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HomeMy WebLinkAboutDrainage Reports - 02/26/1991DRAINAGE REPORT PROPOSED SPRING CREEK COUNTRY DAY SCHOOL REMINGTON STREET AND SPRING PARK DRIVE FORT COLLINS, COLORADO FOR LEE FETTERS CDS Engineering Corporation 1 1 1 1 1 1 DRAINAGE REPORT PROPOSED SPRING CREEK COUNTRY DAY SCHOOL REMINGTON STREET AND SPRING PARK DRIVE FORT COLLINS, COLORADO FOR LEE FETTERS Prepared by CDS ENGINEERING CORPORATION 100 West 29th Street Loveland, Colorado 80538 (303) 667-8010 CDS Project No. 7044 February, 1991 Prepared by: ��2 U.. cl-tl- Stephen W. Rogers, M.S., E.I.T. ' February 7, 1991 Attn: Mr. Glenn Schlueter ' City of Fort Collins Storm Water Utility Services 235 Matthews ' P.O. Box 580 Fort Collins, CO 80522-0580 RE: Drainage Report - Spring Creek Country Day School CDS Project No. 7044 1 LI 1 Dear Mr. Schlueter: Attached is the drainage report for the proposed Spring Creek Country Day School located in Fort Collins, Colorado, between Spring Park Drive, Remington Street and Matthews Street. The owner of the site is Mr. Lee Fetters. Please note that the grading and site plan have been previously accomplished by Dana W. Lockwood, Architect. This drainage report utilizes information on those design plans and no changes have been made to the grading or site plan by this office. If you have any questions regarding this report and/or our analysis, please contact our office. Sincerely,_ CDS ENGINEERING CORPORATION c� UJY Stephen W. Rogers, M.S., E.I.T. Reviewed by: Z P.E. cc: Mr. Lee Fetters 1 100 West 29th Street • Loveland, CO 80538 • (303) 667-8010 • (800) 933-8011 I 1 1 1 t 1 1 INTRODUCTION This drainage report is made pursuant to criteria set forth by the City of Fort Collins in accordance with "Storm Drainage Design Criteria and Construction Standards", dated May, 1984. Hydrologic and hydraulic analysis have been made to best represent actual existing and proposed drainage conditions in the area. The grading plan for this site has been previously completed by Dana W. Lockwood, Architect. This report intends to verify the grading and incorporation of drainage and flood control structures to adequately meet minimum standards for drainage and flood control purposes. GENERAL SITE LOCATION AND DEVELOPMENT DESCRIPTION /?00keMtjto,t The site of the proposed project lies South of Spring Park Drive between Remington and Matthews Streets, in the City of Fort Collins, County of Larimer, Colorado (See Location Map). More specifically, the site is situated in Tract 2 of the Replat of Block 2, and Lots 1 to 7 inclusive of Block 1, St. Vrain Subdivision. The site comprises 1.34 acres, more or less. The proposed development of the site consists of the construction of a 7244 square foot building, approximately 18,025 square feet of asphaltic pavement parking area installation, and general landscaping. Off -site improvements include approximately 600 linear feet of 5' PVH Fa I t SITE T�h ............ ti............ F F 3: 44' 3: 7r ............. ................. ..... If ............. ...... 0 C4 rlo# hf 4 p SCALE:I'= 3 0 ve .......... E ' sidewalk installation and driveway access through existing curb and gutter. EXISTING DRAINAGE BASIN DESCRIPTION In general, the site has little relief. The average slope across the site is approximately nine -tenths of one ' (.9) percent. Existing elevations range from 49795 to 4978 feet (see Exhibit A - Grading and Drainage Plan). ' Flows typically travel from South to North across the site as sheet flow. It does not appear that flows would be concentrated at any point on the site. ' The areas to the South and West of the site appear to be much higher and have much larger slopes than the subject ' site, defined by a identifiable grade break. The areato the East is relatively flat and slopes North/Northeast. North of the Spring site and Park Drive is Spring Creek ' which flows from the West to the East. This creek is a major off -site conveyance channel and has flooded ' significantly in the past. The 100-year frequency flood plain and floodway boundaries are shown on Exhibit A. The ' existing 100-year computed water surface elevation (CWSEL) ' is estimated as 4978 feet. These values have been confirmed with FEMA floodplain information. The first floor of the ' proposed building has been set at 4980.88 feet, approximately 2.88 feet above the 100-year CWSEL. The proposed building encroaches on the 100-year floodplain boundary slightly but is well out of the 100-year floodway ' ' 3 ' boundary. We understand that the issue of floodplain .' encroachment has previously been addressed and has been resolved by the owner, Mr. Lee Fetters and will not be ' discussed further herein. The adjacent off -site basin is defined by College 1 to the Avenue West, Rutgers Avenue to the South, Matthews Street to the East and Spring Creek to the North (See Basin Map). This off -site basin was determined to be ' approximately 8.88 acres in extent. Much of the off -site flows are expected to be conveyed down the maiorarterial— ' street's curb and gutter. Due to the slope and width of College Avenue, a considerable amount of flow is estimated to be conveyed to Spring Park Drive. However, high points ' in College Avenue exist at East Stuart Street and Rutgers Avenue thus limiting the contributing drainage area for College Avenue flows. HYDROLOGIC ANALYSIS ' The rational method as outlined in the "Storm Drainage Design Criteria and Construction Standards" was utilized to ' estimate on -site and off -site flows for both the existing and proposed conditions. Calculations are included in Appendix A. For the off -site basin, a runoff coefficient ('C' value) of 0.65 was estimated. For the on -site basin, a ' runoff coefficient of 0.2 was estimated for the existing condition and a value o .38 as used for proposed 1 I t CAI 4 conditions. The value of .38 was determined from information on the proposed development of the site. Ice values were estimated using information from the Storm Drainage Design Criteria Manual. The results of the hydrologic analysis are shown in Table 1. c TABLE 1 2-yr 36 --- --- 19 10.9cfs 10-yr 36 0.7cfs 1.32cfs 19 19.6cfs 100-yr 34 l Alcfs 2.67cfs 12 48.3cfs It is estimated that the proposed development would increase on -site flows by atinroximately 0 6cfs for the 10- year event gnd 3__ cfs for the inn -year event. This is approximately a 3% increase for the 10-year and 100-year events over the total on -site and off -site flows. Please note that the flows do not appear to be concurrent and that peaks probably do not occur simultaneously. ' EXISTING DRAINAGE SYSTEM DESCRIPTION Off -site flows are conveyed by the major arterial ' streets curb and gutter. The capacity of Spring Park Drive is estimated to be approximately 50 cfs from curb to curb. The depth the flowline the is at of curb and qutter .5 feet ' and the crown is just inundated. This value of 50 cfs exceeds the estimated 100-year flow of the proposed ' condition of 49.6 cfs (Off -site flows plus increase in on - site flows.). ' 5 ' A 15" Reinforced concrete pipe (RCP) and two (2) 3' ' wide curb inlets with grates exist at Spring Park Drive adjacent to the site. The capacity of the two (2) inlet ' structures is estimated to be approximately 39.6 cfs. The capacity of the existing 15" RCP is estimated to be ' approximately 10 cfs. Therefore, the capacity of the ' existing RCP controls and is less than the estimated 10-year and 100-year events. The culvert will however, convey approximately the estimated 2-year runoff event of 10.9 cfs. Please note that calculations were based on limited survey ' information. Dimensions were determined in the field from a ' site investigation. Excess flows that are not able to enter the 15" RCP ' storm sewer will pond in Spring Park Drive and eventually overtop the North curb and migrate towards Spring Creek. a e The depth of flow the Spring Park is over curb estimated to be approximately 4" for the 100-year event. Therefore, during a 100-year event, the crown of Spring Park Drive will ' be inundated approximately 411. Maximum depth in Spring Park Drive is estimated to be 10" more or less. ' It should be noted that this analysis is done for local off -site and on -site flows only and does not include flooding- from Spring Creek During concurrent flooding from ' spring Creek, Spring Park Drive will be inundated to a depth of 4978 feet for the 100-year event as indicated in the ' Spring Creek Master Plan. This depth is greater than one 1 ' 6 (1) foot over the crown in Spring Park Drive in most ' locations. ' PROPOSED DRAINAGE SYSTEM The proposed on -site drainage system consists of curb in the lot to the and gutter parking area East. A curb ' opening in the Northern most island near the entrance to the site has been incorporated to allow flows to he_convey_e_d_ ' off -site. Capacities of the parking lot are adequate to convey on -site and local off -site flows to the Spring Park ' curb and gutter. Flows generated in the Western half of the site will typically travel as sheet flow or shallow concentrated flow during larger events. Runoff will discharge to the existing Spring Park Drive curb and Sutter ' Off -site and on -site flows reaching Spring Park Drive will be conveyed by the existing 15" RCP and two (2) curb ' inlets to Spring Creek. As stated earlier, it is estimated that the 15" RCP can adequately convey the 2-year runoff event. Larger frequency runoff events will overtop the ' Northern curb and gutter on Spring Park Drive and migrate to Spring Creek. As stated earlier the estimated depth above ' the top of curb and crown on Spring Park Drive due to the ' 100-year runoff event is estimated to be approximately 4 inches. This depth is not expected to be increased ' significantly due to the proposed developments. Also, it is probable that during flooding events, Spring Creek flooding 1 1 rl will control in the vicinity and the existing 15" RCP will be inundated. Increasing the size of the 15" RCP is not expected to be beneficial in facilitating drainage in the area. During construction, erosion protection shall be provided to adequately contain sediment discharge from the site due to a large runoff event. Erosion control shall be provided in accordance with the City of Fort Collins "Erosion Contzol D—F �ence Manual". Straw bales and/or silt fences will be provided as needed to reduce sediment from entering off -site street areas and storm sewers. CONCLUSIONS Hydrologic and hydraulic analysis have been performed in order to estimate peak runoff rates for both the existing and developed conditions for the site in question. Off -site and on=site flows will not be increased significantly due to the development. On -site grading has been performed to adequately convey on -site flows through the site without significantly altering historic flow paths. Off -site flows will be conveyed by existing street curb and gutter. Erosion protection and sediment deposition control structures will be provided during construction. On -site flows will typically travel as sheet flow on the Western half of the site and will be confined by parking lot and drive areas on the Eastern half of the site. First floor elevations of buildings are set at least 18 inches 8 above the nearest adjacent curb and gutter and are at least 18 inches above tle-estimated 100-year floodplain of Spring Creek. Results of this report indicate that the development will not significantly cause increased runoff rates or flooding depths and will not cause significant flood hazards downstream or to structures on the site. t 1 1 1 1 APPENDIX A CALCULATIONS r • •yam.• �` In Y Ly L DS ENGINEERING'CORPC 100 West 49th Si'r LOVELAND,-•COLORADO (303) 667.6010 493 i,;, c S.O. No. 704y ((! Subject: SP2iNV l.fiEEIC (C6UMMY Dxv Se H00t_. Sheet No. �of r Drawing No. Computed by 5� Checked By Date O2 I �� V P�R�a L S�oAF - ,00-) = 3301. AREa,= V 32��ly�sF : `lo imp = 23 COS ENGINEERING CORPORATION S.O. No. '100'West 29tliStmet subject : -sppufu� QA, LOVELAND, COLORADO 8053 (303)'667-8010 ;;493-8010� Sheet NO. Of Drawing No. Computed by Checked By Date ................. ...... Z YAV L6 . ....... ... ......... . .... .......... ...... ...... ...... ...... ...... - - ------ - - ... ........ ........ ...... .... . 7-7 ...... --- '7 ........ .... ..... ....... .... ... ........ . V 0 Noose . ..... ........... . ....... ......... ......... ... . . .............. . . ..... .. Tt5 ko r T15 ... ......... . . . ................ . . ...... . ..... -.12?1-09 ... ........... .... ......... 57 CDS ENGINEERING CORPORA 100 West 29th ttreit LOVELAND. COLORADO 8( (303) - -067-8010• i:-419" Subject Computed by `5W k Chocked By Qoir-.5`VtvvL o� ------- ----------- ---- J 0iD . ..... . .. . . ........ . ----------- AJ . ........ .. .. ... ... .......... .......... ...... A S.O. No. _701-i L-1 7 r QDv Sheet No. of Drawing No. Date 021041CU ,cWVL - - --_---_- ....... ..... K / ..... ............. L'S ENGINEERING CORPORATION 100 West 29th Street LOVELAND, COLORADO 80538 ;Subject: (303) 667-8010 :---�493-8010 I r S.O. No. 7OH (' Sheet No. Ll of 6 Drawing No. Computed by S w R Checked By � Date �,16y Irk Faa�,ut�1, 3 — � T .D (.66) 4 GQ = A'b J v Qioo = = q; .2) GAS I/ Qio = Iq.�i Gf5 Qioo = �a. d5 cl5 4 = o.ar--Fs ICDS ENGINEERING CORPORATION 100 West 29th Street "` 'LOVELAND, COLORADO 80538 (303) 667-8020 4 493-8020 SubjectSP 2i i Computed by - 5 W (� Checked By S.O. No. r 0S y Sheet No. J of Drawing No. Date 021051A1 ICOS ENGINEERING CORPORATION 100 West 29th Street 'LOVELAND. COLORADO 80538 (303)' 667-8010 , 493-8010 Subject: i I Computed by W '_ Checked By S.O. No. 76 H y Sheet No. of .� Drawing No. Data 0-2J(nk i _'..O O (t'J1� UJ.- (lAll1l1 6r .YriU Q� vllil '" :-- '.:. � .•. _.. - .. .'. ... _.-. _. .. ..._ ... ....... ..... _ _ ..... ..-......._ . ... - - - ._ .._... - - -- _..._.. _:.._ .....:............... .... _..: ._.... E� �2tv . YE&%oU..__..,. L......._ .. t . E-)c 1iJCT . .fez PbSE.n :::::: ----- �•-=---- 2 .... _...:.. ..:... _6rltn .:..:-., ..:................. .::: �00 _ ... .........:. ._......: MIA __:._. ........:. -.....:..:.._ ..� :..:_-:._:.... CPrP.ALITY OF SP21AJ& eA(ZK 02tYE CZ CT 5DL7--) .... Cr-t0A(-tTV of I�2 �OLLE/,--E )\vE 62 J,5 LAPAC-1 n/ OF C.u26 tnrLEi s Oti+ SPRW(-- PAIItC ^ .yO(J-5 (-RPA(-ITy OF Ex«-r. IS'� Rc L 10��s 1 4 IF PEI. *aa «M` IMESA' Was SECTION A -A .ma wa. yr m.a na nT: ACCESS RAMP DETAIL VERTICAL. CURB WITHOUT APRON Its NO OVEM AS Is EXPESTINEGIVALK ADDITIONS TO EXISTING SIDEWALKS y YR y r 1 EOaI mAN2 - /f v( MAE T Hrd a 1 MITE "l 91WA Is Off .. N l O ss or (sec iE IwnREv CURB AND GUTTER DETAILS LIDIIIEVIIISILIN unu n.n me..ni.unua,uu. E. AVA IF " 74. 1 NU '....11 mi sm Me 11 N 11111a 11""1 eSPEA ....,aa FEW I.P. DETAIL NO.2 OF raal Fill ij < °'a""«°r) <.a+XrtashlJ cirri r BLOCK & GRAVEL CURB INLET SEDIMENT FILTER Imm sy,• w",inenm e. limielbn G �Ip� �� A m no.,"we PERSPECTIVE VIEW NOTE 9s 6 -A 6 FILE 1 fYUIm u,r SECTION A -A era wwemm w"oTx tort R"MI. b REM.W0 za VA. e r near SEEMS'. rO Fir ReMen wai 31R NEW DRIVEWAY APPROACH DETAILS VERTICAL CURB AND GUTTER Engineering Corporation 3101 V. DESERT IN RA SUITE BA IDS Wet EGGS Shelf LAS WGAE, NEVADA a9im LOVkLVID. COLORADO 60534 (702) 311 (303) 687-8010 183-8010 2. Piece ord S:dkr. 2:-y Bales '. 'h - LOSS)o ,Files Sk WCoJ Rnf�FNke, Fabfc 9R =F `OUP; • � stir, I—Bxkflled Trench 3. Badflla"d Compact Ememoted Coll Faker Feh,:e Alktth Sealindy to I Stmu B°le Skeet o.ri Tw-ne1Wood Pos! C pecked Bttkfalcfxl BSckf�llRuwffl f i Runoff f AIM, CAEAS� Aq,( of ni CROSSSECT 014 VIEW SECTION VIEW STRAW BALE BARRIER SILT FENCE INSTALLATION DN CONTROL DETAILS IFFIFFIFFIFT LEE FETTERS COS ENGINEERING CORPORATION •CmvN"9 E e en u"a Pmrmbnd Gn.wailm N9tee 1. All off site construction shall be subject to inspection by the City Engineer and shell conform to the July, 1996, 'Street Design Criteria and Construction Standards" for the City o1 Fort Collins. 2. Bituminous pavement and curb and gutter, shall be removed to clean, straight lines by saw or wheel cutting at the locations shown on the drawings. 3. Traffic control devices shall be provided by the contractor for work along public streets. 1. Structural backfill shall comply with CODE Specifications for Class I material. Subgrade and base serial shall be compacted to at least 95% of maximum density within t/ 2e of optimum moisture content as determined by ASTH D698 78. 5. Erosion protection shall be provided during construction in accordance with the City of Fort Collins "Erosion Control Reference Manual". Straw bales or milt fences shall be used a necessary to minimize sediment from entering street areas and curb inlets during runoff events. nTLE. SPRING CREEK COUNTRY DAY SCHOOL 71TLE: DETAIL SHEET =1 .IRE: FO[ OFF'SRE 041NME Ob.IN I Afu l 1EE mrstri E QfflJp5Fal 3 (•1 r ear& U%`CJ"iaa/:. %m+e •If^(. /, ' S Y i - a �• '_ i rwn+ I� <'co PAN i. }- eg e 5 dwam ? i fw'b" .S it g. a SPFLIP/`NS,Rit DF-IV Id L '' I�—oily. o•e<v � � d_Y_•e`_i 0 1 cis J. —rf IciPo a.T �vpw'•YMnmas-tnec. MVEL F1 - aqurt CvmNi ci•edh+�Ft T'9W'aW9f I'St 4GVEL Fl f5^dytuwAAmb I P PFe et1Y sTAxP9,ep � - III'•« � �.ea,p- H.+.nw Anne, roost A wheat a `s.0 _ � iwe •3 grDeastr i FAA t G �fEMfh•rA YHea. aS MO'CC' A NNf4 N SNALC TOM AS HECE�ACY6. ADC IEL EEOS f NeBfS 10 6 114M LLTER !/ �a}4 iVN'a'IA'/.°6.. .( ogLE5 T0661N5iALLTo S"LlI IN JADEe. WRI F5 FI TO l N A6A5 YNFRE PLOW i or suALR. tv f - 3 on.... ,.. —Hro•� a — y a :a \ ' . I C•lai i r /J i BU N6 > S � Arl, s `L.Swm r droved / _t flLRwrr< wemetsi. ✓-w9 ♦ i ' nl el•s5w' , TAL SNEE10.0 \\ Is •ell ve.yn.a ill �, ago AS 11 16rs p wu.tra✓ 6 , i woe -_W _„ I� zeaea-�aTr�, vt"are..:e � se•n' r - JLy OFFSITE SNAFLOW �d QID• I!OFtu le Olio • 2•CF5 - UTILITY, DRAINAGE & GRADING PLAN - aD SCALf F-i?S7 Discharge Table I I ,rpF Atonalfor surta 6YF5 eNAT IOWAXT 4 As1C[V.iES B6"in IQ_vM 100-year SECTION A A 0.2 ere 0.3 cfe ✓" prelimtnaru conarrucrlon S------- B 0.9 cfa 1.8 cfs C 0.7 cfe 1.4 cfa 1. Excavate foundation, construct and backlill Off -Site 1.4 cfs 2_9 cfe z_ET_L_ 2. Building wnstzuction I�_q�� USCG- 1. site grading Total 3.2 cfe 6.4 cfa H e. Curb and gutter installation SEC110N B B. Asphalt pavement �— ®Engineering Corporation jIW W. DESERT D8d RA SO1TE 27 lO0 W 29% Shalt LAS VEGAS, NEVADA 88102 LOYIIAND, COLORADO BOSSE (702) 364-1820 (301 66T-BOLO 493-MO D.. 52 b. I •�� ) Y •'z fee �r J Weak ri•� I I (emu "1Yj �I vn� -; wl_ IleRGa• 41 ,"1Y)dlf/`I_, • l rearw rwu yfNFOW WI.}.wl.}l1R twrF1AySNwwi 4 ata+wwn�rN."v'¢ da•M�r• .yes BF now" I FUSS • }-.4. rf iM Ifnn • .i, •t w.e,. s^f echo novel i ' d' = Q to :. AW ' A4 ib o LiO I + \-I�I �STq d LEo • �`:t e4 n F ' Si.F_ 'HFI :V I I 7i ♦` 1 F WYs 1 N.•1'` e I J C +.}:. Kprr. .i IM( INpvl •9 \ 'I 'inn \-adp • •a I. % IIlown, b.✓ NL4 1 In a GU L 5 �' ✓Izz w ; � i � lYt � A� '�' ,d[MYeAwND�'P�:e (TYP., •• yYy' 6 ON —SITE CONSTRUCTION DETAILS (Nor OFF-51 9 DrfAl:a. SEC SHEET eof 2) 2 f I GENERAL NOTES L to street sanitary Fracre., storm sewer, and eater Lions construction teat date of execution or Fort Collins lo standards agr and specifications <to ibis ev love or t anion or on lowering three agreement a Pertaining In. n of the develop I Asir construction occurring ire r renal utter the u< or me the _ nl er who r snag reqire he to y be madeaiion of of plant to ere end i most who may require that that n<r be made. to confirm lu standards and eeae a -oat Specification current nt bit time. d II IrE I 11 Seen paving shall not start until the soi $ report an saucers design are GO YFl approved by the Eng near and subgrade compeer oy cvs aken and Ne SI�L approved. LAID type. size. local on and number or all known underg•cuAd utilities are CONCRETE PAN approximate when shown on The drawings. It mall N the responsibility of N10 ere contractor le verify ernaa e existence and [motion of all e a ndnst nd utilities along the route of the workBefore commencing n construe. tbin, the contractor shall be responsible for unknown underground utilities. d/ The engineer who has prepared these plant. by `•contained c enc ion and/or sea[ L, hereof, does hereby affirm responsibility t me City, a beneficiary of .y. aid engineer's work• for any errors and emissions conta ed in shoe plant. and approval or these plans by the. City Engineer shall not relieve the engineer o hasprepared these plans of all such responsibility. s. s \ When an existing vpnsli street mutt N cut. the street mist be restated to 'a a condition equal to or bcier than in original condition. The existing q street condemn shall be documented by the City construction Inspector Mrore any cuts are made. Patching shall be done in conformance with the City of Fort Collins Street Repair snndardL The rained patch shall 9dA1 j mend smoothly into the existing surface. All large patches shall be pared 5 ec1 vwith a asphalt lay -down machine. In str«¢ where must than on t e '<" made, overlay of the entire strut width, including m< patched er a may be The determinationof need For a complete overlay shall be de by me Director of Egning. &Prior to the commencement of any eomtruetion, the contractor shall contact all utilities to coordinate icM1edu[eL and the City Forester to schedule A site impeclum for any tree removal requiring a Permit. ). Prior to the commencement of any construction, the contractor shall give the City Engineering cDepartment H (twenty-four) hours advance notice. A Prior to the commencement of any construction that will effect traffic 1- signs or any type, the contractorShall contact the City of Fort Collins Areas Division who wilmporarily remove or Schrum tie sign at no cost to the contractor However, if the contractor moves the traffic sign himself the <o tmet r will be charged for the labor, materials and equipment to reinstall the tin as casting 9/ Nel t f - it t t f illtle h 11 b e e a VICINITY MAP aD rho"resp"onsibility'of the property comars.) 10/ If chwitering is used to install utilities then a State Construction Dewatering wastewater Discharge permit is required if discharged into a atnre sever, channel, irrigation ditch or any waters of the United States. 11. Erosion control to be implemented in accordance with the City of Fort Collins -Erosion Control Reference Eanual for construction Sites', dated January, 1991, or latent addition. CLIENT: P dECT TITLE: SPRING CREEK P91-700M LEE FETTERS COUNTRY DAY SCHOOL COS ENGINEERING CORPORATION s ET TITLE: /Too Rsmtayvr A 'Cmw g Ggawwa and iv,(mm nd O,,Aw m n Nmuq,ri UTILITY, DRAINAGE &GRADING PLAN pma „D LA o �NHCIPK PL, I G L„„D AND CONSTRUCTION SURVIVES LS CtenSIE APHALT ¢snn'C NEW F�9 / / AND NS CPON