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Brighton Manor-SY040712~ul 28 04 08:4Ga DOWDEY.AMDERSOM&ASSOC. IMC (9721931 6787 GROUNDWATER INVESTIGATION FOR BRIGHTON MANOR (FALLS @ WESTMONT) MACARTHUR BOULEVARD AND SAMUEL BOULEVARD COPPELL, TEXAS REPORT NO. S-104-0172 REPORT to STREET CUSTOM HOMES COPPELL, TEXAS by GEE CONSULTANTS, INC. GEOTECHNICAL, CONSTRUCTION MATERIALS AND ENVIRONMENTAL CONSULTANTS DALLAS, TEXAS July 12, 2004 Jul ~8 04 08:4Sa DOSJDEY. RHDERSOH&RSSOC. XHC {97;J]93! 8787 I:.4 · GEOTECHNICAL ENGINEERING · ENVIRONMENTAL CONSULTING · CONSTRUCTION MATERIALS TESTING GEE Consultants, inc. 10046 Monroe Drive Dallas, lexas 75229 July 12, 2004 Street Custom Homes c/o Mr. Rodney Louvicrc Dowdey, Anderson & Associates. Inc. 5225 Village Creek Drive, #200 Piano, Texas 75093 RE: Report No. S-104-0172 Groundwater Investigation Brighton Manor (Falls @ Westmont) MacArthur Boulevard and Samuel Boulewtrd Coppell, Texas (214) 352-5433 Fax (214) 352-6972 Dear Mr. Louviere: This report transmits th~ lindings of the~groundwater investigation performed at the above referenced location. ~lhe objective of"i~is i~ion was to determine the general strangraphy of tile subsurface formations and groundwater present at the boring location. Results of the field program were analyzed to provide engineering rccommendalions for surthce groundwater removal as requested. This study consisted of drilling one,,~exploratory hand auger boring to explore the subsurface ctmditions. The location of this test boring~d on the P/an c~'Bodng included in the Appendix of this report. Jul 28 04 08:47a DOWDEY.R~DE~SO~RSSOC, IMC (872(831 6787 Street July 12. 2004 I. Site Location and Observations The groundwater investigation concentrated on the area located between Lots 8 and 9, Block B, of Brighton Manor (The Falls at Westmont) in Coppell, Texas, The regional topographic gradient in the area of Lots 8 and 9, Block B, was gently sloping downward toward the northeast toward Denton Creek. At the time of our site investigation, surface groundwater was noted flowing along a swale between Lots 8 and 9, Block B, in an east-southeast direction toward Duncan Drive. Upon exiting the swale at the road cut for future Duncan Drive, the surface groundwater flowed in a northerly direction along the east property line of Lot 8, Block B, During current field operations, flowing groundwater was noted at a depth of approximately ouc (i.0) foot below existing grade after a small excavation was made along the side of the swale using a hm~d held shovel. 1I. Field Exploration Thc subsurface exploration consisted of one (1)..~, er boring drilled on June 4, 2004 to a depth of four (4.0) feet. The boring was advanced at ~e approximate location shown on the Plan of Boring included herein. p.5 IlL Subsurface Soil Description The subsurface materials encountered at the test boring locations consisted of clayey sands with large gravel. The clayey sands and gravel were very loose. Auger refusal was encountered at a depth of four (4.0) feet at what was opined to be shale. Detailed descriptions of the various strata encountered are p~csented Oll the individual Log of Bm'i,g in lhe Appendix of this report. [V. Subsurface Water Conditions At the time of field exploration, groundwater or seepage was encountered at a depth of one (l.0~foot at the hand auger boring. The subsurface water regime is subject to change with variations in climatic conditions. If there is a noticeable change from the conditions repot(ed herein, GEE Consultants, inc. should immediately be notified to review the el'feet it may have on the enclosed analysis and recommendations. It is not possible to accurately predict the magnitude of subsurface water fluctuations that mighl occur based upon short-tm~m observations. GEE Consultants, Inc. Report No. S-104-0172 Page 2 04 08:47a DOWDEY.RMDERSOM&RSSOC. IMC ~97~J931 8787 Street CIz~;tom Home~ July 12. 2004 V. Limitations The professional engineering services performed, findings obtained, and recommendations prepared were accomplished in accordance with currently accepted geotechnical engineering principles and practices. The possibility always exists that the subsurface conditions at the site may vary from those enconntered at the borehole. If there are any unusual conditions differing significantly from those described herein, GEE Consnltants, Inc. should inunediately be notified to determine thc effects on the performance of the designed surface groundwater removal system. The recommendations given in this report were prepared exclusively for the use of Street Custom Homes and/or their consultants. The information supplied herein is applicable only for thc design of the surtgce groundwater removal system. This information should not be used for any other purpose. GEE Consnltants, Inc. is not responsible for the conclusions, opinions, or recommendations made by others based on this information. Also, this firm is not responsible for danaages caused by the workmanship of the contractors. The quality of all phases of the consu'uction of the proposed surface groundwater removal system should be checked by qualified persomlel to insure that the work is done in the field in accordance with the accepted plans and spccifications. VI, Analysis and Recommendations A. Groundwater Observations Analysis ,\s previously discussed, tile regional topo~aphic gradient is sloping downward to the northeast. Lo,.~sts 8 and 9 of Block B, are located in northeast portion of the site. It is not anconunon to note shallow groundwater itl the lower areas of a site. Shale was noted at shallow depths at numerous locations in the original geotechnicat investigation. Based oil the current auger boring, the shale is believed to be at a depth of tour (4.0) ~Eet between Lots 8 and 9 of Block B. Overburden soils encountered at the current boring location fi'om the sm'face to tile top of the shale consisted of highly permeable loosc clayey sand and gravel. It is our opinion that shallow water is being trapped on top of the shale formation. The groundwater is Oran traveling horizontally through the highly permeable clayey sand and gravel to the nearest point of relief. ~dwater was encountered at only one (1) boring location at eight ~ dmSng the original geotechnical in~esugation (July, 2003), the appearance of shallow groundwater may occur only on an intermittent or seasonal basis and at limited locations. Prior to advancing the current test boring, total rainfall for year 2004 was well above average. GEE Consultants, Inc. Report No. S.104-0172 Page 3 Jul 28 DOWDEY.RMOERSOM&RSSOC. IMC Street Custom Homg?i July 12. 2004 B. Surface Groundwater Removal System To improve the drainage 'along the swale between Lots 8 and 9, Block B, we recomntend the upper three (3.0) feet of soil along the swale be removed. A six (6) inch diameter slotted PVC or perforated pipe should be placed along the bottom of the excavation. The removed soil should then be replaced wRb three-fourths (3/4) inch to one (1) inch crushed stone to a depth of twelve (12) inches below final grade. The crushed stone should surround the six (6) inch pipe. The crushed stone will do a better job of supporting surface loads than thc current wet clayey sand. The pipe should consist ora six (6) inch diameter slotted PVC or perlbrated pipe surrounded by four (4) to six (6) inches of three-fourths (3/4) inch to one ( 1 ) inch crushed stone cover. The crushed stone should be placed over, under and around the pipe. A filter fabric material should be wrapped around the crushed stone and pipe. All fabric laps should be a mi.imum of six (6) inches. The closure (fabric overlap) should be stitched at minimum intervals of five (5.0) feet. The installatiou of at least two (2) clean-outs is recommended to keep the system free of debris and functioning properly. The pipe should be sloped to drain downward at a minimum fall of one (1) inch per ten dO.O) feet. The remaining upper twelve (12) inches of near surface backfill should consist of a clay cap. Clay cap material should have a minimum plasticity index of twenty-five (25) and be compacted to a minimum of ninety-five (95) percent of the maximum density as detcrlnined by ASTM D 698. Based upon the current grading plan, the swale between Lots 8 and 9, Block B slopes downward toward the east-southeast at a fall of approximately one (I) inch lb~ every eight (8.0) f¢ct. It is recommended that the groundwater collected by the drain pipe be allowed to accumulate in a sump pump and pumped through the proposed curb onto Duncan Drive concrete pavement, This would tend to improve the capture of groundwater traveling downhill and lower the water table. Thc proposed drainage system pipe location is indicated on the ?lat~ o,/'Boring, If shallow grot}ndwater continues to be prevalent after installation of the swale drainage system described above, consideration should also be given to expanding tile drain line along the rear (west) side of Lot 9, Block It. Due to thc cmTent level of groundwater noted along the swale, the potential exists for groundwater to be present in adjacent lot residemial slab grade beam excavations. If groundwater is present in grade beam excavations, structural loads may need to be supported using pier foundation systems. Expanding drain lines along the rear of Lot 9 and possibly Lot 8, Block B, GEE Consultants, Inc. p.? Report No. S-104-0172 Page 4 I I I i ] ! i i I i 04 08:48~ OOWDEY.RMDERSOM&RSSOC. IRC ~9721931-~787 Street Cmtom H~mes .lulv 12. 2004 will help reduce the potential for ~oundwater being present in grade beam excavations. In lieu of a sump pump collection system, consideration could be given to a solid drain pipe that travels from the end of the swale between Lots 8 and 9, Block B, downward to the north-northeast via the existing easement along Duncan Drive. The drain pipe would connect to the storm drain inlet located along the south side of Hood Drive, adjacent to the eyebrow cul-de-sac near the intersection of Hood Drive and Duncan Drive. If shallow groundwater is encountered at any locations in Lots 7 and 8 of Block B, drainage sw~e drain systems could be added and connected into the solid pipe and ultimately the storm drain system. Both the solid pipe gravity outtall system and/or the sump pump collection system will need dcsign input from thc Civil Engineer and approval from the City of Coppell. Additional Recommendations and Discussion To reduce potential for wet spots, we recommend ground cover or grass be planted in current areas of wet spots and standing water. Vegetation will promote transpiration and provide a better living surface for residents. From up s~ope adjacent propellies, water should be prevented I¥om draining into the area. This will reduce the potential for wct spots and standing water on the subject site. If water is pumped onto concrete pavement by way of a sump pump, the potential for pavement distress due to water infiltrating cracks and pavement joints increases. Joints and cracks should be properly scaled as required. Drain construction should be completed at least three (3) months prior to any foundation construction. This will reduce the potential for subgrade shrinkage and groundwater beneath the foundation. To ensure that the recommendations contained in this report are properly implemented, we reconunend periodic inspections be conducted during drain construction. Additionally, we recommend confirmation of all materials to be used prior to construction. It should be understood that groundwater levels and moisture are highly variable and tricky. No guarantee or wmTanty is implied that the recommendations outlined above will correct conditions observed, or that p.8 GEE Consultants, Inc. Report No. S-104-0172 Page 5 Jul ~8 O4 08:48a DO~DEY.RMDERSOM&SSSOC. IMC ( 872 ) 931 -S787 p . 9 Street Custom Hom~ ./ulv 12. detrimental conditions may not occur in the future. Our recommendations should be reviewed by your Civil and Structural Engineer. We appreciate the opportunity to be of service to you on this project. We will be happy to discuss any questions you may have concerning this report. We look forward to serving you in the future. Very truly yours, GEE Consultants, Inc. ,, E,i.T. Division Manager Geotechnical Engineering Division AJ A:RWG/js Attachments GEE Consultants, Inc. Report No. S-104-0172 Page 6 3~1 28 04 08:48a DOWOE¥.BMDE~SOM&~SSOC. I~C ~972~931-6787 p. 10 o~ ~ 0 .~ m< MACARTHUR l~O ULE VAig, D HOOD DRIVE / Jul 28 04 08:48a DO~DEY.RHDERSO~&RSSOC. I~C (972)~31-6787 p. 11 Log of_Boring_ _ Location a-1 SEE PLAN OF BORING _i ?RO~UNOW~ ~TER INVESTiGATiON, BRIGHTON MANOR, MACARTHUR BLVD., COPPELL, TEXAS I. ~ L-___ CONTINUOUS AUG~R , -ho e caved in from 1.Y to 4.0* ~ -ve~ hard (auger re~sal) ~ 4.0 S-104-0172 Page I of1 ompletion ~p'pth ' 4.0' Date j Water Observations __ 6/4/2004 WATER ENCOUNTERED ~ 1.0,: GEE Cnna,,~t..~ ~