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' EXHIBIT 22 <br /> TETRA TECH MEMO <br /> To: Connie Davis and Mike Refer, Aggregate Industries <br /> ' Cc: Tim Flanagan <br /> From: Tom Hesemann R.G., G.E.G. and Gary Linden, P.G. <br /> Date: June 16 2016 <br /> Subject: Hazeltine Mine-Orr Property DRMS Preliminary Adequacy Review Letter Dated February 29, 2016 <br /> This memorandum presents Tetra Tech`s review of the Colorado Division of Reclamation and Mine Safety <br /> (DRMS) Hazeltine Mine Permit No. M-2004-031, Permit Amendment Application No. 1 (AM-01), and <br /> Preliminary Adequacy Review letter to Connie Davis of Aggregate Industries (AI) dated February 29, <br /> 2016. This memo specifically addresses Section 6.4.5 Exhibit E Reclamation Plan Item 1 of Permit <br /> Amendment Application No.1 (AM-01). In the DRMS letter the Division opines that the "Permanent Plan" <br /> proposed in the Amendment Application only address surface water and not groundwater. <br /> Most of the water that is causing the rise in water levels near the Orr property is from the Fulton Ditch and <br /> the Bull Seep. There are two head gates on the Fulton Ditch that release water to the Bull Seep. One <br /> head gate is just south of 104« Avenue and the other is at the southwest corner of the Orr property <br /> (Figure 1). The Bull Seep water is released from the Fulton Ditch during the winter months. Figures 2 <br /> and 3 are hydrographs of staff gage readings in the Bull Seep adjacent to the Orr property. The staff <br /> gage measurements show the winter water releases to the Bull Seep. Al has proposed a revised <br /> ' Permanent Plan that focuses on the management of the Bull Seep water to return the area of the Orr <br /> property to a pre-mining hydrologic regime. <br /> The original "Permanent Plan" (Plan) proposed by Al was presented in a memo prepared by Tetra Tech <br /> dated July 17, 2015. Al has modified its Plan by lowering the invert of the drain pipe by approximately 2 <br /> feet to an elevation of 5036.5 feet. This is consistent with the maximum normal pool elevation of the <br /> future reservoir that will be operated by the City of Thornton. The City of Thornton reservoir will have an <br /> outlet works in the North West corner with an invert elevation of 5036 feet. The reservoir outlet will drain <br /> to the Bull Seep. To satisfy the requirements of the Colorado Department of Water Resources, water <br /> ' from the drain will be returned to the South Plate River by pumping from the reservoir or by gravity. The <br /> reservoir leak test has been approved by the State Engineer (SEO). The SEO approval requires that all <br /> inflows and out flows to the reservoir be accounted for on a monthly basis. Consequently, the drain will <br /> ' be equipped with a flow measuring device. <br /> The Revised Permanent Plan is outlined below. The drain will capture groundwater recharge that is <br /> sourced from the Bull Seep and route it through the City of Thornton reservoir back to Bull Seep and <br /> ultimately to the South Platte River. Because the invert of the drain has been lowered it will be more <br /> effective at returning the hydrologic regime in the area near the Orr property to pre-mining conditions. To <br /> ' avoid the capture of the normal flows in the Bull Seep the permanent drain will be equipped with stop logs <br /> ' Tetra Tech <br /> 1900 S.Sunset Street, Suite I-E, Longmont, CO 80501 <br /> Tel 303-772-5282 Fax 303-772-7039 www.teti-atech.com <br />