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Home My WebLink AboutGrading Plans - 05/01/2006y - i ANdERSON CONSU[TING ENCIINEERS, INC. Civil Water Resources • Environmental May 1, 2006 Mr. Perry Todd Construction Partners 229 W. Mulberry Street Fort Collins, CO 80521 RE: Site Grading for Residential Improvements at 821 W. Mountain Avenue (ACE Project No. COPTCO2) Dear Perry: LOOM I S Anderson Consulting Engineers, Inc. is please to inform you that we have completed our site grading plan for the property located at 821 W. Mountain Avenue (Larimer County Parcel No. 97113-11-007). The grading plan shown in Figure 1 (attached) has been prepared to match existing drainage patterns to the extent possible, while attempting to eliminate the existing sump area at the southeast corner of the property by providing positive drainage to the alley. The proposed grading plan will isolate the low area that is located directly adjacent to the garage on the adjacent property to the east. This will serve to reduce the contributing drainage area to the sump, but also reduce the surface area available for infiltration. Since it is difficult to ascertain whether the net result in this area will create an adverse impact the existing garage to the east, it is recommended that a roof gutter be installed along the west side of that garage with the downspout directed away from the low area. If this cannot be achieved, it is recommended that consideration be given to over - excavating the proposed low area at the southeast comer of the property to a depth of 12 inches and a mixture of 67% sand and 33% peat placed in that area in order to promote infiltration of direct rainfall and roof runoff. As shown, the grading plan will accommodate the existing garage at 821 W. Mountain, but should also be compatible with a garage that covers the same footprint and is elevated to a finished floor elevation of 5008.5 ft, NGVD (unadjusted). It has been our pleasure working with you toward the completion of this grading plan. If you have any questions or comments concerning the plan or the information provided in this letter, please do not hesitate to contact me. Sincerely, ANdERSON CONSULTING ENCiiNEERS, INC. Gre /och,E. President GJK/tlw Attachment COPTCO2-1.etter.doc May 1, 2006 772 Whalers Way, Suite 200 • Fort Collins, CO. 80525 Phone: (970) 226-0120 • Fax: (970) 226-0121 • www.acewater.com -CE3 5Y1b(66 � I/YO1rY)Ji A!.I/ilurr.wrA/W /IF PN. ]oFF7Y�IC 4 "Dfz/llaw TAM' MOUNTAIN A VENUE 100-YR FLOODPLAIN BOUNDARY (MOUNTAIN AVENUE CORRIDOR) 100-YR WSEL=5010.33 FT., NGVD 100-YR WSEL=5010.23 FT., NGVD FL 5009.27 FL 5009.41 x x D.14 10.40 *5010.04 x x 5010.86 5010.59 5010.82x-- 5010.79 X i__.___ 5010.81 x _ _x 5010.60 5010.87x _ _ x5010.8.4 _ x5010.74 5011.05 5010.99 x 5010.70 i � I I i I 130 116115 PORCIH43 �109 501 -011-48 1loir 35 69 31 +. I 821 W. EXISTING BUILDING -� MOUNTAIN AVE. 1-STORY FRAME WITH FOUNDATION (TO BE REMOVED) I PROPOSED HOUSE I160 ` (FF ELEV. = 5012.5) 501 32 010 0 i15010.30 EXISTING BUILDING SHED �y�' 146 (TO BE REMOVED) 51 1 + 11'o°as.66 5500979 cxi 152 Soo- 1 161 3omo PORCH .:�, 100-YR WSEL=5009.20 FT., NGVD 500�" EXISTING 100-YR FLOODPLAIN BOUNDARY (ALLEY CORRIDOR) STEPS 62 I -- 100-YR WSEL=5008.88 FT., NGVD ao6. I B8 66 8.2 tw }F011 I x8.2 X8.1 06x' 8.1 J� ts5 I }50CJ.8 X6.6 1 EXISTING BUILDING 1-STORY WOOD FRAME ARAGE WITH CONCRETE EXISTING SLAB FOUNDATION F F EL.=7.8 (FUTURE PROPOSED F.F. EL.=8.5) ------------- x 7.8 x7.7 77 X7.6 PROPOSED 100-YR FLOODPLAIN BOUNDARY (ALLEY CORRIDOR) KING SURVEYORS 0.5-FT CONTOURS (MARCH 2O06) PROPERTY BOUNDARY cN ASSUMED I�- EXISTING GROUND EL.=7.0 I ALL ELEVATIONS ARE I NGVD 1929 (UNADJUSTED) 16+�FNG'o B 7*R8RW/YPC Ew ALLEY ANdERSON CONSULTING ENGINEERS, INC Civil • Wafer Resources • Environmental 772 Wham Way. Sum 200, Fw CoUim CO W525 (t Phone (970) 226 120 / F. (970) n"121 156 �OHE„ OHE2 CONSTRUCTION PARTNERS 821 W. MOUNTAIN AVENUE PROPOSED GRADING PLAN LEGEND EXISTING CONTOUR PROPOSED CONTOUR X 8.2 PROPOSED SPOT ELEV. (-5000 FT) OVERLAND FLOW DIRECTION N SCALD-E.' 1�--20' 0 10 20 No. COPTCO2 05/01/2006 UK TAW is! IIOMM AVE PRDPUMY FIGURE 1 r* ANdERSON C0NSU1TINCI ENCIINEERS, INC. Civil • Water Resources • Environmental April 5, 2006 Mr. Perry Todd Construction Partners 229 W. Mulberry Street Fort Collins, CO 80521 RE: Floodplain Evaluation for Residential Improvements at 821 W. Mountain Avenue (ACE Project No. COPTCOI) Dear Perry: Anderson Consulting Engineers, Inc. is please to inform you that we have completed our evaluation of the City of Fort Collins regulatory 100-year floodplain for the property located at 821 W.• Mountain Avenue (Larimer County Parcel No. 97113-11-007). Using the site topographic survey provided by King Surveyors (enclosed), we have redelineated the 100-year floodplain along both the Mountain Avenue corridor (front) and alley corridor (back) based on the 100-year water surface elevations reported in the "Old Town Basin Master Drainage Plan, Baseline Hydraulics," Volume H, ACE, July 15, 2003. The resulting 100-year floodplain delineation for the subject property is shown in Figure 1. Due to the more detailed topographic information provided on the site map, relative to the 2-foot contours used for the baseline hydraulic analysis and mapping, the 100-year floodplain does not impact the property to the extent previously designated. The detailed topography indicates that the regulatory 100- year flood flow will not encroach on the north side of the property due to flooding along Mountain Avenue. Furthermore, the encroachment of the regulatory 100-year flood flow on the south side of the property, due to flooding along the alley, will not be as extensive as previously shown. Please note that although the City is in the process of implementing drainage improvements that will reduce flooding potential throughout Fort Collins, including this portion of the Mountain Avenue corridor, this property will be subject to flooding beyond that shown in Figure 1 during storm events which are more severe than that associated with the current regulatory 100-year return period. It has been our pleasure working with you toward the completion of this evaluation. If you have any questions or comments concerning the information provided in this letter, please do not hesitate to contact me. Sincerely, ANdERSON CONSUITIN qINEERS, INC. Grego J. o . P.E. GJK/tlw Enclosures COPTC01-Lettendoc April 5. 2006 772 Whalers Way, Suite 200 • Fort Collins, CO. 80525 Phone: (970) 226-0120 • Fax: (970) 226-0121 • www.acewater.com MOUNTAIN AVENUE 100-YR WSEL=5010.33 FT., NGVD, 1 PORCH I \I I I CITY OF FORT COWNS 2-FT CONTOURS EXISTING BUILDING SHED 100-YR WSEL=5009.20 FT., NGVD- 100-YR FLOODPLAIN BOUNDARY (MOUNTAIN AVENUE CORRIDOR) r- 100-YR WSEL=5010.23 FT., NGVD 501 5010.60 5010.74 5010.70 THIS AREA OF PARCEL NO. 07113-11-007 I� WILL BE DRY DURING THE REGULATORY i 100-YEAR FLOOD EVENT 5009. _ 100-YR WSEL=5008.88 FT., NGVO 41 5p08.50 100-YR FLOOOPLAIN BOUNDARY (ALLEY CORRIDOR) / KING SURVEYORS 0.5-FT CONTOURS (MARCH 2O06) 1 0 PROPERTY BOUNDARY I � II EXISTING BUILDING i REFERENCE: 'OLD TOWN BASIN MASTER 0o REGi 1-STORY WOOD FRAME DRAINAGE PLAN, BASELINE HYDRAULICS,' ••"••'•• lS NTH CONCRETE I VOLUME 11, ACE, JULY 15, 2003 �FzY '� •�(�` -SLAB FOUNDATION-� O• 1 h f� • ALLEY SCALE: ' :' 0 15 30 NA L CONSTRUCTION PARTNERS D1, ` D' 2008 De•Ign: CJK Dmrn: TAW ANdER50N CONSUITINGI ENGINEERS, INC $21 W. MOUNTAIN AVENUE Rw.iI° .: Civil - Wa[er Resources • Environmenml /CADDIE u 0 AWL R IUM MW mWq.8ww2,PonCoUm.CO805M REVISED FLOODPLAIN DELINEATION(t74 FM10FIGURE 1 .(970)22 1201 F.(97012560121 • ANdERSON CONSUITINq ENC�INEERS, INC Project Number Pace of • Civil • Water Resources Environmental co— `b I I owner -Project By Date 8z1 %J- MoL�,,t,-a„j 'C 4- 4-161-b6 Subject Checked By Date 1dc7-y2 FcDa� louz---VA-T-IatilS Mco,,hl4i.1 A-NGrSvE GvD� DoIZ �(-icalt^r aF t.�l 15-n4 - t,lns-F E +A l> vF r`��ar or�rl 55 + go 5-rA - Z>FF i�or rTi = 53+` D /DaYz kjSGL @ 5n9 = 5D IO. a>7 4; , Aab BY Ll A eA-rt I a.J sin - hlvsT V:.i -ZoF --f-zr>I=C;ve7`I = 75t -D M-rA - L-' -r of ram, t�v'2�1 = 75+oD lOa Y,z �.fsr� �- rz,.1a IDO Y2 �� t�,sT Ci.ID aF r��1 = ShcO.Z3 Fr,�I��i� I ao-Y!Z 0,SZ-z @ -7` S-1 = 5a05,31 C-7-, „1GV> )or-Y-iz- visor °I C¢aSS-e-na.l 7&3o = 5oa9.9z Pr, r.IG.JD By �iavfN� 1. }rr fzr�l ar l /oD-YI-- 0.15ML- Was le.t.lD of t�-�1��2`�1 = 5009• ZD fir; n1sVD Iao -Yj?- WSC--- 1=As-r t � ar- --J�A Vib��: z% I - 5oa8. S8 f'rr tJ"tD 5�i�` P(-M-¢AuuaSj Vowmc--7L� f}e-e-, TvW 15, 2003. _ - - v� L f M1tl 6014 601! r��r��nr. .+�..r. W aa� (`J.// _ a_ a R n e _ —► Q100 = 146 CFS sw " �� V TIII �` rl ♦ � s .— .i N S --N _ _ O ft i—+ a—' _` F — /J _ _,—i_` ; a O O _ a_ 8 8 �3 _s a rn r DRY' / I �►' 't , V)nng , „ I e Ile h%El 11. 1 i ^Ao.. I ( I I �� \ N N I� b d -�„ moo �, 1 _ ap a I � v Up11 A •IFf I �i - I a A $� LEGEND DRY 4567 HEC—RAS CROSS SECTION < -lilt ma`4950 \ • o - eoaN _„_ — — — — — - -.—� —.o _ _ a I ao xo x o s .. _ e :, a e_� x BASE FLOOD ELEVATION . t• �, a°' I o _ — A O K ST EFFECTIVE CONVEYANCE ~ � •\ - I CORRIDOR BOUNDARY 100—YR FLOODPLAIN BOUNDARY — — — FLOW PATH DIVIDE I AREAS OF FLOODING DETERMINED BY APPROXIMATE METHODS -�, ..' � I >• - is � _ l..i• • • a pg �i� i �� r `'�., i 7 Jo I a ct IN 0511012002®