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Home My WebLink AboutSW5190201_2019-06-19 Site Plan Stormwater Report_7/16/2019DEVELOPMENT -ENU NEE N NGfl O NC. Pro f e s s i o n a l E n g i n e e r i n g C o n s u/ t o n t s Stormwater Management Report 1-Year & 10-Year Storm For Cambridge Southeast Estates Mobile Home Park 265 Hamp Stone Road Siler City, NC September 7, 2018 Revised: February 27, 2019 Revised: June 19, 2019 06-19-19 Prepared By: David H. Blevins, P.E. Development Engineering, Inc. 244 W. Millbrook Rd. Raleigh, NC 27609 (919) 847-8300 www.d-e-inc.com 244 W, Millbrook Rood, Roleigh, NC 27609 Phone: 919-847-3300 P. 0. Box 17705, Roleigh, NC 27619 FAX 919-847-2130 Abstract This is a 25.71 acre mobile home park site at 265 Hamp Stone Road. The property is on the south side of Hamp Stone Road (SR 1108) approximately 0.95 miles south of the intersection of SR 1108 (Hamp Stone Road) and Old US 421 N. An existing creek (Blood Run Creek) divides the property in half. The property is partially developed. The property drains to the existing creek. The portion of the property on the north side of the creek has been developed with a private street (Hyatt Ct) and 32 existing mobile home units. The portion of the property along the south side of the creek will be developed with this plan. The existing impervious area is 2.07 acres. For the stormwater calculations the existing impervious surface area for the Cambridge Southeast property (2.07 acres) has been subtracted from the total site area. The net property area for the calculations is 23.64 acres. Access to the south side of the creek site will be via the existing private street Santa Fe Court. The adjoining property is the existing Country Living Estates Mobile Home Park owned by Van Ness Apartments, LLC. The proposed new impervious surface area for the Cambridge Southeast property is 1.64 acres. The post development site is 6.94 % impervious. The impervious percentage for the site does not exceed the Town of Siler maximum of 7.0 % impervious. Therefore, the Town does not require stormwater detention for the peak discharge. The proposed new impervious surface area on the Country Living Estates development is 0.16 acres. The Country Living Estates property area is 25.68 acres. The existing impervious is 5.18 acres. For the stormwater calculations the existing impervious surface area for the Country Living Estate development (5.18 acres) has been subtracted from the total site area. The net property area for the calculations is 20.50 acres. The Country Living Estates post development site is 0.78 % impervious. The impervious percentage for the site does not exceed the Town of Siler maximum of 7.0 % impervious. Therefore, the Town does not require stormwater detention for the peak discharge. The rational method is used for the pre and post development calculations. Cambridge Southeast Estates Summary of Calculations - Peak Discharge for the 1 and 10 year storms Rational Method Drainage Area Pre -Development - 23.64 Acres Q, = 23.98 cfs Q, o = 37.54 cfs Drainage Area Post -Development - 23.64 Acres Q, = 29.42 cfs Q, o =46.08 cfs C=0.22 for pervious/grass (23.64 Ac) C=0.95 for impervious (0.00 Ac) C= C composite = 0.22 I,=4.61 in/hr, I,o=7.22 in/hr. A= 23.64 ac. C=0.22 for pervious/grass (22.00 Ac) C=0.95 for impervious (1.64 Ac) C= C composite = 0.27 I,=4.61 in/hr, I,o=7.22 in/hr A= 23.64 ac. Peak Post Development Discharge Summary Pre -Development Post Development Q1 = 23.98 cfs Q1 = 29.42 cfs - 22.7% increase Qio = 37.54 cfs Qio = 46.08 cfs - 22.7% increase Country Living Estates Summary of Calculations - Peak Discharge for the 1 and 10 year storms Rational Method Drainage Area Pre -Development - 20.50 Acres Q, = 20.79 cfs Qio = 32.56 cfs Drainage Area Post -Development - 20.50 Acres Q, = 21.74 cfs Qio =34.04 cfs C=0.22 for pervious/grass (20.50 Ac) C=0.95 for impervious (0.00 Ac) C= C composite = 0.22 I,=4.61 in/hr, I,o=7.22 in/hr. A= 20.50 ac. C=0.22 for pervious/grass (20.34 Ac) C=0.95 for impervious (0.16 Ac) C= C composite = 0.23 I,=4.61 in/hr, I,o=7.22 in/hr A= 20.50 ac. Peak Post Development Discharge Summary Pre -Development Post Development Q1 = 20.79 cfs Q1 = 21.74 cfs - 4.5% increase Quo = 32.56 cfs Qio = 34.04 cfs - 4.5% increase Conclusion The site development meets the Town of Siler built upon area (BUA) allowance of 7%. The site is also under the NCDEQ threshold of 30% BUA for a Low Density development. See enclosed calculations for each rip rap apron design. User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #1 Total Drainage Area (acres) 0.57 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 1.59 Velocity (ft./s) 8.3 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #2 Total Drainage Area (acres) 1.59 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 4.43 Velocity (ft./s) 5.5 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 4 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 5.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #3 Total Drainage Area (acres) 0.72 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 2.15 Velocity (ft./s) 8.3 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #4 Total Drainage Area (acres) 0.4 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 1.27 Velocity (ft./s) 8.3 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #5 Total Drainage Area (acres) 0.29 Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailw•ater depth is less than half the outlet pipe diameter. it is classified minimum tailwater condition_ Lfit is greater than half the pipe diameter, it is classified maximum condition_ Pipes that outlet onto 'Wide flat areas with no defined channel are assumed to have a mm- u- niiml tailw•ater condition unless reliable flood stage elevatiarrs shoe otherwise_ Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Q10 Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 0.88 8.9 Step ?. Based on the tailwater conditions determined in step 1; enter Figure 8_46a or Figure 8_06b, and determine d50 riprap size and mininntm apron length (L). The d, size is the median stone size in a well -graded riprap apron_ Step 3. Detemiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end front the same figure used im Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Figure 8.06a 0.33 3 3.75 Maximum TW Figure 8.06b 3.75 Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaximum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.495 Step 5. Detemune the apron thickness - Apron thickness = '1.5 x d,,. ,. Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 0.7425 0 Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #6 Total Drainage Area (acres) 0.18 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Q10 Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 0.44 9.5 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Figure 8.06a 0.33 3 3.75 Maximum TW Figure 8.06b 3.75 Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaximum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.495 Step 5. Detemune the apron thickness - Apron thickness = '1.5 x d,,. ,. Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 0.7425 0 Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #7 Total Drainage Area (acres) 0.07 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Q10 Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 0.11 6.3 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Figure 8.06a 0.33 3 3.75 Maximum TW Figure 8.06b 3.75 Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaximum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.495 Step 5. Detemune the apron thickness - Apron thickness = '1.5 x d,,. ,. Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 0.7425 0 Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #8 Total Drainage Area (acres) 0.06 Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailw•ater depth is less than half the outlet pipe diameter. it is classified minimum tailwater condition_ Lfit is greater than half the pipe diameter, it is classified maximum condition_ Pipes that outlet onto 'Wide flat areas with no defined channel are assumed to have a mm- u- niiml tailw•ater condition unless reliable flood stage elevatiarrs shoe otherwise_ Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Q10 Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 0.15 9.5 Step ?. Based on the tailwater conditions determined in step 1; enter Figure 8_46a or Figure 8_06b, and determine d50 riprap size and mininntm apron length (L). The d, size is the median stone size in a well -graded riprap apron_ Step 3. Detemiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end front the same figure used im Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Figure 8.06a 0.33 3 3.75 Maximum TW Figure 8.06b 3.75 Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaximum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.495 Step 5. Detemune the apron thickness - Apron thickness = '1.5 x d,,. ,. Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 0.7425 0 Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #9 Total Drainage Area (acres) 0.23 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 0.84 Velocity (ft./s) 8.3 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #10 Total Drainage Area (acres) 0.35 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 1.29 Velocity (ft./s) 8.9 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #11 Total Drainage Area (acres) 0.53 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 1.84 Velocity (ft./s) 8.9 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #12 Total Drainage Area (acres) 0.62 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 2.15 Velocity (ft./s) 10 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 3 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 4.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #13 Total Drainage Area (acres) 0.78 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 2.66 Velocity (ft./s) 10 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 4 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 5.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: T Harrell Date: 2/25/2019 Checked By: D Blevins Date: 2/25/2019 Company: DEI Project Name: Cambridge Southeast Project No.: 16-154 Site Location (City/Town) Siler City Culvert Id. Driveway Pipe #14 Total Drainage Area (acres) 0.94 ,Step 1. Determine the tailwater depth front channel characteristics below the pipe outlet for the design capacity of the pipe_ If the tailwater depth is less than half the outlet pipe diameter. it is classified mitumum tailwater condition_ Lfit is greater than half the pipe diameter, It is classified maxinmi condition_ Pipes that outlet onto -Wide flat areas with no defined channel are assumed to ha-ve a n,;niinuni tailwater condition unless reliable flood stage elevations sho,kv otherwise - Outlet pipe diameter, Do (in.) 15 Tailwater depth (in.) 7.5 Minimum/Maximum tailwater? Max TW (Fig. 8.06b) Discharge (cfs) Q10 3.18 Velocity (ft./s) 9.5 Step 2. Based on the tailwater conditions determined in step 1, enter Figure S_U6aorFigure 8_06h, and determine d50riprap size and mininnun apron length (L). The d_, size is the median stone size iu a well -graded riprap apron_ Step 3. Determiine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end fron7 the same figure used im Step 2_ Minimum TW Maximum TW Figure 8.06a Figure 8.06b Riprap d50, (ft.) 0.5 Minimum apron length, La (ft.) 4 Apron width at pipe outlet (ft.) 3.75 3.75 Apron shape Apron width at outlet end (ft.) 5.25 1.25 ,Step 4. Determine the inaxirnum stone diameter: drcax 1.5 x d5d Minimum TW Max Stone Diameter, dmax (ft.) 0.75 Step 5. Detemune the apron thickness - Apron thickness = 1.5 x dr1 ,: Apron Thickness(ft.) Maximum TW 0 Minimum TW Maximum TW 1.125 0 ,Step 6. Fit the riprap apron to the site by making it level for the rninimtun length, L. , from Figure 8.06a or Figure 8.06b_ Extend the apron farther downstream and along channel banks itntil stability is assured_ Keep the apron as straight as possible and align it with the fio%v of the recen-1-ug stream_ Make any necessary alignment bends near the pipe outlet so that the entrance into the recei7,-ing stream is straight_ Some locations may require lining of the entire channel cross section to assure stabilitv_ It may be necessary to increase the size of riprap where protection of the channel side slopes is necessary (Appendie 8.05_4'here a-erfalls exist at pipe outlets or flows are excessive, a phinge pool should be considered, see page 8.06.8_ User Input Data Calculated Value Reference Data Designed By: Tom Harrell Date: 6/12/2019 Checked By: TH Date: Company: DEI Project Name: Cambridge Southeast Project No.: Site Location (City/Town) Raleigh Culvert Id. FES 16 Total Drainage Area (acres) 1.98 Step 1. Determine the tailwater depth froth channel characteristics 'below the pipe outlet for the design capacitor of the pipe_ If the tailwater depth is less than half the outlet pipe diameter, it is classified minimum tailwater condition_ If it is greater than half the pipe diameter, it is classified maxtnnini condition_ Pipes that outlet onto Vvide flat areas with no defined channel are assumed to have a rr,;n;,nuni tailwater condition unless reliable flood stage elevations show other-,ise. Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 10 6.8 Step 2. Based on the tailwater conditions determined in step 1 _ enter Figure 8_06a or Figure 8_06b, and determine d,, riprap size and miniuiu m apron length (L)_ The d_. size is the median stone size iu a well -graded riprap apron_ Step 3. Deterniine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end from the same figure used iu Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Maximum TW Figure 8.06a Figure 8.06b 0.5 8 3.75 3.75 Apron width at outlet end (ft.) 9.25 1.25 Ttili _}3C3_'11111'c 111t ilia-a'1num stone diameter- dn.n. =1.5xd50 Minimum TW Max Stone Diameter, dmax (ft.) 0.75 telj 5, er3a111'tie the apron thickness: Apron Thickness(ft.) Apron thickness = 1. Minimum TW 1.125 Maximum TW 0 Maximum TW 0 ,Step 6. Fit the riprap apron to the site by making it level for the iriinirniun length, L, from Figure 8-06a or Figure 8-06b. Extend the apron farther doxnstreani and along channel banks until stability is assured- Keep the apron as straight as possible and align it With the flow of the recei%-iug stream - Make any necessary alignment bends near the pipe nutlet so that the entrance into the receiving stream is straight- Soine locations may require lining of the entire charnel cross section to assiue stability - It may be necessary io increase the size of riprap where protection of the channel side slopes is necessary (Appendix 8.05)- 'Where overfalls exist at pipe outlets or flows are excessive, a phinge pool should be oonsidered, see page 8-06-8- User Input Data Calculated Value Reference Data Designed By: Tom Harrell Date: 6/12/2019 Checked By: TH Date: Company: DEI Project Name: Cambridge Southeast Project No.: Site Location (City/Town) Raleigh Culvert Id. FES 24 Total Drainage Area (acres) 0.67 Step 1. Determine the tailwater depth froth channel characteristics 'below the pipe outlet for the design capacitor of the pipe_ If the tailwater depth is less than half the outlet pipe diameter, it is classified minimum tailwater condition_ If it is greater than half the pipe diameter, it is classified maxtnnini condition_ Pipes that outlet onto Vvide flat areas with no defined channel are assumed to have a rr,;n;,nuni tailwater condition unless reliable flood stage elevations show other-,ise. Outlet pipe diameter, Do (in.) Tailwater depth (in.) Minimum/Maximum tailwater? Discharge (cfs) Velocity (ft./s) 15 7.5 Max TW (Fig. 8.06b) 2.17 5.8 Step 2. Based on the tailwater conditions determined in step 1 _ enter Figure 8_06a or Figure 8_06b, and determine d,, riprap size and miniuiu m apron length (L)_ The d_. size is the median stone size iu a well -graded riprap apron_ Step 3. Deterniine apron width at the pipe outlet, the apron shape, and the apron width at the outlet end from the same figure used iu Step 2_ Riprap d50, (ft.) Minimum apron length, La (ft.) Apron width at pipe outlet (ft.) Apron shape Minimum TW Maximum TW Figure 8.06a Figure 8.06b 0.5 6 3.75 3.75 Apron width at outlet end (ft.) 7.25 1.25 Ttili _}3C3_'11111'c 111t ilia-a'1num stone diameter- dn.n. =1.5xd50 Minimum TW Max Stone Diameter, dmax (ft.) 0.75 telj 5, er3a111'tie the apron thickness: Apron Thickness(ft.) Apron thickness = 1. Minimum TW 1.125 Maximum TW 0 Maximum TW 0 ,Step 6. Fit the riprap apron to the site by making it level for the iriinirniun length, L, from Figure 8-06a or Figure 8-06b. Extend the apron farther doxnstreani and along channel banks until stability is assured- Keep the apron as straight as possible and align it With the flow of the recei%-iug stream - Make any necessary alignment bends near the pipe nutlet so that the entrance into the receiving stream is straight- Soine locations may require lining of the entire charnel cross section to assiue stability - It may be necessary io increase the size of riprap where protection of the channel side slopes is necessary (Appendix 8.05)- 'Where overfalls exist at pipe outlets or flows are excessive, a phinge pool should be oonsidered, see page 8-06-8- NCDOT STREET SIDE DITCH LINING CALCULATION SCHEDULE (20 ft. pavement width / 50 ft. right-of-way width) Project: Cambridge Southeast - Siler City street : Howard Court Ditch Drainage Flow Lining Station Side Slope Area C I Flow Depth V Material % ac in/hr cfs ft fps 1+00 Left 3.00 0.13 0.35 7.22 0.33 0.25 1.77 GRASS 2+00 Left 3.00 0.30 0.35 7.22 0.76 0.34 2.18 GRASS 3+00 Left 4.00 0.99 0.50 7.22 3.57 0.58 3.58 JUTE 4+00 Left 4.00 1.35 0.50 7.22 4.87 0.65 3.87 JUTE 5+00 Left 4.00 0.83 0.50 7.22 3.00 0.54 3.42 JUTE 6+00 Left 4.00 0.20 0.35 7.22 0.51 0.28 2.19 GRASS 7+00 Left 4.00 0.34 0.35 7.22 0.86 0.34 2.50 JUTE 8+00 Left 4.00 0.56 0.35 7.22 1.42 0.41 2.84 JUTE 9+00 Left 4.00 0.71 0.50 7.22 2.56 0.51 3.29 JUTE 9+50 Left 4.00 0.80 0.50 7.22 2.89 0.53 3.39 JUTE DISCHARGE SWALE 1 3.00 1.98 0.40 7.22 5.72 0.73 3.61 JUTE DISCHARGE SWALE 2 2.00 0.67 0.45 7.22 2.18 0.55 2.44 GRASS