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HomeMy WebLinkAboutHARMONY COMMONS - PDP - PDP150027 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFinal Drainage and Erosion Control Report for Harmony Technology Park Sixth Filing (Pond Only Portion) Fort Collins, Colorado December 1, 2015 December 1, 2015 Mr. Shane Boyle City of Fort Collins Water Utilities--Storm water 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage and Erosion Control Report for the Harmony Technology Park Sixth Filing (Pond Only Portion) Dear Shane: We are pleased to submit to you, for your review and approval, this Final Drainage and Erosion Control Report for the Harmony Technology Park Sixth Filing (Pond Only portion). All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Respectfully, Aspen Engineering John Gooch, P.E. Principal TABLE OF CONTENTS DESCRIPTION PAGE I. GENERAL LOCATION AND DESCRIPTION 5 A. LOCATION 5 B. DESCRIPTION OF PROPERTY 5 II. DRAINAGE BASINS 5 A. MAJOR BASIN DESCRIPTION 5 B. EXISTING SUB-BASIN DESCRIPTION 6 III. DRAINAGE DESIGN CRITERIA 6 A. REGULATIONS 6 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 7 C. HYDROLOGIC CRITERIA 7 D. HYDRAULIC CRITERIA 8 E. VARIANCE 8 IV. DRAINAGE FACILITY DESIGN 8 A. GENERAL CONCEPT 8 B. SPECIFIC DETAILS 9 C. DETENTION POND 11 D. STREET CAPACITIES 12 V. STORM WATER QUALITY 12 A. GENERAL CONCEPT & SPECIFIC DETAILS 12 VI. EROSION CONTROL 13 A. GENERAL CONCEPT 13 VII. CONCLUSIONS 13 A. COMPLIANCE WITH STANDARDS 13 B. DRAINAGE CONCEPT 14 C. STORM WATER QUALITY 14 D. EROSION CONTROL CONCEPT 15 E. EROSION CONTROL ESCROW ESTIMATE 15 REFERENCES 16 APPENDIX PAGE VICINITY MAP A RATIONAL METHOD HYDROLOGY B POND CAPACITY CALCULATIONS & RATING CURVES, C OUTLET STRUCTURES & STORM SEWER PIPE SIZING, ORIFICE SIZING, & OVERFLOW WEIR SIZING RIPRAP, SWALE SIZING, & EROSION CONTROL CALCULATIONS D EROSION ESCROW E PROPOSED DRAINAGE BASIN EXHIBIT, EXHIBITS & EXCERPTS, F EROSION CONTROL PLAN, & EROSION CONTROL NOTES AND DETAILS SHEET 5 FINAL DRAINAGE AND EROSION CONTROL REPORT FOR THE HARMONY TECHNOLOGY PARK SIXTH FILING (POND ONLY PORTION) FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Pond Only portion of the Harmony Technology Park Sixth Filing (referred to as “HTP Sixth Filing Pond” here-forward) is bounded to the north by undeveloped land and Timberwood Drive, to the east by undeveloped land and Lady Moon Drive, to the south by undeveloped land and Precision Drive, and to the west by undeveloped land and Technology Parkway. The project site can also be described as situated in the northwest quarter of Section 4, Township 6 North, Range 68 West of the 6th P.M., of the City of Fort Collins, Larimer County, Colorado. Please refer to the vicinity map in Appendix A for the site location. B. Description of Property The HTP Sixth Filing Pond project is comprised of an approximate 7.08 acre limits- of-development footprint area; however, for the purposes of this report, the HTP Pond project is being combined with the proposed developed portion of the HTP Sixth Filing and will account for approximately 21.08 acres (Basins 1-8) being conveyed to the proposed HTP Sixth Filing Pond (Pond 100), located south of Timberwood Drive. Currently, the HTP Sixth Filing Pond project area is undeveloped, irrigated agricultural land. The majority of existing topography of the HTP Sixth Filing Pond site (and surrounding, internal future development area) generally slopes from the northwest to southeast at approximately 0.40%. II. DRAINAGE BASINS A. Major Basin Description The site lies within the McClellands Basin. The site drainage has been previously accounted for in the Harmony Technology Park Site Master Plan (HTPSMP) and 6 HTP Infrastructure Improvements Project. The project drainage will be in conformance with these two studies, in which Masterplan information can be found in the East Harmony Portion of the McClellands Creek Master Drainage Plan (August 1999). Please also refer to the Final HTP Infrastructure drainage report for additional information, as may be applicable. B. Existing Sub-Basin Description The existing HTP Sixth Filing Pond project site is contained within existing sub- basin EX1 of the HTP Masterplan, and SWMM basins 401, 600, and 601 of the HTP Masterplan report. Existing basin EX1 contains approximately 57.08 acres, and was modeled with the entire 57.08 acres having a 'c' value of 0.32, with a 100-year runoff rate of approximately 72.86 cfs, for the historic condition of the basin. However, the HTP Masterplan Report specifies the HTP Sixth Filing Pond site being contained within SWMM Basins 401, 600, and 601 (48.3 acres total) and being allowed a developed impervious value up to 80%, with all flow from the HTP Sixth Filing Pond and associated future, adjacent development within the said basins allowed to release at a combined release rate of 17 cfs (or approximately 0.35 cfs/acre for the 48.3 acres, per the SWMM Model, for attributing basins). The runoff from the existing site basin area of the Pond Only portion of the HTP Sixth Filing project flows primarily from northwest to southeast across the existing agricultural field, with the majority of runoff infiltrating into the existing field. During irrigation of the existing field, additional runoff flows to the southeast and in to existing tailwater pits, located along the west side of Lady Moon Drive. The runoff is conveyed east in existing irrigation/storm sewer pipe and into the storm line in Lady Moon Drive. Please refer to the HTPMSP report for masterplan details (excerpts can be found in Appendix F of this report). Please also see the rational calculations (Appendix B) and the drainage exhibit (Appendix F) of this report for the existing and proposed drainage basins for the subject site. III. DRAINAGE DESIGN CRITERIA A. Regulations Because the HTP Sixth Filing Pond project is being constructed with the associated, proposed HTP Sixth Filing development, water quality and detention pond calculations are required and have been provided for the associated 21.08 acres of development (basins 1-8) anticipated to occur with the HTP Sixth Filing project. 7 It’s important to note that proposed Pond 100 (combined SWMM Ponds 101, 600, and 301) is anticipated to be a future, regional water quality and detention pond, and therefore has been sized to provide water quality and detention for 48.3 acres (as required by the HTP Masterplan), even though only 21.08 acres is anticipated for the HTP Sixth Filing project. Future development, as well as the proposed HTP Sixth Filing onsite development will be required to adhere to the McClellands Creek Master Drainage Plan and the Harmony Technology Park Site Master Plan (HTPSMP), as well as HTP Masterplan SWMM Model, which allows for a combined impervious ratio of 80% for the developed and associated, adjacent roadway portions for the attributing parcels. LID improvements are not required for the HTP Sixth Filing Pond portion, as no development is occurring or being proposed with the Sixth Filing Pond only project portion. Please refer to the HTP Sixth Filing onsite design and drainage report, by Interwest, for applicable LID improvements for the HTP Sixth Filing development. B. Development Criteria Reference and Constraints The criteria and constraints from the City of Fort Collins will be met. Water quality and detention requirements have been provided by proposed Pond 100; however, additional BMP’s and LID measures will be required and shall be provided by current and future development of adjacent parcels, with said parties providing applicable treatment, as required by the City of Fort Collins. C. Hydrologic Criteria The Rational Method for determining surface runoff was used for the Pond Only portion of the HTP Sixth Filing utilizing the rational calculation excerpt from the HTP Infrastructure Improvements project. The 2-year and 100-year storm event intensities were used in calculating runoff values to size Swale A. The City of Fort Collins intensity duration frequency curves were used to obtain rainfall data for each storm specified. 8 It’s important to note that the current onsite portion of the HTP Sixth Filing, and future development of adjacent parcels will be required to meet the 80% impervious ratio for the developed condition of the parcels and associated, adjacent roadways, rather than match the rational ‘c’ values shown in the rational calculations in Appendix B of this report. Rational calculations (and corresponding ‘c’ values) shown in Appendix B of this report were used solely to size (possibly oversize) the storm sewer in Timberwood Drive and Technology Parkway to provide for future development of the adjacent parcels to the north and south of Timberwood Drive, and east and west of Technology Parkway to allow for future conveyance of those parcels to Pond 100 (ultimate condition), and for a second, future regional pond (or onsite pond) for the area west of Technology Parkway. D. Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Drainage Criteria and are also included in the Appendix. Final storm sewer pipe, water quality and detention pond capacities, culverts, swale calculations, and riprap and erosion control calculations have been completed using UDSewer and UDInlet from UDFCD, as well as other spreadsheets and hydraulic software. Please refer to the appendices of this report, as well as the Final Drainage Report for the HTP Infrastructure Improvements for applicable and additional calculations. E. Variance No variances are being requested for the project. IV. DRAINAGE FACILITY DESIGN A. General Concept Ten proposed drainage basins (basins 1-10) will provide conveyance (or future conveyance, as applicable) of runoff to the proposed water quality and detention Pond 100, located south and north of Timberwood Drive and Precision Drive, respectively, and east and west of Technology Parkway and Lady Moon Drive, respectively. Pond 100 will provide water quality and detention for basins 1-10, with all basins allowed up to an 80% impervious ratio for each basin. Two outlet structures within Pond 100 will provide controlled releases (5 cfs to the west, 12 cfs to the east), prior to runoff being directed downstream. 9 Pond 100 provides approximately 13.47 acre-feet of combined water quality and detention volume for not only the 21.08 acres of the HTP Sixth Filing, but also for additional adjacent areas (total of 48.3 acres), per the HTP Masterplan. Pond 100 has been sized to detain up to the 100-year event, while receiving the 100-year flow from the 48.3 acre masterplan area (at 80% impervious ratio). Upon development of basins 1 and 8 (HTP Sixth Filing), runoff from these two basins and adjacent runoff from basins 2-5 will be routed to Pond 100 via proposed storm sewer inlets and piping (from HTP Infrastructure Improvements project) and proposed Swale A, which is shown and contained within the HTP Sixth Filing plans. Upon future development of areas immediately south of Timberwood Drive, it is anticipated that Swale A will be replaced with a piped storm sewer system; however, this will be provided and shown with future development, as may be applicable. Please refer to the proposed drainage basin exhibit in Appendix F, and the rational and storm sewer pipe sizing calculations in Appendices B and C for the proposed roadway and HTP Pond portion areas, and also for the future development areas. B. Specific Details (The following basin information contains excerpts taken from HTP Infrastructure Improvements Final Drainage Report. Please also refer to the said report for additional information, as may be applicable.) Basin 1: A CDOT Type C Inlet with close mesh grate will be installed at design point 1 to provide an outfall for the future development of the parcel in this area. The CDOT Type C Inlet will also serve as the outfall point for the median underdrain that will be installed under the median in Technology Parkway with the HTP Infrastructure Improvements project. Future development of Basin 1 shall provide for runoff being conveyed to the CDOT Type C Inlet. Basins 2 & 3: Proposed 5’ Type R Inlets will be placed at design points 2 and 3 to capture runoff from basins 2 and 3. Runoff will combine with that from Basin 1 (as may be applicable) and will be conveyed east in the proposed storm sewer system towards design point 3A. Runoff will flow south in Swale A and in to Pond 100. Please refer to the drainage exhibit for cross-section information and sizing of Swale A. Basins 4 & 5: Proposed 5’ Type R Inlets will be placed at design points 4 and 5 to capture runoff from basins 4 and 5. Runoff from basins 4 and 5 is conveyed south in the proposed 10 storm sewer system and into an interim cobble pit on the south side of Timberwood Drive, which will be constructed with the HTP Infrastructure Improvements project. Future development in this area (south of Timberwood Drive) will extend the pipe (or provide a swale system) to Pond 100, as approved by MAVDevelopment. Basins 6 & 7: Basins 6 and 7 will convey their runoff east along a short segment of Timberwood Drive, then north and south, respectively, down Lady Moon Drive and into the existing inlets and storm system in Lady Moon Drive, as historically occurs. Basin 8: Two, 2’ x 5’ RCB’s will be installed at design point 8 to serve as an outfall for the development of basins 1 and 8, and the associated Harmony Road and Lady Moon Drive frontage to basin 8, as historically flows to and through parcel 8. The two, 2’ x 5’ RCB’s will also serve the developed condition of the roadway for basins 2-3. Runoff from basins 1-3, and 8 will be conveyed to and through the two, 2’ x 5’ RCB’s. The two, 2’ x 5’ RCB’s have been modeled to carry ½ of the attributing 100-year flow (for the future developed condition) from basin 8 (Q100 = 85.26 cfs), as well as the 100-year, routed flow from basins 2-3, and basin 1(for the future developed condition of basin 1: Q100 = 33.23 cfs). This provides for approximately 70.14 cfs being utilized to size the western 2’ x 5’ RCB. It’s important to note that the runoff from basins 1-3 will only discharge to the westerly 2’ x 5’ RCB. The easterly 2’ x 5’ RCB will convey the remaining 42.63 cfs (other ½ of the 100-year from basin 8) south under Timberwood Drive. Please refer to Interwest’s plans for the upstream inlet structure(s) to be constructed and for connection details to the north end of the 2’ x 5’ RCB’s. This measure will provide for the 100-year flow from basin 8 being conveyed under Timberwood Drive and to Pond 100. It’s important to note that the combined imperviousness ratio for basin 8 shall not exceed 80%, as required by the HTP Masterplan. Basins 9 & 10: Runoff from basins 9 and 10 will be conveyed south down Timberwood Drive to proposed 10’ Type R Inlets at design points 9 and 10. Runoff will be conveyed, via storm sewer pipes, east and west of Technology Parkway, to interim cobble pits (for the interim condition only). Runoff will infiltrate into the existing fields, as historically occurs. Future development east and west of basins 9 and 10 will be required to connect to the existing storm sewer stubs and extend the storm sewer systems to the Pond 100 and to a second regional pond or onsite pond for areas west of Technology Parkway, as may be applicable for these specific areas. 11 Please refer to the proposed drainage basin exhibit in Appendix F, and the rational and storm sewer pipe sizing calculations in Appendices B and C for the proposed roadway and HTP Pond portion areas, and also for the future development areas. Overflow Conditions: Should outlet structures, outlet pipes, or culverts become clogged, runoff will spill east-southeast and over the existing field, as historically occurs. C. Detention Pond Pond 100 has been sized to provide water quality and detention for not only the proposed 21.08 acres of the HTP Sixth Filing, but also for the future ultimate development (build-out) of the total 48.30 acre area, as shown in the HTP Masterplan, for SWMM basins 401, 600, and 601. Pond 100 will provide 13.47 acre- feet of combined water quality and detention volume (1.59 acre-feet of water quality), thus exceeding the 5.88 acre-feet of combined water quality and detention volume (0.69 acre-feet of water quality) required for the 21.08 acre build out of the attributable HTP Sixth Filing drainage basin areas. Pond 100 will allow for detention up to the 100-year event (for 48.3 acres of developed area) and will contain two outlet control structures. The east structure will be a water quality and outlet control structure and will have a water quality plate set to control and provide up to 0.69 acre-feet of water quality volume (for 21.08 acres) at an elevation of approximately 4904.05. The 100-year WSEL for the 21.08 acre development (HTP Sixth Filing) will be approximately 4906.55. The east structure will be a 100-year single stage box control structure with an orifice control plate at the back of the box over the entrance of the 24” RCP outlet pipe. Orifice sizing provides for the orifice plate utilizing an 11.30” diameter opening, thus discharging the allowable 12 cfs east and into the existing storm sewer system in Lady Moon Drive, as allowed by the HTP Masterplan. The second outlet structure will be located on the west side of Pond 100 and will entail a modified CDOT Type C inlet with close mesh grate and an orifice control plate constructed at the back of the box over the entrance of the 24” RCP outlet pipe. Orifice sizing provides for the orifice plate utilizing a 9.11” diameter opening, thus discharging the allowable 5 cfs west and into the storm sewer system in Technology Drive (constructed with the HTP Infrastructure Improvements project), as allowed by the HTP Masterplan. The structure and inlet grate shall be constructed to provide for the east side of the inlet grate set at 4906.00 and the west side of the inlet grate at an elevation of 4908.00. It’s important to note that the 100-year WSEL for the ultimate build-out of the 48.3 acre masterplan area will be approximately 4908.60. Pond 100 and the east and west 12 orifice control plates are being constructed for the ultimate build-out condition of the 48.30 acres at a combined impervious ratio of 80%. However, the WQCV plate and WQCV structure height on the east outlet structure may require modification in the future to accommodate the ultimate build-out of the 48.3 acres, as may be applicable. The emergency spillway has been sized and shall be constructed along the east side of Pond 100. The proposed spillway shall be 103’ wide, with a bottom-of-weir overflow elevation of 4909.00. The top-of-weir elevation will be 4910.00, thus providing a weir flow depth (free-board depth) of approximately 1.0’ (overflow is anticipated to reach a depth of approximately 0.8’ for the estimated 100-year flow of 231.84 cfs for 48.3 acres at c=0.80, I = 6in/hr). Should Pond 100 overtop, flows will spill east-southeast and over the existing field, as historically occurs. D. Street Capacities Street capacity calculations were provided for in the HTP Infrastructure Improvements Final Drainage Report. Please refer to this report for details on applicable roads. V. STORM WATER QUALITY A. General Concept & Specific Details The water quality aspect of stormwater runoff must be addressed on all final utility plans. Therefore, the proposed water quality/ detention pond (Pond 100) will have adequate capacity, in accordance with the HTP SWMM Model, and will provide all of the required water quality and detention up to the 100-year event for the developed condition of the subject site (HTP Sixth Filing) and offsite adjacent areas (up to an impervious ratio of 80% for onsite parcel areas and associated, adjacent roadways) (total of 48.3 acres), prior to releasing flows downstream. Best Management Practices (BMP’s) for the treatment of stormwater will be provided in the HTP Sixth Filing Pond area through the utilization of grass scrubbing across the bottom of Pond 100 during first flush conditions, as well as a 40-hour extended detention structure with orifice control (east side of Pond 100) and a secondary orifice outlet control structure (west side of Pond 100). These water quality features/structures will provide a mechanism for pollutants to settle out of the stormwater runoff before flows are directed downstream to the McClelland’s Drainage Basin. 13 Best Management Practices (BMP's) for the treatment of stormwater runoff shall also be provided with development of future, adjacent parcels and may include grass/ sod- lined swales with soft pans, riprap pads at culvert discharge points, permanent erosion control fabric or riprap at curb cuts and swale entrances into the future, regional or onsite pond(s), and grass scrubbing across the bottom of the future, regional water quality and detention pond(s) during first flush conditions. Please refer to plans by Interwest for onsite BMP’s and LID’s for the HTP Sixth Filing, and future plans by others for other BMP’s and LID’s attributable to future, development basins/areas. VI. EROSION CONTROL A. General Concept The subject site lies within the Moderate Rainfall Erodibility Zone and the Moderate Wind Erodibility Zone per the City of Fort Collins zone maps. The potential exists for erosion problems during construction, but should be minimal after completion of proposed Pond 100. Silt fence will be installed along the boundaries of the grading areas, as shown in the erosion control plan, to prevent sediment from leaving the project area. A gravel tracking pad(s) will also be placed at entrances/exits to the Sixth Filing pond area(s). Gravel inlet filters may be placed at nearby existing and proposed inlets, with straw wattles installed in green areas and swales to mitigate the build-up of sediment and transport of debris. Riprap and erosion control fabric will also be utilized at concentration points (riprap pads and pipe outlets) to minimize erosion and increase soil stabilization. VII. CONCLUSIONS A. Compliance with Standards All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. The City of Fort Collins Storm water Utility will not maintain the private storm drainage facilities within offsite parcels. The owners of the offsite parcels will maintain their on-site storm drainage facilities on a regular basis. The following shall be implemented for the private stormwater improvements’ operations/ maintenance procedures for the project on an annual or bi-annual basis: 1) Storm Sewer Inlets, pipes and flared-end-sections, curb cuts and concrete sidewalk culverts/chases, structures, manholes, and the water quality/ outlet control structures, as may be applicable, shall be cleaned through the removal 14 of debris and sediment from the associated items to allow for adequate drainage through the site to the interim facilities. 2) Sedimentation/ silting shall be removed to allow for adequate drainage along the bottom of the swales. 3) Re-vegetation through the use of Natural Seeding/ Sod shall be provided for disturbed areas and other permanent erosion controls shall be provided for areas where erosion has taken place and requires remediation back to the proposed condition shown in the plans The Stormwater Operating/ Maintenance Procedures listed above are guidelines to the minimum procedures that shall be implemented for the HTP Sixth Filing Pond project, with these and additional measures being utilized on an as-needed basis. B. Drainage Concept The proposed drainage concepts presented in this study and shown on the utility plans, as well as that from the HTP Infrastructure Improvements project, adequately provide for the transmission of developed runoff from the proposed HTP Sixth Filing development and adjacent roadway improvements to Pond 100. Future development will provide for the removal of applicable cobble pits and shall extend storm sewer piping to Pond 100, as applicable. Runoff for all other areas will provide for the 100-year developed (and historic) flows and drainage patterns from adjacent offsite basins to continue to be conveyed to discharge points, per the HTP drainage Masterplan, or as historically occurs, and to drainage facilities, as required by the HTP Masterplan, and subsequent plans and reports. If groundwater is encountered at the time of construction, a Colorado Department of Health Construction Dewatering Permit will be required. C. Storm Water Quality The final design for the Pond Only portion of the HTP Sixth Filing project has addressed the water quality aspect of stormwater runoff. The proposed grass-lined detention pond with extended detention and water quality and outlet control structures will provide an opportunity for stormwater pollutants to filter out of the stormwater runoff before flows are directed downstream. 15 Furthermore, the proposed grass-sod-lined swale, riprap pads at culvert outlets, permanent erosion control fabric and other erosion control devises that may be utilized for side-slopes and embankments will provide additional mechanisms for pollutants to settle out of the stormwater runoff before flows are directed south and ultimately to Fossil Creek Reservoir Current proposed development for the onsite portion of the HTP Sixth Filing and other adjacent and future development shall also provide final design which addresses the LID and BMP aspects of stormwater runoff. Please refer to onsite plans and onsite drainage report, by Interwest, for the applicable onsite portion for the HTP Sixth Filing project. It’s important to note that in the interim condition for undeveloped land adjacent to Pond 100, runoff will flow historically across the agricultural field areas and is anticipated to infiltrate into the soil, thus maintaining water quality for the area. Please also refer to the HTP Infrastructure Improvements Final Drainage and Erosion Control Report for additional information regarding adjacent areas that will be treated and routed to Pond 100, once development occurs. D. Erosion Control Concept Proposed erosion control concepts have been provided for and adequately provide for the control of wind and rainfall erosion from the HTP Sixth Filing Pond development. Through the construction of the proposed erosion control concepts, the City of Fort Collins performance standards will be met. The proposed erosion control concepts presented in this report and shown on the erosion control plan are in compliance with the City of Fort Collins Erosion Control Criteria. Erosion Control Escrow Estimate The Erosion Control Escrow Estimate for the Pond Only portion of the HTP Sixth Filing is approximately $29,214.00. Please refer to Appendix E for this calculation. 16 REFERENCES 1. Storm Drainage Design Criteria and Construction Standards by the City of Fort Collins, Colorado, May 1984, Revised January 1997. 2. Erosion Control Reference Manual for Construction Sites by the City of Fort Collins, Colorado, January 1991, Revised January 1997. 3. East Harmony Portion of McClellands Basin 100-Year Master Plan, by Icon Inc., Fort Collins, Colorado, August 1999. 4. Final Drainage and Erosion Control Report, Harmony Technology Park 2nd Filing, by JR Engineering, June 20, 2001. 5. 2004 High School Drainage and Erosion Control Study, Poudre School District R-1, by Nolte Associates, Inc., June 24, 2002. 6. Final Drainage and Erosion Control Report, Harmony Technology Site Master Plan, by Stantec Consulting, May 19, 2008. 7. Final Drainage and Erosion Control Study for Harmony Technology Park Third Filing, by Stantec Consulting, May 19, 2008. 8. Final Drainage and Erosion Control Report for the Harmony Technology Park Infrastructure Improvements, by Aspen Engineering, November 4, 2015. 17 APPENDIX 18 APPENDIX A 19 VICINITY MAP 20 APPENDIX B 21 RATIONAL METHOD HYDROLOGY (Excerpt from HTP Infrastructure Improvement Project) 22 APPENDIX C 23 POND CAPACITY CALCULATIONS & RATING CURVES, OUTLET STRUCTURES & STORM SEWER PIPE SIZING, ORIFICE SIZING, & OVERFLOW WEIR SIZING (Excerpts from HTP Infrastructure Improvement Project also included) 24 APPENDIX D 25 RIPRAP, SWALE SIZING, & EROSION CONTROL CALCULATIONS 26 APPENDIX E 27 EROSION CONTROL ESCROW ESTIMATE 28 APPENDIX F 29 PROPOSED DRAINAGE BASIN EXHIBIT, EXHIBITS & EXCERPTS, EROSION CONTROL PLAN, & EROSION CONTROL NOTES AND DETAILS SHEET