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Home My WebLink About20231579 Ver 1_More Info Received_20240202 (8)Homewood, Sue From: Danielle Clark <dclark@harthickman.com> Sent: Friday, February 2, 2024 11:44 AM To: Homewood, Sue Cc: Perez, Douglas J CIV (USA); Michael Cain; Dan McCauley; Luke Bugenske Subject: [External] RE: Request for Additional Information for Eastfield Warehouse Project - Mecklenburg County - DWR#20231579 Attachments: Updated Jurisdictional Determination Map (1-30-24).pdf; Updated PCN Form (2-1-24).pdf, Updated Environmental Impact Exhibit (1-29-24).pdf Follow Up Flag: Follow up Flag Status: Flagged CAUTION: External email. Do not click links or open attachments unless verified. Report suspicious emails with the Report Message button located on your Outlook menu bar on the Home tab. Hi Sue, Good morning and Happy Friday. Please find our responses to your questions/comments below in red text. I'm also attaching additional documentation for your use, as well. 1. DWR has been made aware that the USACE has conducted a site visit of the project for review of jurisdictional areas. Please provide an updated jurisdictional map, confirmation from the USACE for any non -jurisdictional areas. Please provide updated impact maps, impact tables, and mitigation acceptance letters if appropriate. • Site visit with Corps was completed on November 30, 2023. A finalized Jurisdictional Determination from the Corps is pending. We've attached an updated jurisdictional map based on comments received from Doug during the site visit; however, we are awaiting final confirmation from Doug. 2. The application makes reference to an existing riser structure and pond dam. Please show the existing conditions and riser structure and outlet location on a plan sheet or the updated jd map. It is unclear as to whether the proposed impact amounts incorporate the length of stream already piped within the riser structure or not. It is also unclear whether there are any additional impacts proposed below the current pond outlet structure (additional riprap, culvert length, etc) • Former riser structure and outlet location approximately depicted on the updated Jurisdictional Determination Map prepared by Hart and Hickman dated January 30, 2024. Unfortunately, the surveyor did not pick up the riser structure or pond outlet during their survey of existing conditions at the site. However, H&H has photographic documentation of the riser structure and used this information to depict the approximate location of the riser structure on the updated JD Map. H&H also had a GPS point of the pond outlet and used that information to depict the approximate location of the pond outlet on the updated JD Map. H&H can provide photos of the riser structure and outlet if needed. • Please see Existing Conditions exhibits included as sheets 3 through 7 of the Construction Drawing Package prepared by Oak Engineering dated December 18, 2023. As noted above, the surveyor did not pick up the riser structure or pond outlet, so they are not depicted on these drawings. • Proposed impact quantities do not account for features that may have been historically impacted by the installation of the former riser structure and outlet pipe. The proposed culvert pipe will replace the riser pipe. • The current outlet structure is located off -site, and additional impacts are not proposed to features located downgradient of the outlet. 3. Please provide documentation and/or a construction sequence that clearly show how the work will be conducted "in the dry' and include any temporary impacts above and below the proposed permanent impact on the impact tables and impact drawings. • Please see the Stormwater Management Plan included as sheets 20 and 21 of the Construction Drawing Package prepared by Oak Engineering dated December 18, 2023. • Please see the Erosion Control Plan included as sheets 22 through 27 of the Construction Drawing Package prepared by Oak Engineering dated December 18, 2023. • The Stormwater Management Plan and Erosion Control Plan will be reviewed and approved by the Town of Huntersville as the delegated authority. • No temporary impacts are proposed. 4. Please provide proposed roadway dimensions and fill slopes for the roadway and proposed buildings. Please discuss the possibility of utilizing end walls for the culvert and/or retaining walls for fill shoulders to provide additional minimization of impacts to streams and wetlands on site. • Please see the Construction Drawing Package prepared by Oak Engineering dated December 18, 2023 for roadway dimensions, and fill slopes for the roadway and proposed buildings. • An end wall has been implemented on the upgradient end of the culvert proposed in the northern portion of the site, which will reduce impacts to the on -site stream channel. An updated PCN form is attached to account for this reduction in impact. • Please see the updated Environmental Impact Exhibit prepared by Oak Engineering dated January 29, 2024, which depicts the end wall and the current proposed impacts. • Retaining walls were considered but determined to be cost prohibitive for this project. 5. Please provide plan and profile for the proposed culvert. • Please see project details included as sheet 33 of the Construction Drawing Package prepared by Oak Engineering dated December 18, 2023. 6. The Division is concerned that replacement of a riser structure with a typical culvert will promote sediment movement from the old pond bed into downstream waters. Please provide a description and/or plan sheets to show how the project proposes to permanently retain existing sediments/pond bed materials during project construction and upon project completion. • Please see the attached Construction Drawing Package prepared by Oak Engineering dated December 18, 2023 for the Stormwater Management Plan and Erosion Control Plan. • Hart & Hickman conducted a site visit on November 30, 2023 and the majority of the pond footprint has become stabilized with the growth of dense emergent vegetation, which will assist with preventing sediment transport. • The stormwater pond and associated dissipation pad proposed upgradient of the former pond will filter sediment and dissipate flow velocity prior to discharging into the former pond. • A large riprap apron is proposed downgradient of the culvert outlet in the northern portion of the site, which will dissipate flow and capture sediment discharged out of the former pond. Attachments - Link to Construction Drawing Package prepared by Oak Engineering - Updated Environmental Impact Exhibit prepared by Oak Engineering - Updated Jurisdictional Determination Map prepared by Hart & Hickman - Updated PCN form Everette Keith Logistics Park 2024.01.29.pdf (dropbox.com)