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HomeMy WebLinkAboutTract Map 20591 Lot 9 Rancho Baptist Church Soils Report Fp11- 0183 Lawrence R.Phelps,PE Civil a Structural Engineering 91 Lawrence R. Phelps, RCE 35280, Calif. Lic. Renewal 9/30/2011 31130 Avenida Del Reposo - Temecula, California 92591 Phone (951)694-6336 - Fax (951) 694-6326 Soil Type and Permeability Report Rancho Baptist Church (Sanctuary Addition) 29775 Santiago Road, Temecula, Ca. 92592 County of Riverside Total Parcel Area: 4.04 acres net APN: 922-130-017 Prepared For: Owners: Rancho Baptist Church 29775 Santiago Road Temecula, California 92592 (951) 676-2911 Attn: Pastor Lew Dawson (951) 551-1797 Project Site• 29775 Santiago Road Temecula, California 92592 Riverside County Date off:eld testing: May 16, 2011 Date of report: May 19, 2011 / Soil Type & Permeability Report. May 19, 2011 Parcel 4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road, Temecula, Ca. 92592 APN: 922-130-017 Page 1 To: City of Temecula Department of Public Works 41000 Main Street Temecula, Ca. 92590 Attn: Aldo Licitra, NPDES-Land Development (951) 308-6387 • (Fax)694-6475 Subject: Report of findings regarding type of soils encountered and permeability (soil percolation) rates in the area of project drainage for the purpose of designing water infiltration/filtration systems to be incorporated into'the on-site drainage and grading,plan for,the project. Also the site was investigated for the possibility of perched groundwater or impervious soil beneath,the proposed drainage discharge area. The permeabilitg_ofsoil and recommendalionsregardina-location depth and percolation rate for the design of said drainage facility of the-project site is the subiect of this report. Soil Testing date: 5/16/2011 Test performed by: Lcnvrence R. Phelps, P.E. Purpose of report: To summarize findings, state recommendations for permeability of soil for use in the design of the on-site drainage discharge including location and depth and stated rates of soil percolation established herein by field testing. Gentlemen, This office has been requested to prepare the following report describing the subsurface soil conditions, including possible groundwater, impervious materials that may exist within an unacceptable range from the proposed drainage discharge and state the soil permeability rates in areas which may be used for the treatment of on-site drainage into the ground (soil). Lawrence R. Phelps, RCE 35280, Calif. Lic. Renewal 913012011 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 Soil Type & Permeability Report May 19, 2011 r Parcel4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road, Temecula, Ca. 92592 ' APN: 922-130-017 Page 2 1.0 Summary of Testing: 1.1 One 12' deep exploratory trench was examined by the undersigned (see Site Map) in a local low area where water would overflow in the event of a major event or might be utilized for a sump location. This deep trench is cross-sectioned on page 4. 1.2 In addition to the deep trench, (8) permeability test locations were chosen to give a random.sample to all those close-to-the-surface locations where the drainage swale or surface runoff will discharge into relatively shallow trenches (see section A-A on Site Map). Note test pits 3-8, inclusive, are.in the area of the long'drainage Swale to be constructed in the gravel area southwest of the buildings and south of the cellular-towers. Test pits I & 2, which are shallow, are to determine the permeability rate north of the cellular towers since a some of the drainage will need to discharge into this location (approximately 25%of the drainage). In this area, excess runoff would flow into a culvert (west of the cell towers) which passes under the 1-15 freeway. 1.3 The tests were conducted at different depths as well (as in different locations). The depths varied from 10" to 48", since this is the depth range (and somewhat below)of the proposed' discharge basins and swales to accept the runoff.'The shallowest pits were dug only with a 6" diameter hand-held post hole digger. The deeper test holes were first dug with a.backhoe (by Veasey Backhoe, Temecula), then finished with the.bottom 12" dug with the hand-held post hole digger. 1.4 The tests were`conducted "in-situ" to get the natural absorption rates. In.one case (pit 1), a gopher hole was encountered, so this was abandoned and anew hole wasdug. Readings were taken down from a fixed reference point to get an accurate water level drop without regard to caving or siltation (which would alter soundings). The readings were read to the nearest 1/8." to determine a very accurate permeability rate. 1.5 The tests were conducted initially with a dry condition to determine the permeability of the soil at the first storm or drainage event of the season. Testing was conducted until each test location showed a consistent permeability rate over two consecutive readings. In all (8) test holes a total of approximately 28 gallons of water was consumed over a 15-45 minute period. Lawrence R. Phelps, RCE 35280, Calif. Lic. Renewal 913012011 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 Soil Type & Permeability Report May 19, 2011 Parcel 4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road, Temecula, Ca. 92592 APN: 922-130-017 Page 3 2.0 Summary of Results (Permeability Rates): 2.1 The results for the first few minutes indicated fast percolation rates as the soil was absorbing the water. This is to be expected with dry conditions. Some of the soils were consistent from beginning to end (Test pits 4 &.6). The permeability rates for these tested soils are between 6" to 7 ''/2" per hour. As the tests proceeded (15-40 min. in duration), the results settled down to be fairly consistent. All the permeability rates were between 6 inches per hour and 9 inches per hour, whether shallow (10") or deeper(4'). This is the permeability range of the absorption of water in the first minutes, up to about 45 minutes, of a storm event falling on relatively dry conditions. However, the soil was moist in the deep excavation below about 6'. (Testing did not take place at this level). 3.0 Site Topography/Surface Characteristics and Proposed Development: 3.1 Testing was conducted on the bare soil at the westerly side of the parcel (approx % acre) The site slopes very mildly(approximate 2% to the-south) in all of the tested area of pits 3-8, inclusive and the 12` exploratory trench. This area will be left cleared and not paved. It is presently used for overflow parking. It could be graveled and this would not alter the permeability of the soil beneath. In the area of test pits 1 & 2, the ground slopes at about 5% towards the culvertmentioned in section 1.2. 3.2 There is and will be no vegetation in the tested area. However, to the west, there are mature pine and eucalyptus trees lining the parcel boundary. There are no rock outcroppings anywhere on the parcel. 3.3 The terrain on thisportion of the parcel (where the drainage discharge is to take place) in the area of the testing is natural. No filling or cutting has or will take place in this area. The only minor exception is the small amount of backfill (less than 2') east of the cellular towers where there has been a 30" high retaining wall built to create the pad for the tower units. In this area, east of this backfilled wall, the proposal is only for a paved driveway to connect parking area together for better traffic circulation. This driveway will drain along the top of this retaining wall to the natural discharge locations and not be allowed to drain into the ground behind (east of) this wall. 3.4 All of the soils percolate well near the surface. The surface soils are light brown to tan silty sands and densely to moderately compacted. Water does not stand on the surface long. Laurence R. Phelps, RCE35280, Calif. Lic. Reneual9130120/1 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 Soil Type& Permeability Report May 19, 2011 Parcel 4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road, Temecula, Ca. 92592 APN:922-130-017 Page 4 4.0 Soil Types and General Geology: The surface soils to about 6' of depth in the area of the_proposed drainage,are consistently fine grained, light brown silts and sands. This material is meta-sedimentary bedrock. It is not igneous rock. It is second generation soil brought in by transport from surrounding hill erosion and hardened by compression over time. The top 12"or so is relatively recent siltation from storm runoff (hundreds of years). Below 6', the soil is markedly more coarse in grain size with few or little fines. The soil classification is shown by groups below. Below 6' of depth the soils are moist sands with little fines. The deeper soils are moderately consolidated. There was no impenctrable soil within-the trench. All soils were easy to dig with the backhoe (no igneous bedrock). The soil profile below de_ scribes the soils observed in the 12' deep excavation made with a backhoe. Surface Group depth Description SM 00=6': Slightly moist light brown silty sand. Moderately cohesive. Sticks slightly together with moisture. 6' 6'-12': Moist tan, clean (few fines), well graded sands. SW A few cobbles and small rocks to 6" in diameter. Very slightly cohesive. 12' No impervious layers nor any water nor evidence of any previous high ground water was encountered in the trench excavation. Lawrence R. Phelps, RCE 35280, Calif. Lic. Renewal 91301201! 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 Soil Type.& Permeability Report May 19, 2011 Parcel 4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road, Temecula, Ca. 92592 APN: 922-130-017 Page 5 4.0 Permeability Rates: Test No. North/South Initial percolation Final percolation Initial permeability Final permeability Depth of cell tower rate min/inch rate min/inch rate inches/hour rate inches/hour (inches) (first 5 minutes) after 10-37 min. rate stabilized rate stabilized 1 north 10 min/in 6.7 min/in 6 in/hr 9 in/hr 12" 2 north- 5 min/in 10 min/in 12 in/hr 6 in/hr 12" 3 south 2 min/in 6.7 min/in 30 in/hr 9 in/hr 101, 4 south 10 min/in 10 min/in 6 in/hr 6 in/hr 30„ 5 south 3.3 min/in 10 min/in 18 in/hr 6 in/hr 28" 6 south 8 min/in 8 min/in 7.5 in/hr 7.5 in/hr 26 7 south 1 min/in 10 min/in 60 in/hr 6 in/hr. 30" 8 south 3 min/in 8 min/in 20 in/hr 7.5 in/hr 48" Lawrence R. Phelps, RCE 35280. Calif. Lic. Renewal 913012011 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 Soil Type & PermeabilitN Report May 19, 2011 Parcel 4, Parcel Map Book 5, pages 55-56, Riverside County records Owner: Rancho Baptist Church Project Site: 29775 Santiago Road,Temecula, Ca. 92592 APN: 922-130-017 Page 6 5.0 Recommendations: 5.1 Based on the information contained in this report,the surface soils in the test areas as shown on the Site Map range from the surface to 48"deep. In that range they are capable of absorbing water at the rate of between 6"and 9"per hour. Below that range, the absorption rate would be faster due to the larger grained soils at depths below 5'. 5.2 Where drainage is diverted to the area north of the cellular towers, drainage should be discharged into a sufficiently large/deep sump to allow time for the water to infiltrate. The "first flush" discharge should not be allowed to enter the culvert passing under the 1-15 freeway. Here, the concern is for water escaping the project too fast and entering the culvert which takes water in a hard conduit to the Murrieta Creek across the freeway from the project. The reason this is a concern to the north of the cell towers and is not a concern for the drainage south of the cell towers is because this "north" area is small and the gradient to the culvert is relatively steep. 6.0 Conclusions: 6.1 During a first storm event of the season, water will infiltrate the soil at acceptable rates which are neither to slow as to cause surface off-site runoff, nor so fast as to cause a concern of pollutants contaminating sources of domestic water supply underground. 6.2 The amount of space available to infiltrate into the ground is about one-half acre, which is ample for the surface drainage from the project to infiltrate. The tributary drainage to this infiltration area is not much bigger than the infiltration area itself. Therefore, in the judgment of the undersigned engineer, the type of soils are perfect for infiltration at depths required to absorb sufficient quantities of storm water without contaminating the water supply underground nor allowing run-off from the site, which could take"first flush"pollutants to downstream tributaries of the Santa Margarita Watershed. Should you have any questions or other concerns, please address them to the undersigned. Thank you for your cooperation and understandi OQPOfESSION� ect y itted, cE R. w IN e e R. Phelps, P.E. * NO.RCE 35280 * / Exp. CIVIL r ce R. Phelps, RCE 35280, Calif. Lic. Renewal 913012011 P 31130 Avenida Del Reposo, Temecula, California 92591 Phone (951) 694-6336 - Fax (951) 694-6326 P<?ti 922 - ('n -p17 51TE � - PcL. 4-/PM 0 5 at c,-to 1 ST Cj�1 t::>ATE 5 I 1& 1 FIELD PERCOLATION TEST DATA R : t�^1hl�INCN Inches Inches R Rdg. Time Q R. Rdg. Time L fj- Q Pitl 1 q 22 (4 Pit92 11 �� Depth 2 10 2 142 Depth (2 Cj 2 cy)� Q 31Z. 4 9: 46 i /z� to ' 4 _52 ` DDe— an Rate: 5 '3�/ Design Rate: 5 9 .�Z 3 ' toT. . e11in �P, '6 �j Q QY O rn11 \O 6 `�S7 4 '/ 3 . 8 9 9 o. 10 I 10 / 1E1 I1 \� 11 12 1f1C7uC 12 Inches Inches Rdg. Time LEvfd Q R Rdg. Time Le4eL Q r Pit R3 i1 1 ; 2 3 3/ : . Pit 94 tI E�, 2 t 1 'a2 Depth © /L 2 ( : 2 Co�I� 2/ Depth O to :Q 23� 13d- 13 ; + . 39 4y4 t`� 1° ` a ( 5 2V2- `/ Design Rate: 5 Design Rate: 5 l( So1 (2 6 l d� 5 (� M t Ip 6 l l ' 2S 2 7 Y 1 nc(�I , ds 7 3 8 9 9 10 9 11 % 11 No ` ? 0 1 1 �ovr 12 q�OF CA= � StiE FIELD PERCOLATION TEST DATA R : h^11J�1NGt-1 Inches In hes R Rdg. Time R. Rdg. Time � Q Pit 4 55 1 u dye Pita Depth 2 ( ( ff Depth '- (2' 3 4 2 5 Design Rate: 5 �h �p ' Design Rate: 5 7 i o�1• 7 Fy 3 N � g 9 0 10 0 .y o l Cn�� 11 itn 11 ti .a 12 Inches Inches Rdg. Time ►�r_.tE,_ Q R Rdg. Time L{.vEL Q Pit " 7 1 IZ :02 2 Pit ag tt 1 t� l Depth ( (2'0 5 2'/ Depth 2 I2 �2 '2 Design Rate: i ( z.'( I Z Design Rate: 5 12 46 lr'� I l0 6 (2' 22I tT 8 rI�1 8 6 ('2 dS i cl 7 12 2� y 1 7 8 9 9 10 10 w to 11 71/Zin�'1 11 12 (nc o r 12 I MAJOR DIVISIONS GROUP TYPICAL NAMES SYM2G-S ..3o. itb" GW Well gradedgmvsh n, g.al-sane mnslures, ' CLEAN 'De mile or M Imes. i.. GRAVELS (Little ar eo firs I GP Poorly graded vonN or vnN-land ma Wrtl, GRAVELS lime ar M hMs. (More than 50% of coarse froctwn is URGER than Inc GM Silty gavels, grcial-Sand-sill m.. r Re. Bien n.d GRAVELS WITH FINES COARSE (App ecioDN amt. GRAINED a lines) GC Clayey grants, easel-sure-clayOvA misfurtl. SOILS (Mare than SO% of Well material is LARGER SW vadee SwMF, gra•elly sands,little Or na _ than No.20o.yen flues. sic) CLEAN SANDS (Linty a no Inn) SANDS SP �gliPoodraaw la:M ar gravelly srerde, little than 50% of - coarse fraction is SMALLER than IM SM Silty said., sad-uN mislurtl. No.s slaw size) SANDS WITH FINES (ApprnicDN amt. SC Cla of lines) lay serves.laid-clay ,m,strlrtl. Inagonic silts and eary fine soma,rock flour. ML sdy ar ctal'ey fnc sods w clayey,silts iodh 91,91if plasticdr. SILTS AND CLAYS Inorganic clays of lore to modeem plasticity, (LiW-d limit LESS ttm SO) CL oanly clays. sandy ploys. silty clays. lean clays. FINE _ OL 0n90mc sills and argonic Silty clays of low GRAINED dosticily i SOILS (Mae it is SO% o/ Inagamc MUs„mlrnceoas v e�atomaceeua moteth"'N'l n SMALLER MH One sonar a silty ",it,elastic .Its. Mon Na.200 hero size) SILTS AND CLAYS (Liquid limit GREATER CI 50) CH lnorgonm clap of high plasticity,In clays. OH Orgom,c clays of rnel,eni to high plOslieity, agonrc silts. HIGHLY ORGANIC SOILS Fit Pact vd other highly apan,c surfs. BOUNDARY CLASSIFICATIONS: SO-4 possesnmg choracler,st.cs of I.o pmDmatlor,e of 7roups aro Oengnalea by C voup sympels. P A R T I C L E S I Z E L I M IT S SANG GRAVEL t SILT OR CLAY COBBLES I BOULDERS •ins oto,ur cO..se "(31.2 0 1pe0 NO.10 NO.e Y. S. STAIs DA Is 3 1 E VE SIZE UNIFIED SOIL CLASSIFICATION SYSTEM Re Vu En Mnuttn d..rUe SG Army Technical Momaaneum_-f No ,3 357. W 1, March,1953. (Reeked Aarrl, 1%0) 4' GEODETIC COORDINATE LOT 10 :..00A'rION EX\SS 8U1\.0\NO 8 -- , �., ' \ \NK FENCE �• �----��% � Z 4 q A.C. PVM T �.o �2 �". ' RK\PAC �� 273 P 106e � X !%/ '';' PFtOPo/ •� APE; OCo , 202 p t# °o• L 1038.19 �, CO: i ( °°° EOC O1112 o 19 Q • FD IP 401104280 °• Nil a� 1� 01 ..0 ao5 , 1 400 08e30 447 1032.80 / KR ;• %/ Y i/, � / • /I �i//./r 1 Z Lp LIP r to CO. • /i C=> 45' x 50' % TEMPORARY 8' PROPOSED DRIVEWAY STOCKPILE HYORO ED OR SOD Q� PARCEL LINE- 6' AREA • Pv EXISTING GROUND 1' MIN. O.8' v _ DEEP \NA, O�P� m 8' TOP SOIL 8' SAND 12'-18' OF 1 1/2' NON—COMPACTED GRAVEL 40u 100 LB MIN FELT OR MIRAFI I I` THROUGHOUT TRENCH aELM 'A - \ ESS NO SCALE Q ET l2 0Eej=> �x� c�RY T2E�1cH 1033.50ILI I 9 -rY T>✓ST PITS * o.RCE 352E0 Cpe-(-T : PEl2l�Ea.(�lLf Exp.�sb/ 4 oFcauF�� l C,1-t0 -n ST C v--t v rzC H pb"� -rESr 29775 F c?L%, D MEcU L­Aa , cam,. ` 25c�2