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3.1 TOWN OF LOS ALTOS HILLS January 17, 2008 Staff Report to the Planning Commission RE: SITE DEVELOPMENT PERMIT FOR A NEW 10,975 SQUARE FOOT TWO STORY RESIDENCE, 960 SQUARE FOOT SECONDARY DWELLING UNIT, TENNIS COURT, SWIMMING POOL, AND HORSE BARN; LANDS OF LOS ALTOS HOMES LLC; 26462 PURISSRvIA ROAD; FILE#166-07-ZP-SD-GD. FROM: Brian Froelich, AICP, Associate Planner APPROVED BY: Debbie Pedro,AICP,Planning Director RECOMMENDATION: That the Planning Commission: Approve the requested Site Development Permit for the new residence, subject to the conditions of approval in Attachment 1. ALTERNATIVE: Continue the project to a future Planning Commission hearing and direct the applicant to work with neighbors to address the issues raised. BACKGROUND The subject property is located on the west side of Purissima Road. The flag shaped property has a net size of 2.00 acres. The site is undeveloped with an average slope of 7.3%. The site is largely devoid of trees except a row of pine trees that will be preserved. The proposal complies with all of the Town's development standards and was heard at a Fast-Track hearing on October 23, 2007. Nine neighbors attended the hearing and voiced project concerns. that were not resolved,and the hearing was rescheduled for Planning Commission review.The applicant has met with neighbors to discuss and attempt to.work through the issues since the October hearing. CODE REQUIREMENTS Per Section 10-2.1305.1 (c), The Planning Director shall submit an application for a project to the Planning Commission if the Director determines that there is substantive neighborhood opposition to the project. DISCUSSION Site Data: Gross Lot Area: 2.032 acres Net Lot Area: 2.004 acres Slope:Average e: 7.3% P Lot Unit Factor: 2.002 Planning Commission j Lands of Los Altos LLC January 17,2008 Page 2 Floor Area and Development Area: Area Maximum Proposed Existing Increase Left Development 30,060 30,029 0 30,029 1 Floor 11,935 11,935 0 11,935 0 Site and Architecture The design of the proposed residence and site amenities utilizes all of the developable square footage for the site. The design, however, does not include a basement. The exterior materials include smooth stucco and concrete file roof. The proposed residence complies with floor area, development area, setback, and height standards per Title 10 of the Municipal Code. The proposal would also comply with the recently heard Estate Homes Ordinance (although the timing of this review makes this proposal exempt from the Estate Homes requirements). Driveway&Parking The proposed driveway will enter from Purissima Road and extend approximately 400 feet to the residence. The building design incorporates an attached, four (4) car garage and one uncovered parking space. The proposed driveway conforms to Fire Department standards for a Fire Truck Turnaround. Outdoor Li hting Outdoor lighting is shown on the floor and elevation plans (sheets A-2.1 and A-3.3). Standard lighting is requested, with two (2) per double door exit,.1 light per single door exit, and building perimeter lighting. The standard lighting condition (#4) for outdoor lighting, requires that fixtures be downshielded or have frosted/etched globes. The applicant will submit landscape lighting details with the required landscape screening plan. Accessory Structures The applicant proposes to fally develop the site. The proposal includes: • A detached single-story secondary dwelling totaling 960 square feet sited to the southwest of the main residence. • Swimming pool and pool decking totaling 3,120 square feet of development area south of the main residence. • A tennis court totaling 3,520 square feet of development area. • A horse stall totaling 215 square feet of development area. Planning Commission Lands of Los Altos LLC January 17,2008 Page 3 Neighbor's Concerns Nine neighbors attended the October 23, 2007 Fast Track hearing. The primary issues raised were site drainage, building bulk and visibility, and potentially increased freeway noise due to reflected sound from the new building. Neighbors have also written letters to the Planning Department documenting project concerns (Attachments#7-10). Site Drainage-Neighbors have written the Planning Department noting the existing drainage patterns in the area and seasonal flooding. There is concern that increased runoff will result from the proposed development and increased flooding. The Town currently requires that all new residences and major projects be accompanied by hydrology calculations and drainage system designs to mitigate increased runoff due to development. The system must be designed to capture runoff so that post development calculations match the predevelopment calculations. The calculations are based on an Intensity-Duration-Frequency(IDF) chart established by Santa Clara County for use by engineers in calculating runoff. The proposed drainage design consists of down spouts tied to perforated pipes and an underground detention facility that has a storage capacity of 945 cubic feet or approximately 7,500 gallons of water. The design complies with the Town's requirements based on the County's IDF chart. Building Bulk and Visibility-Several neighbors at the hearing noted the possibility of resiting the building to the south of the proposed location because of the size and magnitude of the proposal. The applicant has responded by increasing the setbacks to comply with the Estate Homes standards (although not enforceable at this time). The Planning Department also received a letter from the adjacent neighbor at 26430 Purissima Road who is not in favor of relocating the building to the south side of the property because it will severely impact his views and privacy. (Attachment#11) The proposed building complies with all height, floor area, and setback standards. Bulk and visibility of a structure is an issue that can be addressed during the landscape screening hearing. Staff is recommending that the landscape screening plan be reviewed by the Planning Commission for this project (condition#2). Reflected Sound-Freeway noise in the neighborhood is a concern and neighbors raised the issue of increased noise due to reflected sound off of the proposed building. The applicant has submitted an acoustical analysis prepared by Mei Wu Acoustics (Atachment #3). The study take_s into account potential for increased noise levels from four(4) locations: 1. 26469 Purissima Road-Lands of Broydo 2. 26470 Purissima Road-Lands of Kirkpatrick 3. 26500 Purissima Road-Lands of Hickman Planning Commission , Lands of Los Altos LLC January 17,2008 Page 4 4. 26462 Purissima Road-Applicant The study summarizes that the predicted noise reflection will at location#2-Lands of Kirkpatrick is the most susceptible to a noise increase. However, the predicted noise increase at location#2 would be 0.2 dBA, an increase that is not considered significant and is not audible to human hearing. Grading The Engineering Department has reviewed the plans and has recommended conditions of approval as specified in Attachment 1. Grading quantities include 3,470 cubic yards of cut and 700 cubic yards of fill. The maximum cut depth is four(4) feet. The Engineering Department will review the final grading and drainage plan prior to acceptance of plans for building plan check. Final grading and drainage will be inspected by the Engineering Department, and any deficiencies will be required to be corrected prior to final inspection. Fire Department Review The Santa Clara County Fire Department reviewed the plans and has required that the building be sprinklered and the driveway to accommodate a .standard Fire Truck Turnaround. Committee Review The Pathway Committee recommends construction of a Type 2B pathway along the property frontage adjacent to Purissima Road. The Environmental Design Committee commented that there should be no lighting in the proposed skylight wells and that the existing trees on site should be retained for screening. ENVIRONMENTAL REVIEW(CEQA) The proposed single family residence is categorically exempt from the provisions of the California Environmental Quality Act by provision of Sections 15303(a)&(e). ATTACHMENTS 1. Recommended conditions of approval 2. Fast-Track Hearing Fact Sheet, October 23, 2007 3. Mei Wu Acoustics-Acoustic Evaluation, December 17, 2007 4. Recommendations from Santa Clara County Fire Department dated August 16, 2007 5. Recommendations from Pathways Committee dated August 27, 2007 6. :Recommendations from Environmental Design Committee dated August 20, 2007 a Planning Commission Lands of Los Altos LLC January 17,2008 Page 5 7. Letter from Neighbors dated October 14, 2007 8. Emails from from Bob Kirkpatrick, 26470 Purissima Road dated 1/9/08, 11/19/07, 11/13/07, 11/8/07, 10/28/07, 10/27/07, and 10/22/07 9. Letter from Samuel and Lina Broydo, 26496 Purissima Road dated October 17, 2007 10. Letter from Keui-wu and Leslie Tsai, 26510 Purissima Road dated October 18, 2007 11. Letter from Palaniappan Jambulingam, 26430 Purissima Road dated November 20, 2007 12.Proposed development plans (Commission only) Attachment 1 Planning Commission Lands of Los Altos LLC January 17,2008 Page 6 RECOMENDED CONDITIONS FOR SITE DEVELOPMENT PERMIT FOR A NEW RESIDENCE AND SWIMMING POOL LANDS OF LOS ALTOS HOMES LLC, 26462 PURISSIMA ROAD File#1 66-07-ZP-SD-GD PLANNING DEPARTMENT 1. No other modifications to the approved plans are allowed except as first reviewed and approved by the Planning Director or the Planning Commission, depending on the scope of the changes. 2. After completion of rough framing and prior to the time of the pre- rough framing inspection by the Planning and Engineering Departments, the applicant shall submit a landscape screening and erosion control plan for review by the Planning Commission. Particular attention shall be given to plantings which will be adequate to break up the view of the new residence from surrounding properties and streets. Particular attention shall be paid to landscaping that will help break up the view of the house from the adjacent properties. All landscaping required for screening purposes and, for erosion control (as determined by the City Engineer) must be installed prior to final inspection of the new residence. 3. A landscape maintenance deposit in the amount of$5,000'shall be posted prior to final inspection. An inspection of the landscape to ensure adequate establishment and maintenance shall be made two years after the installation. The deposit will be released at that time if the plantings remain viable. 4. All new exterior lighting fixtures shall have white/frosted/etched glass enclosures or be shielded light fixtures. Seeded or bent glass is not acceptable. No landscape or site lighting is approved with this plan. Landscaping and site lighting shall be reviewed with the landscape screening plan. All lighting must comply with the Town's Lighting Policy prior to final inspection. 5. Prior to requesting the foundation inspection, a registered civil engineer or licensed land surveyor shall certify in writing and state that "the location of the residence and roof eaves are no less than 40' from the front property line and. 30' from the side and rear property lines.". The elevation of the residence shall be similarly certified in writing to state that "the elevation of the residence matches the elevation and location shown on the Site Development plan." The applicant shall submit the stamped Planning Commission Lands of Los Altos LLC January 17,2008 Page 7 and signed letter(s) to the Planning Department prior to requesting a foundation inspection. 6. Skylights shall be designed and constructed to reduce emitted light. No lighting may be placed within skylight wells. 7. Air conditioning units shall be located a minimum of 40' from the front property line and 30' from the side and rear property lines. 8. No new walls, fencing or gates shown on site plan sheet ALL are approved with this permit. Any new walls, fencing or gates require a Fence Permit and shall require review and approval by the Planning Department prior to installation. 9. Fire retardant roofing(class A) is required for all new construction. 10. For swimming pools, at least one of the following safety features shall be installed to the satisfaction of the Town Building Official: a. The pool shall be isolated from access to the residence by an enclosure (fencing). b. The pool shall be equipped with an approved safety pool cover. c. The residence shall be equipped with exit alarms on those doors providing direct access to the pool. d. All doors providing direct access from the home to the swimming pool shall be equipped with a self-closing, self-latching device with a release mechanism placed no lower than 54 inches above the floor. 11. Standard swimming pool conditions: . a. Lights shall be designed so that the source is not visible from off-site. b. Drainage outfall structures shall be constructed and located to the satisfaction of the City Engineer. c. Pool equipment shall be enclosed for noise mitigation and screening. The pool equipment enclosure shall be screened with landscaping and may not encroach into any required setbacks. 12. All existing Blue Gum(E. globulus), Pink Ironbark(E. sideroxylon rosea), River Red Gum (E. camaldulensis), Swamp Gum (E. rudis), Honey Gum (E. melliodora), or Manna Gum (E. viminalis) eucalyptus trees on the property located within 150' of any structures or roadways shall be removed prior to final inspection of the new residence. Removal of eucalyptus trees shall take place between the beginning of August and the end of January to avoid disturbance of nesting birds protected under the Federal Migratory Bird Treaty Act (MBTA) and California Department of Fish and Game Code Section 3500 et seq unless a nesting bird survey is first _ Planning Commission Lands of Los Altos LLC January 17,2008 Page 8 conducted and there is a determination that there are no active nests within the tree. ENGINEERING DEPARTMENT 13. Peak discharge at 26462 Purissima Road, as a result of Site Development Permit 166-07, shall not exceed the existing pre-development peak discharge value of the property. Detention storage must be incorporated into the project to reduce the anticipated peak discharge to the pre- development value. Provide the data and peak discharge hydrologic model(s) utilized, as well as, the calculations of the peak discharge value prior and post development. Determine the design peak runoff rate for a 10-year return period storm and provide detention storage design plans to reduce the predicted peak discharge to the pre-development value. All documentation, calculations, and detention storage design (2 plan copies) shall be submitted for review and approval to the satisfaction of the City Engineer prior to acceptance of plans for building plan check. Prior to final inspection, a letter shall be submitted from the project engineer stating that the detention storage design improvements were installed as shown on 'the approved plans and in accordance with their recommendations. 14. Any, and all, changes to the approved grading and drainage plan shall be submitted as revisions from the project engineer and shall first be approved by the Town Engineering Department. No,grading shall take place during the grading moratorium (October 15 to April 15) except with prior approval from the City Engineer. No grading shall take place within ten feet of any property line except to allow for the construction of the driveway access. 15. All public _utility services serving this property shall be placed underground. The applicant should contact PG&E immediately after issuance of building permit to start the application process for undergrounding utilities which can take up to 6-8 months." 16. At the time of foundation inspection for the new residence and prior to final inspection, the location and elevation of the new residence shall be certified in writing by a registered civil engineer or licensed land surveyor as being in/at the approved location and elevation shown on the approved Site Development plan. At the time of framing inspection for the new residence, the height of each building shall be similarly certified as being at the height shown on the approved Site Development plan. 17. Two copies of an erosion and sediment control plan shall be submitted for review and approval by the Engineering Department prior to acceptance of Planning Commission Lands of Los Altos LLC January 17,2008 Page 9 plans for building plan check. The contractor and the property owner shall comply with all appropriate requirements of the Town's NPDES permit relative to grading and erosion/sediment control. The first 100 feet of the driveway shall be rocked during construction and all cut and fill slopes shall be protected from erosion. All areas on the site that have the native soil disturbed shall be protected for erosion control during the rainy season and shall be replanted prior to final inspection. 18. Two copies of a grading and construction operation plan shall be submitted by the property owner for review and approval by the City Engineer and Planning Director prior to acceptance of plans for building plan check. The grading/construction operation plan shall address truck traffic issues regarding dust, noise, and vehicular and pedestrian traffic safety on Purissima Road and surrounding roadways, storage of construction materials, placement of sanitary facilities, parking for construction vehicles, clean-up area, and parking for construction personnel. A debris box (trash dumpster) shall be placed on site for collection of construction debris. Arrangements must be made with the Los Altos Garbage Company for the debris box, since they have a franchise with the Town and no other hauler is allowed within the Town limits. 19. The property owner shall inform the Town of any damage and shall repair any damage caused by the construction of the project to pathways, private driveways, and public and private roadways,prior to final inspection and release of occupancy permits and shall provide the Town with photographs of the existing conditions of the roadways and pathways prior to acceptance of plans for building plan check. 20. The driveway shall be required to be fully constructed and to be roughened where the pathway intersects, to the satisfaction of the City Engineer,prior to final inspection. 21. The property owner shall be required to connect to the public sanitary sewer prior to final inspection. A sewer plan that is prepared by a registered civil engineer shall be required to be approved by the City Engineer prior to acceptance of plans for building plan check. An as-built mylar copy of the sewer plan shall be required to be submitted to the Town prior to final inspection. An encroachment permit shall be required by the Town's Public Works Department for all work proposed within the public right of way prior to start work.A sewer hook-up permit shall be required by the Town's Public Works Department prior to submittal of plans for building plan check. Planning Commission Lands of Los Altos LLC January 17,2008 Page 10 22. The property owner,shall dedicate a 30' wide half-width public right of way to the Town over Purissima Road. The property owner shall provide legal description and plat exhibits that are prepared by a registered civil engineer or a licensed land surveyor and the Town shall prepare the dedication document. The dedication document, including the approved exhibits, shall be signed and notarized by the property owner and returned to the Town prior to submittal of plans for building plan check. 23. The property owner shall construct a type 2B pathway adjacent to Purissima Road to the satisfaction of the Engineering Department prior to final inspection. FIRE DEPARTMENT 24. Approved numbers or addresses shall be placed on all new and existing buildings in such a position as to be plainly visible and legible from the street or road fronting the property. Numbers shall contrast with their background. 25. The applicant shall install an approved fire department engine driveway and turnaround with a minimum radius of 36 feet outside and 23 feet inside. Installations shall conform to Fire Department Standard Details and Specifications D-1,prior to final inspection. 26. The property owner shall provide an automatic residential fire sprinkler system approved by the Santa Clara County Fire Department throughout all portions of the new residence. Three copies of plans prepared by a State of California licensed fire protection contractor shall be submitted to the Planning Department-prior to acceptance of plans for building plan check. The fire sprinkler plans shall be approved by the Fire Department prior to issuance of building permit. The sprinklers shall be inspected and approved by the Fire Department,prior to final inspection. 27. The driveway shall be required to be fully constructed, to the satisfaction of the Santa Clara County Fire Department,prior to fi"nal inspection. BUILDING DEPARTMENT 28. Properties must pay School District (Los Altos or Palo Alto) fees prior to acceptance of plans for building plan check from Los Altos Hills. The applicant must take a copy of required fee payment forms that have been completed by the Town to both the elementary and high school district offices, pay the appropriate fees and provide the Town with a copy of their receipts. Planning Commission Lands of Los Altos LLC January 17,2008 Page 11 Please call 650-941-7222 extension 235 to schedule a final inspection with the Planning . and Engineering Departments at least two weeks prior to scheduling the final building inspection approval. CONDITION NUMBERS 13, 17, 18, 19, 21, 22, 26, AND 28 SHALL BE COMPLETED AND SIGNED OFF BY TOWN STAFF PRIOR TO ACCEPTANCE OF CONSTRUCTION PLANS FOR PLAN CHECK BY THE BUILDING DEPARTMENT. NOTE: This Site Development permit is valid for one year from the approval date (until January 17, 2009). All required building permits must be obtained within that year and work on items not requiring a building permit shall be commenced within one year and completed within two years. Attachment 2 Town Of Los Altos Hills October 23, 2007 Fast Track Hearing Fact Sheet Project Description: New Residence, Secondary Dwelling Unit and Swimming Pool File Number: 166-07-ZP-SD-GD Site Address: 26462 Purissima Road Owner(s): Los Altos Homes LLC Staff Planner: Brian Froelich,AICP, Associate Planner Site Data Net Lot Area: 2.004 acre Average Slope: 7.3 % Lot Unit Factor: 2.004 Floor and Development Area: Area Maximum Proposed Existing Increase Left Development 30,060 29,765 0 29,765 295 Floor 12,024 11,922 0 11,922 102 Height: Maximum Proposed On Vertical Plane 27 feet 27 feet Lowest to Highest 35 feet 27 feet Setbacks: Minimum Proposed Front 40 ft. 300 ft. Sides 30 ft. 31 ft. Rear 30 ft. 31 ft. Parking: Required spaces: 5 out of setbacks. Proposed: 5 (4 garage spaces) ) Grading: 3,470 cu.yds. cut 700 cu.yds. fill Sewer/Septic: Connect to sewer. Environmental Design Committee:No lighting skylight wells. Preserve existing trees. Pathways Committee: Install Pathway in the right-of-way along Purissima Road. Attachment 3 RECEIVED Mei Wu Acoustics DEC 2g 2007 _ Experts in acoustics, noise and vibration TOWN OF LOS ALTOS HILL To: Dipesh Gupta,LC Engineering dipeshgupta@shashillc.com From: Travis Lawrence,Mei Wu Acoustics travis.lawrence@mei-wu.com Mei Wu,Mei Wu Acoustics meiwu@mei-wu.com Date: December 17,2007 Subject: Los Altos Hills Residential Reflected Traffic Noise Study MWA Project- 07060 A sole, new housing development is under construction at 26462 Purissima Road in Los Altos Hills, CA. The location of this new two story house is approximately 500 feet from Highway 280 and approximately 200 feet from the nearest neighbor's house. The close proximity of Highway 280 and the particular geometry of the traffic noise incident on the future house have brought a request by the neighbors to review how this new house will reflect traffic noise. This request is to specifically review reflections of traffic noise off of the new house and determine if these reflections will produce bothersome noise problems at the neighbors' houses. The reflected noise will be considered bothersome if, based on measurement and calculation; the noise is determined to violate any noise ordinances for the City of Los Altos Hills or if there is a predicted increase in the neighbors' yards exceeding 5 dB. 1. Community Noise Equivalent Level (CNEL) CNEL stands for "Community Noise Equivalent Level". It represents the average (the original did not say energy average) noise level during a 24-hour day, adjusted to an equivalent level to account for the lower tolerance of people to noise during evening and nighttime periods relative to the daytime period (this means adding 5 and 10 "penalty" decibels to the actual evening and nighttime noise levels, respectively). It is usually used for airport noise. The usual criterion is that the interior CNEL due to aircraft noise is 45 dB or less in all habitable rooms. 2. Los Altos Hills Noise Ordinances The city of Los Altos Hills provides noise ordinances using the CNEL scale. Based on the document titled General Plan: Noise Element 10/17/07, the rating of noise is dependant on how close a residence is to a major road or highway. The CNEL ratings range from 65 CNEL on the highways and major roads, to 60 CNEL for areas that are along a highway or major road, to 55 and lower CNEL for all areas that are further from highways and roadways. A composite map that includes the Purissima Road site and CNEL designations is shown in Figure 1. The CNEL ratings for the red, yellow, and blue lines are 65, 60 and 55 CNEL respectively. Mei Wu Acoustics 1 3 Twin Dolphin,Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675/www.mei-wu.com -fc_�' ,s -`fi`•.tx"'4" r �� .� i�- -�` # - ''.r.Si' q•'V 'a-n tea.-5 .� i° O s � � Vii,'` �-�; ��da -rTa -mid-�-�' � Y .+. t+ y-�' � ,•� a�-.t'r"1_� ,�'�,-3• ��'3' f�.:.z 3:.a��.4 �. I: �r a t § G� ,z�• -e �t t .yam s r: s} ��� Ng�IS sue 1 �'b3 � j it -r 4'I �a4'�,7�i$sl5 91d LOSi�fiD 0W�+�{04 L -{� _ l- - .4. v 16 —VV� x.5 !Ag, Ws �,$ r-` jjp I • /• 1 • of • ° /• • • / 11 so 1 1 •/1 / �1 1 1 1 / • • / • 11 1 • 1 / • ° 1 • 1 1" I 1 " 11" • • • • of • 1 11 • "/ / /' • / "/ •• • • - '1 -• ••• •'1. _ �:_.. - - - - •yr =- II � L - AMR Figure 2:Measurement Locations The results from these measurements are providing octave band data as well as the overall noise level (Leq) in Table 1 with the corresponding graph in Figure 3. Location Leq (dBA) Fre uency (Hz) 63 125 250 500 1000 2000 4000 3000 1 52.1 57.9 52.1 49.0 49.1 48.3 43.0 39.1 34.8 2 51.5 60.4 57.3 49.5 48.6 47.5 42.5 31.4 22.7 3 51.0 64.5 54.6 1 47.5 46.7 46.3 44.3 34.7 30.3 4 54.6 65.0 59.2 1 47.9 46.0 50.6 49.2 38.7 26.8 'Fable 1:Measured Traffic Noise Data(Leg)(SOLD denotes highest level) The distance from the Highway 280 is furthest at measurement location #1 (-600 feet NE) and the closest location #2 (160 feet NE). Measurement location #4 .was taken at the approximate location of the future building facade. The measurement at location#4 will help to estimate the amount of reflected noise towards the other three locations. It is noted that measurement #4 was performed on Monday, October 29`h between the hours of 4 and 5pm, with the other three measurements performed on Thursday, November 1" between the same hours. It was of interest to perform measurements occurring while traffic density was high and avoiding traffic gridlock conditions. Mei Wu Acoustics 3 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675 /www.mei-wu.com Leq 80 _ , } 70 it i1 a 60 1 � f 5 50 2 a 3 30 4: --4 20 x 10 r 0 63 Hz 125 Hz 250 Hz 500 Hz 1.0 k 2.0 k 4.0 k 8.0 k Frequency(Hz) Figure 3:Plots of Traffic Noise from Table 1 4. Geometry of Neighborhood The general distances and angles of the Purissima Road neighborhood (Figure 4) encompass an area of approximately 8 acres, and include four properties (including the proposed new residence). An accurate depiction of the geometry of this neighborhood is necessary for determining how traffic noise will behave with the addition of the new two story building. Geometry is based on topographical contour maps, and distances are determined by architectural scale drawings. Satellite imaging software (Google Earth) is used for approximate distances outside the scope of the architectural drawing. Initial observation of the neighborhood puts location #2 as the worst case scenario for possible reflected noise, the geometry of this house can be viewed in Figure 5. This figure is drawn based mainly upon the drawing and contour maps provided by LC Engineering dated 9/10/2007, 9/12/2007 and 12/04/2007. These maps were mandatory in determining the accurate elevation of the residence at location #2, Highway 280, and the location of the future residence. The new residence in all geometry and mathematical calculation of sound propagation is defined as the worst case situation. All partitions of the new residence are defined as worst case surfaces; which infers that east exterior wall is a smooth, rectangular, absolute reflecting surface. Absolute reflecting is defined by no loss of sound energy due to absorption by any incident sound waves upon this surface. Ground and atmospheric absorption is ignored in all directions. Mei Wu Acoustics 4 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675 /www.mel-wu.com r r u - Figure 4: Overview of Purssima Road Neighborhood(New House site in Red) This designation of the neighborhood is to provide predictions of noise levels based on the source noise of traffic at location #1 and #2, reflections off of the future residence, and any distance attenuation occurring between the houses and Highway 280. Highway 280 Height=430' Height=42W Loc.#2 Height=414' 113' FF= 11 b - 30' New House 135, FF=387 Total 280 feet Figure 5:Location#2 Geometry to New House(not drawn to scale) 5. Methodology and Calculation of Reflected Traffic Noise Determining the amount of noise reflected off of a perfectly reflecting surface back towards location #2 will be done to review. the worst case scenario..This enables that a real-world result will have unaccounted factors that will further reduce the predicted value of noise due to absorption, atmospheric diffraction, and non-perfectly reflected sound waves. The amount of noise incident upon the new residence will be estimated based on the closest location measurement (location #4). Location #4 had a time averaged value (Lq) of 54.6 dB (CNEL 55 dB), and this value will be used as the amount of noise at the future facade of the Mei Wu Acoustics 5 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675 /www.mei-wu.com east wall of the new residence. The location#2 noise value was measured at 51.5 dB (CNEL 52 dBA) and is assumed to be lower than other measurements due to the barrier effect of the Kirkpatrick's residence. The sound power level(PWL) of noise can be used to predict the amount of noise that will be reflected back towards the Kirkpatrick's house. Sound power level can be extrapolated by the sound pressure level (SPL) by using the total area of reflection (entire east wall). Based on _ the 9/10/2007 drawings the east wall has a maximum surface area of 1,998 f? (186 m2). This represents the amount of noise that can reflect off of this wall, the angles of incidence upon this surface are shown in plan view (Figure 6). N IM S 3. r - - P;- - <�� "f M V � � µ H Figure 6: Plan View of Noise Geometry The plan view shows the theoretical angles that incident traffic noise would be possible to reflect back towards location#2. The angles of incidence from the traffic noise regarding the elevation of the houses is anticipated as being blocked from line of sight from the Kirkpatrick's (Figure 5) and/or the new residence will be well below the ridge line of Highway 280. The calculated noise value at location #2 from reflected noise will be approximately 38 dBA. When this is added to the originally measured value of 51.5 dBA the total noise is 51.7 dBA (CNEL 52 dBA). Mei Wu Acoustics 6 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675/www.mei-wu.com The predicted change nl traffic noise at the Kirkpatrick's house due to reflections will be less than l dB (0.18 dB) which is not a large enough differential to produce an audible change in noise level. 6. Remaining Purissima Road Residences The proposed new residence does not appear to have any significant surfaces that may cause traffic noise to reflect towards the neighbors at 26496 and 26500 Purissima Road. The residence of 26500 (Hickman's) does not present any angles of reflection for traffic noise. There is also the possibility that a new residence built may act as a noise barrier from traffic noise, reducing the measured noise at location #3. The residence at 26496 (Broydo's) has a very acute angle (Figure 7) that could allow for reflections of traffic noise. This acute angle and the increased distance between houses would not appear to increase the current traffic noise levels. It is calculated that the noise reflected from the new residence to the Broydo's back yard would be approximately 32 dB, and when combined with the current measured level 52.1 dBA (CNEL 53 dBA) increases the noise by 0.05 dB, an insignificant difference. R. ' A Figure 7: Geometry to Location#1 (Broydo's residence) 7. Los Altos Bills Noise Ordinances According to calculations the amount of increase in noise "to any of the surrounding residences will be very minimal. This leads to the understanding that all city noise ordinances for the city of Los Altos Hills will remain the same or similar to their current noise levels. According to the drawings and reviewed plans for this Purissima neighborhood no noise ordinances will be violated. 8. Summary • The traffic noise measured at the four locations along Purissima Road has CNEL ratings below 55 dBA. Mei Wu Acoustics 7 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675/www.mel-wu.com © The predicted noise from reflections is 38 dBA, and the existing noise level at location#2 is 51.5 dBA. This will give a net noise of 51.7 dBA, a differential of 0.2 dBA. The house at location #2 is considered tobe the most susceptible to any reflected noise. This increase in noise is not audible to human hearing. The planned location of a new two story residence at 26462 Purissima Road will not introduce any significant increases to noise levels to any of the neighboring houses. Mei Wu Acoustics 8 3 Twin Dolphin Drive, Suite 190, Redwood City, CA 94065-1516 (650) 592-1675 /www.mei-wu.com FIRE DEPARTMENT Attachment 4 FI �,� SANTA CLARA COUNTY RE :. 14700 Winchester Blvd., Los Gatos, CA 95032-1818 '�Cry pT•,�`` COMTESYB SERVICE (408) 378-4010 0 (408) 378-9342(fax) •www.sccfd.org Internationally Accredited Agency PLAN REVIEW NUMBER 07 2265 BLDG PE DEVELOPMENT REVIEW COMMENTS nFILE NUMBER 166-07-ZP-SD CODEISEC. SHEET NO. REQUIREMENT Review site plan for a new proposed 11,935 square foot single family residence with 960 square foot secondary unit and an attached garage. Note on cover sheet indicate applicant proposing fire sprinkler system throughout all portion of the main residence and the secondary unit. Review of this Developmental proposal is limited to acceptability of site access and water supply as they pertain to fire department operations, and shall not be construed as a substitute for formal plan review to determine compliance with adopted model codes. Prior to performing any work the applicant shall make application to, and receive from, the Building Department all applicable construction permits. AA pendia 1 Required Fire Flow: The fire flow for this project is 3000 gpm at 20 psi residual - pressure. As an automatic fire sprinkler system will be installed, the fire flow has been reduced by 507o establishing a required adjusted fire flow of 1500 gpm at 20 psi residual pressure. The adjusted fire flow is available.from area water mains and fire hydrant(s) which are not spaced at the required spacing. 03.1.2 as 2. Automatic Fire Sprinkler System Required: Buildings requiring a fire flow in Amendedby excess of 2,000 GPM shall be protected throughout by an automatic fire sprinkler LAHMC system, hydraulically designed per National Fire Protection Association (NFPA) 8-8.0.1 Standard #13D. A State of California licensed fire protection contractor shall submit plans, calculations, a completed permit application and appropriate fees to this department for review and approval prior to beginning their work. City PLANS SPECS NEW RMDL AS OCCUPANCY CONST.TYPE ApplicantName DATE PAGE LAH ® ❑ ❑ ❑ . ❑ TD BUILDING DESIGN 8/16/2007 1 OF 3 SECJFLOOR AREA LOAD DESCRIPTION BY Residential Construction Amadkani, Fred NAME OF PROJECT LOCATION SFR 26462 Purissima Rd Organized as the Santa Clara County Central Fire Protection District Serving Santa Clara County and the communities of Campbell, Cupertino,Los Altos, Los Altos Hills,Los Gatos,Monte Sereno,Morgan Hill,and Saratoga pLARA eon FIRE DEPARTMENT Go�m;FR SANTA CLARA COUNTY 14700 Winchester Blvd., Los Gatos, CA 95032-1818 COIIRTESY65ERVICE (408) 378-4010 ® (408) 378-9342(fax) ® WWW.sccfd.org - Internationally Accredited Agency PLAN REVIEW NUMBER 07 2265 BLDG PERMIT NUMBER DEVELOPMENT REVIEW COMMENTS FILE NUMBER 166-07-zP-SD. CODE/SEC. SHEET NO. REQUIREMENT �C . 3 Fire Apparatus (Engine)Access Driveway Required: Provide an access driveway 2.2.4.1 with a paved all weather surface, a minimum unobstructed width of 14 feet, vertical clearance of 13 feet 6 inches,minimum circulating turning radius of 36 feet outside and 23 feet inside, and a maximum slope of 15%. Installations shall conform to Fire Department Standard Details and Specifications sheet D-1. The proposed driveway meets the Standard Details and Specifications sheet D-1 requirements. PPendix 4. Fire Department (Engine) Driveway Turn-around Required: Provide an .A approved fire department engine driveway turnaround with a minimum radius of 36 feet outside and 23 feet inside. Installations shall conform with Fire Department Standard Details and Specifications D-1. The proposed fire department turn around meets the Standard Details and Specifications sheet D-1 requirements. FC 5. Emergency Gate/Access Gate Requirements: Gate installations shall conform with )2.2.4.1 Fire Department Standard Details and Specification G-1 and, when open shall not obstruct any portion of the required width for emergency access roadways or driveways. Locks, if provided, shall be fire department approved prior to installation. 6. Gates across the emergency access roadways shall be equipped with'an approved access devices. If the gates are operated electrically, an approved Knox key switch shall be installed; if they are operated manually,then an approved Knox padlock shall be installed. City PLANS SPECS NEW RMDL AS OCCUPANCY CONST.TYPE AppllcantName DATE- PAGE AH ® ❑ ❑ .❑ ❑ TD BUILDING DESIGN 8/16/2007 2 OF 3 ;C./FLOOR LOAD DESCRIPTION BY Residential Construction Amadkani, Fred LAME OF PROJECT LOCATION SFR 26462 Purissima Rd Organized as the Santa Clara County Central Fire Protection District Serving Santa Clara.County and the communities of Campbell,Cupertino,Los Altos, Los Altos Hills,Los Gatos, Monte Sereno,Morgan Hill,and Saratoga FIRE DEPARTMENT FIRE "� SANTA CLARA COI. NTY 14700 Winchester Blvd., Los Gatos, CA 95032-1818 LOURiESY a SFA VICE (408) 378-4010 • (408)378-9342(fax) •VJWW.sccfd.org _ Internationally Accredited Agency PLAN REVIEW NUMBER 07 2265 NUMBER BLDG PERITNUMBER 166-®7-ZP-S® DEVELOPMENT REVIEW COMMENTS CODE/SEC. SHEET NO. REQUIREMENT UFC 7. Premises Identification: Approved numbers or addresses shall be placed on all 901.4.4 new and existing buildings in such a position as to be plainly visible and legible from the street or road fronting the property. Numbers shall contrast with their background. To prevent plan review and inspection delays, the above noted Developmental Review Conditions shall be addressed as "notes" on all pending and future plan submittals and any referenced diagrams to be reproduced onto the future plan submittal. City PLANS SPECS NEW RMDL AS OCCUPANCY CONST.TYPE ApplicantNama DATE PAGE LAH ® ❑ ❑ ❑ ❑ TD BUILDING DESIGN 8/16/2007 3 OF 3 SEC./FLOOR AREA LOAD DESCRIPTION BY Residential Construction Amadkani, Fred NAME OF PROJECT LOCATION SFR 26462 Purissima Rd Organized.as the Santa Clara County Central Fire Protection District Serving Santa Clara County and the communities of Campbell,Cupertino,Los Altos, Los Altos Hills,Los Gatos,Monte Sereno,Morgan Hill,and Saratoga li Attachment 5 Los Altos hills Pathway Committee DRAFT Minutes of Meeting August 27,2007 1. ADIVIINSTRATIVE Chairman Ginger Summit called the meeting to order at 7:10 PM Members present: Jim Bliss,Courtenay Corrigan,Nick Dunckel,Ginger Summit, Bill Silver,Bob Stutz,Jolon Wagner,Chris Vargas,Sue Welch Members absent: Anna Brunzell,Nancy Ginzton, Council Members present: Councilman Mike O'Malley Town Staff present: Brian Froehlich,Associate Planner Members of public present: Orrs,owners of 26285 Altamont Road Linda Yee and Dipesh Gupta,representing owners of 26462 Purissima Road Lili Milano,architect,26990 Arastradero Road(Lands of Ng) The agenda was approved as amended below. 1. NEW BUSINESS A. Review of pathway in-lieu fee calculation.Brian Froelich,Associate Planner,LAH Planning Department,presented a summary of different methods to calculate pathway in-lieu fees based on 1)square root of square footage of lot;2)average width of lot;3)perimeter of lot; 4 length of street frontage.Brian favors using the square of square footage of lot because it is more consistent and objective than other methods and thus spreads the cost of the Town pathway system more equitably among all property owners.It is also the easiest to calculate. The LAH General Plan specifies that the in-lieu fee should be roughly proportional to the cost of installing a pathway.PWC members will review the wording about calculating the fee in the General Plan.Additional questions about in-lieu fees were raised(e.g.,whether an in-lieu fee must be paid every time a property sells). Brian will return to the PWC with the regulations addressing these issues. B. The following properties were reviewed for pathway recommendations: i. 26285 Altamont Road(Lands of Orr).The reason for pathway review is construction of a new residence.The property owners (the Orrs)were present.The property is at the corner of Altamont Road and Corbetts Lane adjacent to Packard property.Driveway access will be from Corbetta.A dirt pathway exists on this side of Altamont,which is heavily used. Construction of a IIB path along Altamont would enhance access and safety.Corbetta Lane has public access in the road and no pathway is needed. Bob Stutz moved that the PWC request the owners of 26285 Altamont Road bring the pathway along Altamont up to IIB standards.Nick Dunckel seconded.The vote was unanimously in favor. ii. 26462 Purissima Road(Lands of Los Altos Homes).The reason for pathway review is construction of a new residence.Linda Yee and Dipesh Gupta were present representing the owners.This is a flag lot on the southwest side of Purissima and is incorrectly marked as 26270 Purissima on Town parcel maps.According to LAH Resolution 38-96 (May 1996),Purissima Road should have roadside pathways on both sides.Purissima is heavily used by both cars and pedestrians. Chris Vargas moved that the PWC request that the existing pathway along Purissima on 26462 Purissima be upgraded to IIB pathway standards.Bill Silver seconded.The vote was unanimously in favor. DraftPWC_Min_o82707 i Attachment 6 I (Environmental Design and Protection Committee New Residence/Remodel JEvaluation ApplicantDate ' Name 1-tP &me--s 8- es Address Reviewed by: Site impact/lighting/noise: �vu 1 &W -Ir, Grading: Creeks, drainage, easements: Existing vegetat' n: p c t7 1 QT'S h••Q `fir AD As"W 4P A— Significant issues/comments: i Attachment 7 CED_ 723 V Purissima Neighbors a���tF�^C�5�:, 4��.SSG CdEI `ry,C i• October 14, 2007 s '••a..�. .. tet @,ti, Debbi Pedro, AICP Planning Director Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This letter is from the neighbors of the currently empty lot located.at 26462 Purissima Road.(".the Lot")which was recently purchased by speculative builders operating under the names of Shashi Corporation and Los Altos Home LLC (collectively "the Developers"). At the initiation of the Developers, a meeting was held with some of the neighbors at our home at 26470 Purissima Road, which is directly behind the Lot, on Saturday, October 13, 2007 during which the Developers shared their plans for the Lot. While the neighbors respect the right of the Developers to profitably develop the lot for resale("the Proposed Project"), there is concern that the Developers' desire to maximize such profits comes at the expense of an adverse impact on the adjacent properties and upon the general character of the neighborhood. A follow-up meeting with respect to the concerns of the neighbors has been scheduled on October 25, 2007 (two days after the public hearing on the Proposed Project) at which time the Developers indicated.that they would share their findings with respect to at least some of the issues set forth below. Magnitude of the Proposed Project The homes surrounding the Lot are relatively modest by Los Altos Hills standards, ranging from approximately 2000-4000 square feet. The Proposed Project includes a two-story mansion (the main house) of approximately 10,000 square feet, a two-bedroom guesthouse of approximately 1,000 and other structures such as a horse barn. Also included in the plan are a swimming pool, a tennis court, a sunken barbeque pit, a gazebo and a reflecting pool. The total Proposed Project, in fact, comes within a few hundred feet of the maximum development permitted on a two acre lot of this type in Los Alto Hills. The Proposed Project is clearly the desire of a"spec builder"to maximize its profits upon the sale of the developed property. The design does not reflect a"dream home"by a new neighbor and, in fact,the Developers indicated they haven't even begun to think of how. they will market the property. This is unfortunate because the intangible benefits of owning a home in which you will live such as becoming an integral part of a_c(ose-knit 4 , Page 1 of 4 neighborhood along with preserving some open space and privacy do not show up on the balance sheet of the Developers. . It is the recommendation of the neighbors that the size of the Proposed Project be scaled back to preserve additional open space and privacy with respect to the neighbors. It is the further recommendation of the neighbors that the main house be redesigned as a one- story structure. Location of the Main house The Lot is a flag lot located between Purissima Road and the 280 freeway. The main portion of the Lot, which is the location of all of the Proposed Project other than the reflecting pool and part of the driveway, is roughly rectangular. However,the main house in the Developers' proposal is not located centrally with respect to the Lot but, rather,is located in the northwest corner of the Lot directly adjacent to its neighbors at 26470 and 26500 Purissima Road. Due to the two-story design of the main house,the privacy of the neighbors is greatly reduced since the new occupants of the main house would be able to look into the yards and through the windows of its neighbors. The only apparent reason for locating the main house in this corner of the Lot is to make it maximally visible from Purissima road thereby increasing its "curb appeal." It is also positioned so that the image of the house would appear in the proposed reflecting pool. The location of the main house is,therefore, designed to stand-out, rather than to blend in, with the surrounding environment. The neighbors have recommended to the Developers that the maul house at least be moved more centrally to the main portion of the Lot. The neighbors pointed out that this could be easily accomplished by moving the location of the tennis court to the northwest corner of the lot where the main house is currently located. The neighbors have also recommended that trees be fairly densely planted around the perimeter of the Lot to reduce intrusion on their neighbors, and that outside floodlight be reduced in number and permanently aimed towards the ground. It was pointed out to the Developers that the perimeter trees would need irrigation and.that they should be selected to have a root structure which would.not endanger the integrity of the neighbor's driveways. Septic and Drainage The neighbors pointed out that the Lot is on the beginning of a watershed which runs generally northwardly towards Palo Alto. In consequence,the swale at about the location of the proposed reflecting pool turns into a swamp during the rainy season, and drains though conduits provided under the driveways of the neighbors to the north. It has been the experience of the neighbors that conduits leading under the 4 driveways to the north (and the Proposed Project calls for a 5th driveway) are not always sufficient to accommodate the runoff from the Lot, causing a partial flooding of their driveways. With the much greater ground coverage contemplated by the Proposed.Project, this condition is sure to get worse as water that would normally be absorbed into the ground is, instead, collected in the swale. Page 2 of 4 . The Developers have indicated that, in recognition of the drainage problems of the Lot, they are going to extend the city sewer line down Purissima Road to the Lot. The neighbors approve of this decision since,in our view,this is the only practical solution for the development of the Lot. Nonetheless,the neighbors to the north are concerned with increased runoff from the Lot with the potential of flooding the downstream driveways. The neighbors recommend that an engineering study be performed to determine how this problem can be addressed. Noise The Lot is a buffer zone between the 280 freeway and many of its neighbors. In its undeveloped state, it serves as an absorber of freeway sound since the freeway is elevated higher than most of the surrounding properties and,therefore,much of the sound that is heard by the neighbors is downwardly directed. There is great concern that insufficient thought has been given to the placement and configuration of the structures and/or any proposed sound walls to ensure that the Proposed Project does not increase freeway noise for the neighbors by the mechanisms of reflection and/or refraction. The neighbors proposed that the Developers obtain the services of an acoustical engineer to access the acoustical environment of the neighbors prior to finalizing the plans for the Proposed Project with the assurance that after the completion of the project that the neighbors are no worse off with respect to freeway noise than they were before, Parking Parking for the Proposed Project includes only a four car garage and one ex emal parking spot. There is relatively little street parking in our area, and what little there is, is quite a bike from the proposed main house. This amount of parking is clearly insufficient, given the fact that the Proposed Project is clearly designed as a showy entertainment home that will attract many guests. As such,the limited parking along the street is likely to become quite congested and may induce guests to drive down adjacent neighbor's driveways by mistake or in search of additional parking. The neighbors strongly recommend that additional parking be required for this project. If the tennis court was moved to the northwest comer of the lot as recommended by the neighbors, it could additionally serve as supplemental parking for large events and for emergency vehicle tum-around. Fast Track The Developers indicated that they were applying for fast-track approval. The neighbors respectfully submit that fast-track approval is inappropriate for a complex project such as this. This is no simple project of a family wanting to build a home but,rather, a project designed to maximize the profits of a spec builder. As such, full consideration of the plans of the Developers is imperative. Page 3 of 4 k ery'Frru?ly Yovers.Kfip � rick Cc: S'hashl Corp :raaion Los ;altos Homes l,i_C ✓ Brian Froelich., AICP Paul & RQ!-beeca Hickman Ueda. Yee f ag:,, =i of 4 Attachment 8 Debbie Pedro From: Bob Kirkpatrick [ Sent: Wednesday, January 09, 2008 8:41 PM To: Debbie Pedro Cc: Brian Froelich; John Chau Subject:, Lot 166-07-ZZP-SD-GD Debbie Pedro,AICP Purissima Neighbors Planning Director January 9,2008 Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This document is in response to the Mei Wu noise study the Town received on 12/28/07. A study was requested by the neighbors. Specifically the request was to compare the 1280 noise at report sites 2 and 4 to evaluate reflected noise. Since freeway noise is quite variable,I expected the measurements to be made simultaneously. Since the acoustics experts had only one Norsonic— 118 Type I sound level meter,the measurements were made serially. Therefore, the data represents general noise level not accurate comparative noise levels. Below are comments on the report but first are some paragraphs from the Town noise ordinance I noted as reference 720. Compatibility of land uses in Los Altos Hills is best achieved through analysis of each proposed use on a case-by-case basis through the site development review process. To ensure that new development is not adversely impacted by noise sources,or is itself a source of noise,the Town uses land use compatibility guidelines as part of planning and site development review. 721. The potential impacts of traffic noise and other unwanted sound should be identified and mitigation measures required as needed to meet the Town's noise standards. The most effective measures for noise attenuation include the following: ❑Site planning that is sensitive to potential noise impacts ❑Careful orientation of buildings and placement of windows ❑Increased setbacks 723. In many communities, sound walls are used to reduce freeway noise impacts on adjacent residences. In Los Altos Hills,however, sound walls are prohibited on private property adjacent to Interstate 280,primarily because they block views of surrounding countryside and tend to bounce sound to other locations. Program 2.1 Evaluate noise impacts on surrounding land uses during the site development review and permitting process. Program 2.2 Utilize the Land Use and Noise Compatibility Guidelines as a basis for - determining the compatibility of land uses. Program 2.3 To determine noise exposure,use the noise contour maps or more detailed noise analysis if appropriate. Program 2.4 Require the mitigation of all significant noise impacts as a condition of 1/11/2008 Page 2 of 2 oject approval. the last line of the report introductory paragraph; "or if there is a predicted increase in the neighbors'yards exceeding 5 3."I found no reference to 5 dB in the Town document. icidentally,by the information in figure 5,the 500 should be 278, and the 200 should be 135.) xagraph 1 and 2 are of interest to the architect but of no particular interest to the neighbors. xagraph 3 again would be of interest to the architect but the data was not taken as simultaneous measurements as expected. )wever,it is the only data available and the developers went to a lot of trouble to provide it. xagraph 4 indicates the calculations are worst case for the reflecting surface. xagraph 5 uses a value of 1998 sq ft of a perfect reflecting surface. determine the effect of reflected noise on location 2 from location 4,the existing level at 2(51.5)is modified by adding a lculated noise power reflected from location 4. its was done by taking the 51.5 dB (relative value)and finding the absolute value: i raised to the power 51.5/10, ie same was done to the 38 value shown at the bottom of page 6. ie 2 resulting values were added and returned to dB. That is: 10 log(sum) or 51.7 dB sere is no indication of where the 38 came from. This is the basis of the report conclusions. ie Town should not accept this value without supporting information. ease consider this as a sanity check for the unexplained number, 38. )nsider the 1998 sq ft perfect reflecting surface as a 20 foot high by 100 foot long wall. (Similar to the proposed house wall) )utile the wall length to 200 feet. The sound power would double and the 38 would become 41. )r reflected noise to be just noticeable on the Kirkpatrick patio, (a 3 dB noise increase)the reflected noise would have to crease from 38 to 51.5. ir this change to happen,how long wood the 20 foot high wall have to be? 2240 feet! lis is a gross simplification but if the 38 has solid basis,the Town may be able to substantially reduce restrictions on sound ills because any home 135 feet away, and on the receiving side, of a 20 foot high sound wall could not detect a noise level fference. . xagraph 6. The acoustic engineers may not have seen the development layout. They may not have known that much of the ass between the Broydo back yard and 280 will be replaced with concrete and asphalt. Since 3 of the 8 octave noise bands ow the Broydo backyard measurements as the highest noise power,reevaluation of this situation is important. addition,no thought has been given to noise at the Tsai property. xagraph 8.Again, only the architect needs this number. Very Truly Yours, G.R. Kirkpatrick '11/2008 Pagel of 2 Brian Froelich From: Bob Kirkpatrick[ Sent: Monday, November 19, 2007 12:46 PM To: Debbie Pedro Cc: Brian Froelich Subject: Lot 166-ZP-SD-GD Debbie Pedro,AICP Purissima Neighbors Planning Director November 19 , 2007 Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This e-mail addresses an aspect of encroachment of outdoor lighting that may not be routinely considered for site development. It must be considered in this case. The driveway of the proposed development approaches the garage on an up hill slope. Projecting a line following this slope intersects our wall between our living room and dinning room. In this picture,the projected line following the slope is created by parking a vehicle on the proposed driveway with the headlights turned on. The target of the headlight is seen as the bright rectangle at.the top center of the photo. This is the wall of our home. To the left are living room windows. To the right is the glass door that leads from our dinning room to our deck. An individual.sitting at our dinning room table facing this door is subject to the full direct impact of headlights about 100 feet away. Although this situation is probably temporary, it will most certainly destroy the mood at the table. As a point of reference, the orange netting seen at the upper left comer of the photo represents the corner of the proposed garage. Page 2 of 2' From the standpoint of these neighbors,there is a more serious problem. To the left and above our living room is our bedroom A time honored way of waking someone from a sound " sleep is simply to turn on the bedroom light. This picture is a view of our bedroom wall and ceiling taken with a vehicle parked in the proposed driveway. It shows a snapshot of the light that would wake the occupants as it sweeps through the room as a car enters the proposed garage. s situation is not acceptable. Very Truly Yours, G.R. Kirkpatrick 27/2007 Page 1 of 1 Debbie Pedro From: Bob Kirkpatrick[ Sent: Tuesday, November 13, 2007 10:48 AM To: Debbie Pedro Cc: Brian Froelich; John Chau Subject: Lot-166-07-ZP-SD-GD Debbie Pedro, AICP Purissima Neighbors Planning Director November 13, 2007 Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: Earlier Cyrus Kainpour reviewed for me the Santa Clara County method of determining the required runoff storage capacity for a project of this size and indicated the proposed plan exceeds this capacity. I now believe this calculation is for a containment system used to prevent roadway flooding when unusual amounts of rain runoff exceed the capacity of an existing culvert. When the rain rate decreases, the culvert is able to empty the containment system in a mater of minutes. The fill time and the empty time are similar. The proposed system is not connected to the culvert. This would defeat its purpose. Contained water dissipates by percolation, not a connected culvert. A search for perc rate specifications was found for other areas. The simple test is to create a hole in the test area, fill it with water, and measure how quickly the water surface sinks. Acceptable perc rates for septic system drain fields ranged from 1 inch per hour to 20 inches per hour. Since a summer time perc test was run on this lot, this broad requirement was likely met. The proposed winter time containment system is next to the area where a pond often forms at our culvert entrance. This ground is saturated. When the rain stops, the pond water flows through the culvert.`Small puddles remain. These puddles do not percolate at one inch per hour casting-doubt on the containment systems ability to achieve one inch per hour percolation rate. Even if the percolation rate in this saturated area met the one inch per hour minimum,when full, the five foot deep gravel pit with the 36 inch diameter pipes could take up to 2 1/2 days to empty after the rain stopped. With town staffs evaluation of the containment system, the fill time and the empty time are vastly dissimilar. They would match well using a rain per storm basis, not a rain rate over a short period basis. Since the rate of containment system output is unknown, an acceptable containment system design is unknown. Late in the winter, a perc test at the location of the containment system when there is a pond at our culvert must show a minimum of 3 inches per hour percolation rate before approval of this containment system. This is in addition to the requirement that there be no overflow during a theoretical 10 year storm. Very Truly Yours, G.R. Kirkpatrick 1/11/2009 Page 1-of 1 Debbie Pedro .From: Bob Kirkpatrick [ Sent: Thursday, November 08, 2007 10:36 AM To: Debbie Pedro Cc: Brian Froelich;John Chau Subject: Lot 166-07-ZP-SD-GD . Debbie Pedro, AICP Purissima Neighbors Planning Director November 8, 2007 Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: Yesterday November 7, 2007 at the invitation of John Chen, I met with John and the town independent civil engineering consultant, Cyrus Kainpour. The purpose of the meeting was to review proposed changes to the rain runoff containment system. Cyrus reviewed for me the Santa Clara County method of determining the required runoff storage capacity for a project of this size and indicated the plan exceeds this capacity. Cyrus asked why I felt the system is still inadequate. I asked what the rate of water dissipation.by percolation would be. To my surprise,no answer was forthcoming even though perc tests were run on the lot. . The answer to Cyrus's question is: if the rate of output is unknown, an acceptable rate of input is unknown. I believe the equation presented is fora single event and required capacity must be based on an empty storage facility. For a second event, available storage is likely unknown. In an earlier note, I provided some measured data (multiple events over 28 days). Staff simply set this aside because it was an extreme case. Granted, it was an. extreme case but data that is more typical has not been forthcoming. For multiple events,when the rate of percolation is unknown, failure must be the only reasonable conclusion. I was pleased when John suggested moving storage pipes up hill toward the house. Then connect a small pipe near the center of the storage pipe. The small pipe would be set so that water would gravity feed to the existing culvert partially draining the storage pipe over time. This in itself is not a solution but the breakout thinking is very welcome. At an earlier meeting between the developers and the neighbors,the developers were asked to relocate the main house to the south corner of the lot. We were told that town grading restrictions prohibited this change. I asked John and Cyrus about this and was told there were no grading restrictions preventing this relocation:We would be grateful for the towns' support in this matter for several of our concerns stated earlier. Very Truly Yours, G.R. Kirkpatrick 1 Page 1 of 1 Debbie Pedro From: Bob Kirkpatrick [ Sent: Sunday, October 28,2007 9:36 AM To: Debbie Pedro Cc: Brian Froelich Subject: Lot 166-07-ZP-SD-GD Purissima Neighbors October 28, 2007 Debbie Pedro,AICP Planning Director Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This e-mail is an addendum to the October 27 2007 e-mail The 450 cubic feet of rain runoff storage capacity was my recollection of the value given by the developers. With numbers on the plan, the pipes would hold 565 cubic feet with additional storage in the 1835 cubic feet of gravel. Using higher numbers and even doubling storage is not a solution to the runoff problem. Again,we request the town acknowledge this problem and seek solutions. Very Truly Yours, G.R. Kirkpatrick 1/11/2008 Page 1 of 2 Debbie Pedro From: Bob Kirkpatrick[ Sent: Saturday, October 27, 2007 9:43 AM To: Debbie Pedro Cc: Brian Froelich Subject: Lot 166-07-ZP-SD-GD Purissima Neighbors October 27, 2007 Debbie Pedro,AICP Planning Director Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This letter is a review of some things discussed during a meeting of the neighbors and the developer at the Kirkpatrick home on October 25 2007. The meeting you were unable to attend. There was some interest of homeowners along Purissima to connect to the proposed private sewer line at some later date. This is a separate issue and will involve only interested parties. The developers provided a sound level meter to test noise at various locations. The measurements showed about a 4 dB higher level at the new house relative to our patio. Our concern that there will be objectionable reflected sound is real. The developers will bring an acoustical engineer to our next as yet unscheduled meeting. Several issues of privacy were discussed with repeated requests to move the house to the south corner of the lot. We were told that town grading requirements prohibited placing a 2 story house at this location. We request the town clarify this problem and seek solutions. Again, drainage was discussed. The following excerpt is included to verify that the neighbors and the developer are working with the same requirement. Sec. 10-2.502. Drainage standards. Drainage systems shall be designed to minimize the effects of erosion, situation, and flooding on immediate or distant downstream neighbors. They shall follow regional patterns and use natural swales wherever possible. Provisions shall be made to prevent surface waters from damaging the cut face of an excavation or any portion of a fill. All drainage ways and structures shall carry surface waters to the nearest practical street, storm drain, or natural watercourse approved by the City Engineer as a safe place to receive such waters. The City Engineer may require drainage structures to be constructed or installed as necessary to prevent erosion damage or to prevent the saturation of the fill or material behind cut slopes. Drainage facilities and impervious surfaces shall be designed to prevent adjacent properties from receiving run-off from a project site, except through approved drainage channels. Drainage 9 facilities shall be constructed according to standard specifications developed by the City Engineer. To avoid additional down stream flooding the change in runoff is to be controlled. During an extensive discussion, the developers pointed out that common civil engineering practice uses a coefficient of 0.9 in calculating runoff from an impervious surface and 0.5 for an undeveloped surface. Using these guidelines,.the runoff increase of an impervious surface is the difference between 0.5 and 0.9 giving a coefficient of 0.4 for the 29,765 square feet of 1/11/2008 Page 2 of 2 :velopment. For simplicity, I will use 100 percent runoff from 12,000 square feet. (about 0.4 times 29,765) recalculation of plan suitability using the known data from the October 25 2007 e-mail and the developer's plan r about 450 cubic feet of storage which is emptied only by percolation follows below. the meeting, no one felt qualified to guess the daily volume of water that would percolate from the bottom rface of a 12 by 40 foot gravel pit given a 5 foot pressure head. This factor will make an unknown difference in calculation; however, considering how long standing water stands in this area, percolation is probably not a -ge factor to consider. ie rain fall of 11 inches in February 1998 or 11/12 feet per month times 12,000 square feet is 11,000 cubic feet of cess runoff during this month. .viding the monthly quantity by 28 days yields almost 400 cubic feet of average excess runoff per day. Since the )rage capacity of the system is about 450 cubic feet, it would fail completely on the second day and remain in the fled condition for at least 3 weeks. Le developer suggested willingness to double the storage capacity. This is not a solution. .rt of town code Section 10-2.502 is written to avoid additional down stream flooding caused by this velopment. The current design will not do this. A solution was suggested by Kirkpatrick and Broydo but was not ibraced by the developer since the town accepted their plan. We request the town acknowledge this problem and ek solutions. Very Truly Yours, G.R. Kirkpatrick 11/2008 Page 1 of 2 Debbie Pedro From: Bob Kirkpatrick [ Sent: Thursday, October 25, 2007 9:05 AM To: Debbie Pedro Cc: Brian Froelich Subject: Lot 166-07-ZP-SD-GD Purissima Neighbors October 22, 2007 Debbie Pedro, AICP Planning Director Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road Lot 166-07-ZP-SD-GD Dear Ms. Pedro: This letter is in addition to the letter dated October 22, 2007. It is an additional review of the Developers Proposed Rain Runoff Storage. At the planning meeting on Oct. 23, 2007, I asked town staff to identify rain amounts for a typical storm. Since that time, I located relevant data on the net. http://www.sfmuseum.org/histlO/98wx.html A SERIES OF STORMS CONTINUED THROUGH FEBRUARY AND BY MONTH'S END... MONTHLY RAINFALL TOTALS HAD BROKEN RECORDS. IN SAN FRANCISCO...14.89 INCHES OF RAIN FELL...BREAKING THE PREVIOUS RECORD OF 12.52 INCHES IN FEBRUARY...1878. OTHER FEBRUARY RAINFALL RECORDS INCLUDED REDWOOD CITY WITH 12.46 INCHES...SAN JOSE'S 10.23 INCHES AND MONTEREY WITH 15.00 INCHES. RAINFALL ACCUMULATIONS DURING FEBRUARY WENT A LONG WAY TOWARD SETTING RECORDS FOR THE 1997- 98 RAINFALL SEASON. SAN FRANCISCO'S RAINFALL TOTAL FOR THE WATER YEAR ENDING JUNE 30...1998 WAS 47.22...THE SECOND WETTEST YEAR ON RECORD. I believe this is a strong indication that Los Altos Hills received about 11 inches of rain in February 9 years ago. My understanding of the proposed system is that it is a passive percolation system. Using 11 inches of rain, or 11/12 feet of rain, times 29,765 square feet of impervious surface, divided by 28 days yields about 900 cubic feet of average runoff per day to percolate. To add some perspective,this is 9 (water company 100 cu ft per unit)units per day. I believe that 9 units is close to the typical monthly domestic water use for homes connected to a well proven septic tank and leach field system. The proposed passive percolation system occupies less area than a typical leach field. To expect it to be anywhere near 28 times better is very unlikely. I suspect a desperate measure to show apparent success of the plan would be to increase the depth of the gravel pit to allow the disaster of direct access to the underground water supply. I believe this alternative simple analysis shows the proposed runoff storage plan is inadequate. 1/11/2008 Page 2 of 2 Very Truly Yours, G.R. Kirkpatrick ase join us this afternoon at 5:30 at our home. 11/2008 Purissima Neighbors October 22, 2007 Debbi Pedro,AICP Planning Director Town of Los Altos Hills Re: Proposed new construction 26462 Purissima Road OCT 2 3 2007 Lot 166-07-ZP-SD-GD TOWN OF LOS ALTOS HILLS Dear Ms.Pedro: This letter is from the neighbors of the currently empty lot located at 26462 Purissima Road("the Lot")which was recently purchased by speculative builders operating under the names of Shashi Corporation and Los Altos Home LLC(collectively"the Developers This letter is in addition to the letter dated October 14,2007. It is a review of the Developers Proposed Rain Runoff Storage. As a solution to the rain storm runoff problem,the architects' specifications show three 80 foot long perforated pipes 3 feet in diameter providing about 1700 cubic feet of runoff storage. The runoff comes from about 30 000 square feet of area. Maximum runoff capacity is reached when rain depth is: 1,700 cubic feet divided by 30,000 square feet. This equals 0.057 feet or 0.68 inches (About 3/4 inch of storm rainfall) Our AVERAGE annual rainfall is 21 inches. For each storm to be limited to 3/4 inch of rain there would be 21 divided by 3/4 or 28 rain storms of equal precipitation amounts during the year. Clearly,this is not the case. I believe this simple analysis shows the proposed runoff storage plan is inadequate. Again,when the storage system is full,the neighbors to the north are concerned with increased runoff from the Lot with the potential of flooding the downstream driveways. The neighbors recommend that an engineering study be performed to determine how this problem can be properly addressed. Additionally the stored runoff must percolate between storms to restore the 1,700 cubic feet of capacity. This percolation will raise the local water table and may seriously affect the up stream septic system at 26450 Purissima Road. Very Truly Yo/urs, G.R.Kirkpatrick _: Page 1 of 1 Attachment 9 Date: October 17, 2007 --R F: To: Debbie Pedro, AICP, Planning Director, Town of Los Altos Hills From: Samuel and Lina Broydo, 26496 Purissima Rd., Los Altos Hills Subject: Public Hearing on. October 23, 2007 Re: Site Development Permit for Lands of Los Altos Homes, LLC, 26462 Purissima Rd. , File 166-07-ZP- SD-GD Dear Debbie, This is our third letter (replacing the first two) reflecting our concerns and requests regarding the peak discharge, landscaping and noise as related to this project. PEAK DISCHARGE Our lot, 26496 Purissima, is the next lot North ("downstream") from 26462. We are very concerned about any increase in peak discharge from 26462 that.may result due to the proposed project. During any substantial rain the lower part of the 26462 lot becomes a lake which serves as a holding pool which reduces the peak discharge in a downstream direction. The water flows North under two driveways, then flows through our 26496 lot and exits our lot under two other driveways. All four driveways have 12 in. diameter drainage pipes under them; which are barely large enough to handle the peak discharge during a strong rain. Heavy utilization of the area envisioned by the proposed development will drastically reduce the water absorbing area of the 26462 lot and increase the speed of the runoff. This will expose our lot to the danger of flooding and the four driveways, with water flow over the top, to the danger of severe damage. While the Recommended Condition #14 for the project states that the peak discharge from this lot "shall not exceed the existing predevelopment peak discharge value of the property" and while it also states that the "detention storage must be incorporated into the project to reduce the anticipated peak discharge to the predevelopment value" the implementation of those conditions is envisioned on the basis of calculations only. Those calculations can not be perfectly accurate and their satisfaction can not be practically tested. In addition, those conditions are only recommended, not demanded. Therefore WE REQUEST the following: 1) The Recommended Condition #14 has to become a nonnegotiable condition for project.approval. 2) The area of the lot extending two hundred feet West from Purissima along. the planned driveway can not be elevated above present level, except for the driveway itself. In other words, the part of Recommended Condition#14 that states "no grading shall take place within ten feet of any property line except to allow for the construction of the driveway access" has to be - changed to "no grading shall take place within two hundred feet from Purissima and within ten feet of any property line except to allow for the construction of the driveway access." 3) The new driveway has to be elevated above the height of the parallel driveway adjacent to the North boundary of the lot. 4) The diameter of the drainage pipe under the new driveway should not exceed the diameter of the drainage pipes under the four driveways to the North of the new driveway. 5) All five driveways should have 18 in. diameter drainage pipes installed at project builder's expense (four existing drainage pipes with 12 in. diameter to be replaced). LANDSCAPING FOR PRIVACY Recommended Condition#2 states that "particular attention shall be given to plantings which will be adequate to break up the view of the new residence from surrounding properties and streets.". This-is not clear enough, since the element.of time is not specified. Therefore WE REQUEST the following: 1) The Recommended Condition #2 has to be modified to clearly state that the landscaping must be adequate to "break up the view" right away, by mature trees planted from the beginning, not after indeterminate number of years of gradual growth. The above sentence should read: "Particular attention shall be given to mature plantings which from the beginning will be adequate to break up the view.of the new residence from surrounding properties and streets". 2) The modified Recommended Condition #2 has to become a nonnegotiable condition for project approval. REFLECTED NOISE ABATEMENT The building of this size will have tremendous effect on the neighbors by deflecting the highway 280 noise. There is no mention of the noise issue in the Recommended Conditions. Therefore WE REQUEST the following: 1) Mature trees have to be planted from the start along the perimeter of the lot in question to help minimize the effect of the highway 280 noise reflected by the new large building towards the neighbors (another reason to modify the Recommended Condition #2). 2) The builder should be requested (and assisted to receive the proper permits) to build a noise barrier wall on top of the hill next to highway 280, with the proper height and width to be determined through a professional acoustics evaluation. Respectfully, � Samuel and Lina Bra do. Y �, Attachment 10 Date:Oaobei I g,2007 To:Debbie,Pedro,AICP,Plaming Dimer;71 of Los Altos Imls From: Dr. Kuei-wu d Leslie'Tsai,Viers of 26510 Purissim Road.,Los Altos 1 ils (Mailing address:60 Mancsr Avenue, Wellesley, ISA 02482) Subject:Public Hearing on Oember 23,2007 Re: Site Development Perms for Lands of Los Ahos.Homes,LLC, 26462 Plurissima Rd., File°.166-07-ZP-Sly-G13 Dear Debbie, We are the owners of the house pirated at 26510 Purissimza Road,Los Altos bills. Due to job relocation to Massachusetts,we are not residing,but still own the house. We were informed recently by our neighbors abc he proposed development at 26462�r-issima. . Road which is adjacent to our house. We are verge concerned about the potential negative impapt on our horse caused by the new develop€nent. Someof the impacts are listed as foll6ws: Noise: The proposed new structure will refled the traffic noise flom.adjacent freeway 280 to our hDuse. A possiW e,Mffiga#on is the developer to build a.sound barrier wall along and immediately adjacent W leeway 280. 'l is is the most effective way for freeway noise abatement for all houses including the new development. Drainage:-and Septic: T"ne°proposed development cavi wase.flooding,of the low level areas to the n€3rtli,i€iAi ft a part of my driveway. En add tion, it can impact.tbe effectiveness of egg:septic systems- 'T"hese problems tweed to be addressed by the Tandscaping- The proposed large house will drastically change the rural nature of the neighborhood. Mature ft-ees surround=—ng the new house should be a part of the proposed development. Lnghfmg., Proper design of the outdoor fighting to avoid negative i-npiact on neighbors. should be rel" ed_ R-espectfully, -RECEIVED OCT 18 2007 Kuei=wu and Leslie Tsai TOWN Of LOS ATOS HILLS Mr-%.j vl V r-E.; N O V ° Attachment 11 TOVgN OF LOS ALTOS HILLS From November 20, 2007 Palaniappan Jambulingam Los Altos Hills, CA 94022 To Ms. Debbie Pedro,AICP Planning Director City of Los Altos Hills CA 94022 Dear Madam, Sub: - Site Development Permit for 26462 Purissima Road,File 166-07-ZD-SD-GD. I attended the hearing on October 23, 2007 at the Council Chambers regarding the above petition. I understand that there will be a full planning commission hearing on the above matter. Since I did not receive any further notice regarding this, I wanted to state my concern in writing about one of the alternate proposals that was discussed during the hearing on October 23,2007. It was suggested that.the building be moved to the base of "L" area,behind my house. I have captured this proposal as Alternate(1). At that time,I had mentioned that I may not have any objections as long as there are enough bushes and trees to protect our privacy. Last week, my wife and I studied the building plan further, and realized that if the building got laterally moved as is from current location to Eastward behind our property at the current elevation(385+ft),there will be 31+feet tall building roughly at 31 feet from our property line. It will be impossible to hide such a tall building with bushes when the building is close to our property line. Our property building is at approximately 3 81 feet. Alternate Proposal Being Objected 26462 Purissima Alternate(1) --Current Lost Privacy&Views 26430 If this alternative is pursued,here are the implications to us: - Our privacy will be severely impacted as the proposed building is a two storey building and it is very close to our property - This tall building will obstruct the natural hill views that are available today at our backyard. - Both of these will not only affect our quality of life but also future value of our property Hence,my wife and I strongly object to laterally moving the proposed house towards East,behind our house. we prefer the current location as presented now,because it preserves our privacy and does not obstruct the natural views. If the City and other neighbors object to the current location, following alternates could be considered - Alternate(2): Make the section of the house behind our property to be a single storey building or have a basement. - Alternate(3): Right now,the building is proposed at the corner of the'T" shaped property. Instead, suggest this to be an elongated one that spans the base of the 'T""(a)giving about 50 ft clearance to our property(b)preserving some of the available natural views for our property. AQtemate-3 Proposal 28462 Purisslrna Altemate(3) ---Current Preserves Privacy&Views 26430 In summary,we prefer that building be constructed as per the current plan.If there is any change to this proposal, we request you take into account of the impact of any such change to our privacy as well as the natural views and consider alternate(3). Thanking You, Yurs truly', P aniap an Jambulm* Thenmozhi Palaniappia Copy to: Mr.Brian FroeHch