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Home My WebLink AboutCDP 00-54; JENSEN RESIDENCE; ASSUMPTION OF GEOTECHNICAL RESPONSIBILTY; 2001-03-15roo-4 OWEN ENGINEERING GROUP . Civil; Geotechnical and Structural Engineering March 15, 2001 . City of Carlsbad Planning Director 1 Attn: Mr. Micha J Holzmiller ' 5950 El Camino Real -r Carlsbad, CA 1 - •'k0 .. . . .. Ar . .• Subject!Jens Located '• . 2 Located in Parcel Map Number 18236 Carlsbad, California - 0. re: "Assumption of Geotechnical- Responsibility, Updated Geotechnical Report" Prepared by C. J. Randle, Civil -Engineer; Dated March 16, 1998 Dear Mr. Holzmiller: Owen Engineering Group has been retained to prepare a' response report addressing staff's concerns with the proposed debris removal on the property which is the subject of CDP 00-54. The subject property is located on Carlsbad Boulevard, Carlsbad, California and is comprised of a portion of Map 18236. ' Pursuant to the owners request and in response to the' staff's letter, our firm performed visual observations around the subject site on February 22, 2001. In addition, our firm has previously performed observations and inspections of the subject site in prior years. The previous reports and recommendations for the property at large have dealt with erosion, drainage, stair construction, home construction, geological conditions, and set back requirements on the property. The purpose of the most, recent site evaluatioi and observations was to determine and evaliate potential geotechnical impacts and hazards associated with leaving the.debris in place, or in removal of the existing debris and to determine if the debri1. s should be left in place or removed.. This report summarizes our observations and provides recommendations regarding the debris as follows:• Based on our knowledge of the site and on our site inspections and evaluations of the site, it is our recommendation that the debris should be removed and can be .removed without geotechnical impacts. This conclusion has been reached due to the, need to provide for public safety in theárea and due to the size and location of the debris and the potential for parts or portions of the debris to fall to areas below the debris ,onto individuals using or located on the beach. In additiori, the removal of the debris will also enhance the stability of th6 bluff, reduce erosion and slope failure, and benefit the area following the debris removal due, to allowing for the uniform absorption of water and the elimination of channeling and diversion of surface water around the debris. It is our further conclusion that the debris removal will not affect any prior approvals for the property, or any set backs previously, established by this firmoiprovided for in prior CPP,'s. - , 1800 Thibodo Road, Suite 320 Vista, California 92083 . . - Tel ehône (760)599 - 6767 Fax (760) 599-6070 14661 Myford Road; Suite C,Tustiñ, California 92806 4\ Telephone .(714),,734.-17993 Fax (714) 734-9732 ,, .b:) • - ,. •, t ..' Based on our conclusions, our further recommendations regarding the debris field and the manner and method for its removal is as follows: The subject parcel is a coastal property sloping mildly toward the west. At the western most edge of the lot exists a coastal bluff face. An existing small gently sloping "valley" is found inside and behind of the existing bluff face approximately midway between the top of slope and the toe of slope (See Figure No. 1). It appears that this area has been used for many years as a pathway or trail to the beach below. This "valley" appears to be naturally occurring, but could have been previously improved to create the pathway or trail. An existing debris field, comprised of concrete slabs in various sizes and shapes, was located within this "valley pathway" (See Figure No. 1) and the debris was most likely end dumped from above or within the "valley" into the debris area. In order for this debris to be dumped at this location, a piece of heavy equipment would have had to back up to the existing edge or into the "valley" and end dump the load of material in this area. The majority of the concrete slabs are found scattered at the surface of the bluff in a loose condition. However, some slabs were found to be slightly embedded in the "valley" edges due to prior erosion materials filling in around the debris. Although some slabs were found to be slightly embedded in the "valley," little, it any, excavation is anticipated to be required for their removal. Both the loose slabs of concrete and those slightly embedded will present a safety and public welfare issue if left in their current state and, as stated in our conclusions, should be removed. Based on our observations, there will be no geotechnical impact or detriment to the existing bluff area if the debris is removed. The removal of the debris will not result in acceleration of bluff recession or alter existing drainage patterns and will reduce erosion after removal and allow for the uniform absorption of surface water. The area near where the debris removal will take place on the other edge of the bluff is normally deemed to be sensitive. However, areas inside the bluff face, such as this area, and areas which appear to have been previously improved, used, or where illegal dumping has occurred is not deemed as sensitive as previously untouched native areas. The debris removal should be overseen and inspected by this firm or by a qualified individual experienced in the practice of soils engineering to ensure that the removal is properly undertaken and completed in a manner as to comply with or exceed all applicable city standards, and in such a manner as to enhance slope stability, diminish erosion, and mitigate any potential impacts encountered in the filed should any develop. The size and quantity of the debris are shown on Figure No. 1 and can be easily removed by hand and equipment. Hand removal should be used to facilitate the removal by equipment in order to protect the safety of the work persons undertaking the removal and in order to eliminate safety hazards for any bystanders or onlookers. The size of the equipment used should be selected by the supervising engineer and be sufficient to safely complete the work, but no greater than required for the purpose intended. It is anticipated that field conditions and further surveys at the time of commencement of the work and during the work will also dictate the minimum size of equipment 3 — I — S - • i needed forUtlie removal Uhv addition, sufficient pers&nel should be utilized to insure that no persons, bystanders (* onlookers enter an area sufficient to "provide for the safeU removal of the debns and sufficient to ensure that no debris can become dislodged and endanger any persoil, bystander Pr onlooker located on or in the beach area Due to the location of the debris, it is not anticipated that any e4uip11ent will enter upon the beach or and area at the bottom of the bluff. The professional opinions presented m this repoh have been develcped using that degree of care and skill ordinarily exercised, under similar circumstances, by reputable civil engineering rand geotechmcal consultants practicing in this or similar localities No other warranty, expressed or implied, is made as to the professional advice included in this letter. If you have any questions or wish to contact me, please feel free to phone at (760) 599-6767 ext U _I 2. 'Sincerely, Owen Engineering Group 1 : - a,4-1 o. Charles J Randle, P F %\EXP Date 9/3O1JJJ " RCE 22096, exp 09/30/01 * Principal Engineer 4 r U U — U - I "S It U ' U ' .k • '- i f U 4 , _4---, • _S' - S - & I U - b - - ,.. 54 • a' - S - I * • S - - •. _ IS 151 55 's • - .• .5 IS ,,• iF - : * .......- - , - - -• - - . _• •. •. ' U - - ,: - -. I .1;.. -. .5 - - ___ . s - U, IS 5