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Home My WebLink AboutCT 83-21; CALAVERA HILLS VILLAGES; STORMDRAIN CUTOFF WALLS; 1986-09-23RECE~VED . e SEP 251986 CITY OF CARLSBAD DEVELOP. PROC. SERVo DIV. •• SOUTHERN CALIFORNIA SOIL AND TESTING. INC. 6280 RIVERDALE ST. SAN DIEGO, CALIF. 92120 • TELE 280-4321 • PaD. BOX 20627 SAN DIEGO, CALIF. 92120 7 4 - 8 :3 1 VEL. lEW A Y PAL. M DES E R T. CAL. I F. 9 2 2 6 0 • TEL. E :3 4 6 - 1 0 7 8 678 ENTERPRISE ST. ESCONDIDO. CAL.IF. 92025· TEL.E 746-4544 September 23, 1986 Pacific Scenes, Inc. 3900 Harney Street San Diego, California 92110 ATTENTION: Mr. Bob Fontana SCS& T 8421QOO Report No. 33 SUBJECT: Stormdrain Cutoff Walls, Calaveras Hills Subdivision, Carlsbad, California. Gentlemen: In accordance with your request, this letter has been prepared to address the need for stormdrai n trench cutoff walls where three exi sti ng stormdra ins extend down fill slopes at the subj ect proj ect. The stormdrains in question are shown on Sheet 13A of Unit 1 and 12A and 13 of Unit 2 of the plans for the improvements of offsite stormdrain in Villages "0" and IP_1". These plans were prepared by Rick Engineering Company and approved by the City of Carlsbad. The slopes were constructed between April and August of 1985 and the stormdrains installed in October and November of 1985. Southern California Soil and Testing, Inc., provided the compaction testing and the grading observation during the mass grading operation and tested the stormdrain backfill. During the construction of the stormdrain, the standard cutoff walls (San Diego County Regional Standard Drawing 5-10) as shown on the approved plans were omitted. The purpose of these cutoff walls are to prevent the trench backfill from washing out and exposing the pipe. SOUTHERN CALIFORNIA SOIL AND TESTING. INC. • • SCS&T 8421000 September 23, 1986 Page 2 A recent inspection was made of the slopes where the three stormdrains were installed. This inspection indicated that no erosion or washing out of the stormdrain backfill has occurred in the time since they were installed and that vegetation is well estabished over most of the backfill material. Further, this observation and review of our records indicated that the soils used in the fill and the backfill consist of very rocky metavolcanic soils which have low erosion characteristics. Based on our observation and experience, it is our opinion that. the cutoff walls are not necessary for this case. This opinion assumes that the drain and berm at the top of the slope will be maintained such that runoff from the building pads and streets is not allowed to flow over the slope. If you should have any questions after reviewing this report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA SOIL & TESTING, INC. Charles H. Christian, R.C.E. #22330 CHC:mw cc: (4) Submitted (2) Rick Engineering (1) SCS&T, Escondido ! • 1 ~_.1 ' .. /~6." ••• " .'~'9~ .} • • • ill/III •• IIII,r/c eIIUllleer., IIII} • . August 3, 1984 HCH & Associates 4877 Viewridge Avenue San Diego, CA 92123 Re: Calavera Hills Unit 1 Pump Station Dear Mr. 'Gerry: '. CTB? .. z/ U.,;i I This letter is in response to your "Review Comment~" of July 9, 1984 for the second review of the plans and specifications for th~ Calavera Hills Unit 1 Pump Station. Please reference the above mentioned comments. SEWER LIFT STATION STUDY Variable S')eed Pumps -' Due to head requirements, variable speed pllmps were not used. Sulfide Gases -With the anticipated velocities in the influent sewer and the estimated actual draw-down rates, it is not suspected that ,sulfide gases will be a problem. Groundwater -As stated in the "geo technical Investigatinn-Lake Cal avera Hi" s II, and because of the phys ica 1 Tocat i on of the proposed pump station, it is not anticipated that major groundwater or seepage problems wi 11 occu r. Any mi nor prob 1 ems encountered shou 1 d be corrected as they develop. Head Calculations - Hstatic H1 = .42 1 /100 1 x 3600 1 = 15.15 1 HeadT = 200 1 DrawinQs (c= 110, 8" pip'e) 1. To be addressed by Project Design Engineer. 2. A note has been placed on the draw; ngs, per Mr. Larry Wi 1 ey (Ci ty of Carlsbad), directing the contractor to contact him for instructions on telemetering requirements. 1- Page -2- 3. As stated in the notes, S.D.G. & E.~requireSthe reduced voltage starters. 4. Modifications made to sheet 17. 5. Per Mr. Wiley (City of Carlsbad) only one pump at a time is required to run on emergency power. 6. To be addressed by Project Design Engineer. General Comments Letter to be sent to City requesting exemptions. Should you have any questions, or require any additional information, please do not hesitate to call. Very truly yours, JOHN S. MURK ENGINEERS, INC. /-. ( / / / tJ4."i~.clt'-,k/;,·x. 7~I:'~::;- Daniel E. Schulenourg Vice President and Senior Engineer DES :cd: 1926A "'illuIIWIIlI.I ...... e -REVIEW CX>MMENTS CALAVERA HILLS PUMP STATm-N . July 9, 1984 Sewer ~ Station Study 1. Address the use of variable speed pumps, the potential build~ up of sulfide gases, and the possibility of ground water problems. -2. Inelude calculations for the total dynamic head for the sewage pumps. Drawings 1. Include fresh water service with back flow preventer to pump st"ation site.. See Sheet 12. 2. Identify how alarms are connected to the telephone system. 3. The engineer, not the contractor, should 'make the determination as to the requirement for reduced voltage starters on the pump motors • . 4. Per comments by the Maintenance/Utility Department, the sewage pumps shall be compatible with the em-erg~.ncy gen.erator used by the Ci ty. plans should show a receptacle fOr the emergency generator. See Sheet 17. Generator Specs: KATO 125 Model SR9E Continuous ·KW-125 KVA-156.25 Amperage-376 5. ~s required in the pump station specifications, th~ pumps shall operate in parallel s·hould the level in the wet well rise. above a pre-determined level. The wire siz.es 'shown i.n the single-line electrical diagram -are insufficient for this condition. In addition, it should be verified the emergency generator will be able to start both pumps simultane9usly. . 6. As shown on sheet 3, at stati-on 81+50 -the water line and sewer force main cross at the same elevation. This should be rev~sed to show a minimum v~rtical clearance of one foot. The force main shall cross below the waterline. , I !!! I I I i i I ~ I . I I f I ........ I ,."u trl t M mint 5' tl_'t~ .. t ~, .. - Comments Page Two .~! ~P'-~r', . (l/fPZ i q7,jIf; The plans do not conform to the following requirements of General Commen"ts the· ~ity of Carlsbad-Sewer Design Criteria: 1. Item SF(4) requires explosion proof electrical appurenan¢es below ground of approved type disconnect and time delay. As this _is not commonly found in package pump station, We recommend these plans should be exempt from this requirement. 2. Item SF (7) requires a manual switch adjacent' to the motors which will override the control panel. Due to the close proximity of the motors to the control panel in a package system, we "recommend an exemption be granted from this requirement. 3. Item SB (3) requires a provision for access oth.er thaQ vertical ladders for permanent stations. We recomme~d a maintenance lift be provided within the pump station to allow for ease of access and maintenance of the pump equipment. 4. It is the responsibility of the design engineer to obtain an e~emption from the City Engineer from any of the requirements as set "forth in the Sewer Design Criteria. " Return check prints with one set of revised plans and sewer lift station study ~or final check.