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HomeMy WebLinkAboutItem 7.1 ReprtOnXridgeSlopeSlds CITY CLERK File # DßEJ[QJ-[ZJ~ AGENDA STATEMENT CITY COUNCIL MEETING DATE: November 28,1995 SUBJECT: Report on Crossridge Slope Slides Report Prepared by: Lee S. Thompson, Public Works Director EXHIBITS ATTACHED: 1) 2) 3) 4) 5) 6) Petition ITom Mrs. Janine McCune Minutes ITom November 14, 1995 City Council Meeting Map of Crossridge Slope area Bench detail ITom original subdivision plans Flooding report to Council (January 12, 1995) Slides and maps will be displayed at the meeting RECOMMENDATlO~72~/A-/Rèceive report and direct Staff to include improvements to the slope ~ area as part of the 1996-97 Capital Improvement Program FINANCIAL STATEMENT: Preliminary estimates are in the range of $20,00bto $70,000, depending on the extent of the improverÌìt¡nts made. DESCRIPTION: At the November 14, 1995, City Council meeting, Mrs. McCune, a homeowner at 7750 Crossridge Road, presented a petition signed by 40 residents of Crossridge Road requesting that the Council take the following actions: 1) Make the necessary corrections to the hill on the west side so that it is in accordance with the 1985 Uniform Building Code, Chapter 70, and 2) Make the necessary correction to eliminate the possibility of another landslide and to eliminate the possibility of homes deteriorating in value. In addition, Mrs. McCune stated that there are cracks and weeds in the "V" ditch. Background Last year, during the heavy February rains, two shallow slides (approximately 3 to 4 feet deep) moved down the slope and some mud filled the interceptor "V" ditch near the south end of the slope above Crossridge Road. This area was in the Dougherty Hills open space just above the Crossridge homes. These two slides were about 30 feet wide by 35 feet long and 15 feet wide by 45 feet long. (See map, ------------------------------------------------------------------ COPIES TO: Mrs. McCune ITEM NO.-.ZL g:\agenmisc\xridge Exhibit 3.) Some grass and mud washed over the top of the catch basin on the south end of the "V" ditch. The mud effectively closed off portions of the ditch causing water to go over the top of the slope below. The City's Maintenance Staff did clean off the plugged catch basin and opened up the ditch during the storm and then subsequently removed the mud after the storm and placed plastic over the slides to keep the rain ITom undermining the soil. January and March 1995 Storms It should be remembered that the January and March storms were exceptionally heavy and qualified as disasters State- and County-wide. The City of Dublin experienced ITeeway and business flooding on Scarlett Court, mud slides at the west end of Dublin Boulevard, and water over creek banks along San Ramon Road (see attached summary to Council dated January 12, 1995 - Exhibit 5). Alameda County Flood Control, Zone 7, estimated these storms to be in the range of25- to 50-year events. Local drainage improvements are designed for 15-year events. After the storms, Staff worked with FEMA to obtain reimbursement for various expenses and damages. The City is presently receiving results of claims and still exchanging paper work with FEMA. Dublin was granted the cost of emergency response and cleanup of the Crossridge area, but not the repair costs. Petition In delivering the petition to the City Council at the November 14th Council Meeting, Mrs. McCune also mentioned that there were weeds in the bench "V" ditch, cracks in the ditch, and that the benches were only about two feet wide. An on-site investigation by Staff revealed the following: 1) Weeds: City maintenance crews cleaned the southerly ditch approximately one month ago, but grasses had since built up in the bottom of the ditch. The maintenance crew again cleaned out the grasses in the southerly ditch last week and have completed cleaning the northerly ditches. 2) Cracks: There are some small cracks and offsets in the "V" ditch; however, the cracks are not large enough to become a washout problem. 3) The benches are horizontal cuts in the slopes to allow drainage to be picked up and to allow for maintenance personnel to inspect and clean the drainage improvements. They also serve as a catchment for small slides to keep debris ITom moving entirely downhill. The Uniform Building Code (UBC) calls for benches to be 6 feet wide. The City's Ordinance (carried over from Alameda County) requires a minimum of 8 feet. The plans called for the benches to be 8 1/2 feet wide (including the concrete ditch - see Exhibit 4 for the design cross section of the slope and bench). The benches were measured at various points during the on-site investigation. It was determined that the bench measurements varied between 6 and 9 feet. Page 2 The petition asks that the City 1) "make the necessary corrections to the hill on the west side of :rossridge Road so that it is in accordance with the 1985 Uniform Building Code, Ch. 70," and 2) "make the necessary correction to eliminate the possibility of another landslide and to eliminate the possibility of our homes deteriorating in value." In response to those requests: 1) The UBC requires interceptor ditches along the top of the cut slopes. The City's Ordinance does not but could be amended to add this requirement. There are other differences between the UBC and the City's Ordinance, such as the longitudinal slope of the "V" ditches and locations of downdrains. However, it would not be practical to make these kinds of changes on the Crossridge slopes. New drains would have to be installed down the slope, through yards, and along the street, and the existing "V" ditches and benches would have to be removed and regraded. 2) As far as repairs are concerned, the damage happened during the City's preparation of the Capital Improvement Budget last fiscal year, and it was expected that Staff would develop Capital Projects this year for incorporation into next year's work. It is anticipated that Staff would first hire a soils firm to develop recommendations for repairs and mitigation improvements. Staff would then design and let the contract for the work. Rough Estimates for the repair work were made to include combinations of slope repair and retaining wall catchments above the "V" ditch. These estimates ranged from $20,000 to $70,000 and did not include a new ditch above the slope. .0 preparation for this winter's rains, the City's maintenance crews have (1) remodeled the southerly catch basin on the "V" ditch to create a side opening, rather than a top opening, to better handle debris buildup; (2) cleaned the ditches; (3) covered the two slides with plastic to prevent water from getting back into the slide areas; and 4) installed silt fences below the two slides. Staff recommends that Council direct Staff to develop a Capital Improvement Project for the 1996-97 Fiscal Year to repair and mitigate these two slides. Page 3 ...... ....··........···.·.···<.QriE···A··K·E· ·R'cR··EQ... ·U·· ···ES·T· .. .... ........ ·......·..-·-----·---.··.··,·,·.·-----·.···..----.·.·a:.J.r,- - --··0·-·, ,-- -- --'-...,',.,'---,---,-.-----',..-,,-"-" iTOAbBR~§Š.DUBÐ~NêÍTYèOl(]NC[t······· The MAYOR will give everyone who wishes to address the Council an opportunity to do so at the appropriate time. Please complete this fonn and submit it to the CITY CLERK in order that proper infonnation can be entered into the minutes. NAME: ~ /J1c,~ ADDRESS: ~) ~) ~O &05'ôndq(' D V h1o:J SUBJECT tW'S'5r¡cl¡ ú;Pel /-hu AGENDA ITEM NO. -+- 1 wish to speak. _1 DO NOT wish to speak, but would like to have the following comment(s) entered into the public record: ':'i;:'"":;. :1' -::~ ~.. ...,~.~ . ":';"'" ..., I. K1/fomlS-kk/spkrslip.doc Pe*", hi'>' .---.~...-~~~ DATE: OCTOBER 25, 1995 HOMEOWNERS ON CROSSRIDGE ROAD (HILLSIDE), DUBLIN FROM: TO: MR. GUY HOUSTON, CITY MAYOR MR. RICHARD AMBROSE, CITY MANAGER MS. ELIZABETH SILVER, CITY ATTORNEY MR. LEE THOMPSON, PUBLIC WORKS DEPARTMENT MR. DEAN MCDONALD, PUBLIC WORKS DEPARTMENT PET I T ION The following homeowners live on Cross ridge Road (west side) in Dublin. We are petitioning you, the City of Dublin, to take the following steps immediately: - Make the necessary corrections to the hill on the west side of Cross ridge Road so it is in accordance with the 1985 Uniform Building Code, Chapter 70 -_"'._-.'~_'" - Make the necessary corrections to eliminate the possibility of another landslide and to eliminate the possibility of our homes deteriorating in value (70 7. -..z y C~ðJJ~'~1e C7~b/':"" é~ ... hi;"" DATE: OCTOBER 25, 1995 FROM: HOMEOWNERS ON CROSSRIDGE ROAD (HILLSIDE), DUBLIN TO: MR. GUY HOUSTON, CITY MAYOR MR. RICHARD AMBROSE, CITY MANAGER MS. ELIZABETH SILVER, CITY ATTORNEY MR. LEE THOMPSON, PUBLIC WORKS DEPARTMENT MR. DEAN MCDONALD, PUBLIC WORKS DEPARTMENT PET I T ION The following homeowners live on Cross ridge Road (wes t side) in Dublin. We are petitioning you, the City of Dublin, to take the following steps immediately: - Make the necessary corrections to the hill on the west side of Cross ridge Road so it is in accordance with the 1985 Uniform Building Code, Chapter 70 - Make the necessary corrections to eliminate the possibility of another landslide and to eliminate the possibility of our homes deteriorating in value ~ ';/7 'l'ì 'ry. S(::l" Shelley stated she loves art and she hopes to become a children's book author a illustrator. The City Council requested that Shelley's artwork be displaye the Civic Center. Staff was directed to work with the Dublin Fine Arts Foundaf 0 get it displayed.. INTRODUCTION OF NEW EMPLOY 7:25 p.m. 3.2 (700-10) City Manager Ambrose in uced Alameda County Sheriff's Department Captain Rich Bond, who will be fi . g in as Police Chief until Chief Rose is able to return from his surgery. ..... 'n Bond is a 25 year veteran of the Sheriff's Department. .....'... Flood Control (550-10) Janine McCune, 7750 Cross ridge Road, stated last winter's excessive rainfall caused mud damage to the extenor of their home. She presented a petition signed by homeowners on Crossridge Road requesting the City to take immediate action to avert future problems. They requested the City immediately take the following steps: 1) Make the necessary corrections to the hill on the west side so it is in accordance with the 1985 Uniform Building Code, Chapter 70; and 2) Make the necessary corrections to eliminate the possibility of another landslide and to eliminate the possibility of homes deteriorating in value. She stated the homeowners don't want to hire an engineer. She questioned whether this hill was compacted in accordance with the City's regulations. There are 37 properties located below the v-ditch, There are excessive cracks, weeds, etc., in the v-ditch. They ask that the City make corrections to ensure their safety and the value of their properties. Public Works Director Thompson explained that the slope was cut and therefore no compaction needed. The City Council requested that Staff look into this and report back. .... Air Raid Warn inS?: Siren (520-10) Tom Ford, 7262 Tina Place, stated there is a physical it all' raid siren in the Briarhill area that he wished to add IS airly good potential for toxic spills because of the c . I Y of major freeways. We have prisons in the City and with o er alerts, he is interested in knowing if this could be used to perhaps get CITY COUNCIL MINUTES VOLUME 14 REGULAR MEETING November 14,1995 PAGE 511 !?".'..'. "" f'i!1 i!! "j 16"...! ).1. ( \,', ~~l5 ~~,:.. LO;:",':"'~ \.Wi.! u; S.tl ,y I-U (\.U. t'C0 2. ,......~.y.~" "',: '. "," fh.) ! ! / .. . . ',', ; /. ... .... . ( .' , '/ .;.:"'-:--" , .- "'--.., ."íC' NTÈRCEPTOR DITCHES, \ 1:\\ " "...... /. ..-.--' ..-:.:..---. , " - , <~~-.. :'lp-- .-..--- -. " '::..... ..' ..~_...- " \,,,,--,' ,....-'--' .-' - " TRACI 5511, I :~·~;:_~:~:;.YPL~::::.¡:;~>::::;;·'~(('·,,:{:·:·::!~:J- ~ 1·~ ~ ,.,.... .', .....,.....~. .'. " :, :'....::.......,'.. ....::;:. "",./," .,1:. ',I " .~. ....... .... .... . . / . J.,. .., "- .....,'. "-"-.-.-:~;' .- ~/I..,:"'-'. . :' '" '" . -'" :---" . .~.' " -., ~"-_._._. - "'. . . '. / , /.- -'. ' , "'- , '. . '. ........... ........... .' / , / .............. :,.;~:..-: .~-~~~r--~· ....~:~<..:.:.~~-_.> ,-.- " ;.. /. ~r .' , '\ \. I' I,'. \' .. .V~L :J:.':":":. :'.::'! ).. 1.: /. . . "/' /. 3. é .j:; "; oJ .:, -,; ,_._-_..-~...,.~ P\âp ob é.nŸnrl<ije ~fe-' :T~,f>1f ~; ~ """~-... , ð:~* ð~O- .f~O· ¿% ~. 3' , /15" Ió" ßROW DfTCN See Ddail ·C· DETAIL liB 11 TERRACE BENCH DETAIL IJTS. """, ........ "", f. 'f.e.n::11 &h< l f11>m &-ici~a i .¡:Jans Report from Public Works Department 1/12/95 INCIDENTS FROM STORM OF JANUARY 9-12. 1995 STREETS 1 . Dublin Boulevard A. Road flooded with as much as 1 foot of water between Hacienda Drive and Tassajara Road east of the Tassajara Creek bridge on the evening of January 9th. Crews posted "Road Closed" and "Flooded" signs at Hacienda and Tassajara until the water subsided. B. Three small mudslides slid out onto Dublin Boulevard west of SilvergateDrive. Crews put balTicades at these locations initially and then cleaned them up later in the day on Tuesday 1/10. 2. Scarlett Court and Scarlett Drive Scarlett Drive and Scarlett Court west of Scarlett Drive flooded with as much as 2 to 3 feet of water. affecting many businesses in and around Scarlett Court west of Scarlett Drive and also closed the westbound lanes of 1-580. The water was the result of backups in the drainage culvert underneath the freeway and in the Zone 7 flood control channel at Scarlett Court. Crews put out "Road Closed" and" Flooded" signs while Dublin p.o. kept an officer at Scarlett Court and Dublin Boulevard. City staff was able to hire Kasler Construction Co.. who had a backhoe in the area, to remove about 1 0 to 20 cubic yards of debris from the blocked Zone 7 flood control channel at Scarlett Court. The State pumped water from the freeway and Scarlett Court and cleared the pipes on the freeway. The water finally drained on Tuesday. 3. Douaherty Road A. Water flowed onto Dougherty at Alamo Creek Park. A drop inlet plugged with silt and other debris between the east side of Dougherty Road and the bike path. The crew unplugged the drain. B. A drain backed up at Camp Parks entrance resulting in some mud on the bike path. The drain was unclogged by City staff. 4. Caroline Court There was a report that some backyards were flooded and water was on Caroline Court. By the time City staff got word of the report. the water had ~~, 0/ ~ ~ ~ 'r~'\ ':':'1-' :. ..':.':!. ~ . .. ..j' ; .,' j " ,; ", . - " . ~~'-.;..d ...........;j u. -' ~"_./:J a H~s \'t>fùít VI2-("ìS- m Incidents from Storm of January 9-12. 1995 Poge 2 receded. The condition was probably caused by the volume of water andlor blockage in the ditch on the east side of San Ramon Road being greater than the system could handle. 5. San Ramon Road Water went over the edge of the embankment in the ditch between Shannon Park and San Ramon Road (between West Vomac and Shannon Avenue). All southbound San Ramon lanes were under water. Crews closed the street and posted "Flooded" signs. The crew returned later in the night and reinforced the bank with sandbags. The water receded quickly once the rain slowed. and the road was reopened within a couple of hours. 6. Staaecoach Road Small amounts of mud washed onto Stagecoach Road near Jade Circle due to catch basin that takes water from the Dougherty Hills Open Space which backed up. The crew barricaded around the debris and removed it on 1/10. 7. Villaae Parkwav The V-ditch at the rear of the business properties on the east side of Village Parkway was three-quarters full of water due to debris plugging the inlet to the pipe under Lewis Avenue. At the request of the property owner, who asked if the "City could help him out on this one." a City crew cleared the inlet and removed the debris. 8. Amador Valley Blvd. Alameda County Flood Control. Zone 7. had crews working to clear the box culvert under Amador Valley Blvd. near Wildwood on 1 III and 1/12. Several trees from upstream were lodged in the culvert. 9. General Several drop inlets in residential areas backed up temporarily. There were no reports of damage. Calls were also received from residents who expressed concerns about trees they thought might fall and V-ditch flow levels in their backyards. Apparently, there is still some confusion by some owners as to who is responsible for the maintenance of these ditches which are located in many backyards of homes on the west side of Dublin. The City responds only on an emergency basis. as these ditches are on private property and usually inaccessible to equipment. In one case on Manzanita, neighbors helped clear the problem and no water got into homes. Incidents from Storm of January 9-12. 1995 Page 3 The problem was created by another neighbor not maintaining his section of the ditch. A call also came in from a resident on Carlow Way regarding runoff from Murray School. He was referred to the School District. No damaged was reported. PARKS 1. Douaherty Hills Open Space A. Behind homes on Crossridge Road on the east side of the hills: There were two small slides which blocked the V-ditch at the southern end of Crossridge, resulting in water flows down the slope into some back yards and a couple of houses to a small extent. There was also a complaint from the 7900 area of water and mud coming into back yards, although it is not believed water ever went over the V-ditch. Crews dug out the V-ditch on the southern end at the slides with the help of residents. Plastic has been put over the slides and a silt fence installed. B. Two small slides behind the homes on Jade Circle (west side of Dougherty Hills). Crews cleaned out V-ditches and have put plastic over the slides. There is no evidence of any problems with the houses below, nor have we received any complaints from residents on Jade Circle. C. There was a slide from the open space into the landscaping on South Topaz Circle with minor damage to the landscaping. Also, there was some erosion on the North Topaz landscape with minor damage. The areas were cleaned up on Thursday, January 12. 2. Staqecoach Park The playground was flooded. There was no significant damage. 3. Kolb Park Some small branches fell from Eucalyptus trees at the tennis court, and the tennis courts were closed. 4. Dolan Park There were small amounts of erosion and the playground flooded but no significant damage. · hcìdents from Storm of January 9-12.1995 Page 4 5. Alamo Creek Park The playground was temporarily under water, with no significant damage. 6. Shannon Park The playground was flooded. The fountain pit flooded, resulting in probable damage to the electrical panel and two pumps. Water was pumped out and the sump pump put back into operation. A dollar estimate for the fountain pit is not available at this time, but it could be as much as $2- to $3,000. 7. Heritaae Center Some grave sites sank. Repairs will need to wait until the ground dries out more. BUILDINGS 1 . Senior Center Water flooded 1/2 of the social hall and offices. it appears the water came under the east door because water from the exterior downspout got hung up in the landscaping instead of going into the parking lot. The crew put an extension on the downspout into the parking lot. and the janitors cleaned up the water inside the building. The crew also sandbagged the patio off of the office to prevent water from getting into the office. 2. Civic Center Several leaks occurred in the Police Wing and one in the Administrative Wing. The Police leaks were mostly caused by a backed up roof drain. The drain was unclogged and window leaks were resealed. One HV AC unit is leaking rainwater and will require approximately $2,000 to repair. 3. Shannon Center Water came under the door of the AB room and about 12 feet inside the room. The janitor extracted the water on January 12. ESTIMATED DAMAGES The businesses on Scarlett Court were the hardest hit by the flooding from Channel G-1 next to U-Haul. Businesses on Dublin Court were also damaged by flood waters. The following list of damage estimatés are either from newspaper sources or interviews with the businesses: Incidents from Storm of January 9-12.1995 Page 5 Business Kell Mechanical Pool and Electrical Products EI Monte RV Valley Nissan Dolan Lumber Crossroads Toyota Rental World Quoted Damaae (Dollars) $30 - 40.000 $10 - 20.000 $30.000 $1 .5 Million $500.000 $1 .5 Million $4 - 5.000 It was also reported that the California "Z" Clinic had 16 cars damaged. but this was not confirmed as of the date of this report. o:{mointenance)\ 95-1 \stormdmg