Loading...
HomeMy WebLinkAboutDrainage ReportDrainage Report for Castlerock Subdivision Phase 1 College Station, Texas September, 2006 Developer: Greens Prairie Investors, Ltd. By Greens Prairie Associates, LLC. 4490 Castlegate Drive College Station, Texas 77845 (979) 690-7250 EiZ hover: Civil Development, Ltd. 2900 Longmire Drive, Suite K College Station, Texas 77845 (979) 764-7743 CERTIFICATION I, Kent Laza, Licensed Professional Engineer No. 6592-3), State of Texas, certify that this report for the drainage design for the Castlerock Subdivision —Phase 1, was prepared by me in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners hereof. 26 Castlerock Subdivision, Phase 1 Drainage Report GENERAL Location: Castlerock Subdivision, Phase 1 is located on the north side of SH 40 near its intersection with the new section of Arrington Road. Description: ■ Area: 13.4 acres ■ Proposed Land Use: PDD- Single Family Residential ■ # of Lots: 30 lots ■ Existing Land Use: Agricultural — consisting primarily of a wooded pasture used for cattle grazing ■ Land Description: Rolling terrain that falls northwest toward Spring Creek. The site is heavily wooded. Adjoining Land Use: The site is bounded on the north and east by undeveloped sections of the Castlerock Subdivision and on the west by conservation zones that are to be left in their natural state. Castlegate Subdivision and Forest Ridge Elementary School are located across SH 40 from the site. Primary Drainage Facility: Spring Creek — Main Channel Flood Hazard Information: FEMA FIRM: # 48041 CO205 D (February 9, 2000) Floodplain: No portion of any developed lots lies within the floodplain of Spring Creek. The floodplain is wholly contained within greenways and conservation areas outside of the lots. DRAINAGE DESIGN Generallnfornuaion: Stormwater runoff from Phase 1 of the subdivision will be controlled by two independent drainage systems within the development and the SH 40 roadside ditch. In the report that follows, the systems are referred to as: ■ System I — Culvert under Castlerock Parkway at SH 40 ■ System 2 — Inlets/storm drains on Castlerock Parkway ■ System 5 — Inlets/storm drains on Rocky Creek Trail System 1 consists of a single 18" culvert under the main entrance into the subdivision. The entrance is near the high point of a drainage divide, so the amount of water it carries is relatively small. Systems 2 and 5 are interior to the development and consist of a series of curb inlets connected by underground pipes. The outfall for System 2 is a temporary channel that generally follows the alignment of Castlerock Parkway through future phases of the development until it reaches Spring Creek. The outfall for System 5 is a temporary channel that generally follows the alignment of Rocky Creek Trail through future Phase 2 and into a tributary of Spring Creek. The design of System 5 includes two inlets planned for Phase 2 that are not being built with Phase 1, but were included in the computations to determine pipe and inlet sizes. Street Design: Standard cross-section (3% cross -slope, 27' B -B residential, 38' B -B collector) Lay down curb & gutter on residential streets, standard 6" curb on the collector street. Asphalt pavement Standard recessed curb inlets (length varies) T, Methodology: TR 55 7,Mininnnn 10 minutes Design Storm Event: 10 -year -residential strcct & storm sexver 25 -year -collector street culvert at SI1 40 PaL,C I oi`2 DRAINAGE DESIGN (cont.) Pipe Materials: Corrugated HDPE w/smooth interior Ivianning's n. ✓aiue: 0.012 Runoff Coefficients: 0.55 for developed lots Design Constraints: Max. water depth in curb = 4.5 in. or 0.38 ft. Min. flow velocity = 2.5 fps Max. flow velocity = 15 fps Min. freeboard at collector street culvert = 1 ft. 100 -yr storm runoff maintained within the ROW (4 inches above curb) Design Sgftiwwre: Haestad Methods StorinCAD v 4.1 This software computes the rainfall and runoff using TR -55 and the Rational Method. It computes inlet capture efficiencies using the orifice equation using the methodology found in HEC 22. Flows through the pipes are computed using Manning's Equation. StorinCAD routes water down the curb, checks flow depth at the curb, determines bypass flows for inlets on slope, computes pipe capacity, flowrate and velocity through each pipe, and determines hydraulic grade line elevations at each inlet or J unction box. All of this information is shown in the summary tables on Exhibits D and E. The College Station requirement for a 25% reduction in cross-sectional area of pipes less than 27" diameter is achieved by using internal pipe diameters that are less than the standard diameter. The following table shows how the reduced diameters and areas used by the software. The reduced pipe diameters are noted as 18"(-25%) or 24"(-25%) in the output exhibits. Std Pipe Std Pipe Reduced: Reduced Reduction Dia. Area Pipe Dia. Pipe Area in sf in sf 15 1.227 12990 0.920 28 18 1.767 15.300 1.277 28 21 2.405 18.187 1.804 25 24 3.142 20.785 2.356 25 Applicable E_yhibits: Exhibit A — Drainage Area Map Exhibit B — Time of Concentration Worksheet Exhibit C — StorinCAD Inlet Analysis Summary (10 -yr and 100 -yr storms) Exhibit D — StorinCAD Pipe Analysis Summary (10 -yr and 100 -yr storms) DETENTION DESIGN General: Stormwater runoff from Phase 1 and all subsequent phases of the Castlerock Subdivision flow into Spring Creek upstream of the regional detention facility constructed in 2000. This facility was designed to control stormwater releases from the Castlerock Subdivision and other adjoining properties. No additional detention facilities are provided with the development of this project. CONCLUSION Based on the output from the SiormCl41.) software, the drainage system in Phase 1 of the Castlerock Subdivision will function within the requirements and restrictions of the College Station Drainage Policy and Design Standards. ,We X W U) m C tom. C N O ti r M W O O N O d D N ry O H C ~ D N @ C O O O O N N O N O 0 0 F- N > N T U O O O O O O O N O O O 0 C) O O Cl N N Cl M O O O v U C 3s No O L- Q) (D a) LO (n Y _ w > N N J .7 v ✓) t- L,L 3 N w M .- •- N r!' �- N N O U i a) CIL o r L t,- r - r -d' ++ 0 3 M o LO � O �: O N w M O S CO to U) O M N w -'t 't O�� O o ac�i 01 D' n '0 L o T. V LL U N 0 0 0 0 0 0 0 0 0 0 0 fLC . • L � {Z L U = N a� U) O p� w >U � O M c U> N O O O M -� � - .- � N N �y a.�- N 00 > O > - O Y_ y L LO r- �Ln0 N M O Q. O (D Y U o) O a c O N N N N N N N N O O O O O O O O # Q �- N M V Ln (.D 00 N Cl) V CD O 0 0 0 0 0 0 0 - N N N N N N N N N N N N It II II II II II 11 j (n i- J >� N O d O > > O,j p L M yi LO i N J 0 cn Y ry. c O O O L > Q O Qi M O LL .o N O ON O. (Q fC.>.� U Ii I1 w o a� (Do 0 > > r � v O. U � m w � J L v O 3U O O c F- E M O m L u) o p 3 a O cn a o c O LL (0 .>- a+ d C: N � L m z N o U C Vi N N � C:J O c0 J � O C c O Y N O N E (A C C c0 T d - O _O Q O O e J c (n � U) m C tom. C N O ti r M W O O N O d H D N @ C O O O O N N O N O 0 0 F- N > U O O O O O O O N O O O 0 U)O O O Cl N N Cl M O O O > _ LL . L- Q) (D a) LO V Y _ w 00 00 N M N N J v c t- 3 N w M .- •- N r!' �- N N O;> LL! L t,- r - r -d' ++ 0 3 M o LO � O �: O N w M O S CO to U) O M N w -'t 't O�� O o ac�i d D' n 0 0 0 0 0 0 0 0 0 0 0 o T. LL U N 0 0 0 0 0 0 0 0 0 0 0 fLC . U = a� J c O M c U> N O O O M � - .- � N N �y a.�- O . N M �- N LL L LO r- �Ln0 to a J t~ O co c N N N N N N N N O O O O O O O O # Q �- N M V Ln (.D 00 N Cl) V CD O 0 0 0 0 0 0 0 - N N N N N N N N N N N M W C LA •� C 00 r tD 00 N � M !,r M r N r r r u 0 (6 C O — (O00 N to Co H C0c) p) Co Lo O N 0 E r N N r 3 Q O p o N.N r �M rr LL � d d O C O O ti O O M N J It It d' •a' It � d' C N N N N N N N 0 0 0 0 0 0 0 _ Q Q OV d' Lo (t) Ln Lo 0 N N N N N N (N N m O N X 0) wa_ a v i H C.4 > N O co U> O O co co > FL i rte.. (D a o c0 c0 CO 3 CV O O (O t LO U") O N J' a m m C N O r N r r � 30 N N a O j , 00 00 Ci CD r c- .N LO �> V _ v E L 0 � O CO M O (O O U) d' O to M U') /1 U) C:� J r a-. CO r M N Cf) o o a w d O M O r N O O O N O N co O O U c CL m d O C F r O, N O M 'r J C0c) p) Co Lo O N 0 E r N N r 3 Q O p o N.N r �M rr LL � d d O C O O ti O O M N J It It d' •a' It � d' C N N N N N N N 0 0 0 0 0 0 0 _ Q Q OV d' Lo (t) Ln Lo 0 N N N N N N (N N m O N X 0) wa_ `_J 't� C � - -0 a) M i a) M N to O N •- N d O Q- - M M M N Cl) Q M M 't M Q O O d •- ti Q Oti00"ro LO J r-- tiMto d N tf) to p J d N to to p C)) 00 00 v p O 00 00 _ N N N N = N N N N s Q i C O'Itr- Q) C LO �- d J rl- t` LO to 4 N in Lo J rl- 00 dT (D N Lo to p O M 00 O O 00 M _ N N N N j = N N N N i� 'o tf) tl- (7) O x M 7 tf) r- O O C> V. N. -=C j d N. r p a) r- u) 00 00 p ti u) 00 00 E W 0) 0) 00 00 E L W 0) 0)co 0o U' N N N NL (7 N N N N L O O 0 (A ._ U) "O O a) C a) U! � Vii 0J r 0? M O n M LO M CO O Q U N to 4 N Q U d' c6 O co' CO m O p C p C C j(1) N 0 0 t- r C N n (C) V OO �t C UN r -_r - M_ C UNOOOd' � rn U r r- O O U) cn m co 00 N tC U 'o (N ttN O U(D O f3 p � L Y L a 0) Y p Y L C p l0 O O 0 0000 O O 0000 m UU- d UU U Rf �- U N 'EU') C 4-- tf) U') O t .. N C 0) C v= LO to tf) O a) — — .- M w OJ OJ F- w U) a) w CO cn U) ai a) vi cn CO CO mmmm -i mmmm v> Q Q Q Q .Q.Q.o-0 a) >>�� a) �>>D U U U v 5 U U U U OT V O ONO F- E N N N F E N N U to to to to U to to to to LO to LO to to to to to O O O o E 0 0 0 0 M d' M O O M d' (D O O m U to (D T r` m v o r-- Q M. r M Q M M - N LO V <- N to d" @ 0 0 0 �- O O O - J N N N N J N N N N 't� C x W N U O E N X O wa L '0 (a<- M d (O 't " (9 c O 00 to Q00 00 O 00 r-- O O 47 U) _ EL 'n COr( N N N N N N N ItN M 7 L Y o- ti (S) CO N t` N M N (') d' N V 0 0 0 0 0 0 0 0 0 0 0 0 0 O O N V M 00 O II II , :3 O LO L r d Cl) to tf) r- V N O II II j :. d (O O N tT M Lo m y M t` tf) co co N oo 0000 00 00 00 00 (� 00 00 00 00 00 00 0 _ N N N N N N= N N N N N N � c O N d' M 00 O Q c LO to .- V CO Lo N dt (0 O N 0) M tf) r- q N (o r) J 00 r-, L6 M N N J 00 r- co M N , 00 00 00 00 00 00 CO 00 00 CO 00 Op (1) F N N N N N N D = N N N N N N a 00 (O d 00 M N (XO 70 00 0 d 00 Cl) N X j tl- 00 M ti U) LO C j rl- 00 M r- to to m - O 00 0 ( ( O 00 (6 (0 6 7-5 ( 0) 6) 00 00 00 00 w m O 00 00 00 00 N N N N" N E (� N NN N N N E _. L 0 O T- C1 N N t0) Lo to O O O d ((> CO to O O C 0- U N r �- N O o 0 Q U M N Cl) O O a m, o m z o O 0 ',, N d' N M M 0 O r 0 _ wr- ` r- OV' c U M (0 M (o to M C U co 00 co 0 V U) E E N m Q U) U) 0 N co NLO�� Z� to V <- O O N O M 6 4 m cn U CO 00 r- to m 0 �i F- i F i— W F— )c _ F— W 0) a Q J Uc L L C L 0 r r c- r r 0 r C- r — Oc) O LL ' ui J o o v U) LO c -r- Q E "co�o�too c �o(notnLOo C: U QJ —, w a) o 0 � Ca- U U U 0 0 C) n C) U U U U U m m m m m m m m m m m m Q) L L L L L- L UUUUC)U UUUUUU u 00 - 00 (o O co 00 .- 00 � O co F- E r- M N c- F E .-m N - U to (n (o LO to Lo U to to (n to V) io (n(n(otoLo(n LOMto(nLI) Lo. C) O o O o o c o 0 0 0 o O (0 N U r-- I-- O 0) O r- (D (0 N .- t,- -O m ti t` O M O N 0 Q <- N r (D O 41 00 O ,_ Q m O N M O Q ib m N N LO N N N N V)U") N m N N N Ln N _J N N J N N N U O E N X O wa n 'O O O Oji 4 o w1 O U Cl) c V' O Q O = co 7 O O U) :3a:4 o W o L U d U x co ul w U d LO 0) U { O O N Oco fl. 1 UCo V N Y° L � d. O_ d U Cl) Y E O U Nca _ C O 0 o � 3: CD $� ! m U > j W o w 0 > > N u) L1J O F 0 LO C N O N O O LL Q O 0 N 61 _ O j; O SCJ W'O Im C M J N Q O = co O O O OL O Q W� M L U) T cii G H� [1 V) X Q U 4) w coU L _ O O O N iw0� O CL U rt 3 W Y N is d CL w Q1 p V co Y O u U O L cn m � fa C C O U o 0 0 o o o � o m U) o t y > 'C V = T o CO M w- > N '.. N W O ch 0 @ LO C N C2 O O Q 5) O C LL N J U) O 0 0 O Q Z U) _ o zo c6 J M 0 0 n, X LU o U M O to 00 M (0 4 tl_ 0 tl- 0) co O J N 'tet 6 M Ur 0) 00 co 00 _ N N N N t- 0) O O C j N O o to M M M U W; N W N Fj M C O d' ti c- tit-LoM N Lo to 0 0) 0) M 00 _ N N N N _0 torOrn C: > �t N — �- O� O; r,:ui 00 00 0 W N 00 N N N to +>.'.. a)m ''. w O t-- co Q7 Wa U O to d' co c U N m U"'. uU- N to N O ) U 00 N a a) aa, a N o r` E D U N O M S to U tII �? N N C\4 C" O O O O R co ooOo a � Y U O` O r-- 0) CO a) Q $ O M to U) Cn O O O O U 0 0 0 0 N W N N 00 N N >- Q > > �- (O 00 00 C (3) r- 4 M W '.'. N N co 000 D 0 0 0 0 LO to to to C N N N N OO O 00 d N O....._ O N a � r tea' a) J (\j Cl) N O 00 d I •- N C14 LO Ln LL O O O 0 N N N N N d o O O •- O N N N N N (") V LL d d N N N N C(14 0 00 O V M Jaf (,4 to to M (� 0) Oo 00 00 = N N N N t� O O O N''.. to 00 M O Q 00 U W N N N N C to N It �- J t- 00 (.0 V Ljo Lf) 0` 0) � 00 0o = N N N N O4 to � O 0) CO > > v N •- — r 'o oo co O WI' 00 00 N N N N E N N co C W U rn 0 O U N to ED O N O_ U M N Q o U .- _0 E z3 41 0 U N co 4 0 N o T N N N N N C r C C O O O O to ca 0000 a X OL O t` O M d Q O O _ LO O O O O V j � O O 0 LLJ H r- a) � 4 Q W N N N 00 N U) _... CY) > > ,'' �- O 000 000 c O d 4 M W 00 00 N N N N 0 0 0 0 @ to to to to C N N N N 00 00 00 � .- •-- N O a) Q a M N O C 0 c} a) J LL CO O C\l LO LO O O O 0 Q z N N (N N U) '@D N It Lo O 0 0 — 0 z N N N N N N M 'It a- a- d n @ (N N N N J M 0- 0 fl N L a) X 0) W d w X W r a O C/) Cl) m J =a cn Q U CL w a W J U U M (o N to N O d Lo .4 ui O M O_.. _..... O N .2- 0) 0) O O N � 00 N (D O M 00 J O O Q Q CD 6) LL (1) _0N N N Lr) O L0O Z N Lo N N N Lo N to (n 'O 00 OQ m a7 O `- N N Z N N N N N N Q1 '- N M V (f) M - flda_(1.-d m (r) (n (() to (n UD J o V) (D .- to W O t' - Lc; Lc; ti M M 00 00 Cl) (D N O (D N M N (3) It 00 0 M 00 0 0 M = N N N N N N 'D (D 00 00 co N O U) _ > 00 r t- L.() (o O Q1 O O (D M (D 00 Q 00 00 00 00 00 O W' N (14 N N N N c t!) Lr) .--- M L ) L0 t` d (14 (() J 00 t-- (f) M M N iD co 00 00 00 co 00 T- _0 a 00 (D It co Cl) N C/)C: >� r`00Mt-�� a); o 0o cfl co (o O W' N N N N N 00 N U)E 17 Y OX CL (U M m co r 0) It f4 W U C rn _ Qo)(U6 M N N 6) to >+ D o U C) - 0 rn�c0a?r"t N E U M M T N N N O U 0) N N N N N N F` C: 000000 x ca 000000 a) d U N c0 (D M to OD (o co 'd co (D O Vo � O N O O O O — O O O O 0 0 w 0 0 0 0 0 o (n ate) N00coI (D 00 W >> O Cl) 00 (D Cl) O C 4) U) wOOD 000000000000 �- N N N N N N ui 0 If >W C1 00 4 It > ( W ( W 00 00 N N N Lo Lo Lo U U U C N N N C C C M't 00 M M co O (D .- L 0) (D O O N N M N (D (D M w J U) 'U6 O Q Q m O LL O Lr) N N N O Z N N N N N a) Q m z � O N N Lr) N O N M V n (D q- cL d IL n Ln Ln LC) Lr) Lf-) Lr) J M C) O M .0 N x 0) W D 00 Cl) 00 00 ON O cND M O) (D J' 1 t- (M M N N CD m O O oo co co = N N N N N N (D M M Cl) N O (n C > OO tl- th to to O N o i O (D M (fl M OD �W N00ODN00OD C O N It M M O — d' (D O N O Cl) J 1 00 t- (o (M N N O M 00 00 00 M M = i N N N N N N 'D 1 00 (D d' OD M N 0�I - 000co(o(o Z w O O 00 00 M O0 I N N N N N N E au)) ao Lo L a 4' LO (n W U : rn •N c . a) O) U N co N N O (o Q (/) 0- V r- O N 0 M O O U I N .- N M t� a) C to N OD .-- O O O N O U � N _ L m �_ ' N_ N N N N N F- C C c- C 0 0 0 0 0 0 a) @ 0 0 0 0 0 0 (D Y Q 000_'tM(OoN p 0 0 0 0 0 04 0 0 0 0 0 0 O 0 O >> co O co (o M O N 1 h N N O }Cn W OD000ooaoO N Q N N N N NN > > r- (N M W Lo OMO C N Icif tl�O d' �- �- O ( jj co co 00 co CO co N N N N N N Z i to Lo (o U U U co C N N N c c c E O O (o OD � 00 co M M O_.. _..... O N .2- 0) 0) O O N � 00 N (D O M 00 J O O Q Q CD 6) LL (1) _0N N N Lr) O L0O Z N Lo N N N Lo N to (n 'O 00 OQ m a7 O `- N N Z N N N N N N Q1 '- N M V (f) M - flda_(1.-d m (r) (n (() to (n UD J o V) (D .- to W O t' - Lc; Lc; ti M M 00 00 Cl) (D N O (D N M N (3) It 00 0 M 00 0 0 M = N N N N N N 'D (D 00 00 co N O U) _ > 00 r t- L.() (o O Q1 O O (D M (D 00 Q 00 00 00 00 00 O W' N (14 N N N N c t!) Lr) .--- M L ) L0 t` d (14 (() J 00 t-- (f) M M N iD co 00 00 00 co 00 T- _0 a 00 (D It co Cl) N C/)C: >� r`00Mt-�� a); o 0o cfl co (o O W' N N N N N 00 N U)E 17 Y OX CL (U M m co r 0) It f4 W U C rn _ Qo)(U6 M N N 6) to >+ D o U C) - 0 rn�c0a?r"t N E U M M T N N N O U 0) N N N N N N F` C: 000000 x ca 000000 a) d U N c0 (D M to OD (o co 'd co (D O Vo � O N O O O O — O O O O 0 0 w 0 0 0 0 0 o (n ate) N00coI (D 00 W >> O Cl) 00 (D Cl) O C 4) U) wOOD 000000000000 �- N N N N N N ui 0 If >W C1 00 4 It > ( W ( W 00 00 N N N Lo Lo Lo U U U C N N N C C C M't 00 M M co O (D .- L 0) (D O O N N M N (D (D M w J U) 'U6 O Q Q m O LL O Lr) N N N O Z N N N N N a) Q m z � O N N Lr) N O N M V n (D q- cL d IL n Ln Ln LC) Lr) Lf-) Lr) J M C) O M .0 N x 0) W D