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Home My WebLink AboutBDR FOUR-PLEX, 621 S. MELDRUM ST. - PDP120030 - REPORTS - DRAINAGE REPORTNovember 14, 2012 PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT BDR 4-Plex Fort Collins, Colorado Prepared for: Big Deal Real Estate Inc. 2519 Ridge Creek Road Fort Collins, Colorado 80528 Prepared by: 200 South College Avenue, Suite 10 Fort Collins, Colorado 80524 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 876-001 3This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double-sided printing. November 14, 2012 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Preliminary Drainage and Erosion Control Report for BDR 4-Plex Dear Staff: Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for your review. Comments from the Conceptual Review letter dated 10.08.12 have been addressed. Written responses can be found in the comprehensive response to comments letter on file with Current Planning. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM), and serves to document the stormwater impacts associated with the proposed BDR 4-Plex multi-family student housing project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Herman Feissner, PE Project Engineer BDR 4-Plex Preliminary Drainage and Erosion Control Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ......................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS ............................................................. 4 III. DRAINAGE DESIGN CRITERIA ......................................................................... 5 IV. DRAINAGE FACILITY DESIGN .......................................................................... 7 V. CONCLUSIONS............................................................................................... 8 References ............................................................................................................... 9 APPENDICES: APPENDIX A – Hydrologic Computations APPENDIX B – Hydraulic Computations B.1 – Storm Sewers (reserved for future use) B.2 – Street Flow (reserved for future use) B.3 – Inlets (reserved for future use) B.4 – Detention Facilities APPENDIX C – Water Quality Design Computations APPENDIX D – Erosion Control Report LIST OF TABLES AND FIGURES: MAP POCKET: EX1 – Existing Conditions Drainage Exhibit C4.00 – Drainage Exhibit NOTE: TABLE OF CONTENTS WILL BE UPDATED/CORRECTED WITH SUBSEQUENT REPORT ISSUANCES. BDR 4-Plex Preliminary Drainage and Erosion Control Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map Figure 1 – Vicinity Map 2. BDR 4-Plex (project site) is located in Section 14, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. More specifically, the project is located at 621 South Meldrum Street. 3. The project site is bordered to the north and south by single-family homes; to the east by Meldrum Street (100' Right-of-Way); and to the west by an existing alley (20' Right-of-Way). 4. There are no major drainageways within or adjacent to the site. The existing Arthurs Irrigation Ditch cuts diagonally, from east to west, across the project site. The existing irrigation ditch receives excess runoff from the alley through an existing area inlet near the southwest corner of the project site. The ditch's concrete top slab is at grade and visible on-site. The structural integrity of the ditch has yet to verified by a registered professional engineer. This work will take place prior to final design. B. Description of Property 1. BDR 4-Plex is comprised of ±0.22 acre. BDR 4-Plex Preliminary Drainage and Erosion Control Report 2 2. The existing site improvements (See Figure 2 - Aerial Photograph) include: one (1) single-family home which fronts to Meldrum Street, a detached garage and a small shed. Figure 2 – Aerial Photograph 3. The existing groundcover currently consists of several mature trees, grass, weeds and bare soil. 4. The existing conditions runoff from sub-basin EX1 (see Existing Conditions Drainage Exhibit) sheet flows from the west property line and the top of the Arthurs Irrigation Ditch across flat grades (e.g., <2.00%) to a local low-point. The excess surface runoff in sub-basin EX2 flows from the east edge of the Arthurs Irrigation Ditch toward Meldrum Street. 5. The borings were drilled on November 13, 2012. The relevant information from the completed soils report will be included with the next submittal. According to the Natural Resources Conservation website (www.websoilsurvey.nrcs.usda.gov), the on-site soils consist of Fort Collins Loam, 1 to 3 percent slopes. These soils are NRCS HSG 'B' soils. 6. There are no major drainageways within or adjacent to the project site. 7. The proposed BDR 4-Plex project will include a single multi-family building with four- (4) units and a plan area of approximately 2570 ft2. The completed structure will be two stories. Other proposed improvements include: a new asphalt parking area and updated landscaping. 8. The existing Arthurs Irrigation Ditch cuts diagonally across the project site. This general alignment persists to the north and south of the project site (See Figure 3 – Existing Drainage and Irrigation Infrastructure). Project Site BDR 4-Plex Preliminary Drainage and Erosion Control Report 3 Figure 3 – Existing Drainage and Irrigation Infrastructure 9. The proposed land use is residential, multi-family dwellings. This is a permitted use in the Neighborhood Community - Buffer District (NCB). Project Site BDR 4-Plex Preliminary Drainage and Erosion Control Report 4 C. Floodplain 1. The subject property is not located in a FEMA regulatory or City of Fort Collins designated floodplain. In particular, the project site is not located within a FEMA designated 100-year floodplain per Map Number 08069C0979H (Effective date: May 2, 2012). Figure 4 – FEMA Firmette (Map Number 08069C0979H) II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. BDR 4-Plex is located within the City of Fort Collins Old Town major drainage basin. This basin is located in north-central Fort Collins and has a drainage area of approximately 2,120 acres, including approximately 400 acres of the Colorado State University campus. The Old Town major drainage basin generally drains from west to east. It receives some runoff from the Canal Importation Basin directly west of Old Town. Most of the runoff from the Old Town major drainage basin drains into the Poudre River. Street flooding is a common occurrence in Old Town. Several capital projects such as the Howes Street, Locust Street and Oak Street Outfall projects have addressed the problem and improved drainage in the area. Project Site BDR 4-Plex Preliminary Drainage and Erosion Control Report 5 2. As previously mentioned, the Arthurs Irrigation Ditch cuts diagonally across the project site. This irrigation conveyance was not historically influenced by excess developed runoff from the project site. However, with this design, we propose releasing developed flows into this irrigation conveyance as described below. B. Sub-Basin Description 1. The subject site can be historically defined by two (2) sub-basins (i.e., EX1 and EX2). Existing runoff from both basins generally drains east toward Meldrum Street. Sub- basin EX-1 is situated between the west property line and the west edge of the Arthurs Irrigation Ditch. This sub-basin drains to an existing low point. The low point has no defined outfall. If the excess runoff is significant, and the low area fills, the overtopping flows will spill into sub-basin EX2. This sub-basin is situated between the east edge of the Arthurs Irrigation Ditch the east property line. The existing runoff in sub-basin EX2 sheet flows from the west to east. 2. Arthurs Irrigation Ditch does not currently receive runoff from the subject site. 3. The project site does not receive any notable runoff from off-site properties. III. DRAINAGE DESIGN CRITERIA A. The overall stormwater management strategy employed with BDR 4-Plex utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By choosing an already developed site with public storm sewer currently in place, the burden is significantly less than developing a vacant parcel absent of any infrastructure. BDR 4-Plex aims to reduce runoff peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (80th percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies. Wherever practical, runoff will be routed across landscaped areas or through a grass-lined swales. This LID practice reduces the overall amount of impervious area, while Minimizing Directly Connected Impervious Areas (MDCIA) at the same time. The combined LID/MDCIA techniques will be implemented, where practical, throughout the development, thereby slowing runoff and increasing opportunities for infiltration. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release.The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring storm events; however, urban development of this intensity will still have stormwater runoff leaving the site. The primary water quality will occur in an Extended Detention Basin (EDB) along the northwest property line (sub-basin A). This design will be more fully developed at Final Design. Step 3 – Stabilize Drainageways. As stated in Section I.B.6, above, there are no major drainageways in or near the subject site. BDR 4-Plex Preliminary Drainage and Erosion Control Report 6 Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments. B. Development Criteria Reference and Constraints 1. The subject property is not part of an Overall Development Plan drainage study or similar “development/project” drainage master plan. 2. There are no known drainage studies for any adjacent properties that will have an effect on BDR 4-Plex. 3. The site plan will be constrained on two sides by existing single-family development; by an alleyway; and by Meldrum Street. The drainage outfall for Basin A is an existing area inlet that ties into an existing 12” RCP storm sewer in the alleyway. The proposed design releases at the 2-year historic release rate for sub-basin EX1 (i.e., 0.055cfs). C. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations associated with the BDR 4-Plex development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables RO-11 and RO-12 of the FCSCM. 3. The Rational Formula-based Federal Aviation Administration (FAA) procedure has utilized for detention storage calculations. 4. Two separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. D. Hydraulic Criteria 1. The drainage facilities proposed with the BDR 4-Plex project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual. 2. As stated in Section I.C.1, above, the subject property is not located in a FEMA regulatory or a City of Fort Collins designated floodplain. F. Floodplain Regulations Compliance 1. As previously mentioned, this project is not subject to any floodplain regulations. G. Modifications of Criteria 1. The design contained herein changes the direction that excess runoff historically travelled. We are proposing to release attenuated developed runoff BDR 4-Plex Preliminary Drainage and Erosion Control Report 7 (Qout=0.055cfs) into existing storm infrastructure in the alley. This inlet discharges into Arthurs Irrigation Ditch. The concept was discussed with Mark Taylor prior to submittal. Considering the proposed release rate and the existing ditch flows, he felt that it was okay to release into the existing infrastructure and, ultimately, Arthurs Irrigation Ditch. IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objective of the BDR 4-Plex drainage design is, to the maximum extent practicable, maintain existing drainage patterns, while not adversely impacting any adjacent properties. 2. No notable off-site runoff flows directly through the project site. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. 4. The project site has been divided into two (2) drainage sub-basins, designated as sub- basins A and B. The drainage patterns anticipated for each basin are further described below. Sub-Basin A Basin A encompasses a little over of one-half of the total project site area. It is comprised of landscaping, concrete walks and asphalt parking. A large part of the parking area in this basin will comprise the on-site detention pond (Pond A). D.P. A is situated at the proposed outfall. A short section of pipe will connect to an existing area inlet in the alleyway. This basin releases at a rate of 0.055 cfs during the 100-year storm event. Sub-Basin B Basin B encompasses the eastern portion of the project site. It is comprised of roof area, concrete walks and landscaping. The downspouts will direct developed runoff from the roof into a below grade infrastructure that outfalls to the existing curbline in Meldrum Street. During the 2-year and 100-year storm events, the proposed condition increases runoff into Meldrum Street by ±0.08cfs and ±0.33cfs, respectively. Overall, the project site will increase flows to Meldrum Street by ±0.06cfs during the 2-year storm event and ±0.07cfs during the 100-year storm event. A full-size copy of the Drainage Exhibit (sheet C4.00) can be found in the Map Pocket at the end of this report. B. Specific Details 1. The required storage volume was estimated with the FAA method using the procedure outlined below. The design contained herein takes credit for the existing impervious area, ±0.048 acre. The proposed development will add ±0.077 acre of impervious area. This includes the entire site and not just the BDR 4-Plex Preliminary Drainage and Erosion Control Report 8 increase in sub-basin A, which is tributary to the on-site detention pond. To estimate the required volume, we calculated the 2-year historic release rate (0.055 cfs) for the pervious area (0.077 acre) that was converted to impervious area in sub-basins A and B. The total pervious area that was converted to impervious area (0.077 acre) was used in the Pond A sizing calculation. The runoff coefficient was set to 1.00. Refer to Appendix B.4 for the calculation. An FAA method computation has been performed to determine the additional storage volume required for the pervious area converted into impervious area, by this development. 2. The detention storage information for Pond A is contained in Appendix B.4. The drainage features associated with BDR 4-Plex project are private facilities and located on private property. 3. As previously mentioned, the outfall for the BDR 4-Plex project is the existing storm sewer in the neighboring alleyway. This storm sewer flows north and discharges into the Arthurs Irrigation Ditch. There are no additional facilities or upgrades needed off- site in order to accommodate the developed runoff from BDR 4-Plex. V. CONCLUSIONS A. Compliance with Standards 1. The design elements comply without variation except as noted above with respect to the request to release attenuated developed runoff into the Arthurs Irrigation Ditch. 2. The drainage design proposed with BDR 4-Plex complies with the City of Fort Collins Master Drainage Plan for the Old Town Basin. 3. There are no regulatory floodplains associated with the BDR 4-Plex development. 4. The drainage plan and stormwater management measures proposed with the BDR 4- Plex student housing project are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. BDR 4-Plex will detain for the pervious area converted to impervious areas to release at the 2-year historic rate during the 100- year storm. 2. The proposed BDR 4-Plex development will not impact the Master Drainage Plan recommendations for the Old Town Basin. BDR 4-Plex Preliminary Drainage and Erosion Control Report 9 References 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. APPENDIX A HYDROLOGIC COMPUTATIONS APPENDIX B HYDRAULIC COMPUTATIONS B.1 – Storm Sewers (reserved for future use) B.2 – Street Flow (reserved for future use) B.3 – Inlets (reserved for future use) B.4 – Detention Facilities APPENDIX B.1 STORM SEWERS (reserved for future use) APPENDIX B.2 STREET FLOW (reserved for future use) APPENDIX B.3 INLETS (reserved for future use) APPENDIX B.4 DETENTION FACILITIES APPENDIX C WATER QUALITY DESIGN COMPUTATIONS APPENDIX D EROSION CONTROL REPORT BDR 4-Plex Preliminary Erosion Control Report EROSION CONTROL REPORT A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the contractor. Staging and/or phasing of the Best Management Practices (BMPs) depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters and job site restrooms shall also be provided by the contractor. Grading and Erosion Control Notes can be found on Utility Plans. The final construction drawings will contain a full-size Erosion Control sheet as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the contractor shall be aware of, and adhere to, the applicable requirements outlined in the Development Agreement for BDR 4-Plex. Also, the site contractor for this project will be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, prior to any earth disturbance activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive Storm Water Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections and maintenance of construction BMPs. BDR 4-Plex Preliminary Erosion Control Report MAP POCKET C4.00 – DRAINAGE EXHIBIT S. MELDRUM STREET (100' RIGHT-OF-WAY) PUBLIC ALLEY (20' RIGHT-OF-WAY) EX1 EX2 �� EX1 0.35 0.09 0.44 �� EX2 0.41 0.13 0.51 EXISTING ARTHURS IRRIGATION DITCH LOT 11 BLOCK 86 N�. R��: B�: D��: REVIEWED BY: N. H�� DESIGNED BY: DRAWN BY: SCALE: DATE: 07.14.12 PROJECT: 876-001 S�� O� 7 S�� BDR 4-P�� T�� N�� E�� S��, I��. �� P�� E�� N�� E�� S��, I��. NOT FOR CONSTRUCTION REVIEW SET 07.14.12 200 S�� C�� A��, S�� 010 F�� C��, C�� 80524 E N G I N E E R I N G � � � � � � �� PHONE: 970.221.4158 FAX: 970.221.4159 ��.��.�� EX1 DRAINAGE EXHIBIT EXISTING CONDITIONS H. F�� H. F�� 1" = 20' CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO K�� '� ��. LOT 11 BLOCK 86 �� A 0.66 0.13 0.82 �� B 0.70 0.09 0.88 ALLEY (20' PUBLIC ROW) PROPERTY LINE PROPERTY LINE PROPOSED MULTIFAMILY BUILDING CO CO CO UD UD UD CO CO S. MELDRUM STREET (100' PUBLIC ROW) B ROOF ROOF ROOF ROOF POND A A N�. R��: B�: D��: REVIEWED BY: N. H�� DESIGNED BY: DRAWN BY: SCALE: DATE: 07.14.12 PROJECT: 876-001 S�� O� 7 S�� BDR 4-P�� T�� N�� E�� S��, I��. �� P�� E�� N�� E�� S��, I��. NOT FOR CONSTRUCTION REVIEW SET 07.14.12 200 S�� C�� A��, S�� 010 F�� C��, C�� 80524 E N G I N E E R I N G � � � � � � �� PHONE: 970.221.4158 FAX: 970.221.4159 ��.��.�� C4.00 DRAINAGE EXHIBIT H. F�� H. F�� 1" = 20' CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO K�� '� ��. C�� . R D�� D�� D�� D�� D�� D�� APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: C�� E�� W�� & W�� U�� S�� U�� P�� & R�� T�� E�� E�� P�� C�� F�� C��, C�� UTILITY PLAN APPROVAL NORTH ( IN FEET ) 1 �� = ��. 20 0 20 F�� 20 40 60 GRAPHIC SCALE: LEGEND: 4953 PROPOSED CONTOUR 93 PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 1 1 PROPOSED 100-YEAR WATER SURFACE ELEVATION NOTES: 1.REFER TO THE "PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR BDR 4-P��" BY NORTHERN ENGINEERING, DATED NOVEMBER 14, 2012 FOR ADDITIONAL INFORMATION. 2.THE SIZE, TYPE AND LOCATION OF ALL KNOWN UNDERGROUND UTILITIES ARE APPROXIMATE WHEN SHOWN ON THESE DRAWINGS. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR TO VERIFY THE EXISTENCE OF ALL UNDERGROUND UTILITIES IN THE AREA OF THE WORK. BEFORE COMMENCING NEW CONSTRUCTION, THE CONTRACTOR SHALL BE RESPONSIBLE FOR LOCATING ALL UNDERGROUND UTILITIES AND SHALL BE RESPONSIBLE FOR FOR ALL UNKNOWN UNDERGROUND UTILITIES. 3.REFER TO THE PLAT FOR LOT AREAS, TRACT SIZES, EASEMENTS, LOT DIMENSIONS, UTILITY EASEMENTS, OTHER EASEMENTS, AND OTHER SURVEY INFORMATION. 4.ALL PROJECT DATA IS ON THE CITY OF FORT COLLINS VERTICAL DATUM; NGVD 29 (UNADJUSTED). SEE COVER SHEET FOR BENCHMARK REFERENCES. 5.ALL CURB SPOTS ARE FLOWLINE ELEVATIONS. ALL OTHER SPOTS ARE FINISHED GRADE ELEVATIONS. BASIN DESIGNATION BASIN AREA (AC) �� RUNOFF COEFFICIENTS 0.XX 0.XX X.XXX A C�� . R D�� D�� D�� D�� D�� D�� APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: C�� E�� W�� & W�� U�� S�� U�� P�� & R�� T�� E�� E�� P�� C�� F�� C��, C�� UTILITY PLAN APPROVAL NORTH ( IN FEET ) 1 �� = ��. 20 0 20 F�� 20 40 60 GRAPHIC SCALE: LEGEND: A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL BASIN DESIGNATION BASIN AREA (AC) DRAINAGE BASIN BOUNDARY 1.REFER TO THE "PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR BDR 4-P��" BY NORTHERN ENGINEERING, DATED NOVEMBER 14, 2012 FOR ADDITIONAL INFORMATION. 2.THE SIZE, TYPE AND LOCATION OF ALL KNOWN UNDERGROUND UTILITIES ARE APPROXIMATE WHEN SHOWN ON THESE DRAWINGS. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR TO VERIFY THE EXISTENCE OF ALL UNDERGROUND UTILITIES IN THE AREA OF THE WORK. BEFORE COMMENCING NEW CONSTRUCTION, THE CONTRACTOR SHALL BE RESPONSIBLE FOR LOCATING ALL UNDERGROUND UTILITIES AND SHALL BE RESPONSIBLE FOR FOR ALL UNKNOWN UNDERGROUND UTILITIES. 3.REFER TO THE PLAT FOR LOT AREAS, TRACT SIZES, EASEMENTS, LOT DIMENSIONS, UTILITY EASEMENTS, OTHER EASEMENTS, AND OTHER SURVEY INFORMATION. 4.ALL PROJECT DATA IS ON THE CITY OF FORT COLLINS VERTICAL DATUM; NGVD 29 (UNADJUSTED). SEE COVER SHEET FOR BENCHMARK REFERENCES. 5.ALL CURB SPOTS ARE FLOWLINE ELEVATIONS. ALL OTHER SPOTS ARE FINISHED GRADE ELEVATIONS. NOTES: EX1 0.XX X.XXX 0.XX �� RUNOFF COEFFICIENTS