tc 0.6 hours Lag 0.33 hours

Shallow Concentrated Flow

Elevation

MP - 287 Date: 4/17/2014 Station 43+40 Checker: JMB

Date: 5/27/2014 Drainage Area 59.66 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 4050.0 feet Low Elevation 4005.0 feet n= 0.4 L= 300 ft So = 0.15 ft/ft P2-24 = 3 inches

Tol 0.40 hours Tol = 24 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

1915 4005 3690 315 0.164 N 6.54 4.9

4.9

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 28.7 minutes Tc 0.5 hours Lag 0.29 hours

Shallow Concentrated Flow

Elevation

MP - 287 Date: 4/17/2014 Station 56+65 Checker: JMB

Date: 5/27/2014 Drainage Area 14.84 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3740.0 feet Low Elevation 3715.0 feet n= 0.4 L= 300 ft So = 0.083333 ft/ft P2-24 = 3 inches

Tol 0.50 hours Tol = 30 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

763 3715 3695 20 0.026 N 2.61 4.9

4.9

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 35.0 minutes Tc 0.6 hours Lag 0.35 hours

Shallow Concentrated Flow

Elevation

MP - 288 Date: 4/17/2014 Station 9+60 Checker: JMB

Date: 5/28/2014 Drainage Area 13.35 acres copy

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3890.0 feet Low Elevation 3845.0 feet n= 0.4 L= 300 ft So = 0.15 ft/ft P2-24 = 3 inches

Tol 0.40 hours Tol = 24 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

1393 3845 3695 150 0.108 N 5.29 4.4

4.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 28.2 minutes Tc 0.5 hours Lag 0.28 hours

Shallow Concentrated Flow

Elevation

MP - 288 Date: 4/17/2014 Station 12+00 Checker: JMB

Date: 5/28/2014 Drainage Area 45.07 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3960.0 feet Low Elevation 3890.0 feet n= 0.4 L= 300 ft So = 0.233333 ft/ft P2-24 = 3 inches

Tol 0.33 hours Tol = 20 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

1855 3890 3688 202 0.109 N 5.32 5.8

5.8

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 25.8 minutes Tc 0.4 hours Lag 0.26 hours

Shallow Concentrated Flow

Elevation

MP - 288 Date: 4/17/2014 Station 18+35 Checker: JMB

Date: 5/28/2014 Drainage Area 165.79 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 4090.0 feet Low Elevation 4065.0 feet n= 0.4 L= 300 ft So = 0.083333 ft/ft P2-24 = 3 inches

Tol 0.50 hours Tol = 30 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

1373 4065 3716 349 0.254 N 8.13 2.8

2.8

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

1423 3716 3670 0.032 5 1.5 1.0 0.055 5.0 4.8

4.8

Tc 37.8 minutes Tc 0.6 hours Lag 0.38 hours

Shallow Concentrated Flow

Elevation

MP - 288 Date: 4/17/2014 Station 18+35 Checker: JMB

Date: 5/28/2014 Drainage Area 165.79 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3810.0 feet Low Elevation 3785.0 feet n= 0.4 L= 300 ft So = 0.083333 ft/ft P2-24 = 3 inches

Tol 0.50 hours Tol = 30 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

497 3785 3715 70 0.141 N 6.06 1.4

1.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 31.5 minutes Tc 0.5 hours Lag 0.32 hours

Shallow Concentrated Flow

Elevation

MP - 289 Date: 4/17/2014 Station 8+20 Checker: JMB

Date: 5/28/2014 Drainage Area 5.03 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3850.0 feet Low Elevation 3825.0 feet n= 0.4 L= 300 ft So = 0.083333 ft/ft P2-24 = 3 inches

Tol 0.50 hours Tol = 30 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

447 3825 3785 40 0.089 N 4.83 1.5

1.5

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc ######## minutes Tc 0.5 hours Lag 0.32 hours

Shallow Concentrated Flow

Elevation

MP - 290 Date: 4/17/2014 Station 33+25 Checker: JMB

Date: 5/28/2014 Drainage Area 5.48 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3850.0 feet Low Elevation 3830.0 feet n= 0.4 L= 300 ft So = 0.066667 ft/ft P2-24 = 3 inches

Tol 0.55 hours Tol = 33 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

411 3830 3820 10 0.024 n 2.52 2.7

2.7

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 35.7 minutes Tc 0.6 hours Lag 0.36 hours

Shallow Concentrated Flow

Elevation

MP - 290 Date: 4/17/2014 Station 48+05 Checker: JMB

Date: 5/28/2014 Drainage Area 5.08 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3850.0 feet Low Elevation 3800.0 feet n= 0.4 L= 300 ft So = 0.166667 ft/ft P2-24 = 3 inches

Tol 0.38 hours Tol = 23 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

481 3800 3790 10 0.021 N 2.33 3.4

3.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 26.3 minutes Tc 0.4 hours Lag 0.26 hours

Shallow Concentrated Flow

Elevation

MP - 291 Date: 4/17/2014 Station 11+25 Checker: JMB

Date: 5/28/2014 Drainage Area 5.16 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3860.0 feet Low Elevation 3805.0 feet n= 0.4 L= 300 ft So = 0.183333 ft/ft P2-24 = 3 inches

Tol 0.37 hours Tol = 22 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

523 3805 3670 135 0.258 N 8.20 1.1

1.1

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 23.1 minutes Tc 0.4 hours Lag 0.23 hours

Shallow Concentrated Flow

Elevation

MP - 291 Date: 4/17/2014 Station 21+50 Checker: JMB

Date: 5/28/2014 Drainage Area 95.41 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3850.0 feet Low Elevation 3840.0 feet n= 0.4 L= 300 ft So = 0.033333 ft/ft P2-24 = 3 inches

Tol 0.73 hours Tol = 44 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

1159 3840 3580 260 0.224 N 7.64 2.5

2.5

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

308 3580 3555 0.081 5 1.5 1.0 0.055 7.8 0.7

0.7

Tc 46.7 minutes Tc 0.8 hours Lag 0.47 hours

Shallow Concentrated Flow

Elevation

MP - 291 Date: 4/17/2014 Station 33+85 Checker: JMB

Date: 5/28/2014 Drainage Area 8.65 acres

Time of Concentration

Tr 55 Methodology *All Elevatons are estimated from USGS Quad Maps

Overland Flow Component

Overland Flow Elevation High Elevation 3605.0 feet Low Elevation 3558.0 feet n= 0.4 L= 300 ft So = 0.156667 ft/ft P2-24 = 3 inches

Tol 0.39 hours Tol = 23 min

Paved y Unpaved no

L H So Paved Velocity Ttravel ft Upper Lower ft ft/ft ft/sec min

680 3558 3500 58 0.085 N 4.71 2.4

2.4

L So Bw Depth R @ z=2:1 n Velocity Ttravel ft Upper Lower ft/ft ft ft ft/sec min

0.0

Tc 25.8 minutes Tc 0.4 hours Lag 0.26 hours

Shallow Concentrated Flow

Elevation

Blue Ridge Parkway - 2F24

USGS REGRESSION EQUATION (Per WRI 4207) Low Standard Road (25-Year Flood) Hydrologic Area - Blue Ridge-Piedmont

Location

MP - 285

Station - 51+50

Q25 = 476DA0.645

DA = 646.83 Acres (From USGS Quad Maps) = 1.01 Square Miles

Q25 = 479.27 CFS

Low Standard Road (25-Year Flood) Hydrologic Area - Blue Ridge-Piedmont

Location

MP - 286

Station - 37+00

Q25 = 476DA0.645

DA = 876.78 Acres (From USGS Quad Maps) = 1.37 Square Miles

Q25 = 583.16 CFS

Low Standard Road (25-Year Flood) Hydrologic Area - Blue Ridge-Piedmont

Location

MP - 286

Station - 43+00

Q25 = 476DA0.645

DA = 863.30 Acres (From USGS Quad Maps) = 1.35 Square Miles

Q25 = 577.36 CFS

Low Standard Road (25-Year Flood) Hydrologic Area - Blue Ridge-Piedmont

Location

MP - 286

Station - 50+00

Q25 = 476DA0.645

DA = 324.04 Acres (From USGS Quad Maps) = 0.51 Square Miles

Q25 = 306.87 CFS

Blue Ridge 2F24 - Culvert Flow Culvert Design 6/19/2014

National Park Service By: ZAS Blue Ridge Parkway - PRA BLRI 2F24 Date 4/21/2014

Checked PGD Date 6/16/2014

Culvert Design Calculations Checked JMB 25 - Year Design Event using the FHWA inlet control equations per HDS-5 for grooved end and headwall conditions Date 6/16/2014

Outlet control calculated using full flow velocities and Manning's equation with a C= 0.35 1.5 exit/entrance loss coefficient Manning's "n"= 0.013

Structure Number Mile Post Station

Inlet Type Side

Drainage Area

(acres) Tc

(min)

Rainfall Intensity (in/hr) Q (cfs)

Pipe Size

(in) Pipe n

Invert @ Upstream

(ft)

Invert @ Downstream

(ft) Length

(ft) Estimated

So % D ft Span Q

Capacity Q/Qcap = d/D Ynormal ft

Pipe velocity

(ft/s) Span W

(ft) Depth D

(ft) Inlet Cond HW/D

HW inlet control

HW outlet control

HW

Maximum

1 283 8+12 DI RT 1.49 10.0 5.75 3.0 18 0.013 3271.12 3264.50 47.0 14.09% 1.50 40 0.08 0.28 13.2 2 0.62 0.93 -6.24 0.93 2 283 9+75 DI RT 0.68 10.0 5.75 1.4 18 0.013 3268.77 3236.16 96.0 33.97% 1.50 61 0.02 0.15 14.2 2 0.4 0.60 -32.43 0.60 3 283 15+80 HW RT 3.06 10.0 5.75 6.2 18 0.013 unk unk unk unk 1.50 unk unk unk unk 2 1.0 1.47 unk 1.47 4 283 20+60 HW LT 1.9 10.0 5.75 3.8 18 0.013 3258.90 3254.71 58.0 7.22% 1.50 28 0.14 0.37 11.2 2 0.7 1.08 -3.63 1.08 5 283 24+50 DI LT 2.0 10.0 5.75 4.0 18 0.013 3262.52 3261.41 47.0 2.36% 1.50 16 0.25 0.51 7.6 2 0.7 1.12 -0.41 1.12 6 283 27+50 HW LT 11.3 25.2 3.75 14.8 24 0.013 3269.61 3266.96 62.0 4.27% 2.00 47 0.31 0.77 13.2 2 1.06 2.13 -1.10 2.13 7 283 33+34 DI LT 1.3 10.0 5.75 2.5 18 0.013 3310.11 3309.60 43.0 1.19% 1.50 11 0.22 0.48 5.2 2 0.6 0.84 0.04 0.84 8 283 36+54 DI LT 1.1 10.0 5.75 2.2 18 0.013 3330.69 3328.31 44.0 5.41% 1.50 24 0.09 0.31 8.6 2 0.5 0.79 -2.02 0.79 9 283 42+80 HW RT 8.9 21.4 4.00 12.4 24 0.013 3367.75 3307.08 160.0 37.92% 2.00 140 0.09 0.40 27.5 2 1.0 1.93 -59.42 1.93

10 283 52+17 HW RT 4.7 10.0 5.75 9.4 Box 0.013 3428.02 3336.09 238.0 38.63% 2.00 2.00 179 0.05 0.21 22.3 2.0 2.0 1 0.7 1.45 -91.33 1.45 11 284 5+25 HW RT 10.8 22.0 3.95 14.9 Box 0.013 3476.42 3450.27 155.0 16.87% 2.50 3.00 274 0.05 0.28 17.9 3.0 2.5 1 0.6 1.50 -25.70 1.50 12 284 11+75 DI LT 1.6 10.0 5.75 3.1 18 0.013 3487.46 3482.47 57.0 8.75% 1.50 31 0.10 0.32 11.3 2 0.6 0.95 -4.55 0.95 13 284 17+00 HW LT 4.1 10.0 5.75 8.3 18 0.013 3437.19 3402.52 145.0 23.91% 1.50 52 0.16 0.41 21.4 2 1.2 1.75 -32.86 1.75 14 284 26+25 DI RT 1.9 10.0 5.75 3.8 18 0.013 3384.30 3377.77 51.0 12.80% 1.50 38 0.10 0.32 13.7 2 0.7 1.08 -6.03 1.08 15 284 36+40 HW LT 1.0 10.0 5.75 2.1 18 0.013 3332.86 3319.36 89.0 15.17% 1.50 41 0.05 0.23 12.1 2 0.5 0.75 -13.20 0.75 16 284 39+25 DI LT 1.3 10.0 5.75 2.6 18 0.013 3333.73 3326.89 50.0 13.68% 1.50 39 0.07 0.26 12.5 2 0.6 0.86 -6.50 0.86 17 284 41+50 DI LT 1.1 10.0 5.75 2.3 18 0.013 3325.12 3320.45 50.0 9.34% 1.50 32 0.07 0.27 10.5 2 0.5 0.79 -4.34 0.79 18 284 46+10 DIR LT 1.2 10.0 5.75 2.5 18 0.013 3299.22 3293.91 53.0 10.02% 1.50 33 0.07 0.28 11.1 2 0.6 0.83 -4.96 0.83 19 285 0+50 HW RT 120.1 37.9 2.95 124 Box 0.013 3259.36 3258.45 62.0 1.47% 5.00 6.00 512 0.24 1.49 13.9 6.0 5.0 1 0.8 3.88 1.03 3.88 20 285 4+25 DIR RT 1.9 10.0 5.75 3.8 18 0.013 3262.17 3257.72 62.0 7.18% 1.50 28 0.14 0.37 11.2 2 0.7 1.08 -3.89 1.08 21 285 6+85 DIR RT 1.7 10.0 5.75 3.3 18 0.013 3260.59 3259.63 47.0 2.04% 1.50 15 0.22 0.48 6.8 2 0.7 0.99 -0.35 0.99 22 285 11+90 DIR RT 7.4 43.3 2.85 7.4 18 0.013 3258.15 3257.17 42.0 2.33% 1.50 16 0.46 0.71 8.9 2 1.1 1.62 0.34 1.62 23 285 31+90 DI RT 4.5 10.0 5.75 9.0 18 0.013 3237.07 3235.20 51.0 3.67% 1.50 20 0.44 0.70 11.1 2 1.2 1.86 -0.20 1.86 24 285 37+00 HW RT 4.2 10.0 5.75 8.5 18 0.013 3215.75 3214.48 61.0 2.08% 1.50 15 0.56 0.80 8.8 2 1.2 1.79 0.47 1.79 25 285 44+50 HW RT 6.3 35.1 3.10 6.8 18 0.013 3205.74 3204.01 71.0 2.44% 1.50 16 0.41 0.67 8.9 2 1.0 1.54 -0.42 1.54 26 285 51+50 HW LT 240 Dbl Box 0.013 3197.36 3196.45 61.0 1.49% 5.00 6.00 516 0.46 2.37 16.9 6.0 5.0 1 1.20 6.02 3.14 6.02 26 285 51+50 HW LT 240 Dbl Box 0.013 3197.21 3196.76 61.0 0.74% 5.00 6.00 363 0.66 3.07 13.0 6.0 5.0 1 1.2 6.02 4.30 6.02 27 286 1+90 DI LT 7.3 23.0 3.90 10.0 18 0.013 3222.09 3210.30 76.0 15.51% 1.50 41 0.24 0.50 19.3 2 1.4 2.05 -9.85 2.05 28 286 4+55 DI LT 3.1 10.0 5.75 6.1 18 0.013 3221.78 3209.86 59.0 20.20% 1.50 47 0.13 0.36 18.5 2 1.0 1.46 -11.07 1.46 29 286 7+90 HW LT 15.4 19.8 4.30 23.1 24 0.013 3232.45 3225.01 64.0 11.62% 2.00 77 0.30 0.75 21.5 2 1.5 3.07 -4.76 3.07 30 286 24+70 DI RT 3.2 10.0 5.75 6.4 18 0.013 3309.83 3306.31 47.0 7.49% 1.50 29 0.22 0.48 13.1 2 1.0 1.50 -2.57 1.50 31 286 29+60 DI RT 2.3 10.0 5.75 4.5 18 0.013 3348.28 3346.21 37.0 5.59% 1.50 25 0.18 0.43 10.7 2 0.8 1.20 -1.41 1.20 32 286 32+00 DIR RT 1.5 10.0 5.75 3.0 18 0.013 3366.75 3363.38 45.0 7.49% 1.50 29 0.10 0.32 10.5 2 0.6 0.92 -2.94 0.92 33 286 34+55 DI RT 5.5 23.3 3.89 7.4 24 0.013 3386.51 3385.51 44.0 2.27% 2.00 34 0.22 0.63 8.7 2 0.7 1.39 -0.19 1.39

Formulas for Q, Inlet and Outlet Control

Input Check

Structure Pipes Box Culvert

Q total = 479 cfs USGS Regression647.0

Blue Ridge Parkway - PRA BLRI 2F24 Date 4/21/2014

Checked PGD Date 6/16/2014

Culvert Design Calculations Checked JMB 25 - Year Design Event using the FHWA inlet control equations per HDS-5 for grooved end and headwall conditions Date 6/16/2014

Outlet control calculated using full flow velocities and Manning's equation with a C= 0.35 1.5 exit/entrance loss coefficient Manning's "n"= 0.013

Structure Number Mile Post Station

Inlet Type Side

Drainage Area

(acres) Tc

(min)

Rainfall Intensity (in/hr) Q (cfs)

Pipe Size

(in) Pipe n

Invert @ Upstream

(ft)

Invert @ Downstream

(ft) Length

(ft) Estimated

So % D ft Span Q

Capacity Q/Qcap = d/D Ynormal ft

Pipe velocity

(ft/s) Span W

(ft) Depth D

(ft) Inlet Cond HW/D

HW inlet control

HW outlet control

HW

Maximum

Formulas for Q, Inlet and Outlet Control

Input Check

Structure Pipes Box Culvert

34 286 37+00 HW RT 292 Dbl Box 0.013 3397.99 3397.14 44.0 1.93% 8.00 10.00 2170 0.13 1.61 18.1 10.0 8.0 1 0.6 4.88 1.08 4.88 34 286 37+00 HW 292 0.013 3398.49 3397.36 43.0 2.63% 8.00 10.00 2531 0.12 1.45 20.1 10.0 8.0 1 0.6 4.88 0.65 4.88 35 286 43+00 HW LT 289 Dbl Box 0.013 3427.95 3427.52 49.0 0.88% 8.00 10.00 1463 0.20 2.08 13.9 10.0 8.0 1 0.6 4.85 1.97 4.85 35 286 43+00 HW 289 0.013 3428.02 3427.60 47.0 0.89% 8.00 10.00 1476 0.20 2.07 14.0 10.0 8.0 1 0.6 4.85 1.97 4.85 36 286 50+00 HW RT 153 Dbl Box 0.013 3448.25 3444.12 111.0 3.72% 5.00 8.00 1179 0.13 1.00 19.1 8.0 5.0 1 0.7 3.69 -2.71 3.69 36 286 50+00 HW 153 0.013 3448.86 3444.43 110.0 4.03% 5.00 8.00 1226 0.13 0.98 19.6 8.0 5.0 1 0.7 3.69 -3.04 3.69 37 286 53+70 HW LT 3.5 10.0 5.75 7.1 18 0.013 3471.03 3468.14 66.0 4.38% 1.50 22 0.32 0.58 11.1 2 1.1 1.58 -1.63 1.58 38 287 2+80 DIR LT 2.7 10.0 5.75 5.5 18 0.013 3496.96 3495.55 50.0 2.82% 1.50 18 0.31 0.57 8.8 2 0.9 1.35 -0.48 1.35 39 287 6+10 DIR LT 2.4 10.0 5.75 4.9 18 0.013 3517.02 3514.87 42.0 5.12% 1.50 24 0.21 0.46 10.6 2 0.8 1.26 -1.42 1.26 40 287 8+40 DIR LT 1.0 10.0 5.75 1.9 18 0.013 3525.26 3519.43 51.0 11.43% 1.50 36 0.05 0.24 10.8 2 0.5 0.73 -5.55 0.73 41 287 8+90 DIR LT 3.8 10.0 5.75 7.7 24 0.013 3527.92 3525.07 44.0 6.48% 2.00 58 0.13 0.49 12.8 2 0.7 1.42 -2.17 1.42 42 287 10+50 DIR LT 2.4 10.0 5.75 4.8 18 0.013 3532.08 3521.39 62.0 17.24% 1.50 44 0.11 0.34 16.3 2 0.8 1.24 -10.06 1.24 43 287 11+70 DIR LT 3.6 10.0 5.75 7.2 18 0.013 3536.09 3523.67 56.0 22.18% 1.50 50 0.15 0.39 20.0 2 1.1 1.60 -11.38 1.60 44 287 15+15 DIR LT 1.8 10.0 5.75 3.7 18 0.013 3544.11 3539.03 48.0 10.58% 1.50 34 0.11 0.33 12.6 2 0.7 1.05 -4.59 1.05 45 287 17+45 DIR LT 0.7 10.0 5.75 1.3 24 0.013 3551.13 3546.17 58.0 8.55% 2.00 66 0.02 0.19 8.3 2 0.3 0.54 -4.76 0.54 46 287 18+55 HW LT 7.6 27.7 3.60 9.6 18 0.013 3550.51 3548.65 85.0 2.19% 1.50 16 0.61 0.85 9.3 2 1.3 1.97 0.37 1.97 47 287 20+70 HW LT 12.3 27.9 3.59 15.5 30 0.013 unk unk unk unk 2.50 unk unk unk unk 2 0.8 1.93 unk unk 48 287 28+50 HW LT 132.6 33.1 3.15 146.2 Box 0.013 3622.20 3618.51 110.0 3.35% 5.00 8.00 1119 0.13 1.01 18.2 8.0 5.0 1 0.7 3.57 -2.31 3.57 49 287 36+45 DI RT 2.9 10.0 5.75 5.8 24 0.013 3669.99 3647.36 65.0 34.82% 2.00 134 0.04 0.28 21.2 2 0.6 1.19 -22.23 1.19 50 287 40+15 DI RT 1.5 10.0 5.75 3.0 18 0.013 3672.14 3664.19 51.0 15.59% 1.50 42 0.07 0.27 13.6 2 0.6 0.93 -7.57 0.93 51 287 43+40 HW RT 59.7 28.7 3.55 74.1 Box 0.013 3671.42 3669.48 67.0 2.90% 4.00 5.00 418 0.18 0.97 15.3 5.0 4.0 1 0.8 3.11 -0.59 3.11 52 287 46+65 HW RT 14.8 35.0 3.00 15.6 18 0.013 3685.62 3682.34 67.0 4.90% 1.50 23 0.67 0.90 14.1 2 2.3 3.38 0.89 3.38 53 288 9+60 DI LT 13.4 28.2 3.58 16.7 18 0.013 unk unk unk unk 1.50 unk unk unk unk 2 2.5 3.73 unk unk 54 288 12+00 HW LT 45.1 25.8 3.72 58.7 Box 0.013 3685.61 3681.62 78.0 5.12% 4.00 5.00 556 0.11 0.68 17.1 5.0 4.0 1 0.7 2.66 -3.06 2.66 55 288 18+35 HW LT 82.4 37.8 2.96 85.3 Box 0.013 3665.90 3664.98 52.0 1.77% 4.00 5.00 327 0.26 1.26 13.5 5.0 4.0 1 0.9 3.42 0.83 3.42 56 288 37+20 HW RT 5.5 31.5 3.30 6.3 24 0.013 3712.36 3705.43 55.0 12.60% 2.00 81 0.08 0.38 15.3 2 0.6 1.26 -6.41 1.26 57 289 1+60 DI RT 1.6 10.0 5.75 3.2 18 0.013 3732.98 3731.76 46.0 2.65% 1.50 17 0.19 0.44 7.4 2 0.6 0.96 -0.67 0.96 58 289 4+60 DI RT 1.8 10.0 5.75 3.7 18 0.013 3750.66 3749.24 43.0 3.30% 1.50 19 0.19 0.44 8.4 2 0.7 1.05 -0.82 1.05 59 289 8+20 HW RT 5.0 31.7 3.25 5.7 24 0.013 3769.82 3767.27 52.0 4.90% 2.00 50 0.11 0.46 10.6 2 0.6 1.19 -1.98 1.19 60 289 16+60 DI RT 2.0 10.0 5.75 4.0 18 0.013 3809.25 3807.84 42.0 3.36% 1.50 19 0.21 0.47 8.6 2 0.7 1.12 -0.76 1.12 61 289 23+85 HW RT 2.1 10.0 5.75 4.1 18 0.013 3820.87 3807.11 78.0 17.64% 1.50 44 0.09 0.31 15.7 2 0.8 1.13 -13.20 1.13 62 289 35+55 DI LT 4.2 10.0 5.75 8.5 18 0.013 3817.51 3810.98 51.0 12.80% 1.50 38 0.23 0.48 17.2 2 1.2 1.78 -5.18 1.78 63 290 7+85 DIR RT 1.0 10.0 5.75 2.1 18 0.013 3818.60 3817.67 38.0 2.45% 1.50 16 0.12 0.36 6.4 2 0.5 0.75 -0.53 0.75 64 290 11+20 DI RT 0.9 10.0 5.75 1.8 18 0.013 3795.66 3729.20 137.0 48.51% 1.50 73 0.02 0.16 17.5 2 0.5 0.70 -66.23 0.70 65 290 19+75 DI RT 0.5 10.0 5.75 1.0 18 0.013 3776.80 3775.49 41.0 3.20% 1.50 19 0.05 0.23 5.6 2 0.3 0.50 -1.07 0.50

Q total = 583 cfs USGS Regression Q total = 577 cfs

USGS Regression Q total = 307 cfs

USGS Regression

Blue Ridge Parkway - PRA BLRI 2F24 Date 4/21/2014

Checked PGD Date 6/16/2014

Culvert Design Calculations Checked JMB 25 - Year Design Event using the FHWA inlet control equations per HDS-5 for grooved end and headwall conditions Date 6/16/2014

Outlet control calculated using full flow velocities and Manning's equation with a C= 0.35 1.5 exit/entrance loss coefficient Manning's "n"= 0.013

Structure Number Mile Post Station

Inlet Type Side

Drainage Area

(acres) Tc

(min)

Rainfall Intensity (in/hr) Q (cfs)

Pipe Size

(in) Pipe n

Invert @ Upstream

(ft)

Invert @ Downstream

(ft) Length

(ft) Estimated

So % D ft Span Q

Capacity Q/Qcap = d/D Ynormal ft

Pipe velocity

(ft/s) Span W

(ft) Depth D

(ft) Inlet Cond HW/D

HW inlet control

HW outlet control

HW

Maximum

Formulas for Q, Inlet and Outlet Control

Input Check

Structure Pipes Box Culvert

66 290 23+50 DI RT 1.0 10.0 5.75 1.9 18 0.013 3797.82 3794.92 67.0 4.33% 1.50 22 0.09 0.30 7.6 2 0.5 0.73 -2.55 0.73 67 290 28+30 DI RT 0.5 10.0 5.75 1.0 18 0.013 3818.03 3807.17 57.0 19.05% 1.50 46 0.02 0.15 10.6 2 0.3 0.51 -10.69 0.51 68 290 33+25 HW RT 5.5 35.7 3.05 5.8 18 0.013 3812.85 3799.66 94.0 14.03% 1.50 39 0.15 0.39 16.0 2 0.9 1.42 -12.26 1.42 69 290 41+45 HW RT 2.2 10.0 5.75 4.4 18 0.013 3785.37 3781.24 60.0 6.88% 1.50 28 0.16 0.40 11.4 2 0.8 1.17 -3.48 1.17 70 290 44+65 HW RT 3.0 10.0 5.75 6.0 18 0.013 3769.80 3754.24 91.0 17.10% 1.50 44 0.14 0.38 17.3 2 1.0 1.15 -14.62 1.15 71 290 48+05 DI RT 2.1 10.0 5.75 4.2 18 0.013 3768.55 3763.08 50.0 10.94% 1.50 35 0.12 0.35 13.3 2 0.8 1.15 -4.90 1.15 72 291 3+95 DI LT 4.3 10.0 5.75 8.6 30 0.013 3720.19 3714.91 51.0 10.35% 2.50 132 0.07 0.43 15.2 2 0.5 1.37 -4.75 1.37 73 291 7+35 DI LT 4.6 10.0 5.75 9.3 18 0.013 3693.27 3676.04 66.0 26.11% 1.50 54 0.17 0.42 22.8 2 1.3 1.92 -15.65 1.92 74 291 11+25 DI LT 5.2 23.1 3.89 7.0 24 0.013 3663.03 3652.50 58.0 18.16% 2.00 97 0.07 0.36 17.9 2 0.7 1.34 -9.99 1.34 75 291 14+00 DI LT 4.1…