SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

KLE/NFELDER e.;yn;rcop;e.x;gnsaor:. • depth of approximately 150 to 160 feet (elevation of -28 to -28 feet msl) and flows towards the southwest. According to the U.S.D.A. soil survey perched water conditions may exist in the area. Perched water conditions were encountered by Kleinfelder during the installation of Monitoring Well MW-2 (upslope from the nursery operations, to the east) and in Monitoring Well MW-5 downslope of nursery operations, near the northwest corner of the property). Perched water existed at a depth of approximately 5 feet (within and above a gravel stratum) in both borings. The gravel stratum is underlain by a sandy clay/clayey sand layer. 4. Perched groundwater was not detected in Monitoring Well MW-4 adjacent to Basin B. Because of the lack of water present at that location, and the concerns expressed by third parties over potential percolation of water from the pond, a double-nested monitoring well was constructed in the location (Monitoring Well MW-4D and MW4S). 5. Six soil borings were advanced in mid-December 1997 on the Norman's Nursery property. Perched groundwater was encountered in two of the six boring locations (B- 2/MW-2 and B-5/MW-5). Perched water was not encountered in the other four borings. However, a double-nested monitoring well (MW-4S and MW-4D) was installed adjacent to the north side of Basin B. 6. Soil beneath the site can be very generally summarized as a clayey gravel (with an inconsistently present 2-foot thick interbedded layer of sandy clay or clayey sand present to a depth of approximately 17 feet). The clayey gravel is generally underlain by an approximately 5-10 foot thick layer of silt or clayey silt. The silt layer is underlain by silty sand which may contain interbedded layers of clay or clayey silt. 7. Soil samples collected during the advancement of the 6 soil borings advanced in • December 1997 revealed low concentrations of nitrate-nitrogen in the near-surface soil throughout the site. A soil sample with an elevated nitrate-nitrogen concentration was obtained adjacent to the north side of Basin B (B4/MW-4 location). However, the elevated concentration detected in the sample obtained from a depth of 5 feet had attenuated to a non-detectable concentration by a depth of 25 feet in the boring. 8. Extensive surface water flow appears to pass through the intermittent stream and other drainages on the east side of Norman's Nursery towards Potter Creek. Additionally, flow from other sources in the area enters Potter Creek. Those sources may also include the draining of the near-surface perched water. 9. The production area of the nursery exists at an elevation ranging from approximately 118 to 148 feet above msl. According to the U.S.G.S, topographic map for the area, an intermittent stream and numerous drainages appear to flow across the Norman's Nursery site. According to the topographic survey, three main drainages enter the nursery and flow towards the drainage basin south of the office complex. 10. Review of the nursery's water use (Chart 1A) and the level in the nursery's tail water pond (Basin B, see Chart 2) shows that while water use is consistent with that of last year's irrigation season, tailwater volumes have apparently dropped off. Additionally, according to Ms. Beverly Burdick of the nursery, production has increased. Given these three factors, it appears that the nursery's BMPs and efforts to reduce water use and tailwater have been successful. Norman's Nursery is making significant efforts beyond those required by the RWQCB to implement BMPs to further limit irrigation water and fertilizer use (when the irrigation season begins), limit irrigation tailwater volumes and concentrations of nitrates, and limit potential impact of fertilizers in the irrigation water on surface and ground water quality. • 117226.E02/STO12R0696 Page 9 of 43 September 14, 2012 Copyright 2012 Kleinfelder