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HomeMy WebLinkAboutCorrespondence: Response to Crossroad Engr'g B �'r IIII I Beam, Longest Consulting Engineers ♦ Land August 28, 2012 Gregory J. Ilko Crossroad Engineer,P.C. 3417 Sherman Drive Beech Grove, IN 46107 RE: Bennett Technology Park, Road Plans Secondary Plat&Road Design Docket412050019SP Dear Mr. Ilko: This letter is in response to the Review Letter dated June 29, 2012 for the Bennett Technology Park, Road Plans Road project. The following are responses to each of the review comments using a corresponding numbering system. 1) The survey was updated to read "ALTA /ACSM Land Title Survey" as it was not a full-topographic survey. Therefore, only the information needed to complete the ALTA has been shown. Additional survey information needed to complete this project's design is presented on the plan and profile sheets. The ALTA Survey and General Information Plan were updated per your comments: a. A statement noting that the horizontal datum was based on Indian State Plan Coordinates, NAD83, and that the elevations are given in NAVD 88 was added to the ALTA Survey and the General Information Plan Sheet. i) After a phone conversation with you in mid-July, it was concluded that showing topography of a distance of at least 200 feet surrounding the project site was not warranted. The drainage patterns of the project were well defined due to existing roadways and current land uses, so no additional topography was needed outside the project limits to design the proper drainage conveyance system for this project. e. The existing vegetation cover was added on the ALTA Survey. f. The pertinent storm and sanitary information needed for this project is shown on the plan and profile sheets. See response 91. g. The land uses of all the adjacent properties were added to the ALTA Survey. h. See response "e" and 91. All pertinent survey information needed for design not shown on the ALTA Survey is presented on the plan and profile sheets. 2) No new utility facilities are proposed for this current project. 3) The storm sewer plan and profile sheets (C103a& C103b)were revised per your comments: L Casting type, structure type, subsurface drains and elevations, and the hydraulic grade lines were added to the storm sewerplan and profile sheets (C103a & C103b). IL The storm sewer statement was added to the structure table on sheet C104. 4) The road plan and profile sheet(C102)was revised per your comments: b) Lot delineation and identifications including existing and proposed property lines were labeled on the roadway plan and profile sheet. c) The project site is not located within any floodplains, floodway fringes, or floodways per FEMA and this has been noted on the Cover Sheet. g) The 100-year overflow paths/ponding areas are temporary and a final routing path will not be determined until the outlots are fully developed. The current routing paths use temporary diversion swales and the proposed roadway, which will be located within right-of-way and does not require an 8126 Castleton Road ■ Indianapolis,Indiana 46250 ■ Phone:317.849.5832 ■ Fax: 317.841.4281 ■ Web:www.B-L-N.com Docket#1205 0019SP-Bennett Technology Park,Road Plans Page 1 of 3 Bennett Technology Park,Road Plans —Review Response easement. No easements will be created at this time, but as the outlots are developed and final 100- year overflow paths are determined, the easements will be created at that time. h) A statement was added to the storm sewer plan and profile sheets and the structure table that states that the storm sewers will be public. k) An overflow path exhibit was added to sheet C104. This shows the flood routing path to the detention pond. o) The pad elevations are not the minimum allowable elevations and were designed for earthwork balancing purposes. By definition, the minimum flood protection grade (MFPG) does not appear to pertain to this project since the outlots do not adjoin a body of water, floodplain,permanent swale, or detention pond. The minimum lowest adjacent grade elevations were added to the plans, which shall govern all future building elevations. p) Since the minimum flood protection grade does not apply, this definition was not added to the construction plan set. r) Slope labels and spot elevations are currently labeled on the temporary diversion swales. Additional labels were added for clarification. 5) The curve numbers and acreages of each drainage basin were added to the pre-developed watershed map. 6) The post curve numbers and acreages of each drainage basin were added to the post-developed watershed map. 7) The drainage report was revised as follows: i. Acreages were added to each inlet basin on the Storm Sewer Basin Map. ii. Inlet grate capacity calculations were provided in the drainage report under Appendix F. The inlet capacity calculations in sump conditions used weir, orifice, and Manning's equations under 50% clogged conditions as specified per the Carmel's drainage manual. The roadway gutter spread calculations used Manning's equation (as approved by the Carmel's drainage manual) and the on- grade inlets stormwater capture efficiency was calculated using INDOT methodologies. Carmel's drainage manual does not appear to provide a preferred method to calculate on-grade inlet calculations. The Neenah method was not used for roll curb inlets since Neenah charts for these casting are not available. As a result, INDOT methodologies were used. iii. Calculations have been added to the drainage report (page 7) determining the capacity of existing structure 9625. The inverts, pipe sizes, and length of pipe were obtained from surveyed "As-Built" information. It was determined that the existing connection pipe did not have the capacity to drain all the stormwater associated with the fully-developed outlots. The outlot's runoff coefficient was back calculated to max out the existing connection pipe capacity, which equated to a runoff coefficient for the outlots of 0.55. This results in only allowing 52 percent impervious area be constructed within the outlots. If the outlots are developed with greater than 52 percent impervious area, onsite detention will be necessary before draining into the roadway storm sewer system. These limitations are discussed in the drainage report. vi. Please see the above response and the drainage report for explanation on why the runoff coefficients for the outlots were not set at 0.75. If 0.75 was used for the outlot's coefficients (which would allow for greater impervious area), the existing connection storm pipe (str. # 625) would not be able to handle the stormwater runoff associated with this project under full-developed conditions. ix. The rainfall intensity table was added to Appendix F of the drainage report. xiv. The hydraulic grade lines were calculated and are presented in Appendix F of the drainage report. 8) A statement indicating that the FEMA Base Flood Elevation will not flood portions of the project via outfall or storm piping system was added to the drainage report (page 8). 9) The construction plans were revised per your comments: a) This note was added to sheet C101 of the the construction plans and the plat. 8126 Castleton Road ■ Indianapolis,Indiana 46250 ■ Phone:317.849.5832 ■ Fax: 317.841.4281 ■ Web:www.B-L-N.com Docket#12050019SP—Bennett Technology Park,Road Plans Page 2 of 3 Bennett Technology Park,Road Plans —Review Response b) i) This note is not required since the Minimum Flood Protection Grade does not pertain to this project as previously mentioned. ii) This note has been added to the cover sheet (C100), the roadway plan and profile sheet (C102), and sheet 1 of the plat. 10) The CN value for the entire Detention Pond Watershed (PRl) was evaluated using the current developed conditions, the proposed development, and the future fully-developed outlots. The CN value was calculated to be under the masterplan CN value. Please see the Proposed Conditions Section (page 6) of the drainage report for further information regarding this topic. 11) The overall design runoff coefficients are less than the masterplan runoff coefficients of 0.75. 12) The 100-year overflow paths/ponding areas are temporary and a final routing path will not be determined until the outlots are fully developed. The current routing paths use temporary diversion swales and the proposed roadway, which will be located within right-of-way and does not require an easement. No easements will be created at this time, but as the outlots are developed and final 100-year overflow paths are determined, the easements will be created at that time. The notes requested to be added to the plat are now shown on the plat. 13) The note specifying the storm pipe material was added to the storm plan and profile sheets and the structure tables. 14) All structures were re-designed with at least 0.1 foot drop through the manholes. The construction plans and the drainage report have been updated to reflect this change. 15) The underdrains are now shown on the storm plan and profiles with inverts connecting into the storm structures. After a phone conversation with you in mid-July, you indicated if the underdrains were shown with inverts in the plan and profiles,the underdrain table was not required. Attached are the revised construction plan set, secondary plat, and drainage report. If you have any questions or require additional information to complete your review and approval of this application, please let me know. Yours Truly, V Ashton L.Fritz,PE Project Manager Beam Longest&Neff, L.L.C. Cc: Jeremy Stephenson Nickolas Schmitt, BLN Angie Conn, Carmel Planning Gary Duncan, Carmel Engineering Lance Lantz, Town of Zionsville 8126 Castleton Road ■ Indianapolis,Indiana 46250 ■ Phone:317.849.5832 ■ Fax: 317.841.4281 ■ Web:www.B-L-N.com Docket#12050019SP—Bennett Technology Park,Road Plans Page 3 of 3