NOTE: A HARDCOPY OF THE DRAINAGE REPORT AND CONSTRUCTION DRAWINGS MUST BE SUBMITTED TO PUBLIC WORKS FOR REVIEW.

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1 Weld County Public Works Change of Zone Drainage Report Outline The following checklist is to be utilized as guidance, and may not be all inclusive. Other concerns not included in this checklist may arise during the review process. NOTE: A HARDCOPY OF THE DRAINAGE REPORT AND CONSTRUCTION DRAWINGS MUST BE SUBMITTED TO PUBLIC WORKS FOR REVIEW. Comment Headings Included Not Included N/A All reports shall be typed on 8-1/2 x 11 paper and bound. Drawings (24 x 36 ) shall be included. The drawings shall be bound within the report or included within a pocket attached inside the back cover of the report. The report shall be a stand-alone document and therefore all important reference material, supporting documents, and calculations shall be copied and included within the report appendix. The report shall include a cover letter presenting the drainage design for review and shall be prepared or supervised by an engineer licensed in Colorado. Only original documents sealed in ink will be accepted. The sealed report shall contain a certification sheet as follows: I hereby certify that this report for the preliminary drainage design of (Insert Name of Project) was prepared by me (or under my direct supervision) in accordance with the provisions of the Weld County storm drainage criteria for the owners thereof. The Drainage Report is stamped, signed, and dated by a registered P.E. licensed to practice in the State of Colorado. All submitted construction plan sheets are stamped, signed, and dated by a registered P.E. licensed to practice in the State of Colorado. The following items at a minimum should be discussed in the Drainage Report narrative and should be supported with maps and calculations in the Appendix. Include a copy of this checklist with the Drainage Report submittal. I. General Location and Description A. Location Township, Range, Section, ¼-Section. Local streets within and adjacent to the development. Major open channels, lakes, streams, irrigation and other water resource facilities within and adjacent to proposed project site. Names of surrounding developments including jurisdiction (municipalities). B. Description of Property Area in acres. Ground cover and soil types. Major open channels and property ownership. General project description. Existing irrigation facilities and facility ownership information within 200 ft. of property. Page 1 of 5

2 6. Groundwater characteristics (where applicable). II. Drainage Basins and Sub-Basins A. Major Basin Description Reference to Weld County Master Drainage Plan(s) where applicable. Major basin drainage characteristics. Identification of all FEMA-defined 100-year floodplains and floodways affecting the property. B. Sub-Basin Description Historic drainage patterns on the subject property and adjacent properties. Off-site drainage flow patterns and impacts on the subject property (minimum 200 ft outside property boundary, or until no further off-site contributing flow area is encountered). III. Drainage Design Criteria A. Regulations Discussion of the optional criteria selected or the deviation from the Weld County Storm Drainage Criteria, if any. B. Development Criteria Reference and Constraints Discussion of previous drainage studies (i.e. project master plans) for the subject property that influence or are influenced by the proposed drainage design for the site. Discussion of site constraints such as slopes, streets, utilities, existing structures, irrigation ditches, and the site plan impacts on the proposed drainage plan. C. Hydrological Criteria Identify design rainfall amounts and source of design storm depth information, NOAA Atlas, UD&FCD maps, etc. Identify design storm recurrence intervals. Reference the appropriate information in the Appendix. Identify runoff calculation method(s) and any computer models. Include summaries of the routing and accumulation of flows at all identified design points for minor and major storm runoff. Reference the results in the Appendix. Identify detention discharge and storage calculation methods and computer models. Reference the results in the Appendix. Discussion and justification of other criteria or calculation methods used that are not presented or referenced by the Weld County Storm Drainage Criteria. D. Hydraulic Criteria Identify conveyance capacities from County references and any computer models. Identify detention outlet type. Identify check/drop structures criteria used. Page 2 of 5

3 Discussion and justification of criteria or calculation methods used that are not presented in Weld County Storm Drainage Criteria. IV. Drainage Facility Design A. General Concept Discussion of concept and typical historical drainage patterns. Discussion of compliance with off-site runoff considerations and constraints. Discussion of the content of all tables, charts, figures, or drawings in the report. Discussion of anticipated hydraulic structures (channels, pipes, rundowns, etc.). B. Specific Details Discussion of compliance with drainage criteria (street, inlet, pipe capacities, etc.) Discussion of drainage problems encountered and solutions at specific design points. Discussion of detention storage and outlet design. 4 Discussion of maintenance access and aspects of the design. Provide copies of Draft CDPHE, CAFO, DRMS, or State Engineer s permit applications where applicable. V. Conclusions A. Compliance with the Weld County CODE Statement of whether or not the design will meet Weld County Code. B. Drainage concept Effectiveness of drainage design to control damage from storm runoff. Influence of proposed development on any applicable Weld County Master Drainage Plan recommendations. Identification of and intent to obtain written approval of affected irrigation company or other property owner(s). Weld County may require that the applicant provide evidence that offsite impacted jurisdictions have been notified of the proposed plans. Reference all criteria and technical resources utilized. The Appendices should include at a minimum the following information. The Drainage Report should be a standalone document and needs to include copies of all pertinent references used in the generation of the Drainage Report. VI. Appendices A. Hydrologic Computations Vicinity Map showing location of the site in relation to surrounding area. Show the approximate boundaries of the site. FIRMette showing location of the site in relation to the FEMA mapped floodplains/floodways. Show the approximate boundaries of the site. Soil Survey Information/Map showing soil types and soil hydrologic groups for the project site. Page 3 of 5

4 Rainfall Maps with the project location identified. Maps can be from UDFCD or NOAA as applicable. Land use assumptions regarding adjacent properties. 6. Initial and major storm runoff computations at specific design points. (5- yr, 10-yr, and 100-yr) 7. Historic and fully developed runoff computations at specific design points. 8. Computer model input and output. Include model files and/or spreadsheets on a CD-ROM to be attached to the Drainage Report. B. Hydraulic Computations Preliminary culvert sizing. Preliminary storm sewer and storm inlet sizing. Include the street capacity evaluations. Preliminary swale or channel sizing. The calculations need to show stability calculations for unvegetated and vegetated conditions. Preliminary riprap or other revetment design. The calculations need to include design for bedding and geo-fabric. Preliminary pond area/volume capacity and outlet sizing. Show calculations for the 100-year water surface elevations and overflow facilities. 6. Preliminary check dam and/or drop structure sizing Changes to calculation methods. If applicant/ design engineer modifies any portion of the UDFCD spreadsheets used for hydrologic or hydraulic calculations, the applicant/design engineer shall identify all changes to calculation assumptions or computer programs as to the type of change and specific factors that were modified. Any computer model input and output. Include model files and/or spreadsheets on a CD-ROM to be attached to the Drainage Report. C. 24 x 36 Maps 2a. 2b. A General Location (Vicinity) Map shall be provided at a scale of 1 =2,000 or larger in sufficient detail to identify upstream off-site drainage areas flowing into the proposed development and general drainage patterns. Drainage Plan of the proposed development shall be provided at a scale of 1 =100 or 1 =200 on a 24 x36 drawing. The plan shall show the following information: Existing contours at a 2-ft maximum interval. Contours must extend at least 200 feet from all project boundaries or further if necessary to show upstream and downstream drainage relationships that impact the proposed development. The plans and report shall describe the horizontal and vertical datum (NGVD-29, NAVD-88, NAD83, etc) used on the plans and reconcile the differences where necessary. Property lines, existing and proposed lot lines, and existing and proposed easements. 2c. Streets with names. 2d. Existing drainage facilities, pipes, structures, irrigation facilities, and sizes. 2e. Overall drainage area boundary and sub-area boundaries. 2f. Proposed contours and flow directions using arrows. 2g. Location of proposed storm sewers, swales, open channels, culverts, detention ponds, and other appurtenances. Page 4 of 5

5 2h. 2i. Proposed outfall point(s) for runoff from the development area and facilities to convey flows to the final outfall point without damage to downstream properties. Locations and elevations of all defined 100-year floodplains and floodways affecting the property. 2j. Location and types of proposed permanent erosion control features. Historic Drainage Basin Map. Show drainage basin boundaries (on-site and off-site), 2 ft on-site and off-site drainage boundaries, design points, historic flow path, flow path length, and flow path slope. Fully Developed Drainage Basin Map. Show drainage basin boundaries (on-site and off-site), 2 ft on-site and off-site drainage boundaries, design points, developed flow path, flow path length, and flow path slope. Show drainage easement including metes and bounds description around all drainage related features. Show any other drainage easements that may exist on the project site. Page 5 of 5