The scope of this project included the drainage design for the construction of 9 miles of new NB & SB ML bridges impacting 9 culverts & 2 bridges. HCI performed H&H modeling, hydraulic reports and plans for all 11 crossings, as well as survey and SWPPP. For each model the effective FEMA HEC-RAS model was obtained to create a Duplicate Effective, Effective Corrective and Existing & Proposed geometry files within HEC-RAS. For Walnut Creek 3 crossing, a CLOMR was prepared to document the rise, but USACE & City of Mansfield & Arlington FPA’s were adamant about NO FILL (loss of storage) in the flowage easement & ZERO RISE to the BFE. HCI exported the effective HECRAS into ARCGIS and used GEORAS to adjust the reach lengths. The reach lengths were then geo-referenced by re-importing back into HEC-RAS where a lateral weir was modeled to represent the wide floodplain overtopping the upstream frontage road, which eliminated the upstream WSE rise. Additionally, HCI prepared reports & exhibits for the USACE 408 Permit which re-delineated existing vs. proposed floodplains on aerial maps showing existing residents were removed from the 100-yr floodplain. The FPA accepted the H&H model for use in regulating future street improvements within the watershed.
Hayden performed the necessary surveying to prepare 27 parcels maps and legal descriptions for Acquisition and/or Denial of Access, as well as field surveying for the main project control which consisted of tying 98 control points using GPS and a digital level network as the backbone for all surveying and construction layout.
Hayden also performed field surveying to locate 350+ photo identifiable points for use as LIDAR control, pavement ties at all street intersections and for MOT tie ins, drainage verification at 2 major channels including valley sections for these and numerous smaller areas along the entire route, utility locations including overhead wire sag elevations and locations for 100+ test bores.