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Home My WebLink AboutEDUCATION / LIFESTYLE TRAINING CENTER - R-C SITE PLAN REVIEW - 31-96 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER P. 2 Proposed Roof Surface 100 year Storm Event Analysis PROCESSED FIL-E:ELTCROOF.DAT DATE: 11-08-1995 TIME:11:30:49 VERSION-11-22-1993 FLOW TIMES AND VELOCITIES ------------------------------- ------------------------------ OVLNO FLOW OF 1ST WATERWAY SCS TYPE FLOW OF 1ST WATERWAY SCS TYPE FLOW OF 2NO WATERWAY SCS TYPE FLOW OF 3RO WATERWAY -------------------------------------- LENGTH SLOPE VELOCITY TIME FT PERCENT FPS MINUTES --------------------------------------- 54.00 4.17 4.04 1.24 0.00 4.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MAX LENGTH FOR OVERLAND FLOW WAS 300 FEET. . ' AIRPORT FORMULA WAS USED FOR OVERLAND FLOW UP TO THE MAXIMUM LENGTH. SCS METHOD WAS USED FOR THE REST OF ORAINAGEWAY. SCS CODES FOR VARIOUS FLOWS ARE: 1.MEADOW 2.TILLAGE 3.LAWN 4.BARE SOIL 5.GRASSED CHANNEL 6.PAVEO CHANNEL SCS TYPE FLOW FOR 1ST WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 2NO WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 3RD WATERWAY- 4 WAS USED. THE COMPUTED TIME OF CONCENTRATION OF THE BASIN - 1.23852 MINUTES THE REGIONAL TIME OF CONCENTRATION OF THE BASIN WAS 0 MINUTES. (REGIONAL TC=10+TOTAL LENGTH/180) MINUTES THE TIME OF CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. RATIONAL METHOD FOR A SINGLE BASIN ANALYSIS METRO OENVER CITIES/COUNTIES AND UO&FCO POOL FUND STUDY USER:MERRICK Engineers 8 Architects .......................................... PROCESSED FILE:ELTCROOF.OAT DATE: 11-08-1995 TIME:11:30:49 VERSION=I1-22-1993 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE.TRAINING CENTER P. 1 Proposed Roof Surface 100 year Storm Event Analysis BASIN DRAINAGE DATA; BASIN SLOPE ALONG EACH FLCWLINE: --------------------------------------------------------------------------- BASIN 1ST WATERWAY 2NO WATERWAY 3RO WATERWAY BASIN ID FLOW GROUND FLOW GROUND FLOW GROUND AREA NO LENGTH SLOPE LENGTH SLOPE LENGTH SLOPE --------------------------------------------------------------------------- 1002 54.00 4.17 0.00 0.00 0.00 0.00 0.03 BASIN LANOUSES AND THEIR IMPERVIOUSNESS: --------------------------------------------------------------------------- BASIN" LANOUSES AND THEIR IMPERVIOUNESS z ID 1ST 1ST 2NO 2NO 3RO 3RO WT'0 NO IMP AREA IMP AREA IMP AREA IMP x z x z z x x ---------------------------- 1002 0.95 100.00 0.95 0.00 0.95. 0.00 0.95 NOTE: LENGTH IN FEET; AREA IN ACRES; SLOPES IN z DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) - 100.00 RAINFALL INTENSITY -DURATION FORMULA IS GIVEN AS: I(IN/HR)-CONSTI'H1/(T+CONST2)-CONST3 ONE -HOUR DEPTH (INCHES)- 2.60 CONST 1 - 28.5 CONST 2 - 10 CONST 3 - .786 BASIN RUNOFF COEFFICIENT AND PEAK RUNOFF THE TIME OF CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. BASIN WEIGHTED RUNOFF COEF . 1.00 COEF FOR A 5-YR EVENT C5 . 0.95 URBANIZATION INDICATOR (RUNOFF COEF) - 0.30 DESIGN RAINFALL INTENSITY (INCHIMR) . 8.82 DESIGN PEAK RUNOFF (CFS) - 0,26 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER Proposed Roof Surface 2 year Storm Event Analysis P. 2 PROCESSEED FILE: ELTCROOF.OAT DATE: 11-08-1995 TIME:11:32:39 VERSION=11-22-1993 FLOW TIMES AND VELOCITIES ------------------------- ----------------------------- OVLNO FLOW OF 1ST WATERWAY SCS TYPE FLOW OF 1ST WATERWAY SCS TYPE FLOW OF 2NO WATERWAY SCS TYPE FLOW OF 3RO WATERWAY -------------------------------------- LENGTH SLOPE VELOCITY TIME FT -------------------------------------- PERCENT FPS MINUTES 54.00 4.17 4.04 1.24 0.00 4.17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MAX LENGTH FOR OVERLAND FLOW WAS 300 FEET. AIRPORT FORMULA WAS USED FOR OVERLAND FLOW UP TO THE MAXIMUM LENGTH. SCS METHOD WAS USED FOR THE REST OF DRAINAG&AY. SCS CODES FOR VARIOUS FLOWS ARE: I.MEADOW 2.TILLAGE 3.LAWN 4.BARE SOIL S.GRASSc0 CHANNEL 6.PAVEO CHANNEL SCS TYPE FLOW FOR 1ST WATERWAY- '4 WAS USED. .SCS TYPE FLOW FOR 2NO WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 3RO WATERWAY- 4 WAS USED. THE COMPUTED TIME OF CONCENTRATION OF THE BASIN = 1.23852 MINUTES THE REGIONAL TIME OF CONCENTRATION OF THE BASIN WAS 0 MINUTES. (REGIONAL TCa10+TOTAL LENGTH/180) MINUTES THE TIME OF CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. RATIONAL METHOD FOR A SINGLE BASIN ANALYSIS METRO DENVER CITIES/COUNTIES AND UO&FCD POOL FUND STUDY USER:MERRICK Engineers & Architects . ....................... PROCESSED FILE: ELTCROOF.OAT DATE: 11-08-1995 TIME:11:32:39 VERSION=11-22-1993 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER P. ) Proposed Roof Surface 2 year Storm Event Analysis BASIN DRAINAGE DATA; BASIN SLOPE ALONG EACH FLOWLINE: --------------------------------------------------------------------------- BASIN 1ST WATERWAY 2NO WATERWAY 3RO WATERWAY BASIN IO FLOW GROUND FLOW GROUND. FLOW GROUND AREA NO LENGTH SLOPE LENGTH SLOPE LENGTH SLOPE ------------ ------------------------------------------------------------- 1002 54.00 4.1T 0.00 0.00 0.00 0.00 0.03 BASIN LANDUSES AND THEIR IMPERVIOUSNESS: ---------------------------------------------------------------------------- BASIN LANDUSES AND THEIR IMPERVIOUNESS x ID 1ST 1ST 2NO 2NO 3RO 3RO WT'0 NO IMP AREA FMP AREA IMP AREA IMP - z z z x x x z 1002 0.95' 100.00 0.95 0.00 0.95 0.00 0.95 NOTE: LENGTH IN FEET; AREA IN ACRES; SLOPES IN x DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) = 2.00 RAINFALL INTENSITY -DURATION FORMULA IS GIVEN AS: I(IN/HR)=CONSTI"H1/(T+CONST2)-CONST3 ONE -HOUR DEPTH (INCHES)= 0.95 CONST 1 = 28.5 CONST 2 = 10 CONST 3 = .786 BASIN RUNOFF C13EFFI1CIENT ANO.PEAK RUNOFF -?HE TIME Of tONtENTRATION OF THE BASIN USED WAS 5 MINUTES. BASIN WEIGHTED RUNOFF COEF = 1.00 COEF FOR A 5-YR EVENT CS = 0.95 URBANIZATION INDICATOR (RUNOFF COEF) = 0.30 DESIGN RAINFALL INTENSITY (INCH/HR) - 3.22 DESIGN PEAK RUNOFF (CFS) = 0.10 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER P. 2 Graveled Surface 100 year Storm Event Analysis PROCESSED FILE:ELTCGRAV.DAT OATE:11-08-1995 TIME: 11:26:36 VERSION=11-22-1993 FLOW TIMES AND VELOCITIES LENGTH SLOPE VELOCITY TIME '----------------------------------------------------------- FT PERCENT FPS MINUTES OVLNO FLOW OF 1ST WATERWAY 54.00 4.17 1.01 4.95 SCS TYPE FLOW OF 1ST WATERWAY 0.00 4.17 0.00 0.00 SCS TYPE FLCW OF 2NO WATERWAY 0.00 0.00 0.00 0.00 SCS TYPE FLOW OF 3R0 WATERWAY 0.00 0.00 0.00 0.00 MAX LENGTH FOR OVERLAND FLOW WAS 300 FEET. AIRPORT FORMULA WAS USED FOR OVERLAND FLOW UP TO THE MAXIMUM LENGTH. SCS METHOD WAS USED. FOP, THE REST OF ORAINAGEWAY. SCS CODES FOR VARIOUS FLOWS ARE: I.MEAOOW 2.TILLAGE 3.LAWN 4.8ARE SOIL 5.GRASSEO CHANNEL 6.PAVEO CHANNEL SCS TYPE FLOW FOR 1ST WATERWAY= 4 WAS USED. SCS TYPE FLOW FOR 2NO WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 3RO WATERWAY- 4 WAS USED. THE COMPUTED TIME OF CONCENTRATION OF THE BASIN = 4.95408 MINUTES THE REGIONAL TIME OF CONCENTRATION OF THE BASIN WAS 0 MINUTES. (REGIONAL T610+TOTAL LENGTH/180) MINUTES THE TIME OF CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. RATIONAL METHOD FOR A SINGLE BASIN ANALYSIS METRO DENVER CITIES/COUNTIES AND UO&FCO POOL FUND STUDY USE-R:MERRICK Engineers & Architects ............. ............................. PROCESSED FILE:ELTCGRAV.OAi DATE:11-08-1995 TIME: 11:26:36 VERSION=11-22-1993 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENT -ER P. 1 Graveled Surface 100 year Storm Event Analysis BASIN DRAINAGE DATA: BASIN SLOPE ALONG EACH FLGWLINE: --------------------------------------------------------------------------- BASIN 1ST WATERWAY 2,NO WATERWAY 3RO WATERWAY BASIN IO FLOW GROUND FLCW GROUND FLOW GROUND AREA NO LENGTH SLOPE LENGTH SLOPE LENGTH SLOPE --------------------------------------------------------------------------- 1001 54.00 4.17 0.00 0.00 0.00 0.00 0.03 BASIN LANOUSE-S AND THEIR IMPERVIOUSNESS: ---------------------------------------------------------- ---------------- BASIN LANOUSES AND THEIR IMPERVIOUNESS z ID 1ST 1ST 2NO 2N0 3RO 3R0 WT10 NO IMP AREA IMP AREA IMP AREA IMP x z x x z x z --------------------------------------------------------------------------- 1001 0.50 100.00 0.50 0.00 0.50 0.00 0.50 NOTE: LENGTH IN FEET; AREA IN ACRES; SLOPES IN x - DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) - 100.00 RAINFALL INTENSITY-OURATION FORMULA IS GIVEN AS: I(IN/HR)-CONST1-H1/(T+CONST2) CONST3 ONE -HOUR DEPTH (INCHES)- 2.60 CONST 1 - 28.5 CONST 2 - 10 CONST 3 - .786 `BASIN -RUNOFF COEFFICIENT AND PEAK RUNOFF THE TIME Of -CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. BASIN WEIGHTED RUNOFF COEF - 0.63 COEF FOR A 5-YR EVENT C5 - 0.50 URBANIZATION INDICATOR (RUNOFF COEF) = 0.30 DESIGN RAINFALL INTENSITY (INCH/HR) = 8.82 DESIGN PEAK RUNOFF (CFS) = 0.16 PROJECT TITL'c: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER P• 2 Graveled Surface 2 year Stomn Event Analysis PROCESSED FILE: ELTCGRAV.OAT DATE: 11-08-1995 TIME: 11:24:53 VERSION=11-22-1993 FLOW TIMES AND VELOCITIES LENGTH SLOPE VELOCITY TIME ----------------------------------------------------------------- FT PERCENT FPS MINUTES OVLNO FLOW OF 1ST WATERWAY 54.00 4.17 1.01 4.95 SCS TYPE FLOW OF 1ST WATERWAY 0.00 4.17 0.00 0.00 SCS TYPE FLOW OF 2ND WATERWAY 0.00 0.00 0.00 0.00 SCS TYPE FLOW OF 3RO WATERWAY 0.00 0.00 0.00 0.00 MAX LENGTH FOR OVERLAND FLOW WAS 300 FEET. AIRPORT FORMULA WAS USED FOR OVERLAND FLOW UP TO THE MAXIMUM LENGTH. SCS METHOD WAS USED FOR THE REST OF ORAINAGEWAY-. SCS CODES FOR VARIOUS FLOWS ARE: I.MEADCW 2.TILLAGc 3.LAWN 4.BARE SOIL 5.GRASSEO CHANNEL 6.PAVEO CHANNEL SCS TYPE FLOW FOR 1ST WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 2NO WATERWAY- 4 WAS USED. SCS TYPE FLOW FOR 3RO WATERWAY- 4 WAS USED. THE COMPUTED TIME OF CONCENTRATION OF THE BASIN - 4.95408 MINUTES THE REGIONAL TIME OF CONCENTRATION OF THE BASIN WAS 0 MINUTES. (REGIONAL TC-10+TOTAL LENGTH/180) MINUTES THE TIME OF CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. RATIONAL METHOD FOR A SINGLE BASIN ANALYSIS METRO DENVER CITIES/COUNTIES AND UO&FCO POOL FUND STUDY USER:MERRICK Engineers & Architects .......................................... PROCESSED FILE: ELTCGRAV.DAT DATE: 11-08-1995 TIME:11:24:53 VERSION-11-22-1993 PROJECT TITLE: FORT COLLINS EDUCATION AND LIFE TRAINING CENTER P. I Graveled Surface 2 year Stain Event Analysis BASIN DRAINAGE DATA; BASIN SLOPE ALONG EACH FLCWLINE: --------------------------------------------------------------------------- BASIN 1ST WATERWAY 2NO WATERWAY 3RO WATERWAY BASIN ID FLOW GROUND FLOW GROUNO FLOW GROUND AREA NO LENGTH SLOPE LENGTH SLOPE LENGTH SLOPE --------------------------------------------------------------------------- 1001 54.00 4.17 0.00 0.00 0.00 0.00 0.03 BASIN LANOUSES AND THEIR IMPERVIOUSNESS: BASIN LANOUSES AND THEIR IMPERVIOUNESS x 10 1ST IST ZNO 2NO 3RO 3RD WT'D NO IMP AREA IMP AREA IMP AREA IMP z z x z z x x ------------------------------- 1001 0.50 100.00 0.50 0.00 0.50 0.00 0.50 NOTE: LENGTH IN FEET; AREA IN ACRES; SLOPES IN x DESIGN RAINFALL STATISTICS DESIGN RETURN PERIOD (YEARS) 2.00 RAINFALL INTENSITY-OURATICN FORMULA IS GIVEN AS: ((IN/HR)=CONSTI'H1/(T*CONST2) CONST3 ONE -HOUR DEPTH (INCHES)- 0.95 CONST 1 = 28.5 CONST 2 = 10 CONST 3 = .786 "9ASIA RLMOFF COEFFICIENT AND PEAK RUNOFF THE TIME DP CONCENTRATION OF THE BASIN USED WAS 5 MINUTES. BASIN WEIGHTED RUNOFF COEF = 0.50 COEF FOR A 5-YR EVENT C5 = 0.50 URBANIZATION INDICATOR (RUNOFF COEF) = DAD DESIGN RAINFALL INTENSITY (INCH/HR) = 3.22 DESIGN PEAK RUNOFF (CFS) = 0.05 w N 0 m a L1 z n D HI D D 2 0 = 5 CIC a cn w 4 x U Z 0 3 F- a. wix 2 a a,i S TIME IN MINUTES 11 r; PROPOSED SICE- e)OSTR(C OF- 0.03 eb a,=- 3.16 eft .NEW 20' AIDE WALK CHASE r,Oaa�YS`tNC EzsnNc UCE CONCRETE P — . _ CONCRETE PAO NEWSCJPPE AIS NO OOw(SPCUTS NEW ORYWE L OPl PROPOSED 0 - al eh G T Im ate <h SF) L NEW CRIO(ET `DO+O CRIOOT E%ISTINC CRICKET i E)eTINC RCCF (2.e22 S.F.) SLOPE:- O/e'/FT. `EO05'.ING N000 FENCE —EOCC OF iv JPLA.90E`NMXiSTINONIE AL7HRE NFORANT LICHT P01` �—OIRT PARI(01G AREA --� O 0 �EOCE DF EJQSTINC PAYENENT I ROOF PUN SHOWING NEW ADOITION' SCALE 10. 25' " P.luaT u ------------------------ TMEJ PPwq.aeNA<t Lev .00lTidyTlsTIIIC 0o.mart ANa arts r NORTU SIDE ELEVATION SF,O,INc ROOF ORAINACE SYSTEM SCALE S' 9 1 ) BVILOINC INFORMATION EXLS NG SF. -1846 AoonION S-F. - I,137 TOTAL S.F. - S.00] ® MERRICK =N...AapIa A `' '°""'�"' !. P411. SLIM( 6C(X�(TION MO(�B TTAMO CEI(191 '.l(11da( C. TLLLt dTOQO •. �� aWIK 4:mllG M-w Acornm CwVUR1 ,fTUOY OATC II/I•/n .A V. iNll urT ( PAa[O Education and Life Training Center New Addition Drainage Impact APPENDIX 11/13/95 i Merrick Ref,": 1501 872 Mr. Glenn Schluter November 16, 1995 Page 3 These facts lead to the conclusion that increases in rugoff_rates by replacing an aggregate surface with a roof will not adversely impact surrounding property. Better control of flows from this area may. reduce runoff from this property onto surrounding properties. The direction and degree of slope of the existing curb and gutter into which the runoff from the proposed new roof will flow, will direct all flows away from the building site and easily handle the flow volumes from the street and surrounding basins. Therefore, the replacement of an aggregate surface by the creation of a roof surface in the Education and Life Training Center complex will not have a significant impact on local ,. conditions. ._............._...._._ _ drainage For and on behalf of MERRICK & COMPANY Gregg S. Ee T. Project Enginee cc: Steve White, Facilities Division Brad Andersen, Merrick & Company ZT_L�� Russell T. Nelson, P.E. Project Manager A:%W O RO_TXr,ELTCORAN.00C Merrick Ref#: 15011872 Mr. Glenn Schluter November 16, 1995 Page 2 Contour mapping shows that the longitudinal slope of Linden Street along the ELTC building is about 2 percent downward to the northeast toward the Cache La Poudre River bridge. The improved east side of Linden Street appears to carry runoff away from the ELTC site in curb and gutter at a slope of 1.8 to 2 percent downward to the northeast. Similarly, the street immediately to the southwest of the ELTC site also drains runoff away from the site toward the northwest. The Old Town Basin Master Drainage Plan, dated January 7, 1993, presented to the City of Fort Collins by Resource Consultants and Engineers shows that reach of a potential shallow flood of less than 1.5 feet lies to the southwest of this site. The reach of this flood potential is to the southwest of and does not reach beyond the Cache La Poudre River. Figure 5.1 from this report showing these reach designations is provided as an attachment in an appendix to this letter. The analysis for this report was confined to the graveled courtyard area that will be replaced by the roofed surface. A computer program, RATIONAL, was used to make rational method runoff calculations. RATIONAL was developed through the Civil Engineering Department at University of Denver for the Metro Denver Cities/Counties and UD&FCD pool fund study. Rainfall data for one hour intensities for the 2 year and 100 year storm event were taken from Figure 3-1, City of Fort Collins. Colorado Rainfall Intensity Duration Curve in the City of Fort Collins' Storm Drainage Design Criteria and Construction Standards manual (Revised March 1991). These rainfall intensity figures and runoff coefficients found on pages 3-4 and 3-5 of the referenced manual with the appropriate frequency adjustment factors applied were entered into the RATIONAL program. Results from the analysis runs of this program applied to the graveled courtyard area and the proposed roofed area are attached in an appendix to this letter. Results Comparisons between the flow rates and times of concentration for the new roof surface and the existing graveled( - parking area show that, as expected, the flow rates are larger for the roofed surface because the basin size is the same. It should be noted that, since the two surfaces are relatively impervious, the total volume of runoff for any given storm event will be approximately the same. However, the rate at which runoff is released is faster for the proposed roofed area. The time of concentration for the existing parking area is about 5 minutes, while the actual time of concentration for the roof is under 2 minutes (5 minutes appears in the RATIONAL program analysis sheets due to a minimum Tc of 5 minutes built into the program). The RATIONAL analyses show that the flow rate from the existing aggregate surface for the.2 year storm event is 0.05 cfs and 0.16 cfs for the 100 year event. These rates compare to the runoff predictedfor the roofed surface of 0.1 cfs for the 2 year event and 0.26 cfs for the 100 year event. Conclusions The volumes of flow from this limited area are very small compared to flows from the surrounding localized basins. Several aspects of the proposed building and roof construction will improve and better control drainage from this site. Presently, the drainage runoff from the graveled courtyard runs toward the property boundary fence to the north of the lot with a potential of passing through the fence onto adjacent property. Replacing this courtyard with a roof will channel runoff to roof drains and to a piping system which will confine and ultimately direct the flows toward Linden Street. A:%W OR0-rAMELTCORAN.00C co❑ i CCaa MEPPICK Memck i Camcami Mail: PC Sox 22025 / Oemer, CC / 20222 / USA ... „................... Ceirver/: 2450 S. Pecra Sc. / Aurora. CC / 5001 A 3031751.0741 / Fax 30?/751.2531 November 21, 1995 Merrick Ref;*: 15011872 Mr. Glenn Schluter, P.E. Project Engineer, Stormwater and Utilities City of Fort Collins 235 Mathews Street Fort Collins, CO 80524 NOV 2 7 i995 Gr" : (rx? ,`.:LL!N rr �. DRAINAGE IMPACT OF EDUCATION AND LIFE TRAINING CENTER NEW ADDITION ROOF Dear Mr. Schluter. This letter is in response to your request for a discussion of the impacts on site drainage resulting from the addition of new building space at the Education and Life Training Center (ELTC) at 401 Linden St. This new addition will be built with walls common to the original building and will fill the vacant portion of the lot north of the "L' shape of the existing building. This addition will make the building more rectangular in shape. Discussion It is our understanding that the area over which the floor slab of the new addition will be built is now .a -graveled courtyard area consisting of a few inches of aggregate spread over compacted clay soil. This surface is likely to be relatively impermeable. An aggregate surface of this type will absorb a small amount of precipitation before releasing flow as the aggregate particles are wetted. This effect adds to the time of concentration (Tc) in drainage calculations for such a surface and makes release of precipitation slower than a less rough surface such as pavement or smooth roofing. Slope calculations performed using an aerial contour map shows that this graveled area has slopes away from the existing building of between 3 and 5 percent. Site plans show that runoff from this area may be intercepted by a wood fence line along the north property boundary. A portion of this flow may pass through this fence and the remainder follows the fence line and flows to the east side of Linden Street. This graveled courtyard area will, in effect, be replaced by a built-up composition roof ; the majority of which will be sloped at 4.17% (Y: inch per foot). A built-up roof of the type proposed for the referenced project releases and runs off precipitation almost immediately. Runoff from the existing roof segment is channeled by crickets and parapets to the west side of the new roof segment where it combines in the guttering system proposed for the north faces of the existing building and new addition with flows from the remaining new roof segment. Parapets enclose all roof edges and. prevent spill over of runoff at the edges. The majority of the area of the new roof is drained by six drain openings, scuppers, connected to downspouts. The new and existing downspouts all connect to a piping system on the north building face, which is directed to a proposed new concrete sidewalk chase that runs west under the existing sidewalk to the curb and gutter along the east side of Linden Street. A:1W CRO_rAT%EITCORAN.00C .......................................... An emo"-O w+ed Comoarry