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HomeMy WebLinkAboutSW6190903_SW Report_20191114Storm Wafer Design Calculations November 11, 2019 Short Stop Arabia Road Raeford, NC Hoke County Prepared for: Neal Holdings, LLC Attn. Chris Neal 1007 Aresenal Avenue Fayetteville, NC 28305 910-433-4490 Prepared by: Triangle Site Design, PLLC 4004 Barrett Drive, Suite 101 Raleigh, NC 27609 (919) 553-6570 NC License#P-0619 TRIANGLE S I T E D E S I G N TABLE OF CONTENTS OVERVIEW STORMWATER NARRATIVE FIGURES SOILS SURVEY & SOIL INFORMATION USGS TOPOGRAPHIC MAP FEMA FIRM MAP WATER QUANTITY/QUALITY WET DETENTION POND DESIGN SUPPLEMENT CN VALUES PRE -DEVELOPMENT HYDROGRAPHS POST -DEVELOPMENT HYDROGRAPHS TIME VS. VOLUME (STORAGE) TIME VS. ELEVATION (STAGE) ELEVATION -VOLUME -FLOW SUMMARY POND OUTLET/STRUCTURE SUMMARY RIP -RAP APRON CALCULATION OVERVIEW Background This report contains the storm water calculations for the proposed Short Stop convenience store site. The project site is located on Arabia Road at the intersection with Davis Bridge Road. A portion of the site is currently developed as a convenience store. The existing store and portions of the associated paved areas will be demolished as part of the development of the site. The overall size of the development is 2.09 acres. The existing impervious area of the site is 17,236sf (0.40ac) which will be demolished. The proposed impervious area of the site is 37,848sf (0.86ac, 41.56%). The increase in impervious area for the property is 20,612sf (0.47ac). The proposed Short Stop parcel is located within a FEMA designated flood zone per FEMA FIRM 3710948300L with an effective date of January 1, 2007. There is a proposed storm water management facility (wet detention pond) for the site. The SCM is outlined in this report has been designed for post —development peak attenuation and water quality. The SCM is designed to capture a drainage area of 1.15 ac with an impervious area of 0.75 ac. The site grading and storm drainage systems are designed to convey stormwater runoff from the impervious areas of the site to the wet —detention pond. The wet detention pond is designed to provide peak flow attenuation for the 1, 2, 10 & 100 year storm events. The design storm for water quality is a 1.0" storm event. FIGURES Southeastern Soil & Environmental Associates, Inc. P.O. Box 9321 Fayetteville, NC 28311 Phone/Fax (910) 822-4540 Email mike@southeastemsoil.com February 18, 2019 Mr. Lee Humphry Double D Engineering, PLLC 110 Commerce Avenue Southern Pines, NC 28387 Re: Hydraulic conductivity (permeability) analysis & Seasonal High -Water Table determination (SHWT) for proposed stormwater retention/treatment area, Ratley Property, PIN 794830101216, Arabia Road, Hoke County, North Carolina Dear Mr. Humphry, An evaluation of soil properties and hydraulic conductivity (Ksat) has been conducted at your request on a portion of the aforementioned property. The purpose of the investigation was to determine soil water table depths (SHWT) based on soil profiles. In addition, Ksat was to be provided at a depth at least 2.0 feet above the SHWT elevation for use with stormwater retention basin design. Saturated hydraulic conductivity of the unsaturated zone was measured in a similar method as described in the Soil Science Society of America Journal, Vol. 53, no 5, Sept. - Oct. 1989, "A Constant Permeameter for Measuring Saturated Hydraulic Conductivity of the Vadose Zone" and Comparison of the Glover Solution with the Simultaneous Equations Approach for Measuring Hydraulic Conductivity." This consists of advancing a small diameter bore hole to a predetermined depth (typically 2 feet above SHWT). At this depth, a constant head (pressure) was established and maintained. Flow measurements were made at timed intervals after flow stabilized. Soils at the proposed basin site are most similar to the Candor soil series (see attached boring log). One boring was advanced to a depth of 10.50 feet below the soil surface. Seasonal High -Water Table (SHWT) as determined by evidence of colors of chroma 2 or less (and/or concentrations of high redox mottles) was encountered at a depth of 86 inches below the ground surface (see chart attached). SOIUSITE EVALUATION • SOIL PHYSICAL ANALYSIS • LAND USE/SUBDIVISION PLANNING • WETLANDS GROUNDWATER DRAINAGE/MOUNDING • SURFACE/SUBSURFACE WASTE TREATMENT SYSTEMS, EVALUATION & DESIGN One compact constant head permeameter (CCHP) test was conducted at a depth of 62 inches below the ground surface. The measured Ksat rate was 40.89 cm/hr (equivalent to 16.10 inches/hour). The attached map shovers the location of the sample point as well as Ksat location. It should be noted that the reported SHWT does not necessarily reflect the elevation of static groundwater (due to variations in groundwater recharge rates, annual rainfall, drought conditions, etc.). The data presented in this report are limited by a number of considerations. The primary consideration is that soil formations can be highly variable. The soils found on this site can be subject to inclusions of other soil types, perched water, artesian conditions and/or layers of undulating low permeability clay seams. These and other soil conditions can have an effect on the steady state of groundwater flow. To the extent possible, we have identified the soil types that will impact the flow of groundwater, and have provided a professional opinion as to the depth of SHWT. I trust this is the information you require at this time. Sincerely, Mike Eaker NC Licensed Soil Scientist #1030 p SQ1'� Ak'*A �1 �a5llli�•� _ `����c �I{ F�� r ,f{ /03 _C C; Southeastern Soil & Environmental Associates, Inc. P.O. Box 9321 Fayetteville, NC 28311 Phone/Fax (910) 822-4W Email mike @southeastemsoil.com SHWT depths, Ratley Property, Arabia Road, Hoke County, North Carolina BORING SHWT DEPTH (inches), Observed Water (inches) 1 86 None SOIUSITE EVALUATION • SOIL PHYSICAL ANALYSIS • LAND USE/SUBDIVISION PLANNING • WETLANDS GROUNDWATER DRAINAGE/MOUNDING • SURFACE/SUBSURFACE WASTE TREATMENT SYSTEMS. EVALUATION R DFRIAN Southeastern Soil & Environmental Associates, Inc. P.O. Box 9321 Fayetteville, NC 28311 Phone/Fax (910) 822-4540 Email mike@Southeastemsoil.com Measured Ksat Rate, Ratley Property, Arabia Road, Hoke County, NC Ksat Ksat Location Depth (in) em/hr in/hr 1 62 40.89 16.10 SOIUSITE EVALUATION • SOIL PHYSICAL ANALYSIS • LAND USE/SUBDIVISION PLANNING • WETLANDS GROUNDWATER DRAINAGE/MOUNDING • SURFACE/SUBSURFACE WASTE TREATMENT SYSTEMS. EVALUATION R rwsi ;N Southeastern Soil & Environmental Associates, Inc. P.O. Box 9321 Fayetteville, NC 28311 Phone/Fax (910) 822-4540 Email mike@southeasternsoil.com Soil Boring Log, Ratley Property, Ratley Property, Arabia Road, Hoke County, NC This map unit consists of somewhat excessively drained soils that formed in sandy and loamy sediment on uplands. Slopes range from 3 to 6 percent. A - 0 to 4 inches; dark grayish brown (1 OYR 4/2) sand; weak fine granular structure; very friable; few fine roots; abrupt smooth boundary. E - 4 to 20 inches; light yellowish brown (2.5Y 6/3) loamy sand; weak fine granular structure; very friable; few fine roots; abrupt wavy boundary. Bt - 20 to 31 inches; Iight yellowish brown (10YR 6/4) sandy clay loam; weak fine suba.ngular blocky structure; firm, gradual wavy boundary. E' - 31 to 73 inches; pale brown (10YR 6/3) coarse sand; single grained, loose; very friable; gradual diffuse boundary, C1 - 73 to 86 inches; yellow (10YR 7/6) coarse sand; many medium prominent yellowish brown (IOYR 5/4) mottles; single grained; loose; very triable; gradual dif-use boundary, C2 - 86 to 130 inches; mottled brownish yellow (IOYR 6/8) and gray (IOYR 6/1) coarse sand; very friable; massive structure. SHWT @ 86 inches (10YR 6/1) SOIL/SITE EVALUATION - SOIL PHYSICAL ANALYSIS - LAND USE/SUBDIVISION PLANNING - WETLANDS GROUNDWATER DRAINAGE/MOUNDING - SURFACE/SUBSURFACE WASTE TREATMENT SYSTEMS. EVAI I IATInN R nF-,ir,N r, ��(' ,� s, "'�Q w �� ❑ ha 0 d KI f M.TT.£ & M.ST .£ o6C z h zp� R ii �i m 'T M.TT£ e(V N O O y OD m 00 a a� z Z� � w = m O � a U 3 �p� � C O 8 Z i Ll x � f t� o is V W ,a0y 3 C � O 7 H ZQ Z U MBT.£ o5C ^� i Z O G O LL Z Ca G Z W 0 W —i a Q a m ' al In �o 0 U p a C U y O U O O O E ai C U m m al Q m n E m m E C T) OI O O Iu a 3 m m n o C U m L al rnEa � >LO o o al C > C .m o L al a >, a CO) al n >, .0 m 0 m W E .... E a 0 O m m m E��N 6 t i• al rn n w E a) cE d N m a .` q a ai O O C LLI E u O (U w m m O a`l r 1O m a a_�i n E U O N N a) V Ul I a) p .� a a m O O N .0 Y O 0 a O O E O N E N.0 In M Q ate.+ n 7 0 C (n U m C O 0 0 loll «w+-' t Z U) m. a) -0 N s-0 N LL' Z 00 m N 3 N U EO 17A U a ',,QQ77± o a O > E 0 LU Ial CO ` O d n N O ❑ N L m O. O L N o C p m o O n Z a) m f`0 o a) < m a, '� 'a �w o al m (n a al O a ma aE 0 0 a) > o a) U C 0 O 0 =O rn o t E >, m rn E N O i' a= O m (n 0'o m p-0 a C U o ' d m N N m `m N m 'o n U o a a/ al fn m Y `m ?� a E m Q ) a� O 2 p m LL' Z E N Q U C p p a/ N C f0 a) rn �O N o >2 O �Ldmm rn� .. m� pov�0 c N c a 0) (n Z m m m 5 L o c ❑ rn m � m n o o m w a p Q .. N a Q m ocr c mo a t o(U 0o 2o�co I E n d � o'au O a)>O m��� :E — 0 7 — O LPm ;0 al E m t FLE (n > U 2m n U Q m F- O (n (n (n - ❑ N p E L H U .- (n N > N y T N C (Ta t a7 d O U L N C m y y m c O 'O cc cc N o o t E _m o a _a a) y y m O al al d - U ❑ Z 3 In o a 5 ❑ � a A m c y 0 1( 0 R ` A l �. � � m Iu a 0) a occ cu N N O C O C N y O O O `o 0 m m m y , w c d a. ❑ ❑ ❑ o c ❑ ❑ ❑ c a° ❑ o Q Im Q a m 6-3 U U ❑ Z m Q a m ro U U ❑ Z of Q a m m a c c c w❑ ❑ ❑ 11 ❑ ❑ El ❑ •p i I� N y l 7 { 0 w ...j •� U)to 0 to Q rnv 0 0 N N O O 00 a m Z U N al O �N � 0 OC d a' a7 7 U) l�0 o Z U U4 Hydrologic Soil Group —Hoke County, North Carolina Hydrologic Soil Group Map unit symbol I Map unit name BaB Blaney loamy sand, 2 to C 8 percent slopes JT Johnston loam A/D Totals for Area of Interest Description Rating Acres in AOI Percent of AOI 1.2 99.6% 0.0 0.4% 1.21 100.0% Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Natural Resources Web Soil Survey 8/10/2019 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group —Hoke County, North Carolina Component Percent Cutoff- None Specified Tie -break Rule: Higher Natural Resources Web Soil Survey 8/10/2019 Conservation Service National Cooperative Soil Survey Page 4 of 4 8/10/2019 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Lumber Bridge, North Carolina, ,�•�,� USA* Latitude: 34.95040, Longitude:-79.0547° 1 ? Elevation: 140.59 ft * ._, n �a "source: ESRI Maps "source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G M Bonnin, D Martin, B Lin, T Parzybok, M Yekta, and D Riley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches�l Average recurrence interval (years) Duration 1 ���������� 2 5 10 25 50 100 200 500 1000 5-min 0: 95 0.481 0.467---0.56 0.54-0 662 0.602 0.733 0; ,70 0 81 0,720-a 878] (D.765-0 937) (0.808 0 994) (0.858 1207) 0.897--11,12 0.695 0.821 0.960 1.06 1 1.27 1.36 1.44 1.54 1.61 10-min 0.631-0.768) (0.746-0.907) (0.872-1.06) (1962-1.1 (.t.07-1. 1.15-1.40) (1.22-1.4 1.28-158) 11 0.36-1.69) 0.868 1.03 1.21 1.34 1.50 1.61 1.72 1.81 1.94 2.02 15-min (0.789-0.959) 1 (0.938-1.14) (1.10-1.34) (1.22-1.45) 1 (1.35-1.65) 1.45-1.77) 1.54-1. (1.62-1.99) (1.71-2.12) (1.77-2.22) 30-min 1.08 1932 1.304358 1.57 1391 . (1.76 2AS 2.00-2.44 (2. 9 236 (2.35 2388) 1 (25283,09 .7203.37) 2.87-3.59 1.48 1.79 2.21 2.64 2.96 3.29 3.62 3.96 4.42 4.78 60-min (1.35-1.64) (1.63-1.98) (2.01-2.44 (230-2:80) 11 (2.67-3.26) 1 (2.96-3.61) (3.24-3.97) JI(153-4.34) (3.90-4.84) [ 4.19-5.24 1.73 2.09 2.64 3.05 3.62 4.08 4.54 5.02 5.67 6.18 2�tr (1.55-1.95) 1 (1.88-2.36) (2.37-2.9 (2.74-3A4) 1 (3,23-4,08) 1 (3.62-4.58) 1 (4,01-5.10) 1 (4.40-5.63) (4.92.Z.36) (5.33-6.94) 3�tr 1.6582.07) 1,99 2?51 2.52 311 (2.93�3.70 [3.5094.4 {3.9545.04 (4. 205.66) 1 (4,90-6-3 5.5747 27 (6: 9-8.03) 2.18 6 hr (1.97 2.45) (2.39 2596) (3. 233.74) (3.52-4.38) 1 (4,21 5.26) 1 (4.7735.99) 1 (5.35.6.75) 1 (5.9487.5&) (6.78 8973) (7. 4-9.68) 2.57 3.12 3.97 4.67 5.67 6.50 7.38 8.34 9.73 10.9 12a1r 2.32-2.89) (2.81-3.49) j(3.57-4.44) (4,18-5,22) 1 (5.03.6.31) (5.72-7.21) 1 (6.4".18) 1 (7.20.923) (8.28-10B) (9.13-12.0) 3.03 3.67 4.67 5.47 6.58 7.48 8.42 9.40 10.8 11.8 24atr (2.81-3.2 3.41-3.96) 1 (5.06-520) (6.06-7.10) (6.87.8.0 70-9.08 8.57-10.i 75-11.6 10.7-1 2.8) 2�iay 3.27 3178) (3.9524.5 4.9835.76 (5. 9-6.71) {6.90 8.04) (7.8049.11} (8.7�1-r,10.2) (9.6161.d) (1110-13.0 (12.10- 4.3 3.73 4.50 5.65 6.57 7.83 8.85 9.91 11.0 12.5 13.7 3�ay (3.49-4.00) 4.21.4.83) 1 (5.27.6.06) I (6.11-7.03) (7.26-8.39) 1 (8.17-9A8) I (10.1-11.8) (11.4-13:5) (12.4-14.8) 3.96 4.76 6.95 6.89 8.19 9.23 10.3 11.4 13.0 14.2 4�ay 3.71-4.23) 1 (4.46-5.09) {5.55-6.35} (6.42-7.35) 7.61-8.74] 8.55-9.86 9.51-11.0 (10.5-12.. (.11.9-13.8) 1(12.9-15.3 4.60 5.51 6.80 7.82 9.22 10.3 11.5 12.7F 14.3 15.6 7�ay 4.30-4.92) (5.15-5.9tl} (6.34-728) (7.28-.37) 1 (6.56-9.86) 1 (9.57-11,1) (10.6-12.3) {11.7-13. (13.1-15.43 11 (14.2-16.8 10ilay (4.96�5.61) 5. 236.70) 7.1768.13 (8. 5-9.24) .45-10,0) {10.5-1Z .9 11 5- 3.2] 12.5.14_ 132-16.1 15.0-17.5 7.11 8.43 10.1 11.4 13.1F 1-4-6-7 15.8 1 17.2 19.1 20.6 20�ay 6.71-7.55 (7.96-8.96) j (10.7-12.1) (14.8-16.8) (16.0-18.3) 07.7-20.4) (19.0-22.0) 8.84 10.4 12.3 13.7 15.5 16.9 18.3 19.8 21.6 23.1 30�1ay (8.37-9.36) 1 (9.88-11.1) (11.6-13.0) (12.9-14.5) 11 (14.6-16.4) 1 (15.9.17.9) (17.2-19.4) 11 (18.5-21.0) (20.1-23.0) 1 (21.4-24.6) 16.7 21.8 45�iay 12.5-13.9 [14.4- B.f3 15.8-17,7) (17.1789.8) (1921021.4) 20.5-3.0 21.8--24. 23.6-6.7) (24.9 8.315.7 El (14.9-16.5) 180 (17.0-18.9) 19.7 [1$.7-20.7) 21.9 (20.7-23.0) 23.5 [22.3-24.8) 252 (23.8-26.5) 26.7 (25.2-28.2) 288 (27.0-30.4) 30.3 (28.4-32.1) Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Tog PF graphical https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=34.9504&lon=-79.0547&data=depth&units=english&series=pds 1 /4 C m Q W W I LL L m J L m N m 2 'a O _O LL ca C O c0 Z S i e • � C g &� EE - g Ei s= 101H ap v� W e$E$ l y$$ v 9 R z � E`-a F �..FgEg E€ME9 Fe .15 m4sq'I"w \ � 0 § 3 � z A a Tµs� Yw q VOy��Fc,O g} FKi a �� Z PH N� a�2y ¢ai } wami� '�?min N (n v�i �m a� �rvLL°.-' a oa W ¢ ug�m lin i n i�sl M i �b1 � m 8°5 8� w -zo 8= �a Fx R S Wo z Iwm= mmw IAo F - 3: =a 01,06, �Q1�9ll� b O �0�0, Y �p b. U) 6 onN - Z z;g=gg o m'Nm BEN = yi b. r U V Z } <0 a 3 0 W aLUZ �O J LL LU CL Q 00 H � N U Yn = O CL Z OZ�M 0 Ow � Y 0 �LU WATER QUALITY/QUANTITY W Q a w O U O LL N W Z CW G W J a IL D c 3 0 V Y _ 0cu m 0 u C r Q ai E Z y to N 0 N 011 a a I I I N c O '� c U O J T N r U a c 0! (n C m E O aa) aD ,t5L) a) C 3 'N Y a� m0— 0 3 Cl) o o a LL iv CD O c� a�a o'caw? oa= «� 0 m .o c � E 3 m m m E C N V N C m O H d > c m J O U a: V N 'O a N Y w c 0 m E 0 m C Em N v U') O O M U c co J QCA U Z c. 0) C. , l0 C, Qj O 0 M Z Q' m M —cu 'L —, a 0 N E a °' IO [CG * 1p m M C N R E c C = o .� U U U a w E C. U 5 a i 5 u N > m u W 'c r c LL Q N O n d n N N U N 3 in Z m 0 N N t M U tU Z f0 ' a O) C N o) E U) R u; a E u.) N 20 O E (6 N N N c m m m U) c 'n rn m o z D to t� a u m c m LE a O N n O � c fd Y T a E C 0 O C O 0 N W a O C 7 m C N N tll aj O ' c E a O_ O O Q E O N O U Cc .L T'C m m E o Ul _0 C O 7 a m 0 o c o � y o. m E o E� a� c o. 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O C O O p z O L C N N y d d N Y00 3 L_ m � 3 °> 4 N O N y L N o UO > > d E 3 to N N o N ui T y W upi > a fn a' O m C E C rn m w O ❑ w _ N — N — !' J N W d W O (n N ❑ ❑ O ❑ O ❑ Q N ¢ an ❑ m ... H D r p❑p 1ri Cn ik Y! M ��p A! W u u u u r W CD m 3 N w o w Q `N G c c C N C C N C N > U) N O O N} M co N p Z t7 p Z o } o } d a O a O W w W 0 Z 0 N Lo M N M N} N N O } 10 cl) N } � } d d 100 M W n N LO M E o a c > 3 o c vi d ELd- o N d of o o' O VI O m 0 o c 0,d Cl.c U 3 ry 0)O n d V y Y N N •{IL "' C O` O C d (D d L a C O J d E °� > a3 c m m a m p c o c y c co ^ S > m J m E v c o aNi ° avi m E o m >_ NO y E a7 l0 C L. O _ N cUoc O 3 Hc`pJ° d uLOO ° Cv'L.o `d m, =n n Eou) a)co c $ E a m mE Cd o mA . ° o E-. d c , E wO.Ud.. ma al U ° � 'ndEm •d H c o o (t) m ° _ ,Lj>O a) >aNNdj... mf > d w y O E EC N Nw U S ts oE O Z md a) a' d N d W E E d Lc) U d , M aGo 'cm ° c E m Ea m c > o0 m d y�'w 0.9 0 � o C dN E N 5o > dd a u 0 N 0 C M> N O dCJ N ca l p jo o L 0 u g ° o d d L nEwm a y cymod o a—dc31d0 c, Z m O P n N N d L N >N O O O Nc y f n W L- d N x d O O O dt E Ovcn.. ZA Oo 43m O C J L O dN3 dddd 0 N Od O L a) O d u Z— W 2 U) w w w ❑ ¢ ❑ E > ❑ ❑ )¢a a)Y O H '--I co d V% cH :7 ik �k # . # ik ' 3t N N N 3k N # M '�t # V. # d i0 LL7 Y"J ,O V1 YJ Proposed Wet Pond Project Information Project Name: Short Stop Project #: Designed by: M E L Date: Revised by: Date: Checked by: Date: Site Information Sub Area Location: Drainage To Proposed Wet Pond Drainage Area (DA) = 1.15 Acres Impervious Area (IA) = 0.75 Acres Percent Impervious (1) = 64.87 % Required Surface Area Permament Pool Depth: 3.18 ft Non -Coastal county SA/DA = 2.23 Min Req'd Surface Area = 1,117 sf (at Permanent Pool I equired WQv Storage Volume Design Storm = 1 inch Non -Coastal County Determine Rv Value = 0.05 + .009 (1) = 0.634 in/in Storage Volume Required = 2.646 cf (above Permanent Pool) _ Elevations Top of Pond Elevation = 134.00 ft Temporary Pool Elevation = 133.20 ft Permanent Pool Elevation = 132.50 ft Shelf Begining Elevation = 133.00 ft Forebay Weir = 131 00 ft Shelf Ending Elevation = 132.00 ft Bottom Elevation = 126.00 ft Permanent Pool Area Area @ Top of Permanent Pool = 2,380 sf Volume of Temporary Storage = 2,662 cf Is Permenant Pool Surface Area Sufficient (yes/no)? Yes ( 2380 > 1117 ) sf Volume of Storage for Design Storm = 2.662 Yes ( 2662 > 2646 ) cf Incremental Drawdown Time Project Information Project Nar Project #: asigned by: iecked by: Water STORMWATER POND INCREMENTAL DRAWDOWN METHOD -Water Quality Volume Date: Date: ity Orifice " Incremental Determination of Water Quality Volume Drawdown Time Zone 2 Orifice Diameter (D) = Cd = Ei = Zone 1 Range = Zone 2 Range = Zone 3 Range = Q3 = 0.0437 CD " D2 (Z-D/24-Ei)^(112) Q2 = 0.372 Co . D'(Z-Ei)n(3n) Q,=0 0.75 in 0.6 132.5 Orifice Inv. 0.00 to 132.5 132.5 to 132.6 132.6 to 134 Incremental Drawdown Method Countour Contour Area Incremental Volume Stage, Z Zone Q Drawdown Time sq ft cu ft ft cfs min 132.50 3196 0 0.00 2.00 0.000 — 133.00 3990 1,796 0.50 3.00 0.010 2,964 133.20 4675 866 0.20 3.00 0.012 1.197 I Total -- 2.662 -- -- -- 4,161 Drawdown Time = Incremental Volume / Q / 60sec/min Summary Total Volume = 2,662 cf Total Time = 4,161 min Total Time = 2.89 days 69.3505401 9/13/2019 Prop Wet Pond- new design.xls 1 of 1 Proposed Wet Pond #1 Project Information Project Name: Short Stop Project #: Designed by: MEL Revised by: Checked by: Site Information Date: Date: Date: Sub Area Location: Drainage to Proposed Pond Drainage Area (DA) = 1.15 Acres Impervious Area (IA) = 0.75 Acres Percent Impervious (1) _ 6487 % (Drainage Area) Orifice Sizing Orifice Size = Drawdown Time = less than 5 days (yes/no) ? yes greater than 2 day (yes/no) ? yes Anti -Flotation Device 4' x 4' Outlet Structure in (Diameter) days (Incremental Draw Down Method) Area: 16.0 sf Volume: 128.0 cf Weight: 7987 Ibs Factor of Safety 1.20 WT Req'd of Anti -Flotation Device: 9,; -- Ibs Volume of Concrete Req'd: cz° cf (Water Displaced - Top of Pond to Bottom of Pond) (Unit WT of Concrete = 150 pcf) Volume Provided: 73.5 cf (4'x4' riser x 2.25' = 36cf, 5'x5' footing x 1.5'=37.5cf) Project: Pond #1 Date: 9/13/2019 Main -Pond Contours -Volumes Elevation Main -Pond Incremental Vol. Accumulated Vol. Description 132.5 2,380 1,039 5,806 A2 (Perm —Pool) 132 1,775 1,588 4,768 Al (Bottom —Shelf) 131 1,400 1,225 3,180 130 1,050 895 1,955 129 740 600 1,060 128 460 335 460 127 210 125 125 126 40 0 0 A3 (Bottom —Pond) 18100 Forebay Contours -Volumes Elevation FBI FB2 FB3 Total -Areas Incremental Vol. Accumulated Vol. 132.5 640 640 285 1,028 132 500 500 403 743 131 305 305 233 340 130 160 160 108 108 129 55 55 0 0 Forebay Volume Average Depth (Option 1) Average Depth Calculation (Option 2) Vpp permeter of shelf width of shelf Al (Bottom —Shelf): Average Depth = 17.7% *Between 15% & 20% 2.69 *At least 3' average depth 5,806 205 3 1,775 3.18 Triangle Site Design, PLLC Curve Number Calculation (CN) Pre -Developed Conditions Drainage Area (acres Z 1.15 Existing Soil Groups: Soil Group Map Symbol Soil Description Acres Percent of DA C BaB Blaney Loamy Sand 1.15 100% Existing Land Uses: Land Use Description Existing Soil Group Acres Curve # Weighted CN Open space C 1.12 74 72.1 Impervious C 0.03 98 2.6 Cumulative Curve # = 74.6 Triangle Site Design, PLLC Curve Number Calculation (CN) Post -Developed Conditions Drainage Area (acres J: 1.15 Existing Soil Groups: Sod Grow Map Symbol Soil Description Acres Percent of DA C BaB Blaney Loamy Sand 1.15 100% Proposed Land Uses: Land Use Description Existing Soil .Group Acres Curve # Weighted CN Open Space - Good Condition C 0.4 74 25.7 Impervious Area - Parking/Bldg C 0.75 98 63.9 Cumulative Curve # = 89.7 C) z 0 0- z O P= z w CJGGcj� k§§§§ }\ 2� §§§§d jam■ § m§§ ee ■e/e >�� tcAcc �.,��� =E9-3 2 w ) Q�\§§ &�� § 22■K§ ® E ® \E■§2 Z o■@ �c3W)0e cmu ° =±'- STAGE/STORAGE TABLE STAGE ELEVATION CONTOUR INCREMENTAL TOTAL (FT) (FT) AREA (SF) STORAGE (CF) STORAGE (CF) 0.0 132.5 3195 0 0 0.5 133.0 3990 1796 1796 0.7 133.2 4675 867 2663 (W0v) 1.5 134.0 9325 5600 8263 Wtz U � N Z U O II Q g J a U U \ \ / nt,t j I C \ o rn \ 1 I I II \ V) ca \ 1 I 1 I \� 1 25 \ cN \ J \ ]0 I \ T \ 4�p1 \ww a-< \ \ TRASH RACK--) REFER TO DETAIL THIS SHEET 6' TOPSOIL A80VE 6' CLAY LINER -REFER TO DETAIL ON LITTORAL SHELF FOR INCREMENTAL WEIR 3 I 1 PRECAST CONCRETE RISER 6FT LITTORAL - SHED _ _ (INSTALL STEPS AS NECESSARY) INV=132.� PVC ELBOW ✓ SEE DETAIL 411vHF'T;TF1 ASTM C-923 SEAL BETWEEN BARREL R RISER. RISER BASE TO BE FILLED WITH CONC. TO INVERT OF BARREL TUIRED) TO ANCHOR RISER TO TS FROM ANGLE TO RISER AND LONG FROM ANGLE TO BASE. WITH ZINC RICH PAINT AFTER :ED UNDER LOWER REINFORCING STEEL. CONCRETE SHALL BE PLACED IN RISER AFTER ANGLES ARE SECURED TO BASE AND RISER. TOP OF EMBANKMENT ELEVATION=134.0 EXISTING GRADE=138.03 100 YEAR STORM ELEVATION=133.97 2 YEAR STORM ELEVATION=133.47 1 YEAR STORM ELEVATION=133.35 1.0-INCH STORM ELEVATION=132.81 NORMAL POND ELEVATION=132.5 2 NOTE: PUMPS SHALL BE USED TO DRAIN THE POND WHEN NECESSARY. REFER TO DETAIL THIS SHEET FOR DEWATERING REQUIREMENTS. 5'z5'z1.5' CONC. BASE REINFORCE WITH 14 BARS AT 12" O.C. TOP AND BOTTOM OF EACH DIRECTION PROVIDE 3' MIN. CLEARANCE BETWEEN EDGE OF CONC. AND STEEL REINFORCING. BOTTOM OF POND (TOP OF SEDIMENT STORAGE)=126.0 (BOTTOM OF SEDIMENT STORAGE)=125.0 6' CLAY SOIL LINER MAIN POOL NOTE 1. 2. TOP OF SNAG N NOT SHOWN roA CIANm �4r ost . I, (NaovAe� TNAVI aAag �lws FT TOTAL WEIR LENGTH AT ELEV=133.2 OUTLET CONTROL ST.R UA — INCREMENTAL WEIR C TOPSON. FOR ALL AAPAS AM THE " W1 POND CLEVATM F016iBAY 8E WIDTH A TOP E= 2. 1 CO YIIDIN AT IOP = 20 FT a• rnnenn �e�wr� 4' PVC SCFEIV CAP FOR CLEANING ACCESS Ir MIN. 41", PVC 1 PEN. PGNQ CLOY: ISI.S 12' MIN. fill HClE C64LE IH[O OWN GAP PVC DRAIN OUTLET Pond Report 5 Hydraflow Hydrographs Extension for AutoCADO Civil 3D0 2009 by Autodesk, Inc. v6.066 Friday, Sep 13, 2019 Pond No. 1 - BMP Pond Pond Data Contours - User -defined contour areas. Average end area method used for volume calculation. Begining Elevation = 132.50 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sgft) Incr. Storage (cuft) Total storage (cuft) 0.00 132.50 3,195 0 0 0.50 133.00 3,990 1,796 1,796 0.70 133.20 4,675 867 2,663 1.50 134.00 9,325 5,600 8,263 Culvert / Orifice Structures [A] [B] [C] [PrfRsr] Rise (in) = 15.00 0.75 0.00 0.00 Span (in) = 15.00 0.75 0.00 0.00 No. Barrels = 1 1 0 0 Invert El. (ft) = 132.50 132.50 0.00 0.00 Length (ft) = 10.00 0.50 0.00 0.00 Slope (%) = 1.00 1.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Multistage = n/a Yes No No Weir Structures [A] [B] [C] [D] Crest Len (ft) = 9.00 7.00 0.00 0.00 Crest El. (ft) = 133.20 133.50 0.00 0.00 Weir Coeff. = 3.33 2.60 3.33 3.33 Weir Type = Rect Broad --- --- Multistage = Yes No No No Exfil.(in/hr) = 0.000 (by Contour) TW Elev. (ft) = 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control Weir risers checked for orifice conditions (ic) and submergence (s) Stage (ft) Stage / Discharge 2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 000 Elev (ft) 134.50 134.30 134.10 133.90 133.70 133.50 133.30 133.10 132.90 132.70 13250 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 Total Q Discharge (cfs) Hydrograph Summary Re PC Frydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc, v6.066 Hyd. No. Hydrograph type (origin) Peak now (cfs) Time interval (min) Time to peak (min) Hyd. volume (cult) Inflow hyd(s) Maximum elevation (ft) Total strge used (cuft) Hydrograph description 1 SCS Runoff 1.539 2 722 4,128 - - BMP Pre -Developed 2 SCS Runoff 3.765 2 716 7,772 ------ - -- BMP Post -Developed 3 Reservoir 1.387 2 724 7,291 2 133.35 3,656 Post Through Pond 5 SCS Runoff 0.282 2 146 1,210 ---- ------ - BMP Post -Developed 6 Reservoir 0.008 2 366 1,121 5 1 Year 132.81 1,127 1.0-in Storm Thru Pond ShortStop.gpw Return Period: Friday, Sep 13, 2019 2 Hydrograph Report Hydraflow Hydrographs Extension forAutoCAD® Civil 3D® 2009 byAutodesk, Inc. v6.066 Hyd. No. 1 BMP Pre -Developed Hydrograph type = SCS Runoff Storm frequency = 1 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 3.03 in Storm duration = 24 hrs Q (cfs) 2.00 1.00 BMP Pre -Developed Hyd. No. 1 -- 1 Year 120 240 360 480 600 720 840 960 Hyd No. 1 Friday, Sep 13, 2019 Peak discharge = 1.539 cfs Time to peak = 722 min Hyd. volume = 4,128 cuft Curve number = 74.6 Hydraulic length = 0 ft Time of conc. (Tc) = 10.00 min Distribution = Type II Shape factor = 484 Q (Cfs) 2.00 1.00 - 0.00 1080 1200 1320 1440 1560 Time (min) 3 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Hyd. No. 2 BMP Post -Developed Hydrograph type = SCS Runoff Storm frequency = 1 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 3.03 in Storm duration = 24 hrs Q (cfs) 4.00 3.00 2.00 1.00 BMP Post -Developed Hyd. No. 2 -- 1 Year Friday, Sep 13, 2019 Peak discharge = 3.765 cfs Time to peak = 716 min Hyd. volume = 7,772 cuft Curve number = 89.7 Hydraulic length = 0 ft Time of conc. (Tc) = 5.00 min Distribution = Type II Shape factor = 484 120 240 360 480 600 720 840 960 Hyd No. 2 Q (cfs) 4.00 3.00 2.00 1.00 0.00 1080 1200 1320 Time (min) Hydrograph Report 4 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Friday, Sep 13, 2019 Hyd. No. 3 Post Through Pond Hydrograph type = Reservoir Peak discharge = 1.387 cfs Storm frequency = 1 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 7,291 cuft Inflow hyd. No. = 2 - BMP Post -Developed Max. Elevation = 133.35 ft Reservoir name = BMP Pond Max. Storage = 3,656 cuft Storage Indication method used. Q (cfs) 4.00 3.00 2.00 1.00 Post Through Pond Hyd. No. 3 -- 1 Year 120 240 360 480 600 720 Hyd No. 3 Hyd No. 2 Q (cfs) 4.00 MY 2.00 1.00 0.00 840 960 1080 1200 1320 1440 1560 Time (min) ® Total storage used = 3,656 cult 6 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 31DO 2009 by Autodesk, Inc. v6.066 Friday, Sep 13, 2019 Hyd. No. 5 BMP Post -Developed Hydrograph type = SCS Runoff Peak discharge = 0.282 cfs Storm frequency = 1 yrs Time to peak = 146 min Time interval = 2 min Hyd. volume = 1,210 cuft Drainage area = 1.150 ac Curve number = 89.7 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 5.00 min Total precip. = 1.00 in Distribution = SCS 6-Hr Storm duration = 6.00 hrs Shape factor = 484 Q (cfs) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 0 BMP Post -Developed Hyd. No. 5 -- 1 Year 60 120 180 240 300 360 Hyd No. 5 Q (cfs) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 420 Time (min) IA Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Hyd. No. 6 1.0-in Storm Thru Pond Hydrograph type = Reservoir Storm frequency = 1 yrs Time interval = 2 min Inflow hyd. No. = 5 - BMP Post -Developed Reservoir name = BMP Pond Storage Indication method used Q (cfs) Friday, Sep 13, 2019 Peak discharge = 0.008 cfs Time to peak = 366 min Hyd. volume = 1,121 cuft Max. Elevation = 132.81 ft Max. Storage = 1,127 cuft 1.0-in Storm Thru Pond Hyd. No. 6 -- 1 Year Q (cfs) r� 0.50 - U.UU 0.45 0.45 0.40 0.40 0.35 0.35 0.30 0.25 - 0.30 0.25 0.20 0.20 0.15 - 0.15 0.10 0.10 0.05 0.05 0 00 n nn 0 480 960 1440 1920 2400 2880 3360 3840 4320 4800 Time (min) Hyd No. 6 — Hyd No. 5 FEEFFITI Total storage used = 1,127 cult Hyd rog ra p h Summary Re pc®raflow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6.066 10 Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 3DO 2009 byAutodesk, Inc. v6.066 Hyd. No. 1 BMP Pre -Developed Hydrograph type = SCS Runoff Storm frequency = 2 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 3,67 in Storm duration = 24 hrs Q (cfs) 3.00 2.00 1.00 BMP Pre -Developed Hyd. No. 1 -- 2 Year 120 240 360 480 600 720 840 Hyd No. 1 Friday, Sep 13, 2019 Peak discharge = 2.286 cfs Time to peak - 722 min Hyd. volume = 6,015 cuft Curve number - 74.6 Hydraulic length = 0 ft Time of conc. (Tc) - 10.00 min Distribution = Type II Shape factor = 484 Q (cfs) 3.00 2.00 1.00 0.00 960 1080 1200 1320 1440 1560 Time (min) 11 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Hyd. No. 2 BMP Post -Developed Hydrograph type = SCS Runoff Storm frequency = 2 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 3.67 in Storm duration = 24 hrs Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 _� 0 120 240 Hyd No. 2 BMP Post -Developed Hyd. No. 2 -- 2 Year Friday, Sep 13, 2019 Peak discharge = 4.828 cfs Time to peak = 716 min Hyd. volume = 10,095 cuft Curve number = 89.7 Hydraulic length = 0 ft Time of conc. (Tc) = 5.00 min Distribution = Type II Shape factor = 484 360 480 600 720 840 960 Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 1080 1200 1320 Time (min) 12 Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6.066 Hyd. No. 3 Post Through Pond Hydrograph type = Reservoir Storm frequency = 2 yrs Time interval = 2 min Inflow hyd. No. = 2 - BMP Post -Developed Reservoir name = BMP Pond Storage Indication method used. Q (cfs) 5.00 4.00 3.00 2.00 1.00 W Post Through Pond Hyd. No. 3 -- 2 Year Friday, Sep 13, 2019 Peak discharge = 1.939 cfs Time to peak = 722 min Hyd. volume = 9,613 cuft Max. Elevation = 133.47 ft Max. Storage = 4,495 cuft Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Time (min) Hyd No. 3 Hyd No. 2 LET I Total storage used = 4,495 cult `6l Hydrograph Summary Rep `"yd`r"aflow Hydrographs Extension for AutoCAD® Civil 3DO 2009 by Autodesk, Inc. v6.066 Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Hyd. volume (cuft) Inflow hyd(s) Maximum elevation (ft) Total strge used (cuft) Hydrograph description 1 SCS Runoff 4.646 2 720 12,050 - - BMP Pre -Developed 2 SCS Runoff 7.805 2 716 16,822 — - ------ BMP Post -Developed 3 Reservoir 4.526 2 722 16,339 2 133.74 6,427 Post Through Pond 5 I SCS Runoff 0.000 2 n/a 0 -- ------ -- BMP Post -Developed 6 Reservoir 0.000 2 n/a 0 5 132.50 0.000 1.0-in Storm Thru Pond ShortStop.gpw Return Period: 10 Year Friday, Sep 13, 2019 16 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Hyd. No. 1 BMP Pre -Developed Hydrograph type = SCS Runoff Storm frequency = 10 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 5.47 in Storm duration = 24 hrs Q (cfs) 5.00 4.00 3.00 2.00 1.00 120 240 Hyd No. 1 BMP Pre -Developed Hyd. No. 1 -- 10 Year 360 480 600 720 840 Friday, Sep 13, 2019 Peak discharge = 4.646 cfs Time to peak = 720 min Hyd. volume = 12,050 cuft Curve number = 74.6 Hydraulic length = 0 ft Time of conc. (Tc) = 10.00 min Distribution = Type II Shape factor = 484 Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 960 1080 1200 1320 1440 1560 Time (min) `rA Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 31DO 2009 by Autodesk, Inc v6.066 Hyd. No. 2 BMP Post -Developed Hydrograph type = SCS Runoff Storm frequency = 10 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 5.47 in Storm duration = 24 hrs Q (cfs) 8.00 MOM IIQ 2.00 BMP Post -Developed Hyd. No. 2 -- 10 Year Friday, Sep 13, 2019 Peak discharge = 7.805 cfs Time to peak = 716 min Hyd. volume = 16,822 cuft Curve number = 89.7 Hydraulic length = 0 ft Time of conc. (Tc) = 5.00 min Distribution = Type II Shape factor = 484 120 240 360 480 600 720 840 960 Hyd No. 2 Q (cfs) 8.00 . W 4.00 2.00 0.00 1080 1200 Time (min) Hydrograph Report 18 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Friday, Sep 13, 2019 Hyd. No. 3 Post Through Pond Hydrograph type = Reservoir Peak discharge = 4.526 cfs Storm frequency = 10 yrs Time to peak = 722 min Time interval = 2 min Hyd. volume = 16,339 cuft Inflow hyd. No. = 2 - BMP Post -Developed Max. Elevation = 133.74 ft Reservoir name = BMP Pond Max. Storage = 6,427 cuft Storage Indication method used Q (cfs) 8.00 . IX 4.00 2.00 Post Through Pond Hyd. No. 3 -- 10 Year 120 240 360 480 600 720 Hyd No. 3 --- Hyd No. 2 Q (cfs) 8.00 .W 4.00 2.00 0.00 840 960 1080 1200 1320 1440 1560 Time (min) Total storage used = 6,427 cult 21 Hydrograph Summary Rep —I-rydl 'flow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6.066 Hyd. No. Hydrograph type (origin) Peak now (cfs) Time interval (min) Time to peak (min) Hyd. volume (cuff) Inflow hyd(s) Maximum elevation (ft) Total strge used (cuft) Hydrograph description BMP Pre -Developed 1 SCS Runoff 8.855 2 720 23,137 -- -- 2 SCS Runoff 12.62 2 716 28,112 -- --- BMP Post -Developed 3 Reservoir 9.843 2 720 27,627 2 133.97 7,998 Post Through Pond 5 SCS Runoff 0.000 2 n/a 0 ---- -- - --- BMP Post -Developed 6 Reservoir 0.000 2 n/a 0 5 100 132.50 Year 0.000 1.0-in Storm Thru Pond ShortStop.gpw Return Period: Friday, Sep 13, 2019 22 Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6.066 Hyd. No. 1 BMP Pre -Developed Hydrograph type SCS Runoff Storm frequency = 100 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 8.42 in Storm duration = 24 hrs Q (cfs) 10.00 4.00 2.00 BMP Pre -Developed Hyd. No. 1 -- 100 Year 120 240 360 480 600 720 840 Hyd No. 1 Friday, Sep 13, 2019 Peak discharge = 8.855 cfs Time to peak = 720 min Hyd. volume = 23,137 cuft Curve number = 74.6 Hydraulic length = 0 ft Time of conc. (Tc) = 10.00 min Distribution = Type II Shape factor = 484 Q (cfs) 10.00 e . We 4.00 2.00 0.00 960 1080 1200 1320 1440 1560 Time (min) 23 Hydrograph Report Hydraflow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6 066 Hyd. No. 2 BMP Post -Developed Hydrograph type = SCS Runoff Storm frequency = 100 yrs Time interval = 2 min Drainage area = 1.150 ac Basin Slope = 0.0 % Tc method = USER Total precip. = 8.42 in Storm duration = 24 hrs Q (cfs) 14.00 12.00 10.00 M 4.00 2.00 120 240 Hyd No. 2 BMP Post -Developed Hyd. No. 2 -- 100 Year Friday, Sep 13, 2019 Peak discharge = 12.62 cfs Time to peak = 716 min Hyd. volume - 28,112 cuft Curve number = 89.7 Hydraulic length = 0 ft Time of conc. (Tc) = 5.00 min Distribution = Type II Shape factor � 484 Q (cfs) 14.00 12.00 10.00 M M 4.00 2.00 0.00 360 480 600 720 840 960 1080 1200 Time (min) Hydrograph Report 24 Hydraflow Hydrographs Extension for AutoCADO Civil 31DO 2009 by Autodesk, Inc. v6.066 Hyd. No. 3 Post Through Pond Hydrograph type = Reservoir Storm frequency = 100 yrs Time interval = 2 min Inflow hyd. No. = 2 - BMP Post -Developed Reservoir name = BMP Pond Storage Indication method used Q (cfs) 14.00 12.00 10.00 4.00 2.00 Post Through Pond Hyd. No. 3 -- 100 Year Friday, Sep 13, 2019 Peak discharge = 9.843 cfs Time to peak = 720 min Hyd. volume = 27,627 cuft Max. Elevation = 133.97 ft Max. Storage = 7,998 cuft Q (cfs) 14.00 12.00 10.00 M 4.00 2.00 0.00 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 3 Hyd No. 2 Total storage used = 7,998 cult Time (min) Project Name Riprap Dissipaior #1 Date Short Stop Arabia Road Oct, 2019 DD Project No. Location Double D Engineering, PLLC DD1812 Hoke County, North Carolina 150 S. Page Street Calculated By Southern Pines, NC 28387 JLH (910) 684-8646 Checked By JLH STORM DESIGN: 10 Year BACKGROUND: Use the E&S Control Planning & Design Manual, Section 8.06. PREFERENCE: (NCDEQ, 2013) Step 1. Minimum Tailwater Condition Step 2. D-o = 15 in. Pipe diameter in inches D-o = 1.25 ft. Pipe diameter in feet Q-10 = 7.81 cls Pipe outlet (from drainage calculations) d-50 = 0.4 ft. from Figure 8.06 a L-a = 10 ft. from Figure 8.06 a Step 3. Step 4. Step 5. 3*D-o = 3.75 ft. W = 11.25 ft. d-max 0.60 ft. d-max 7 in. Thickness = 0.90 ft. Thickness = 11 in. DESIGN DIMENSIONS: 3 times the outlet pipe diameter Pipe diameter + Apron length Maximum Stone Diameter (1.5*d-50) in inches Maximum Stone Diameter (1.5*d-50) in feet Min. Apron Thickness With Filter Fabric (1.5*d-max) in feet Min. Apron Thickness With Filter Fabric (1.5*d-max) in inches Apron Dimensions Riprap Length Width 3-D-o Thick Class 10 12 4 241n. 1 TERMINOLOGY: Q10 = 10-Year Design Storm, Peak Discharge, (cfs) D-o = Pipe Diameter, (in. & ft.) d-50 = Mean Stone Diameter of Rip -Rap, (ft.) L-a = Length of Rip -Rap Apron, (ft.) 3*D-o = Width of Rip -Rap Apron @ Pipe Outlet, (ft.) W = Width of Rip -Rap Apron @ End of Apron, (ft.) d-max = Maximum Stone Diameter of Rip -Rap, (ft. & in.) Thickness = Thickness of Rip -Rap Apron With Filter Fabric, (ft. &in.)