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Home My WebLink About04/07/1992, C-3 - MISSION PLAZA CREEK WALL REPAIR 111111I1IIIg111� �ll � MEETING DATE: C� 0 S� � _.�S �B�Sp� April 7, 1ITEM 992 COUNCIL AGENDA REPORT NUMBEfl: FROM: David F. Romero, Public Works Director SUBJECT: Mission Plaza Creek Wall Repair CAO RECOMMENDATION: By motion, approve the Mission Plaza Creek Wall Repairs in concept and direct staff to prepare plans and specifications and obtain necessary processing approvals. BACKGROUND: During a heavy storm in March 1991, San Luis Obispo Creek undercut several walls in Mission Plaza. During April, staff removed a number of newly exposed reinforcing bars which presented a hazard to the public. During May staff received approval from the Game Warden for repairs to the undermining, with work to be conducted during the summer when creek flows are low, following conditions of our general maintenance permit from the Fish and Game Department. The City did not need to clear at that time with the Corps of Engineers, since this was an emergency project to correct several undermines. In August, City crews poured 33 cubic yards of concrete grout to correct the undermining. There was some surplus grout, and this was placed and rounded in front of existing built-up rubble concrete walls on either side of the creek (Areas 1 and 2 on exhibit) , exposing to public view approximately 2 cubic yards of concrete. After a Councilperson's complaint, staff hired a contractor to chip off the newly poured concrete to near the face of the original rubble concrete wall along the east bank. Staff also tried twice (unsuccessfully) to stain the exposed concrete along the west bank to give it a more natural appearance. At the February 4, 1992 meeting, Councilperson Pinard presented a series of slides showing the condition of the concrete pours. These slides were taken before staff attempts to correct the unsightly appearance. The City Council directed staff to "redo" the repairs. During mid-February, a heavy storm started additional erosion in this immediate area of Mission Plaza. In response to Council direction, Public Works and Planning staff met at the site in late February to reach agreement regarding the best approach toward correction to previous work and correction and protection regarding recent erosion. Staff agreed that work was needed in four areas (see exhibit) . Area #1 Cover face of partially corrected rubble concrete wall with native stone facing to match nearby retaining wall or face with medium-small boulders to match those to be placed in Area #2. C-3- 1 �,,,7�i►►Iu►IIIIIIIII►' ��h city of San t OBISpo COUNCIL AGENDA REPORT Creek Repair Page Two Area #2 Place large boulders (or fabricate concrete boulders in place similar to those at the Apple Farm Millhouse) in front of recently grouted west bank concrete rubble wall. This will cover up the existing exposed concrete pour and provide protection from future erosion. Area #3 Place large boulders (or fabricate concrete boulders) along east bank (and slightly downstream) in area starting to erode. i Area #4 Construct approximately 50 feet of concrete rubble wall about 2 feet high along east bank (slightly north) to protect a fig tree at the water's edge. This wall could also be constructed of native serpentine stone. Modify small corrugated metal pipe (which has been in place since before Mission Plaza was developed) so pipe will not be visible. Note: Areas 1, 3 and 4 would also receive additional landscaping ALTERNATIVES: A. Do nothing. The undermining has been corrected and the final (partially corrected) condition doesn't look too bad. If heavy rains are over for the season, erosion at other spots won't get worse for about a year. Meanwhile, some of the eroding areas may heal UP- A-1. Conduct hand or brush hammer chipping of partially removed concrete still remaining on face of existing concrete rubble wall, so as to expose original concrete rubble slabs (this work would be done by City crews) . B. Do all repair work with laid-up rubble concrete walls or constructed fieldstone walls. This will match existing and will avoid the huge expense and complication of having to put equipment into the creek to move and place large boulders. C. Fabricate concrete imitation boulders in place, instead of moving in real boulders. Much of the cost in placing real boulders involves crane placement of a loader in the creek, modification of the creek bed to allow the loader to travel to the worksite while carrying boulders, and finally cleaning up the creek at the end of the job, all done to strict Fish and Game requirements. This could all be avoided by utilizing a relatively new process of pouring the boulders in place. This process was used at the Apple Farm on a recent project. ��:�►��►IVIIIIIIIIIII�►�uil��1ll city of san ' Is oBispo = COUNCIL AGENDA REPORT Creek Repair ' Page Three I FISCAL IMPACT: At this early stage, it is impossible to come up with firm estimates of the construction cost. Based on discussions with a contractor and engineering staff, the following can be used as general guidelines for construction cost. Full job as recommended by Planning $25, 000 Alternative A No cost at this time Alternative B $15, 000 Alternative C $20, 000 The Mission Plaza account currently has $200, 000 in it, though it may be depleted soon to pay for appraisals, legal fees and acquisition costs. APPROVALS OF OTHER AGENCIES: The project is subject to environmental review, the ARC and Park and Recreation Commission review and approval. It also requires Fish and Game approval and most importantly, Corps of Engineers approval. Because of Corps of Engineers procedures, we estimate this approval will require one year. i ACTION PLAN: 1. Obtain concept approval and prepare preliminary cost estimates - April 1992 . 2. Prepare preliminary plans - May-June 1992 . j 3 . Obtain concept approval from various city agencies and Fish and Game - July-August 1992. 4. Apply for Corps of Engineers permit - July 1992. 5. Obtain Corps of Engineers permit - July 1993. 6. Obtain environmental determination - July 1993. 7 . Prepare final plans and specifications - June-July 1993 . 8. Obtain final approvals of city commissions - July 1993. 9. Council approval of plans and specifications - August 1993 . 10. CAO award contract - September 1993. C �II�»b�►►1VIIIlIII�� N�ll city of San l -3 OBIspo COUNCIL AGENDA REPORT Creek Repair Page Four I 11. Construction - October 1993 . 12 . Completion of work - November 1, 1993. The Action Plan schedule assumes engineering staff prioritizes this design ahead of other already scheduled work, and assumes no glitches (other than routine delays) in obtaining processing approvals. If we limit our creek work to the small walls, we might obtain quicker Corps of Engineers approval but would still not do the work until late summer 1993 when creek flows are low. i I I Attachment: Exhibit A - map of Mission Plaza Exhibit B - detail from Corps of Engineers I i i i creekrepelr/dfr•36 l - - Q mrai LU IF.tX.;.�f� /w T` N •� �• wto 43 ti —� i . ` '�`� � •,.`. :•;-' 41 !%.. 'v'r � '.tib 1 �.' ,� . '. �. •_ - w � I .1t ivy� � �\ `:' / ;;. •�• ; ` - 75 _ moLO CL wLU cr: VD 4m CL— . I u- }T Tr C _. ... . _ .,.--... _ U. Ll1 _ 0 Oc = m Q Z O C 0r 7 I C �- L:1 T 1111M S, 4 = U o LLJ p z ■.� L O y cwLL CZ to LLJ C3 a� c aA MM p mag \ u - I. J O O uLi U] 4odI CIS U3 00 v - • Qt•Cj Z . rA4K =V CIS - � _ p =-:_ .-- - '- :: _.=•��'=�_'=�� Q LL's - C6 r- Cc O v7 CD cc LLJ 40'ja jr iiW U _ _ •'1►� __.-:;.. ,- =+�t/) k-.O LLI 'a o LLS U- v. V YOn a • Yr. UCC AL. - - _ tJ 3iLU `Ad W- 44P ar gL uj cn CJS U _.r.,,-•:�- Z Z f. Q r ci L3 C 3-� 1IIINQ MEETING DATE: WIIM11 1 city of Sap CUis oBiSpo• April 7 1992 COUNCIL AGENDA REPO AE^^NUMB P FROM: Action ElFIA David F. Romero, Public Works DirectorCAoCfl O CDDDIR. L7'ACAo p �� SUBJECT:. d TTOP-NEY CXAvDIR. Mission Plaza Creek Wall Repair ��/CPUC.. 0 POLICECFL P MG1r1T TEA34 [J PEC.DLR ®r CREADFITLE. �UTIr DTR. CAO, RECOMMENDATION: By motion, approve the Mission Plaza Creek Wall Repairs in con and direct staff to prepare plans and specifications and obtain necessary processing approvals, `usinq Alternative B (laid ug concrete rubble walls) as the basic anproach. BACKGROUND: During s heavy; storm .in, March 1991, San Luis Obispo Creek undercut several 'walls in Mission' Plaza. During April, staff removed a number of new l °expose d rye i forci{i9:: axs;. which presented''a,. hazard to the public. During"May staff recezved approval' from the ' Game Warden for repairs to the undermining, . with• work to be conducted during the summer when creek flows are low, following conditions of our general maintenance permit from the Fish` and Game Department. The City did not need to clear at that time with the Corps of Engineers, since this was an emergency project to correct several undermines. In August, City crews poured 33 cubic yards of concrete grout to correct the undermining. There was some surplus grout, and this was placed and rounded in front of existing built-up rubble concrete walls on either side of the creek (Areas 1 and 2 on exhibit) , exposing to public view approximately 2 cubic yards of concrete. After a Councilperson's complaint, staff hired a contractor to chip off the newly poured concrete to near the face of the original rubble concrete wall along the east bank. Staff also tried twice . (unsuccessfully) to stain the exposed concrete along the west bank to give it a more natural appearance. At the February 4, : 1992 meeting, Councilperson Pinard presented a series of slides showing the condition of the concrete pours. These slides were taken before staff attempts to correct the unsightly appearance. The City Council directed staff to "redo" the repairs. During mid-February, a heavy storm started additional erosion in this immediate area of Mission Plaza. In response to Council direction, Public Works and Planning staff met at the site in late February to reach agreement regarding the best approach toward correction to previous work and correction and protection• regarding. recent erosion. Staff agreed that work was needed 'in four areas (see exhibit) . Area #1 Cover face of partially corrected rubble concrete wall with native stone facing to match 'nearby retaining wall or face with medium-small boulders to match those .to be placed in Area ,#2: