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• �� - A Professional Corporation <br /> • - - s 900 "H" ST., SUITE G • R O. BOX 816 • MODESTO, CA 95353 <br /> (209) 526-4214 • FAX (209) 526-0803 <br /> January 24, 1989 <br /> Sa <br /> -1 <br /> yt <br /> San Joaquin County <br /> Department of Public Works <br /> 1810 East Hazelton C`' N < �' °j <br /> Stockton, California 95205 *E 2 M Y <br /> C <br /> Attention: Gabe Karam <br /> Dear, Sir: m Tt <br /> As you ane aware, we are experiencing a fluctuation in the elevation <br /> of the water; table at Hempstead Court Subdivision during the construction <br /> of the subdivision 's improvements. The Soils Engineer's original investigations <br /> of groundwater, in the subdivision resulted in establishing the ground water <br /> table at approximately ELEV. 63.5 (8 ' - 10' depths from the surface) . <br /> Later. borings verified these depths with the exceptions that the water. <br /> level "rose" in two' (2) test holes from ELEV. 62.5 to ELEV. 65.5 (9' deep <br /> to 6 ' deep) . This was explained by the Soils Engineer as a temporary <br /> stabilization of the water table. Later,, on December, 29, ' 1988, high groundwater, <br /> was encountered by the Contractor, D.S.S. , in the western end of the retention <br /> basin bottom. The Soils Engineer, monitored the groundwater, elevations <br /> between December, 29, 1988, and January 11 , 1989, and found that it quickly <br /> subsided to ELEV. 62.5 and stablized below ELEV. 63.5 once the heavy rains <br /> stopped. On January 20, 1989, D.S.S. dug four. (4) "test pits" at the bottom <br /> of the retention pond and encountered free water,. The water. surface elevations <br /> were checked on January 24, 1989, and were found to be at different elevations, <br /> higher than those found by the Soils Engineer. This situation is curr:enly <br /> being examined by the Soil 's Engineer,. <br /> In reviewing the design of the pond, we have -determined that the bottom <br /> elevation can be raised to ELEV. 68.65 (3.15 ' above the highest temporary <br /> water level encountered by the Soils Engineer, of ELEV. 65.5) . This can <br /> be accomplished by installing the 2.85' high cut slopes at 3:1 slopes rather <br /> than the 5:1 slopes. We feel that this configuration will still be accessible <br /> and easily maintainable for the County Sbr;vi ce Area and wi 11 al 1 ow us to <br /> raise the bottom of the basin by 2.15 ' . <br /> Please review the attached sketch and calculations and consider this <br /> request to change the approved plans at your. •ear.liest convenience. <br /> Sincerely, <br /> MID-VALLEY ENGINEERING, INC. <br /> By <br /> Al Toschi <br /> AI./pcl <br /> Enclosure <br /> - _ ..BOY. A._GAL!_C,_F. R0RFRT R _,8 A0 N_•..DFNNIS F. WILSON.-- <br />