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Chaucer-CS 970905 POND SILTATION STUDY CHAUCER ESTATES HEARTZ ROAD AND PARK VALLEY DRIVE COPPELL, TEXAS Patton, Burke & Thompson Engineering Consultants ~.~......:_~ September 4, 1997 10555 Ilev:kirk Street Suite 530 Dallas Texas 75220 972.831 .i 11 1 255 Parkway Blvd. P.O. Box 478 Coppell, Texas 75019 Attn: Mr. Kenneth M. Grifi.m, P.E. Assistant City Manager City Engineer Re: Pond Siltation Study Chaucer Estates Heartz Road and Park Valley Drive Coppell, Texas PBT Project No. 1222 Dear Mr. Ca/fi.m: Patton, Burke & Thompson (PBT) has completed the pond siltation study for the above referenced project, and hereby submits three (3) copies of our letter report. This assignment was carded out in general accordance with our proposal dated July 21, 1997. This study is in addition to the work previously performed in late-1995 (i.e., PBT reports dated November 2 and 30, 1995). PROJECT CHARACTERISTICS The pond is located in the Chaucer Estates subdivision, southwest of the intersection of Heartz Road and Parkway Drive, and immediately south of the library (see Figure 1) in Coppell, Texas. We understand that the subject pond is privately owned by the Chaucer Estates homeowners and is approximately I to 1-1/2 acres in plan and was originally constructed approximately 10-feet deep. The pond was constructed 5-years back with a normal pool elevation of 460-feet and reportedly had an original bottom elevation of 450-feet. Apparently the pond was reported to have signs of siltation, due Patton, Burke & Thompson Engineering Consultants · Pond Siltation Study Coppell, Texas Page 2 to the drainage culverts draining storm water into the pond. The purpose of this study was to provide updated geotechnical subsurface information, specifically the depth of pond water, sediment and pond bottom, to assist the City in quantifying the extent and nature of the siltation. FIELD INVESTIGATION Four (4) probes, P-l, P-2, P-3 and P-4 were made with a 2-man crew in a 18-foot flat bottomed work boat using a 1.5-inch inside diameter PVC pipe. Locations of the probes were approximately at the previous 1995 probe locations and are shown on the Sampling Location Plan, Figure 1. Representative samples of the bottom materials were obtained by using a 1.5-inch 'inside diameter, clear PVC pipe. The pipe was initially pushed by hand into the pond bottom and upon encountering the natural clay (weathered shale) stratum (interpreted as the original pond bottom), was driven using a 20- pound hammer. The PVC pipe was then retrieved slowly and the bottom portion of the pipe, with the sediments, portion of the natural clays and some water, was sawed off and the top and bottom capped, marked and sealed. Four (4) PVC samples were then transported to PBT's laboratory for laboratory testing and analysis. The samples were stored in a secluded area to allow the sediments to settle before conducting any laboratory tests. This also helped to fmalize the depth of water, sediment and pond bottom. Logs of all probes showing visual descriptions of bottom materials encountered are included in Figures 2 thru 5. Sampling information, pertinent field data, and field observations are also included. LABORATORY ANALYSIS The laboratory testing program was directed toward evaluating the physical characteristics and determining the depths of the water, sediments and clay encountered at the site. Laboratory analysis of all sediment and soil samples included visual classification, and moisture content, dry density and sieve analysis tests. [Note: The probe P-1 sample was given unopened to the City.] Results of laboratory Patton, Burke & Thompson Engineering Consultants Pond Siltation Study Coppell, Texas Page 3 testing are presented on the Logs of Probes, Figures 2 thru 5. SUBSURFACE CONDITIONS The four (4) probes conducted for this study indicate that the siltation conditions do exist across the pond. In general, the bottom conditions consists of sediments at depth intervals below the pond water surface (on the sampling day of August 14, 1997) of 2.4 to 3.0-feet, 10.0 to 12.3-feet, 8.6 to 9.5-feet and 5.8 to 6.8-feet in probes P-l, P-2, P-3 and P4, respectively. Dark gray clay was encountered in the probes at depths of 3, 12.3, 9.5 and 6.8-feet in probes P-l, P-2, P-3 and P4, respectively. An attempt was made in the laboratory to make volumetric measurements of the sampling tube to estimate the density of the sediments above the clay in probe samples P-2, P-3 and P-4. The results indicated dry densities between 31 and 53 pcfwith water contents between 82 and 159 percent. At best this data indicates, as would be expected, that the sediments are extremely loose and super saturated. The dry density of the natural clay was 100 pcf at a water content of 22 percent. Sieve analysis tests indicted that coarser (heavier) particles were found near the bottom of the PVC sampling pipe, immediately over the natural clays, and finer (lighter) particles were found near the top and middle portion of the tube. The sieve analysis for the sediments indicated 58 to 68 percent fmcs (passing the No. 200 sieve) and for the clay soil it varied between 61 and 64 percent. Further details concerning the subsurface materials and conditions encountered are shown on the Logs of Probes. The stratification lines shown on the Logs of Probes represent only approximate locations of changes between sediment and water, as indicated by the field sampling methods used. SUMMARY OF FINDINGS The following summary has been developed based on the laboratory testing and materials encountered in the test probes, and the numbers in the bracket indicate the measurements conducted during the previous 1995 study: Pat~on, Burke & Thompso~ Engineering Consultants Pond Siltation Study Coppell, Texas Page 4 P-1 2.4 (8.5) 7.5 (11) 7.6 (13) P-2 10.0 (10.0) 27 (12 to 14) 29 (14.75) P-3 8.6 (9.7) 11 (24 to 27) 15 (0) P4 5.8 (5.0) 12.5 (32) 17.5 (32) LIMITATIONS The findings and recommendations presented in this report are based on the assumption that the depth of sediments do not vary appreciably from those encountered at the probes. The depth of sediments presented in this report does not constitute a direct or implied warranty that the sediments depth at the probe locations can be directly interpolated or extrapolated. Amount of sediments which are different from those disclosed by the probes may be found at other locations in the pond. Patton, Burke & Thompson has prepared this report to aid in the evaluation of the site and to assist in evaluation of the amount of siltation. We have developed our summary in accordance with generally accepted professional geotechnical engineering principles and practices. We make no other warranty either express or implied. Environmental issues regarding this site are not addressed in this study. Only geotechnical recommendations for use in determining the depth of pond water, sediment and pond bottom are presented herein. Patton, Burke & Thompson Engineering Consultants Pond Siltation Study Coppell, Texas Page 5 Our finn appreciates the oppommity to be of professional service to you. We would be pleased to discuss any questions which may arise concerning this report. If we can be of further assistance, please contact us at your convenience. Respectfiflly submitted, PATTON, BURKE & THOMPSON Sd Dinkaran Dis~ibution: (3) City of Coppell P~tton, Burke & Thompson Engineering Consultants Parkway Blvd. /--'-' ,',' Site I . Vicinity Mop (No! t'o scole) P-1 e P-2 o /~ Outlet C3 Drainag~_~ Pipes L Note: Drawing not to scale · indicates approximate location of exploratory probe for this study which was close to the previous 1995 locations. This plan was taken from sheet 2 of 2, "Offsite Drainage & Lake Plan", Dated September 1991, prepared SAMPLING LOCATION PLAN by Dan M. Dowdey & Associates. POND SILTATION STUDY CHAUCER ESTATES Job No. 1222 Coppell, Texas Patton, Burke & Thompson Figure 1 LOG OF PROBE NO. P- CLIENT: City Of Coppell LOCATION: Coppell, Texas JOB NAME: Chaucer Estates Pond RIG TYPE: 18' Work Boat DRILUNG CONTRACTOR: GeD-Marine, Inc. LOGGED BY: SD SURFACE CONDITIONS: Water DATE DRILLED: 08114197 WATER ELEVATION: NA JOB NO.: 1222 PAGE I OF 1 FIELD DATA LABORATORY DATA DRILLING METHOD(S}: The 1.5" I.D. PVC pipe was hand pushed and driven with · 20 lb hammer. ~ ~. GROUNDWATER INFORMATION: C~ "=' ~ !:'. ~ ~_ ~ ~ SAMPLE TYPE ~ Z ZI- ~ ~ ~uJ--;4 Z ~ ~. -- Z~ HP PVC Tube RC Rock Core SS Split Spoon _ ~,,., ~= ..z. o CTCu, .0. TCT.DCo., ~ ~. ........ o ~ GEOTECHNICAL DESCRIPTION WATER 7.5' BOTI'OM SEDIMENTS, from 2.4 to 3' S1 2.4-3.0 HP Recovery ' S2 3.0-3.1 HP 0.1 ' CLAY, sandy, dark gray Recovery Probe was terminated at a depth of 3.1' below the top of water - 5 - - 10- N - STANDARD PENETRATION TEST RESISTANCE REMARKS: The second (2) attempt to obtain a sample was FIELD T - THD CONE PENETRATION RESISTANCE P - POCKET PENETRATION RESISTANCE successful at this location. A sealed sample was given to the TEST R - PERCENTAGE OF ROCK CORE RECOVERY City. RQD- ROCK OUALITY DESIGNATION Patton, Burke & Thompson Figure - 2 LOG OF PROBE NO. P- CLIENT: City Of Coppell LOCATION: Coppell, Texas JOB NAME: Chaucer Estates Pond RIG TYPE: 18' Work Boat DRILUNG CONTRACTOR: GeD-Marine, Inc. LOGGED BY: SD SURFACE CONDITIONS: Water DATE DRILLED: 08/14/97 WATER ELEVATION: NA JOB NO.: 1222 PAGE I OF 1 FIELD DATA LABORATORY DATA DRILLING METHOD(S): The 1.5' PVC pipe was hand pushed and driven with a 20 lb hammer. ~ ~, GROUNDWATER INFORMATION: ;¢ ~ ~ IT, O ~ ~ ~ SAMPLE TYPE C~ ~. m ~ - ~= - ~ z~ g HP PVC Tube RC Rock Core SS Split Spoon WATER -5- - 10 - BO'Fi'OM SEDIMENTS, from 10 to 12.3' - S1 10.0-12.3 HP 27' 82 53 68 Recovery S2 12.3-12.5 HP 2' CLAY, sandy, dark gray Recovery Probe was terminated at a depth of 12.5' below the top of water N - STANDARD PENETRATION TEST RESISTANCE REMARKS: The eighth (8) attempt to obtain a sample was FIELD T - THD CONE PENETRATION RESISTANCE P. POCKET PENETRATION RESISTANCE successful at this location. TEST a - PERCENTAGE OF ROCK CORE RECOVERY ROD- ROCK QUALITY DESIGNATION Patton, Burke & Thompson Figure - 3 LOG OF PROBE NO. P- CUENT: City Of Coppell LOCATION: Coppell, Texas JOB NAME: Chaucer Estates Pond RIG TYPE: 18' Work Boat DRILLING CONTRACTOR: Geo-Marine, Inc. LOGGED BY: SD SURFACE CONDITIONS: Water DATE DRILLED: 08114/97 WATER ELEVATION: NA JOB NO.: 1222 PAGE 1 OF 1 FIELD DATA LABORATORY DATA DRILLING METHOD(S): The 1.5" I.D. PVC pipe was hand pushed and driven with a 20 lb hammer. ~ ~g GROUNDWATER INFORMATION: d ~ .1~ 1~, k- - SAMPLE TYPE _ ~ ~_~ ~ ~ _ o~ ~ PVC Tu~. RC .o~k Co. SS Sp~.t Spoon 2: O, 0 = =: ~ g ¢3 ~ ~ CT Cuttings TC THD Cone CS Califoml. Spoon i < "' ~:~'E~O ~ ~ ~ ~ -~ [ GEOTECHNICALDESCRIPTION WATER -6-- 11 · BOTI'OM SEDIMENTS, from 8.6 to 9.5' ' Sl 8.6-9.5 HP 159 31 58 Recovery S2 9.5-9.8 HP 4' 22 100 61 CI ~Y, sandy, dark gray - 10 - Recovery Probe was terminated at a depth of 9.8' below the top of water N - STANDARD PENETRATION TEST RESISTANCE REMARKS: The f'=st {1) attempt to obtain a sample was FIELD T. THD CONE PENETRATION RESISTANCE P - POCKET PENETRATION RESISTANCE auccessful at this location. TEST R - PERCENTAGE OF ROCK CORE RECOVERY RQD- ROCK QUALITY DESIGNATION Patton, Burke & Thompson Figure* 4 LO(:} OF PROBE NO. P CUENT: City Of Coppell LOCATION: Coppell, Texas JOB NAME: Chaucer Estatee Pond RIQ TYPE: 18' Work Boat DRILUNQ CONTRACTOR: Geo-Marine, Inc. LOQGED BY: SD SURFACE CONDITIONS: Water DATE DRILLED: 08/14/97 WATER ELEVATION: NA JOB NO.: 1222 PAGE I OF 1 FIELD DATA LABORATORY DATA DRILMNG METHOD(S): The 1.5" PVC pipe was hand pushed and driven with I 20 lb hammer. ~ ~ GROUNDWATER INFORMATION: d mm ~ ~'' IT, ~_ ~ ~ =_z ~ SAMPLE TYPE Z I- ~ ~ m Z ~ -- -- O~ HP PVC Tube RC Rock Core SS Split Spoon Q ~ ~ CT Cuttings TC THD Cone CS California Spoon c~ , ¢= z ~: 4',' cc z .... ~ GEOTECHNICAL DESCRIPTION WATER - 5 - 12.5' BOTFOM SEDIMENTS, from 5.8 to 6.8' S1 6.8-6.8 HP 100 41 67 Recovery - S2 6.8-7.2 HP 5' 22 100 64 CLAY, sandy, dark gray I~ecovery Probe was terminated at a depth of 7.2' below the top of water. -10- N - STANDARD PENETRATION TEST RESISTANCE REMARKS: The first (1) attempt to obtain a sample was FIELD T - THD CONE PENETRATION RESISTANCE P - POCKET PENETRATION RESISTANCE successful at this location. TEST R - PERCENTAGE OF ROCK CORE RECOVERY RQD- ROCK QUALITY DESIGNATION Patton, Burke & Thompson Figure - 5