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HomeMy WebLinkAboutGrading Plans - 05/16/2014"JSZCa 5YCAM ST. vv j'7 4� d sjlCrllt LOIN POINT 1 11LT A t-L,6 Y uOym pi" _aewn .- i b A;G oU OPTIONAL -� FILL PAO w�-tae Y►iJ�r i /�` W1u. SI~ DiReCC -D 6 �$w�s •6 i -----------------� `gtQ1' jytfilM$fl $ OVEKED PATIA L -- WiNOOW WELL }� a i1'G { 4 '. y/INOOW '`. WELL T-98 �� 6J I t V D= LtOu/`tSp�u 1,+=+0f HWFi j 4� sloes 5Yc,400fZ s-f. -/ c% -W WUO.� 'CA, 4 cateo- �•Yt�V� ll W INORTHERN ENGINEERING Drainage Memorandum & Grading Recommendations Date: May 14, 2014 Address: 526 Sycamore Street Fort Collins, Colorado 80521 Attn: Mr. Glen Schlueter This memorandum serves to document the pre -development (historic) and post -development (proposed) drainage conditions for the above referenced property. The subject property is comprised of portions of Lots 7 and 8, Block 65, of the Original City of Fort Collins Plat from 1873. The home that previously occupied the site was originally built in 1905. See Historic Aerial Photograph appended to this letter. According to the Larimer County Assessor, the previous home had a finished habitable area of 1,164 sq.ft. City of Fort Collins GIS data indicates a building footprint of roughly 1,800 sq.ft., which would account for total roof area, including garage and porches (See Historic Impervious Area exhibit). The City of Fort Collins Stormwater Utility has historically applied a Rate Factor of 0.4 to the property. This equates to a Runoff Coefficient in the range of 31 to 50. When applied to the entire 13,300 sq.ft. lot, this translates into a historic impervious range of approximately 8% to 32% (assuming clayey soil). With the lawn area carrying a Runoff Coefficient of 25, the resulting roof area would be roughly 1,140 sq.ft. to 4,750 sq.ft. The proposed home at 526 Sycamore Street contains approximately 2,730 sq.ft. of rooftop with the covered patios and porches included. This is roughly equivalent to the previous roof area, and is towards the low -end of the Runoff Coefficient range historically billed to this property. Additionally, the proposed location of the new home is consistent with previous building. Therefore, it is my professional opinion that the proposed home will not adversely impact historic drainage quantities or patterns to or from this lot. That being said, the new home should meet minimum recommendations for protective grading and drainage. Attached is a proposed Grading Sketch containing Finished Grade (FG) and Top of Foundation (TF) elevations for the new structure. Surveyed spot elevations are depicted in parenthesis. An evaluation of the survey elevations, as well as a site investigation to observe the surrounding properties, served as the basis for the recommended FG and TF elevations. Said elevations should provide sufficient drainage and protective grading for the new structure, while at the same time not creating an adverse condition to adjacent properties to any extent greater than that which has historically existed. 301 N. Howes Street, Suite 100, Fort Collins, CO 80521 1 970.221.4158 1 www.northernengineering.com 'NORTHERN I ENGINEERING 526 Svcamore Street The attached Grading Sketch for 526 Sycamore Street also depicts an optional fill pad area. This area has been delineated with two considerations in mind. The first is to be able to accommodate excess dirt from excavation of the new basement. The second is to establish a minor berm along the northern property line for protection from alley drainage. While the fill pad is not likely to protect against all runoff from the alley, it may provide for the beginning of protective grading in this location. An examination of 2-ft aerial contours, as well as site observation, suggests a minor low -point in the dirt alley in this general proximity. The optional fill pad may help direct flows back into the alley and west towards Whitcomb Street. This does not appear to adversely impact the rear lot of 530 Sycamore Street to the west, as no structures are present and grades remain low. In summary, this memorandum serves as documentation that the proposed home at 526 Sycamore Street is not expected to adversely impact the historic drainage condition to or from the subject property. This is based upon a comparison of impervious areas, elevations, and the location of pre - development and post -development structures. Supporting documents are attached to this letter. Additionally, a Grading Sketch has been provided to give recommendations for minimum finished grades and top of foundation elevations. Please feel free to contact me if you have any questions or require additional information. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE, LEED AP Colorado Registration No. 39767 enc. cc: Douglas Bennett — Stratton Custom Homes, LLC Drainage Memorandum & Grading Recommendations City of ns 526 Sycamore St. G5 Historic Aerial Photograph �a Lr.r��nr�:r�t j Legend Street Names Parcels Parks Subject Property Outlined in Red Notes Printed By: Northern Engineering �4 0.1 0 0.04 0.1 Miles WGS_1984_Web Mercator_ Auxiliary_Sphere This map is a user generated static output from the City of Fort Collins FCMaps Internet mapping site and is for reference only. Data layers that appear on this City of Fort Collins - GIS map may or may not be accurate, current, or otherwise reliable. Cgof ltns 526 Sycamore St. Fort Co '•- Historic Impervious Area LEE MAR. TINEZ COMMILINIT `dPAR K rr wvo d r Fort i:nlllti', i v;n'Vrr L;,= "i.brrl ,r,-,rl� I L+ r»rnarit a Legend Parcels Parks Historic Roof Area Outlined in Red Notes Printed By: Northern Engineering 0 0.1 0 0.04 0.1 Miles WGS_1984_Web_Mercator_Auxiliary_Sphere This map is a user generated static output from the City of Fort Collins FCMaps Internet mapping site and is for reference only. Data layers that appear on this City of Fort Collins - GIS map may or may not be accurate, current, or otherwise reliable. i E m N N c N O CL \ O O O C• E _ m O U o N y � N O 0 ~ E u C N .� rn Cl) N lD m o O N M ? �o E m O O 0 0 O O _ M r, v c) � z o u T C1 z Q N m R ty +O+ C C U O y o p •U U O in m 6� m d N M CD T m C C y m O 7 N O E O O O O O o o u U U N Lij a� ra 0 p •� °' ,--� O � 6� E nc mn m (n N N E y o 0 O O O Q in U U * C) W D W o o �,'a o0 0 0 O U w c R i C N Q Ln o Ln O Q 3�� N �00 c J M N O_ O z a w = N E oa _'' �0000 ono °o �� 00 o CD W y i C. a)v E O ,y O � O 4 O 61 N N o ri > r a d tea_ C N � °' LnLOoLn0 LnLn d cu 6-) O 6-) o Ln 0 0 0 O N O cn > O O O O O O o Q � V g0 U a c O 00 r, O o o cm V h o c r, 00 r, J V U Q c m � N W ova v Q c 0 0 0 0 o Q U E s W N 0 o R � d c c o 00 0 O Z y ce U : E 00 O O C o w Q O O O O LL C° V N a m m m m m m m m C m r N 0 c c lJJ A +. (n N 'c� � O in N '^ �' p o R `° U N Cl- w Q Q U C7 C N U o R m w 3 _ cr m 5YCAM 14,11 ol;l ST jLIGNT WIN POINT �IN A1.txY � ��� LJ IIc�N HIGH PetNT � l Li OPTIONAL FILL PAO r 96 6J I I c0 cR' WwDoW—\ WELL ri 6 1 '6 1 1 TF COVERED POR.c.H I i `qto 'I I I WINDOW WELL .l t ;a /tg0. r' seli �IWa�1.l J-4;, N M x x PREVIOUS STRUCTURE AT 526 SYCAMORE STREET W W o U A� Z W N - o a `L C7 � �_ Q 8 ffi W a Q �co U '� =w t— W ° €� § U R CO Cn Z g I 0 0 ry e g � i g 3 R9 lym g� Am G ��IS Ne J LU LU Z w Ale. i-k ji 1" 9 W 1.8 'a HINH ®an i� S�po�N wl 7 ke way I her'nA 10 yf . 1 /? �P t r9 FND #4 REBAR w/ NO CAP 0.07' NORTH AND 0.46' EAST OF DEED CORNER NOT ACCEPTED N 00000'OQ, W 190.00' 8.0' 46,0' A'NY S � .0' b � ./ v ' 13....-•.:,:sale }- 8 43.0' i p _.I 00I rum • u i n+ ati \ V ZPAN G1J�C4P, i �AI1hb If41�. ` FND 1" BAR w/ NO CAP 0.06NORTH AND S 90040'00" E 190.00' 1.91' WEST OF DEED CORNER Noy, nm rat a� NOT ACCEPTED daerTAliON PupPOSEs aNY. SEC aHL "ttc urDSCePE o"Vom BY OWN$ to =tWAL trFpmmt SITE PLAN @ 1 Q uT p riq"� xr TURN RESIDE 52E SYCAM fw=,.v FND #4 REBAR wl NO CAP 9,95' SOUTH AND `"form °"'° !o=rotulJ,cyc 0.12' EAST OF DEED CORNER NOT ACCEPTED tut.i ' W/ O C� 0 0 yj p Q + r 4 �+ c c f ) LP. I A FND #4 REBAR w/ NO CAP 1.84' SOUTH AND 0.16' BAST OF DEED CORNS.� NOT ACCEPTED 0.16, DELTA Y = -1.84 ..r. Wf SCHEIV DESI Aso C