NOTICE OF CLEAN WATER BRANCH RECOMMENDATIONS FOR WATER POLLUTION CONTROL PERMIT FOR THIRTY METER TELESCOPE INTERNATIONAL OBSERVATORY NPDES PERMIT NO. HI S000431 DOCKET NO. HI S000431 April 8, 2021 The Hawaii Department of Health (DOH), Clean Water Branch (CWB) tentatively recommends to the Director of Health (Director) to renew a National Pollutant Discharge Elimination System (NPDES) permit to discharge storm water associated with construction activity from the Thirty Meter Telescope (TMT) International Observatory project site to receiving State waters, subject to special conditions, to: TMT INTERNATIONAL OBSERVATORY LLC 137 W. WALNUT AVENUE MONROVIA, CALIFORNIA 91016 A permit for such discharge would expire five (5) years from the date of issuance. The project is located at TMT International Observatory, Mauna Kea Loop Road Area E, Mauna Kea, Island of Hawaii, Hawaii, TMK: (3) 4-4-015:009 (por.) and 012 (por.). The proposed project is to construct the TMT International Observatory and access way road. The observatory will consist of the dome, which will be roughly 180 feet tall, and a support building, which will be roughly 18,000 square feet in size. The access way road will be roughly 0.65 miles long and asphalt paved. TMT International Observatory LLC requests to discharge storm water runoff from the proposed construction site. Best Management Practices (BMPs) for storm water runoff and non-storm water sources will be implemented to minimize the discharge of erosion and other pollutants from entering receiving State waters. The receiving waters, Kemole Gulch, Kuupahaa Gulch, Puupohakuloa Gulch Pohakuloa Gulch, and Wailuku River, are classified by the DOH as Class 2, Inland Waters. Under Hawaii Administrative Rules (HAR) Section 11 54-3(b)(2), the objective for Class 2 waters is to protect their use for recreational purposes, the support and propagation of aquatic life, agricultural and industrial water supplies, shipping, and navigation. The uses to be protected in this class of waters are all uses compatible with the protection and propagation of fish, shellfish, and wildlife, and with recreation in and on these waters. These waters shall not act as receiving waters for any discharge which has not received the best degree of treatment or control compatible with the criteria established for this class. Persons wishing to comment upon or object to the CWB recommendations with respect to an NPDES permit or to request a public hearing should submit their comments or requests in writing no later than 30 calendar days after the date of this notice, either through E-mail at: cleanwaterbranch@doh.hawaii.gov or by mail at P.O. BOX 3378, Honolulu, Hawaii 96801 3378. Copies of the public notice permit recommended by CWB and other information are available for public inspection, Monday through Friday (excluding holidays) from 7:45 a.m. until 4:15 p.m., at the DOH Clean Water Branch office located at 2827 Waimano Home Road, Room 225, Pearl City, Hawaii 96782, as well as the DOH Hawaii District Health Offices at 1582 Kamehameha Avenue, Hilo, Hawaii 96720, and 79-1015 Haukapila Street, Kealakekua, Hawaii 96750. Copies may be bought. The public notice permit and rationale are also available on the internet at: https://health.hawaii.gov/cwb/clean-water-branch-home-page/public-notices-and-updates/. For more information or if you have special needs that will aid you in inspecting and/or commenting on the public notice permit and related information due to disability, please contact Mr. Darryl Lum, Supervisor of the Engineering Section, Clean Water Branch, at the above address or (808) 586-4309 (Voice) at least seven (7) calendar days before the comment deadline. For those who use a TTY/TDD, please call through Sprint Relay Hawaii, at 1-711 or 1-877-447-5991. All written comments and requests received on time will be considered. If the Director determines that there is significant public interest, a public hearing may be held after at least 30 calendar days of public notice. If CWB believes, after considering all timely written comments and all oral comments at any public hearing that may be held, that no changes to the conditions of the public notice permit are necessary or warranted, then CWB may recommend to the Director that the NPDES permit be issued. Please notify anyone you know who would be interested in this matter. ALEC WONG, P.E. Clean Water Branch Chief (HTH1320875 4/8/21)