X0306 4 2019-11-01 0001783400 US Ecology, Inc. ECOL 0001409319 Gerratt Eric L 101 S. CAPITOL BLVD. SUITE 1000 BOISE ID 83702 1 EVP and CFO Common Stock 2019-11-01 4 A 0 27553 A 27553 D Stock Options 49.97 2019-11-01 4 A 0 8500 0 A 2016-03-10 2025-03-09 Common Stock 8500 8500 D Stock Options 35.05 2019-11-01 4 A 0 2300 0 A 2017-01-04 2026-01-03 Common Stock 2300 2300 D Stock Options 49.15 2019-11-01 4 A 0 6000 0 A 2018-01-02 2027-01-01 Common Stock 6000 6000 D Stock Options 51 2019-11-01 4 A 0 6900 0 A 2019-01-01 2028-01-01 Common Stock 6900 6900 D Stock Options 63.85 2019-11-01 4 A 0 6100 0 A 2020-01-01 2029-01-01 Common Stock 6100 6100 D Performance Stock Units 0 2019-11-01 4 A 0 2000 0 A 2019-12-31 Common Stock 2000 2000 D Performance Stock Units 0 2019-11-01 4 A 0 2400 0 A 2020-12-31 Common Stock 2400 2400 D Performance Stock Units 0 2019-11-01 4 A 0 2847 0 A 2021-12-31 Common Stock 2847 2847 D Acquired pursuant to that certain Agreement and Plan of Merger, dated as of June 23, 2019 ("Merger Agreement"), by and among US Ecology Holdings, Inc. (f/k/a US Ecology, Inc.) ("Parent"), NRC Group Holdings Corp., US Ecology, Inc. (f/k/a US Ecology Parent, Inc.) ("Holdco"), ECOL Merger Sub, Inc. ("ECOL Merger Sub") and Rooster Merger Sub, Inc., in a merger transaction in which ECOL Merger Sub merged with and into Parent, and each issued and outstanding share of Parent's common stock was converted into the right to receive, and became exchangeable for, one share of common stock, par value $0.01 of Holdco. All outstanding derivative securities of Parent, which include Options and Performance Stock Units ("PSUs"), were assumed by Holdco pursuant to the Merger Agreement and were converted into an equivalent number of Options and PSUs, respectively, of Holdco at an equivalent exercise price and under the same terms and conditions as the original award. These Options are fully vested and exercisable. Options vest ratably on the anniversary of the date of original issuance for a period of three years. Upon vesting, the reporting person will receive a number of shares of common stock equal to the number of Options that have vested. Each PSU represents a contingent right to receive one share of Parent common stock. The number of shares reported represents the target number of shares underlying the PSUs. The actual number of shares to be delivered in settlement of the PSUs earned during the performance period will be based on Parent's total shareholder return over the three year vesting period relative to the S&P 600 (weighted at 50%) and a peer group of certain companies in the environmental and facilities services industry (weighted at 50%) and could equal 200% of the target number of shares underlying the PSUs. If earned, PSUs will vest ratably on the anniversary of the date of original issuance for a period of three years. The PSUs will settle as soon as practicable after the expiration date. Each PSU represents a contingent right to receive one share of Parent common stock. The number of shares reported represents the target number of shares underlying the PSUs. The actual number of shares to be delivered in settlement of the PSUs earned during the performance period will be based on achievement of established targets with respect to the Parent's Adjusted Earnings Per Share and Return on Invested Capital, each weighted at 50% of the target PSUs. After the payout under the PSUs is determined, the number of shares to be provided is subject to modification based on the percentage change in the price of the Parent's common stock from January 1, 2019 to December 31, 2021, relative to the percentage change in the price of the common stock of certain peer group companies. If earned, PSUs will vest ratably on the anniversary of the date of original issuance for a period of three years. The PSUs will settle as soon as practicable after the expiration date. /s/ Wayne Ipsen, power of attorney 2019-11-01