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Home My WebLink About8.0 Revised Drainage Plan(970) 945-1004 FAX (970) 945-5948 E'VG'IVEEFS -S,- *M- JUd*ruEJEd :- GONDON MEYER 118 West 6th, Sulte 200 Glenwood Springs, CO 81601 October 30, 1996 Mr. Mark Bean, Director Garfield County Building, Sanitation & Planning Department 109 8th Street, Suite 303 Glenwood Springs, CO 81601 RE: Mountain Meadows at Prince Creek Revised Drainase Plan it, Dear Mr. Bean: This letter shall serve as a transmittal of the revised drainage plan as attached hereto. As of this date, I have not yet been able to receive concurrence from Mr. Hicks or Mr. Gaddis with respect to this drainage plan. lt has been discussed with each. Mr. Hicks has tentatively indicated that use of any type of piping is unacceptable to him. Mr. Gaddis *as presented with alternative alignments across his property for his consideration. I have also attached a reduced version of the site ptan for distribution as part of this package. I realize that this is very difficult to read at this size and we will have full-sized prints of that available at the Commissioners' meeting. Please call me if I can provide any additional information to you. Respectfully submitted, SCHMUESER GORDON MEYER, INC. P.E. DWG:lec/95008A.3 Enclosures cc: John Schenk, Esq., w/encl. Dr. Wilmer Allen, w/encl. David Hicks, w/encl Brian Gaddis, w/encl. -,*r+ rii-''r I lr" ENGINEERS SUBVEYOBS M- :S5 SCHMUESER CORDON MEYER '118 West 6th, Suite 200 Glenwood Springs, CO 81601 (970) 94s-1004 FAX (970) 945-5948 October 3, 1996 Mr. David Hicks 1051 Prince Creek Road Carbondale CO 81623 RE: Atten Subdivision (Mountain Meadows at Prince Creek) Dear Mr. Hicks: This tetter is to follow up our tetephone conversations and meetings over the last couple of weeks regarding the design parameters to be used for the drainage plan for the above- referencedproject. This foltows up my prior correspondence to you of September 11, 1996 in which the overall design concept was discuised. The conceptual plan is stitl appticabte, utilizing the historic tail water or wastewater ditch system on the Allen property and your property. We were able to find the old tail water ditch from the Atten property, located just east of the northwest corner of the Gaddis lot. Since that ditch has not been in use for some time, it has silted in from its original shape and as part of the work, it will be necessary to reestablish the ditch in either its current position or in a retocated position to be used as part of the drainage system. The ditches located on your property appear to have been well maintained and further appear to have maintained their originat shape or a cross-section for continued use for caring of either drainage or irrigation water. We will use a 10O-year storm event for calculation of run-off from the Allen property. We discussed whether the appropriate quantity to design for would be the historic 1Oo-year run-off rate or the run-off rate as a resutt of the construction of the single-family residences. You indicated that your primary concern was removing the run-off water from the property as quickly as possible, and therefore we agreed that we would design for the 1Oo-year flow rate after development; this would etiminate the need for detention of drainage water on site. While we have not calculated what the run-off flows will be using this drainage approach, we anticipate that the drainage facilities required to contain the flows will be equivalent to an 18' to 24' culvert pipe or a ditch section that would need a total depth of 24" or less. We will have a draft design completed by the time you return from your trip to France. At that time, t would like to finalize that design with you so that it can be distributed to the County Commissioners prior to our early November hearing. October 3, 1996 Mr. David Hicks Page 2 Thank you for continuing to work property. Sincerely, SCHMUESER GORDON MEYER, INC. President Dr. and Mrs. Wilmer C. Allen , 437 E 1730 N, Orem, UT 84057 Mr. Flavin Cerise, 1217 Catherine Court, Carbondale, CO 81623 Mr. John Cerise, PO Box 712, Carbondale, CO 81623 Mr. Tom Turnbul!, P.O. Box 686, Carbondale, CO 81623 Bob Emerson, Esq., 86 South 3rd Street, Carbondale, CO 81623 Ms. Marion Smith, Chairman, Board of County Commissioners Mr. Bucky Arbaney. County Commissioner Mr. Arnold Mackley, County Commissioner Don DeFord, Esq., County Attorney Mr. Mark Bean, Garfield County Development Director John Schenk, Esq., 302 8th Street, Suite 310, Glenwood Springs, CO 81601 Dr. and Mrs. Gary Knaus, 1592 Greystone Drive, Carbondale, CO 81623 Mr. and Mrs. Brian E. Gaddis, 1215 County Road 1 1 1, Carbondale, CO 81623 Finley Properties, 1211 County Road 111, Carbondale. CO 81623 Nancy Emerson, Mason & Morse,0304 Highway 133, Carbondale CO 81623 DWG:st/95OO8AO1 .1 SCHMUESER GORDON MEYER, INC. with me on resolving the drainage issues on the Allen (970) 945-1004 FAX (970) 945-5948 - f.*.. - il:tr: q.:S,--M-- ebaoou sevea 118 West 6th, Suite 200 Glenwood Springs, CO 8160'l October 25, 1996 Mr. David Hicks 1051 Prince Creek Drive Carbondale CO 81623 RE: Mountain Meadows Drainage Plan Dear David: Welcome back from your trip. I hope you had a good vacation! ln your absence, we re- designed the drainage ptan for the Mountain Meadows Subdivision based on the design parameters discussed in my prior October 3, 1996, correspondence to you- The attached print is in the form of a preliminary construction drawing as opposed to a formal drainage ptan- I felt this was an easier document for you to review. Comparing it to the prior construction workcompleted on the site and the prior drainage plans completed, the following modifications have been made: 1. The drainage ditch and retention pond along the south boundary of the property are shown as being removed. This addresses the concern of providing an percolation point at this location. 2. Although not shown on the drawing, the southerly road ditch of the Mountain Meadows access road witt intercept overland flow and direct it into the ditch currently constructed between the two lots off the west end of the culde-sac. Drainage water wilt then be directed by the berm currently in place to the northwesterly corner of the project. 3. At the northwesterly corner of the project, the berm will remain in place. The existing drywell witl be abandoned completely by filling it with native materials. This, again, addresses the concern expressed about having a percolation source at this location. 4. I have shown two alternate alignments for a pipeline to carry the runoff water from this location to the irrigation ditch located on your property to the north. Those two alignments are currentty being discussed with the Gaddis's for implementation in the field. 5. The straighter alignment traverses the lawn area of the Gaddis property. lt intersects your property at the historic tailwater/drainage ditch location which is still currently visibte in the field. At this point, there are two choices. The first is to restore the tailwater ditch at that point and then have an open ditch into your ditch system on your property. The second would be to not restore the tailwater/drainage ditch and extend the pipeline further as shown and tie directly into your ditch system. You would need to tell us which would be acceptable to you. October 25, 1996 Mr- David Hicks Page 2 The alternative alignment is not as straight but follows the fence line and' therefore, does not cross the lawn portions of the Gaddis property- ln order to imptement this alignment, it will be necessary for us to fill on the Gaddis property those areas which are not up to grade. No fill would be placed on your property. When we reach the northwesterly corner of the Gaddis irop"rtV,'we are showing a pipeline extending to the location of the irrigation ditch system on your pro-p"tiy. An alternative not shown on the drawing is to remain on the Gaddis property and discharge again at the approximate location of the historical tailwater/drainage ditch location' Either a 1 5" or 18" diameter pipeline will carry the calculated l oo-year storm' lhave shown an 18" culvert on the drawing. Depending on the fina.l inlet configuration at the start of the pipeline, the 15" may be the culvert of choice' on Monday, I am preparing a revised drainage plan for the county commissioners packet for the November + meeiing. -l will be sending yo, u copy of that as well. The drainage plan will contain the calculations, assumption, unl other details relating to the design basis of this drawing. The only decision I need from you at this point in time, assuming that we continue to remain on the Gaddis property, is whether your preferred point of discharge from the pipe system is the historic tailwateridrainage ditch point exactiy on your southerly property line (with reconstruction of the existiig ditch), or whether running the pipeline further onto your property to intersect directty ihe irrigation ditch is acceptabte- Either one will work from an engineering PersPective. I willcal you after you have had a chance to review this so we might discuss this information prior to the Commissioners' meeting. Respectf ully submitted, SCHMUESER GORDON MEYER, INC. n*rlt7-"/*'@) Dean W.Gordon, P-E. / President DWG:lec/95008AO2 [1. *,,*., Allen, o*n"\Dr. Wilmer Allen, Owner ) ,',-7* John Schenk, Esl._------'/ J Enclosure SCHMUESER GORDON MEYER, INC. 6. 7. MOUNTAIN MEADOWS AT PRINCE CREBK GARruETO COUNTY, COLORADO ooo REVISED DRAINAGE CALCUIATIONS ocroBER 1996 Prepared By SCHMWSER GORDON MEWR, INC. 778 West 6th Street, Suitc 2M Cilenwood Springs, CO 81601 970/945-10M =- SUBVEYO)7Sn -M- ENGINEERS SUBVEYOBS (970) 945-1004 FAX (970) 945-5948 SCHMUESER GORDON MEYER '118 West 6th, Suite 200 Glenwood Springs, CO 81601 October 28, 1996 Mr. Mark Bean, Director Garfield County Building, Sanitation & Planning Department 109 8th Street, Suite 303 Glenwood Springs, CO 81601 RE: Mountain Meadows at Prince Creek Revised Drainaoe Plan Dear Mr. Bean: This letter serves to summarize the drainage plan revisions for the Mountain Meadows Subdivision at Prince Creek and transmit the revised drainage plan and calculations. As you are aware, the previous drainage plan was premised on the acquisition of two drainage easements on the Hicks' property to the west in exchange for a roadway easement on this project. Without the exchange of easements, we have revised the drainage plan as shown and described herein. The drainage plan differs from the previously submitted plan in that Drainage Ditch "A" has been eliminated and Drainage Ditch "B" now turns northward and flows to an 18" CMP. This pipe will carcy flow through the Gaddis's property to the location of the historic drainage/tailwater ditch on the Hicks' property to the north. Beginning with a hydrologic anatysis completed by Schmueser & Associates in 1984, all prior analyses considered the effects of a large off-site drainage basin located to the east of County Road 1 1 1. The actualdrainage basin is located approximately one-quarter mile south and east of the Mountain Meadows Subdivision. Given the previous easement conditions, we had "the luxury of conservative design" with respect to this off-site drainage. For a slight oversizing of a ditch line along the southern boundary of the subdivision, any flows from off-site basins to the south and east could be accommodated. ln reality, these off-site flows are intercepted by the east roadside ditch line of County Road 1 1 1, by approximately 30 acres of irrigated field with their system of irrigation ditches and laterals, which are generally perpendicular to any possible flow, and finally by roadside ditches of a private driveway. Calculations and field examination show that most of the off-site drainage from the identified off-site drainage basin would be captured by the east ditch line of the county road. lf that county road ditch were scoured at all during any flow event, then all the flow would be October 28, 1996 Mr. Mark Bean Page 2 intercepted by the county road and taken north of this project. North of this project, there are a coupte of points which apparently have breached in the past and would probably do so during any future storm event. The revised drainage boundaries are shown on Sheet 3 of 5. The heavy solid lines indicate boundaries for proposed conditions, and the dash line indicates the delineation between two sub- areas for existing conditions. While the Subdivision Regulations require a 2l-year design, the revised plan will accommodate a 1OO-year event. Table 1 shows the results of the new hydrologic analysis. TABLE 1 :l r. :: : :::::::):::::i: | ::t: :: ::::: i,i,i,,,.1.i,;.;,;i;.;.,ABEA: .:::.:.;l:::] titi:ttl.tl i:HCie) .. 1OO-YEAR RUNOFF*. . FeAr rrOws (cFS) , 1OO-YEAR, 24.HOUR1' VOLUME (CF.) PROPOSED 1 5.s0 4.2 5,790 2 9.26 7.3 9,748 3 5.93 2.9 3,659 2+3 15.99 8.3 13,407 EXISTING 1 13.64 5.4 6.437 2 7.O2 2.7 2,803 t Rational Method SCS TR-55ti Sub-area 1 represents an area on the north side of the property which will drain via sheetflow to the north as occurred historically. Sub-area 2 represents the area intercepted by the road and Drainage Ditch "B" (formerly below Drainage Ditch "A"). Historically, this area also drained via sheetflow to the northwest and down the steep slope to Prince Creek and the Ella Ditch or to the historic drainage/tailwater ditch. Sub-area 3 is located just off site south of SCHMUESER GORDON MEYER, INC. October 28, 1996 Mr. Mark Bean Page 3 the property. Runoff from this undeveloped area will be intercepted by Drainage Ditch "B". There is no detention/retention provided on this project. For sub-area 1, there is no flow concentration and the runoff volume and peak flow rate are less for proposed conditions than those which would have occurred under pre-devetopment conditions. Mr. Hicks has agreed to accept the undetained flows delivered by the 18" CMP. A complete set of revised drawings is attached. ln addition, copies of recent correspondence with the neighboring property owner have been attached. Please give me a call if you have any questions or comments. Sincerely, SCHMUESER GORDON MEYER, !NC. ,/) U*;flt lqt David M. Kotz, P.E. / DMK:lec/95008A.2 cc: Dr. Wilmer Allen John Schenk, Esq. SCHMUESER GORDON MEYER, INC. 'tI I.>.-..\ 36 iCarbonaLte i\.${-5+, r--_:.- _- l--i\ E.Y$Y(A lz't'/l 6)a VICIN ITY MAP c.At c:. 1"= 22ta0t I 'b:>Rzzc I I I + I I I I IltI l' I ..t.jl t.. 2 --*.,.=-dt {: I l\ Htrr$l EI x\\\"ta.\\\ \\\\r.\ \ \' r$ji,iii wiiil, tit In1 > >r J- *\ L_!l I *---21 al,l\i-\ ll{r '\ B:--'- \* \ !r -t-i iI TI\r\ 1l ) g9 sl Er e E $ a5 ct EL:! B t: e IBr irf,is {::u:' \ N s$* I s:tl s t$ul N Es Q $s6is N ri$i oq oo c'd V-r L,d ,,.{tii' ;Erih 1q*'i '1V iS o .*;--'( lt :s iU i.( N\ o SCHMUESER GORDON r18 W- 6th St. Suite 200 Glenwood SPrings, CO 81601 (303) 945-1004 FAx (303) 94s-5948 MEYER, !NC. P.O. Box 2155 Aspen, CO 81612 GO3) 925-6727 FAX (303) 9254157 bnr(?- { -?6 CALCT'LATED BY. e nt/ ruilD7 D *1+ 1A 15,7 rE z?-l r !0!-t ;DPi vfnn1,3 ,--'. "'t '--' .'Ja Q'o i :'atr, :: L-r +,,jvt : r '@,q.x, )t= ,?-1-/6z60 7q :o.'tJ 1qz x = > b5? 'cF3 pnou,cT mll 6i{k sM)205 1 (Pdded) @7@ h', Groltr ks 01171' To 0&I PtloNt rctt Rtt 1s225{80 Quick TR-55 Ver.5.43 Executed: 15 224:54 S/N: L24o545L1,9 o9-05-1-995 I{OI'NTAIN !,IEADOWS AT PRINCE CREEK GARFTELD COITNTY, COLORADO RIINOFF CURVE NT]MBER DATA ..... ..... ..""""t'!!f !!!:' ..... ...;aiior"ro"oriioiiioo :;;;;;"" Composite Area: l- STIRFACE DESCRIPTION AREA CN ( acres ) -;;- 98 98 '; '; ' i i oo o " r ' i i ii i o Composite Area: 2 (66) SURFACE DESCRIPTION AREA CN ( acres )-;;- GRASS, B, GOOD PAVEMENT ROOF 4.7L o.52 0.28 GRASS, GOOD, B ROOF PAVEMENT 7.95 0.69 98 0.63 98 ""'oiiiiirooe oooriiiier """" Composite Area: 3 SURFACE DESCRIPTION AREA CN ( acres ) GRASS, GOOD, B 5-90 6l- PAVEI.{ENT 0.03 98 ..... iiooo ":;'riiro (61 ) 5 Quick TR-55 Version: 5.43 S/N: L24O545L1-9 TR-55 TABULAR HYDROGRAPH UETHOD Type II Distribution (24 hr. Duration Storm) Executed: O9-05-1995 L5253229 Watershed fite: --> MTNIT{EAD .WSD HYdrograPh file: --> I'ITNMEAD .HYD Page 1 MOT'NTAIN UEADOWS AT PRINCE CREEK GARFTELD COIJNTY, COLORADO ].OO.YEAR STORM Subarea AREA CN Tc * Tt Precip. I Runoff r?/.pSubarea AREA CN Tc * Tt Precl-p. I Runorr La/P Description (acres) (hrs) (hrs) (in) I (it ) input/used L 2 3 5.50 66.0 0.50 0. oo 2 -40 s.26 66.0 0.50 0.00 2-40 5.93 6L. O 0.50 o. o0 2.40-;-;;;;;;-;il-;;;il;;;;;;-;;;;il;;-;;;;;;';-;;;;;;;-;;;;;il-;;';;:------ Total area = 20.69 acres or O-O3233 sq.mi Peak discharge : Jet{ - ---:l::-:::ry::-yi: :1::::::-:1-1T:-:::1i:::::-: ::::--- ---- Input Values Rounded Values Ia/P Sulrarea Tc 't Tt Tc * Tt Interpolated la/p Description (hr) (hr) (hr) (hr) (Yes/No) Messages O.48 O. O0 0.50 O.0O No 0.45 0.00 0.50 0. oo o.5o o.0o ** ** o .29 .43 . 50 o.29 .43 .50 o.t7 .53 .50 No No ComPuted Ia/P > -5 1_ 2 3-;-;;;;;; ;;;-;;;il;;;;;;;;; ;;-;;;;;il;-;;;;;;;;;;; -;;';;:- -- - -- ** Tc & Tt are available in the hydrograph tables. 6 POND-2 Version: 5.14 S/N: L22O5L5L46 Executed 09-05-l-995 18:57:06 AL MBTHOD***** RAINFALLIntensitY Adjust. (in/hr ) f actor Page 1 of 1 DATA DescriPtion **** RATION 5aB AQ:A U WATERSHED DATA 'C' Coefficient 0.190 0.950 0.950 0.300 (weighted) Adj. \c' o. 300 Intensity 2.560 2.564 4.2 cf s L.00 l_00-YR r-00-YR t oo-YR Area ( acres ) 4.7LO 0.520 0.280 5.51-O ( total ) Adjusted rC' : 0.300 1-.00 = 0.300 Q= Q: * * * * Area 5.51- = 7 POND-2 Version: 5.14 S/N: L22O5L5T46 Executed 09-05-l'995 LBz59 222 * * AL I.IETHOD***** RAINFALL IntensitY Adjust. (inlhr) factor Page l- of L DATA Description **** RATION,-)5qt34PfAV,/ WATERSHED DATA 'c' Coefficient 0. L90 0.950 0.950 o.298 (weighted) Adj. rc' o.298 Intensity 2 .650 2.650 7.3 cfs l-.00 L00-vR t-00-YR l_oo-YR Area (acres) 7.950 0.690 0.630 9.270 ( total ) Adjusted rC' = O.298 L. oo o.298 Q: Q: * * Area 9.27 B PoND-2 Version: 5 . 1-4 S/N: L22o5LSL46 Executed 09-05-L995 L9:03:56 AL METHOD***** RAINTALL Intensity Adjust.(in/br ) f actor Page l- of l- DATA DescriPtion **** RATION SorE 4PL4@ WATERSHED DAITA 'C' Coefficient o.l-90 0.950 o. L94 (weighted) Adj. rc' 0.l-94 fntensity 2.560 2.560 2.9 cfs l_. o0 l-00-YR r-00-YR 1-00-YR Area ( acres ) 5.900 o.030 5.930 ( total ) Adjusted rC' = O.l-94 l-.00 : O. L94 * * * * Q= Q= Area 5.93 I nR qroo 8 tu /,i/ /uEir,, LJ( SCHMUESER GORDON 118 W. 6th St. Suite 2OO Gleriuood Springs. CO 81601 (303) 94s-1@4 FAX (303) 945-5948 MEYER, INC. P.O. Box 2155 Aspen, CO 81612 GOr 925-6727 FAx (303) 9254157 SHEET NO 2/-_oF .**,.no* DMK ,on ?-5-?6- CHECKED BY Pnofi.rT m{-l (;inok sl6is) ml gaiiD.]l l@}rrs., Gdm. liles' 01171 ' Io order PHot'Jt IotL RfE 1 {xrz2ffi r0 Quick TR-55 Ver.5.43 Executed: l-8: l-6:10 S/N: L24o545L1-9 09-05-l-995 UOUNTAIN !.IEADOWS AT PRINCE CREEK GARFTELD COUNIY, COLORADO RUNOFF CURVE NUI'{BER DATA ";;;""'ioroo';;;'iiioo composite Area z { X r S it'r/ ( {'0'4P{ AO SURFACE DESCRIPTION CN I'IEADOW, HSG B cR 111- AREA (acres) L3 .47 o.L7 58 98 58.5 (se) 11 POND-2 Version: 5.14 S/N: L22O5L5L46 Page l- of L Executed 09-05-1995 19: l-8:26 **** RAT I ONAL METHOD ***** EYr57 ,t/ b ,* o WATERSHED DATA'c' coerricient rlliS"r 2. OOO l-. O0 l-00-YR 0.200 L3 .64L (weighted) (total) Adjusted rC' = 0.200 * l-.0O : Q = Adj. tc' * rntensity * Area Q = O.2OO * 2.000 * L3.64 RAINFALL DATAIntensity Adjust. Description(in/hr ) factor o. 200 t-oo-YR = 5.4 cfs 100-YR o.190 0.9s0 L3 .470 O.L7L 12 POND-2 Versionz 5.L4 S/N: L22O5I5L46 Page L of 1 Executed 09-05-l-995 20:09:05 **** RAT I ONAL METHO D ***** j \r' ,, " ,: ! '' t' WATERSHED DATA 'C' Coefficient Area ( acres ) 0.1-90 7.O20 o.l_90 7 .o20- (weighted) (total) Adjusted rC' : O.l-90 * l-.00 = Q = Adj. .C, * Intensity :t Area Q:0.L90 * 2.000 * 7.o2 RAINFALL DATA Intensity Adjust. DescriPtion(inlhr) factor 2. OO0 1.00 100-YR 0. L90 1-OO-YR = 2.7 cf s l-00-YR r3 MOUNTAIN MEADOWS Worksheet for Triangular Channel Projest Description Project File Worksheet Flow Element Method Solve For untifled DRAINAGE DITCH "B' Triangular Channel Manning's Formula ChanqelDepth lnput Data Mannings Coefficient ChannelSlope Left Side Slope Right Side Slope Discharge 0.035 0.012500 fuft 4.00 H:V 4.00 H:V 7.30 ff/s Results Depth Flow Area Wetted Perimeter Top Width CriticalDepth CdticalSlope Velocity Velocity Head Specific Energy Froude Number Flow is subcritical. 0.84 ft 2.80 ft, 6.90 ft 6.70 ft 0.73 ft 0.026009 fuft 2.60 fl/s 0.11 ft 0.94 ft 0.71 Sep 5,1995 19:26:34 SCHMUESER GORDON MEYER, INC. Haestad Methods, lnc. 37 Brookside Road Waterbury, CT O67Oa Floud\raster v4.1c Page'l of 1(2O3) 75$1666 r5 SCHMUESER GORDON ll8 W. 6& St Suite 2OO Glenuvood Sprlngs, CO 81501 (97O) 945-roo4 FA"X (97O) 945'5948 MEYER, INC. P.O. Box 2155 Aspen. G! 81612 e70i 925-6727 FN( (970) 9254157 '* ?5oo 8 hrt) PllDow S STIEET NO, /2 -// - qL cALcuLereo av 1)n,(OATE CHECKEO BY DATE SCALE i:ii;l.'::..':': -:- : : i i i i : i ,' . . i i ; i i i i | : i i : : i ........-..a-_.-_+.__..i__-.-_i_.._.".!_- ! ! : ,.....-''1-.'''---.: I : it i^ !- i : 1 : iiiiiiiii:i:ii :iriii::i::i : i: . f),L( /0ot, :' 16" U0/ = I'Ll 3, lld: t! ... . ..: 15" H dr*., =) b, Hv'/ =',,l) : .J., : :a,.'', .' ,,.,,.. ,, '' ::l ?, /3 LTq , )(l*)) : : : //-/ /.,t ,,/ h t. 2 tB' H% =. oo6,i)i=1,47 lg"' ory b t. c 'lltt = t-b fqoolJcT 2s1l ($nqh sM$ ns I p*a1 f@qJrtnc . Groton Mi$ 01{71 To order PHoflt IoL t fFEE I 8r l;:i380 Quick TR-55 Ver. 5.43 S/N: L24O545LL9 Executed: L510B:1-7 LO-L4-L995 MTNMEAD2.TCT MOUNTAIN MEADOWS AT PRINCE CREEK GARTTELD COUNTY, COLORADO TC COMPUTATIONS FOR: PROP. TO PIPE SHEET FLOW (ApPlicable to Tc onIY) Segment ID Surface description Manning's rougrhness coeff ., n Flow length, L (total < or = 300) Two-yr 24-h.r rainfall, P2 Land sIope, s O.g .OO7 * (n*L) I-0.5 0.4 P2*s SHALLOW CONCENTRATED TLOW Segment ID Surface (paved or unPaved)? Flow length, L Watercourse sloPe, s 0.5 Avgr.V: Csf * (s) where: UnPaved Csf = 16.L345Paved Csf : 20.3282 T = L / (36O0:kV) CHANNEL FLOW Segment ID Cross Sectional Flow Area, a Wetted perimeter, Pw Hydraulic radius, Y: a/Pw Channel slope, s Manningr's roughness coeff., n 2/3 L/2 L.49 :t ; * s V_ Flow T:L fL/s 2.6088 ft 41-o hrs 0.04 TOTAL TII,IE 1- GRASSES ft infl/ft hrs ftft/tt ft/s o.2404 250.O 1-.300 o. 0400 0.59 2 Unpaved 370.O o.0400 3.2269 0.59 o. o3 : O.04 hrs O.03 sq. ftftftft/fE 2. B0 6.90 0.406 0. oL25 0. o350 length, L / ( 3600'tV) a..aar....aal....a (hrs) 0.66 MOUNTAIN MEADOWS Worksheet for Circular Channel Projec-t Description Project File Worksheet Flow Element Method untited MM Circular Channel Manning's Formula Solve For ChannelDepth lnput Data ManningsCoefficient 0.012 ChannelSlope Diameter Discharge 0.010000 fr/ft 1.25 ft 6.22 ffls Results Depth FlowArea Wetted Perimeter Top Widtr CrfticalDepth Percent Full CriticalSlope Velocity Velocity Head Specific Energy Froude Number Maximum Discharge Full Flow Capacity Full Flow Slope flow is supercritical. 0.92 ft 0.97 fl3 2.57 ft 1.10 ft 1.01 ft 73.40 % 0.008156 fr/ft 6.41 fl/s 0.65 ft 1.56 ft 1.21 7.53 fF/s 7.00 fl9/s 0.007901 fuft @ 15,1995 09:42:13 SCHMUESER GORDON MEYER, INC. Haestad Methods, lnc. 37 Brookside Road Waterbury, CT 0670g Flo$/Master v4.1c Page 1 of 1(2O3)75$1666 MOUNTAIN MEADOWS Worksheet for Circular Channel Project Description Project File Worksheet Flow Element Method Solve For untifled MOUNTAIN MEADOWS Circular Ghannel Manning's Forrnula FullFfow Slope lnput Deta Mannings Coefficient O.O'12 Diameter 1.25 ft Discharge 8.33 ff/s Results ChannelSlope Depth Flow Area Wefted Perimeter Top Wdth CriticalDepth Percent Full CriticalSlope Velocity Veloci$ Head Specific Energy Froude Number Maximum Disctarge Full Flow Capacity Full Flow Slope 0.014170 fuft 1.25 ft 1.23 fF 3.93 ft 0.00 ft 1.13 ft 100.00 % 0.012432tvft 6.79 ft/s 0.72 ft FULL ft FULL 8.96 fl9/s 8.33 ff/s 0.014170 fuft Oct 14, 19&5 17:26:.59 SCHMUESER GORDON MEYER, INC. Haestad Methods, lnc. 37 Brookside Road Waterbury, CT 06708 FlffiMaster v4-1c Page 1 of 1(203) 755-1 666 SCHENK, KERST & deWINTER, LLP A PARTNERSHIP OF PROFESSIONAL CORPORATIONS ATTORNEYS AT LAW JOHN II. SCHENK DAN KERST WILLIAM J. deWINTER, Ill CAROI-\N M. STRAUTMAN Mark Bean Garfield County Planning Department Garfield County Courthouse 109 Eighth Street Glenwood Springs, CO 81601 302 EIGHTH STREET, SUITE 3 1O GLENWOOD SPRINGS, COLORADO 8160I TELEPHONE: (970) 945-2447 TELECOPIER: (97 0) 945 -47 67 September 24,1998 HAND DELIVERED Re: Dear Mark: Allen/Mountain Meadows at Prince Creek Subdivision Please find enclosed eight (8) copies of a revised Drainage Plan for Mountain Meadows at Prince Creek, plus the supporting letter from Schm Gordon Meyer, the engineer for the project. The Drainage Plan has been the subject of numerous ifications in order to minimize the risk of harm to all parties. We would like to present this plan i$ ttre Board of County Commissioners for their review at the earliest opportunity. JRSiclh Enc. cc: Dr. Wilmer C. Allen (% Dailand Mr. Bob Emerson Mr. Dean Gordon Allen ,o/; &Oc(- - a .A/-rrtr''4- ,*".1 ^7-,-/*4 /r/4--?r.,.( -- I:\l\q.LLEMBeu 7 .r'/.a-fut- (a ";L-;;"4/D \ *fuw.C,(@M!" ENGINEEBS (970) 945-1004 FAX (970) 945-5948 -r- *M scHMUEsER - GORDON MEYER 118 West 6th, Suite 200 Glenwood Springs, CO 81601 September 21, 1998 Mr. Mark Bean, Director Garfield County Building, Sanitation and Planning Department 109 Eighth Street, Suite 3O3 Glenwood Springs CO 81601 RE: Mountain Meadows at Prince Creek Revised Drainaqe Plan Dear Mr. Bean: This letter describes the proposed changes to the Mountain Meadows Drainage Plan as shown on the attached Sheet 3 of 5 (revision No' 5 dated 9-21-98) from the Final Plat drawings' My September 6, 1996, letter to you transmitted the engineering plan which represents the current as-built conditions. The letter also contained detailed calculations and a description of the reasoning behind this design. Now, due to other parties' concerns over the proximity of the drywell to tf," Ella Ditch bank, we are proposing this attached redesign' This revised plan meets all the requirements of section 9:4O DRAINAGE of the Garfield county subdivision Regulations. Historic drainage patterns are maintained and post- development runoff f or the 1oo-year storm will not exceed historic levels. Furthermore, based on reasonable engineering probability, post-development drainage poses no more of a threat to the Ella Ditch than hisioric drainage. Additionally, some gentle berming in the northern portion of Mountain Meadows, adjaclnt to the Emerson property has been incorporated to reduce the ponding that occurred under historic conditions in the backyard of the Emerson residence. The following items summarize the most important changes to the previous Drainage Plan: 1. Re-establishment of Historic Drainage Pattern. Drainage Ditch "8", from the end of the cul-de-sac to the drywell at the northwest corner of Lot 5, will be eliminated. Two roadway culverts will be added as shown to convey runoff across the roadway. A small berm witl be added along the north edge of Lot 6 and on the Emerson property to redirect the overland flow away from the Emerson residence and into the west side yard. At the request of Mr. Emerson, two culverts will be installed to convey flow under the existing driveway (overtopping occurs under existing conditions). Most of the berming along the west and nirtfr sides of Lot 5 will be removed to re-establish the overland pattern. The drywell and a small depression will remain for the use of Lot 5 onlY. 2. Retention to Offset Existing lnrpervious Areas. The upper retention area on the south side of Lot 3 will be kept to offset the increased runoff generated by the existing chip-seal roacl and Dr. Knaus's residence. This retention area has been Septr Mr. t\ Fage ieptember 21, 1998 ilr. Mark Bean 'age 2 sized to retain all f lows generated by a 1OO-year, Z6-hour storm. A drywell has been added to aid in removing water from the surface of this facility. The attached calculations show that, for any significant storm, the runoff retained by this basin will more than offset that generated by the roadway and Dr. Knaus's residence, 3. On-Lot Retention. lndividual homeowners will be required to submit a Drainage Plan at the time of building permit submittal, demonstrating that the runoff generated by any proposed improvements, including driveways, will not exceed historic levels for events up to the 1oo-year storm. This is the common practice in the City of Aspen and has been used in Glenwood Springs. lt is fair in the sense that individual owners must deal with the consequences of their design; the more rooftop and pavement area, the more retention required. These on-lot retention facilities can easily be incorporated into the landscape design. A typical example would be that of the Resource Engineering and John Taufer & Associates office at 909 Colorado Avenue in Glenwood Springs. A small retention area was created in the front yard to offset the increased runoff generated by the larger building and sidewalks. Although a drywell was not used in this example, Mountain Meadows homeowners may wish to install a drywell in tlre retention areaS to remove Water at a faster rate f rom the surface. Such individual drywells will not unduly concentrate drainage water so as to pose any signif icant threat to any improvements now in place or adjacent to the subdivision or ro improvements likely to be constructed in the future. Recapping, the revised Drainage Plan meets the letter and intent of the Garfield County Subdivision Regulations in terms of retaining runoff to the historic amounts and allowing it to exit the property in the historic manner. The use of on-lot retention results in a reduction of flow to the drywell in the northwest portion of Lot 5 and removes, to a reasonable degree of engineering probability, the chance that this project will adversely impact the Ella Ditch more than would have occurred under historic conditions. Additionally, the plan benefits the Emerson residence by redirecting water to their side yard instead of their back yard. Please give me a call if you have any questions or comments' Sincerely, SCHMUESER GORDON MEYER, INC. O.afi'k David M. Kotz, , r. / tMK:lec/95008A02.1 nclosures SCHMUESER GORDON MEYER, INC. Reca Subd exit t flow engir than Emer Sinc, scH DMK Enclc JOHN R. SCHENK DAN KERST MLLIAM J. deWINTER, lll CAROI,\N M. STRAUTN4-{N SCHENK, KERST & dCWINTER, LL A PARTNERSHIP OF PROFESSIONAL CORPORATIONS ATTORNEYS AT LAW 302 EIGHTH STREET, SUITE 310 GLENWOOD SPRINGS. COLOMDO 8160I TELEPHONE: (970) 945-2447 TELECOPIER: (970\ 94s-47 67 October 23,1998 Mark Bean Garfield County Planning Department Garfield County Courthouse 109 Eighth Street Glenwood Springs, CO 81601 ,0CI a J I99o orrceatrrt HAND DELIVERED Re: Allen/Mountain Meadows at Prince Creek Subdivision Dear Mark: Please find enclosed the revised plan for the drainage and utility program for review by the Board of County Commissioners. Four (4) copies are delivered. One point should be noted which may be at a minor variation from the terms of approval. Dave Kotz, for Schmueser Gordon Meyer, believes that the eastern portion of the existing berm should be removed to reduce the risk of excessive ponding on Lot 5 and possible direction of more water at the dwelling on the Gaddis property (Lot 8). This deletion will allow more ofthe water crossing Allen Court through the culvert it the cul-de-sac to pass broadly across this area in the h\storic pattem. If that causes any difficulties, please let me know as soon as possible so we might JRS/clh Enc. '\ cc: Dr. Wilmer C. Allen (% Dailand Al\n) (w/enc.) Mr. Bob Emerson (w/enc.) \\ l:\l\ALLEN\Beil 8 slFGlqiry:t;q fif*-' ';---' ' "'-l'l i