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Details for Benchmark: HT2525

N 37° 46.914 W 122° 09.570 (NAD 83)

Altitude: 1088

Coordinates may not be exact. Altitude is VERTCON and location is ADJUSTED. (more info)

Location:
In ALAMEDA county, CA View Original Datasheet
Designation:
MILLS
Marker Type:
NGS Benchmark
Setting:
setting not listed - see description
Stability:

Reference Points

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Documented History (by the NGS)

01/01/1947 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1947 (SPH) THE STATION IS ON THE SUMMIT OF A BARE, PROMINENT HILL, ABOUT 1100 FEET HIGH, WHICH IS LOCATED ABOUT 1-1/2 MILES EAST OF MILLS COLLEGE IN OAKLAND AND 1 MILE NORTH OF OAK KNOLLS NAVAL HOSPITAL. IT IS ON THE SUMMIT OF THE SAME HILL AS THE U.S. COAST AND GEODETIC SURVEY STATION MILLS 1929, WHICH IS ON THE SOUTH SLOPE, ABOUT 150 METERS DISTANT 20 FEET LOWER IN ELEVATION. THE STATION MARK, STAMPED MILLS 1947, IS A STANDARD EAST BAY MUNICIPAL UTILITY DISTRICT DISK SET IN A 12 INCH SQUARE CONCRETE POST PROJECTING 6 INCHES ABOVE THE SURFACE OF THE GROUND. IT IS ON THE FLAT SUMMIT OF THE HILL, ABOUT 150 YARDS SOUTH OF AN EAST-WEST FENCE LINE, 28.4 METERS WEST OF THE CENTER OF A FIRE BREAK ROAD, AND 1-1/2 METERS SOUTHWEST OF A WHITE WITNESS POST. REFERENCE MARK NO. 1, STAMPED MILLS EBMUD NO 1 1947, IS A STANDARD USC AND GS DISK SET IN A 12 INCH SQUARE CONCRETE POST PROJECTING 4 INCHES ABOVE THE SURFACE OF THE GROUND. IT IS ON THE FLAT SUMMIT OF THE HILL AT THE SAME ELEVATION AS THE STATION MARK AND 20 METERS WEST OF THE FIRE BREAK ROAD. REFERENCE MARK NO. 2, STAMPED MILLS EBMUD NO 2 1947, IS A STANDARD USC AND GS DISK SET IN A 12 INCH SQUARE CONCRETE POST PROJECTING 1 INCH ABOVE THE SURFACE OF THE GROUND. IT IS ABOUT 30 METERS WEST OF THE FIRE BREAK ROAD AND 1 FOOT LOWER THAN THE STATION MARK. STATION BEACON SA EBMUD, ABOUT 1 MILE EAST NORTHEAST, WILL SERVE AS THE AZIMUTH MARK. IT IS ABOUT 0.2 MILE WESTERLY OF THE AIRWAY BEACON ON THE SAME HILL. TO REACH THE STATION FROM THE JUNCTION OF MC ARTHUR BOULEVARD AND SEMINARY AVENUE, WHICH IS AT THE SOUTHEAST SIDE OF MILLS COLLEGE IN THE EAST PART OF OAKLAND, GO EASTERLY ON SEMINARY AVENUE AND THENCE MOUNTAIN ROAD FOR 1.8 MILES TO A NARROW, GRAVEL SIDE ROAD ON LEFT, ABOUT 50 YARDS AFTER PASSING THE UPPER SAN LEANDRO FILTER PLANT ON THE RIGHT AND 50 YARDS BEFORE ARRIVING AT KELLER AVENUE. TURN LEFT AND FOLLOW THE NARROW ROAD NORTH AND EAST FOR 0.15 MILE TO A BOARD GATE. PASS THROUGH THE GATE AND CONTINUE ON THE MAIN ROAD OVER RIDGE AND UP VALLEY FOR 1.2 MILES TO ANOTHER GATE. PASS THROUGH THE GATE AND CONTINUE 0.2 MILE TO A SIDE ROAD ON THE RIGHT. CONTINUE ON LEFT FORK, STRAIGHT AHEAD, FOR 0.15 MILE TO A FORK. TAKE THE LEFT FORK AND CONTINUE 0.05 MILE TO A FORK. AGAIN TAKE THE LEFT FORK AND CONTINUE 0.4 MILE TO THE J.O. RANCH CORRALS AND HOUSE ON LEFT. CONTINUE ON UP HILL ON THE MAIN ROAD FOR 0.4 MILE TO A T INTERSECTION ON TOP OF THE RIDGE. TURN RIGHT ON ROAD ALONG FENCE FOR 0.25 MILE TO A GATE ON THE LEFT. TURN LEFT THROUGH GATE AND GO 0.05 MILE TO A REVERSE Y FORK. THENCE MAKE A U TURN TO THE RIGHT AND FOLLOW THE ROAD UP HILL FOR 0.15 MILE TO THE HIGHEST POINT AND THE STATION SITE ON THE LEFT. STATION MILLS 1929, WHICH WAS TIED IN BY DISTANCE AND DIRECTION TO THE STATION, IS ON THE SOUTH SLOPE OF THE SAME HILL AS THE STATION. THE MARK, STAMPED MILLS 1929, IS A STANDARD DISK SET IN AN OUTCROP, 6 FEET BY 2-1/2 FEET, PROJECTING 18 INCHES ABOVE THE GROUND. IT IS ABOUT 0.1 MILE FROM THE STATION, 23 METERS SOUTH OF A CURVE IN THE ROAD JUST BEFORE IT REACHES THE SUMMIT, AND ABOUT 30 FEET LOWER THAN THE SUMMIT OF THE HILL. IT IS ON THE FLAT RIDGE TO THE NORTHEAST OF THE HUGE QUARRY BELOW, AND 13 METERS WEST OF A DROP OFF INTO A SHALLOW DRAW.
01/01/1964 by CGS (MONUMENTED)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1964 (EHS) THE STATION MARK AND REFERENCE MARK NUMBER 1 WERE RECOVERED IN GOOD CONDITION. REFERENCE MARK NUMBER 2 HAS BEEN DESTROYED BY CONSTRUCTION OF NEARBY QUARRY ROAD SO REFERENCE MARK NUMBER 3 WAS SET ON THIS DATE. THE 1947 DESCRIPTION IS ADEQUATE WITH THE FOLLOWING ADDITIONS ALTHOUGH THE ROUTE TO REACH THE STATION IS UNDERGOING CHANGES BECAUSE OF THE QUARRYING OPERATIONS NOW IN PROGRESS. THE STATION MARK IS 6.6 FEET SOUTHWEST OF A WOODEN WITNESS POST AND 6 FEET NORTHEAST OF THE TOP EDGE OF A CUT BANK ON THE NORTHEAST SIDE OF A NEW QUARRY ROAD. REFERENCE MARK NUMBER 1 IS 17 FEET NORTHEAST OF THE TOP EDGE OF THE CUT BANK AND ABOUT 6 INCHES HIGHER THAN THE STATION MARK. REFERENCE MARK NUMBER 3 IS A COAST AND GEODETIC SURVEY REFERENCE MARK DISK STAMPED MILLS EBMUD NO 3 1947 SET IN THE TOP OF A 10-INCH CONCRETE CYLINDER THAT PROJECTS 5 INCHES ABOVE THE GROUND AND IS ABOUT 8 INCHES HIGHER THAN THE STATION MARK.
01/01/1970 by NGS (MONUMENTED)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1970 (LS) THE STATION MARK AND REFERENCE MARKS 1 AND 3 WERE DESTROYED WHEN THEY AND THE GROUND AROUND THEM SLID DOWN THE HILL AND WERE COVERED BY A LARGE AMOUNT OF DIRT AT THE BOTTOM OF THE HILL IN A LARGE EARTH SLIDE IN FEBRUARY 1970. AIRLINE DISTANCE AND DIRECTION FROM NEAREST TOWN--1-1/2 MILES EAST OF MILLS COLLEGE IN OAKLAND

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in March 1994. The horizontal coordinates are valid at the epoch date displayed above. The epoch date for horizontal control is a decimal equivalence of Year/Month/Day.
  • The NAVD 88 height was computed by applying the VERTCON shift value to the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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