TABLE OF CONTENTS
COMMUNITY DEVELOPMENT 5
Land Use 5
Community Development Policies 8
Circulation and Scenic
Transportation Policies 11
ENVIRONMENTAL RESOURCE MANAGEMENT 14
Conservation and Open
Safety and Seismic Safety 17
Environmental Resource Management Policies 22
PLAN IMPLEMENTATION 23
MAPS AND TABLES
The La Habra Heights General Plan establishes a frarnework for the future development of the citv. The plan encourages an arrangement of land uses and intensities, a transportation system, and public services which will contribute to the physical, social, and economic well being of me community. It also includes statements on housing, open space, conservation of natural resources, noise, safety, and scenic highways. City goals are established and specific policies to be followed in pursult of those goals are enunciated. The adoption of the plan means that decisions regarding the use of land may be made with a high degree of certainty by private individuals and public agencies alike.
Located only 25 miles southeast of downtown Los Angeles, La Habra Heights is an anomaly in the urban sprawl of Southern California. Approximately 1,500 homes are nestled in the hillsides of the six square mile city. Lots are large; drainage courses remain in their natural state; vegetation is varied, including grasslands, oak woodlands and avocado and citrus groves; and farm animals are common household pets. This rustic image could connote an isolated lifestyle, but the people of La Habra Heights have a deep sense of community spirit. The rapid growth of Los Angeles County in the 1950's and 1960's transformed areas south of the present City from agricultural uses to urban residential tracts. Steep hillsides immediately north of the City have been subjected to mass grading and urban development featuring lots of 10,000 to 15,000 square feet. Community groups were organized to fight this intrusion of urban development into La Habra Heights and to preserve the rural lifestyle of the community. As a result, the City of La Habra Heights was incorporated December 4, 1978.
Beginning in July 1973, the unincorporated community of La Habra Heights was the subject of an intense general plan study conducted by the County of Los Angeles. The study featured extensive citizen input through a citizens' advisory council, questionnaire, public meetings, and a public presentation and vote on two land use plan alternatives. A citizens group, the Community Development Committee (CDC), consisted of 100 local residents and property owners who met more than 85 times to advise the County on the plan. Substantial agreement was reached on all elements except land use. As a result, the CDC submitted two alternative land use plans for public vote. The first alternative retained one acre nirnimum lot sizes throughout most of the community but allowed 10,000 square foot and 20,000 square foot lots in several southern areas while requiring 5 acre lots in some rugged northern areas. The second alternative reduced the minimum lot size from 1 acre to % acre. The two alternatives and the balance of the plan were presented to approximately 1,200 people representing over 40% of all Heights property owners and residents. Eighty-three percent of these people voted in favor of Alternative 1.
The resultant community plan was adopted by the Los Angeles County Board of Supervisors on August 14, 1975 with minor modifications. The plan continued to enjoy widespread local support. Indeed, proponents of incorporation of La Habra Heights argued that cityhood was necessary to ensure implementation of the plan.
The City General Plan continues the basic goals and policies of the old community plan. The population projections have been modified to reflect the deletion of approximately 400 dwellings that are not m the City. The resultant projects forecast an additional 400 dwellings and 1,600 people by the year 2000.
The followmg goals have been developed to guide the fur:ure development of the City of La Habra Heights.
1. Recognize and preserve the unique rural character and individualistic lifestyle of La Habra Heights. ("Rural "has been defined by the community as: variety of homes; natural terrain and dense vegetation; houses which blend in with the setting; privacy and large distances between homes; keeping of horses and farm animals; scenic views; no "city" improvements such as curbs, gutters, sidewalks and street lights.)
2. Preserve and enhance the scenic beauty and natural wildlife of the area.
3. Minimize alteration of the natural terrain.
4. Preserve, maintain, and encourage agricultural uses, especially avocado groves, citrus groves, and Christmas tree farms.
5. Reduce potential fire and recognizes geologic hazards.
6. In harmony with the R-A-1 zoning the City supports individual-rights to keep horses, all animals used for 4-H projects and other livestock as allowed by local ordinance; and encourage the private development and maintenance of a system of trails for horseback riding and hiking.
7. Assure that regional traffic demands will be accommodated in a manner consistent with the unique La Habra Heights environment.
8. Protect the Powder Canyon Significant Ecological Area (SEA).
The Community Development Section contains the Land Use and Housing Elements of the General Plan.
The predominant land use in La Habra Heights is, and will continue to be, low density residential. The vast majority of the City is shown in a Rural classification, allowing houses on lots ranging in size from one acre to five acres.
The Urban category applies only to existing subdivisions at the southern edge of the City with lots smaller than one acre. Permitted density ranges from 1.1 to 3.2 units per acre.
The Open Space designation allows recreation uses, such as golf courses and parks. Also permitted are oil and natural gas production and storage.
The Commercial classification allows only office and professional uses. Retail commercial or residential uses are prohibited.
The Land Use Classifications state a range of densities allowed in each category. It should not be assumed that the maximum density permitted will be allowed. In determining the actual density that will be allowed in a particular project, the City will consider such factors as topography, access, seismic and geologic conditions, nearby uses and intensities.
In the past, steep hillsides normally were not developed. However, rapid increases in land values and the diminishing supply of land suitable for development, are now causing such land to be developed, often at the expense of safety and environmental considerations. Hillside development poses safety problems with respect to erosion, sedimentation, drainage, and land instability. Environmental concerns include maintenance of such natural characteristics as landforrns vegetation, wildlife, and scenic' qualities. The General Plan addresses these concerns by imposing slope density standards which directly correlate the intensity of development to the steepness of the land.
Except as noted below, the allowable density may not exceed that shown on the following slope density formula. Average slope is computed by the formula S = 0.002296 1 L/A , where S is average percent slope, I is the contour interval in feet, L is the total length of contours in feet, and A is the area of the site in acres.
* The following Table was revised on February 21, 1991 per Resolution No, 91-6 (Attacbment I).
Average Slope of Each Net
parcel of Project Dwelling Unit In Acres
than 30 1.00
41 & above 5.00
When a project is adjacent to predorninantly developed areas, the intensity and topography of such development may be used to override or modi~ the slope density provisions. In such cases it must be shown that:
1. The variance will not be materially detrimental to the public welfare or be injurious to other improvements in the same vicinity, and
2. The variance is necessary for the preservation of a substantial property right of the applicant such as that possessed by owners of other property in the same vicinity, and
3. The majority of the surrounding area contains similar topography and is developed at a greater intensity than allowed by the slope density formula, or
4. There are special circumstances or exceptional characteristics applicable to the property involved, such as shape, topography, location, or surroundings, which are not generally applicable to other properties in the same vicinity and under an identical Plan classification.
Existing zoning regulations requlre that lots in a one acre zone contain both a gross area of 43,560 square feet and net area of 40,000 square feet. Net area does not include any land that is subject to street or other easements where the landowner does not have the right to use the entire surface level. Gross area includes all land in an ownership, including that subject to street and other easements. The gross area requirement has no impact on the useable size of a parcel and will be deleted from the zoning ordinance.
The City encourages the development of a private trail system for horseriding and hiking through easements across private property. So as not to penalize landowners who offer such easements, these easements will not be deducted from the net area.
During the last year, a controversy has arisen with respect to the growing number of tennis and sports courts in the city. It has been argued that these uses with their high fences, expanses of concrete, and bright lights are not compatible with the rural lifestyle of La Habra Heights. The lights are an especially sensitive issue in this community where street lights are not allowed yet courts larger than typical urban lots have been illuminated with high intensity lamps.
To ensure that tennis and sports courts are harmonious with the rural lifestyle of La Habra Heights, they will be allowed only upon approval of a conditional use permit. In addition to the standards enumerated in the Community Development policies, additional conditions may be imposed as necessary in individual cases to assure that the court will not be detrimental to surrounding property nor the public peace and welfare.
Federal and state law find the subject of housing to be of vital importance and declare the early attainment of a decent home and a satisfYing environment to be a priority of the highest order. It is difficult to assess the housing needs of La Habra Heights because of lack of housing, social, and economic data. The City incorporated in 1978 and has never appeared as an entity in previous censuses. Census data for the eastern pan of the City was irretrievably mixed in with an unincorporated area extending to Diamond Bar. Similarly, prior to incorporation, separate building data for the area was not recorded.
California law states that the provision of housing affordable to low and moderate income households requires the cooperation of all levels of government. It further states that local governments have a responsibility to use the powers vested in them to facilitate the improvements and development of housing to make provisions for the housing needs of all economic segrnents of the community.
The ability of La Habra Heights to provide low and moderate income housing is hampered by many factors. Most of the land in the community is already developed. Approximately 1,200 acres in 50 ownerships are undeveloped. Most of this vacant land consists of relatively steep slopes; except in rare instances, sewers are not available; and, the road system was designed for an agricultural community and can only support very low density residential development.
There are only four sites in the city that might be able to accommodate low or moderate income housing: a 25 acre site at West Road and Hacienda Boulevard, two 10 acre vacant school sites, and the Powder Canyon area. The first three sites are relatively flat and have less severe access problems than most areas of the City. However, all three sites contain citrus and/or avocado groves and are surrounded by residences on 1 acre or larger lots. Any attempt to increase density
The Housing Element was revised on February 11. 1993 per Resolution No. 93-4 (Attachment II includes Resolution No. 934 and the revised Housing Element).
above 1 unit per acre can be expected to generate tremendous opposition. Indeed, a lawsuit on the site at Hacienda and West Road prevented a, cluster development of 2 units per gross acre as allowed by the old community plan.
Most of the Powder Canyon site is part of a 500 acre parcel immediately south of Otterbein Regional Park. The western part of the parcel is very steep and would be difficult to develop. The eastern part of the parcel contains the Powder Canyon area and is better suited for development were it not for environmental concerns. Powder Canyon has been designated a Significant Ecological Area (SEA) by this plan and the Los Angeles County General Plan. In order to minimize environmental impacts, cluster development in the form of Residential Planned Development may be allowed in this area.
COMMUNITY DEVELOPMENT POUCIES
1. Design all new developments to mmimize impacts on community character, surrounding neighborhoods, and natural features.
2. Preserve natural drainage courses in their existing state.
3. Establish a gradual topographic transition between developments. High banks shall not be constructed adjacent to existing development.
4. Limit grading to that necessary for the primary use of each lot.
5. Minimize grading for streets to that necessary for public safety concerns.
6. Utilize contour grading to present a rounded or undulating appearance blending in with the natural grade.
7. Preserve significant distant views. Significant views are scenes such as surrounding hills, valleys, mountains, ocean, or city lights.
8. Utilize design and construction techniques which reflect the features of the site. Innovative approaches such as stepped and cantilevered designs are encouraged.
9. Iaandscape all graded slopes to control erosion.
10. Landscape all new developments to screen or soften the visual impact.
11. Secure City approval of the appropriate environmental documentation and permits before any trees or riparian vegetation are removed.
12. Lot averaging is prohibited except in Residential Planned Development projects.
13. Restrict the amount of impervious coverage in-order to minimize runoff.
14. Residential Planned Development is permitted only in the following situations:
(a) where necessary to preserve Significant Ecological Areas, or
(b) on projects with a density of less than 1 dwelling per gross acre, dwellings may be located on lots having a net area of at least 40,000 square feet or,
(c) where such development will reduce developmental problems in hillside areas, preserve areas of natural scenic beauty, and provide as well or better for light and air, for public safety and convenience, the protection of property values, and the preservation of the general welfare than standard development.
15. Residential Planned Development shall be subject to the following standards:
(a) dwelling units must be of a detached single family nature except in the Powder Canyon SEA. In the SEA, attached units e.g. condominiums, townhouses, or apartments, may be allowed in order to minimize disruption of sensitive environmental areas.
(b) a distance of 35 feet must be maintained between all structures.
(c) 50% of the gross area of the site must be dedicated open space.
16. Require conditional use permits for tennis and sports courts. In addition to the specific conditions that may be imposed in an individual case, the following standards shall apply to all tennis and sports courts:
(a) where courts comply with setbacks, fences shall be no higher than 8 feet above the grade of the grounds outside the court.
(b) where courts encroach into setbacks:
(1) a setback modification is required.
(2) the court shall be depressed at least 3 feet below grade.
(3) fences may not exceed a height of 6 feet measured from outside the court.
(c) landscaping and an irrigation system shall be provided so as to screen the court from adjacent properties and streets.
17. Require proof that sewage can be safely disposed of in compliance with applicable laws before building permits are issued or land divisions approved.
18. Require that adequate water service for fire protection be available before any property is approved for land division or building permits.
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19. Allow continued oil production subject to Conditional Use Permit approval.
20. Establish ordinances governing minimum lot widths and depths.
The Transportation Section contains the Circulation, Scenic Highways, and Noise Elements of the plan.
CIRCULATION AND SCENIC HIGHWAYS
The Circulation Element is designed to provide for the safe and efficient movement of people and goods through the city. Two major north-south routes now traverse La Habra Heights. Hacienda Boulevard carries approximately 18,000 cars a day while Fullerton Road carries approximately 8,000 cars per day. These routes provide two of only three highways across the eleven mile stretch of the Puente Hills between the Orange and San Gabriel Freeways. Only one new route, Turnbull Canyon Road, is planned across this region. Therefore, traffic on Hacienda and Fullerton is expected to increase significantly as this region continues to develop.
Improvements to highways and local streets must be reconciled with topographic and environmental considerations. For this reason, the General Plan prohibits the extension of Azusa Avenue through the Powder Canyon SEA. Instead, a new route, Harbor Boulevard, is planned east of Fullerton Road that will connect with Fullerton to the north and south.
Hacienda Boulevard and the proposed Harbor Boulevard traverse a rural area which provides a stark aesthetic contrast to the large urban areas irnmediately north and south of La Habra Heights. The General Plan recognizes the scenic qualities of the two routes and designates them scenic highways.
The Noise Element provides a basis for local programs to control and abate noise and to protect residents from excessive environmental noise. The element provides quantitative data idenn.fiing noise levels and problem areas, delineates areas with acceptable noise levels, and provides policies to mitigate existing and projected noise problems.
Vehicular traffic is the major source of noise in La Habra Heights. The areas experiencing the highest noise levels are the corridors adjacent to the two major arteries: Hacienda Boulevard and Fullerton Road. Harbor Boulevard is planned for future extension through the community. 'An noise contours have been calculated for these areas using techniques set forth in Estimation of Community Noise Exposure in terms of Day-Night Average Level Noise Contours, May, 1975, prepared by the State Office of Noise Control. The Ldn (Level~day-night) system provides an average noise level for a 24 hour period and penalizes noise occurring between the hours of 10 PM and 7 AM by multiplying by 10 the number of noise occurrences during those hours. An
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increase in 10 decibels results in doubling of the noise level. For example, 60 dB is twice as loud as 50 dB. These predictive techniques represent estimates of noise exposure rather than empirical tests of such exposure. As such, the contours generated are not absolute lines of demarcation, but general indications of bands of similar noise exposure. Noise levels in excess of 70 dBA do not exist outside of the roadway at the present time while levels of 60 dBA are within 100 feet of the roadway. Large scale maps showing existing and projected noise contours in 5dB increments down to 60 Ldn may be viewed in City Hall.
State law requires evaluation of the noise environments of the following noise sensitive facilities: schools, hospitals, rest homes, long term medical or mental health care facilities, or any other use deemed noise sensitive by local jurisdictions. However, there are no such facilities in the community.
The Table on Page 13 shows the number of residences exposed to various levels of noise in excess of 60 dBA. Because the contours indicate only approximate bands of noise exposure there are ranges of exposure shown for each decibel range. The chart also shows the projected noise exposure for the year 2000. The potential constmction of Harbor Boulevard as well as further development will increase noise exposure in the community. Increased traffic on existing routes also will result in higher noise levels and larger areas affected by noise.
1. Designate Hacienda Boulevard and Harbor Boulevard Scenic Highways.
2. Improve Scenic Highways as follows:
(a) vary the right-of-way widths in a manner which will minimize alteration of existing terrain while adequately serving transportation needs.
(b) limit grading and follow existing terrain as much as possible.
(c) use inverted shoulders and adjacent graded but unpaved areas instead of curbs, gutters, and sidewalks.
(d) restrict parking to allow for narrower pavement widths with pull-outs available for emergency parking and scenic viewing.
(e) consider innovative design approaches, e.g. split level roadways, to minimize environmental impacts.
(f) plant all graded slopes with noncombustible plantings.
(g) provide safe crossings for equestrian and pedestrian traffic.
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3. Design and improve streets so as to retain the rural character of the City.
4. Prohibit the installation of curbs, gutters, sidewalks, and street lights except where necessary for safety.
5. Make road widths compatible with the rural character of the City and the environment.
6. Remove vegetation and walls and regrade slopes that pose serious safety hazards by seriously restricting sight distances.
7. Protect a continuous route for Skyline Drive as a local street.
8. Conduct scenic corridor studies of Hacienda Boulevard and Harbor Avenue.
9. In areas subject to existing or projected noise levels of 60 Illdn, insulate all new residences so that the interior noise level is less than 45 dBA.
10. Encourage the use of earth berms and landscaping to mitigate noise problems.
11. Encourage the use of special setbacks along noise impacted corridors so that, where possible, structures are not placed in areas experiencing noise levels in excess of 60 dBA.
12. Discourage the construction of schools or other noise sensitive features within the 65 dBA contour.
13. Consult with school officials to determine ways to improve school bus access to the City.
14. Develop regulations to protect residents from objectionable noise emanating from private property.
15. Provide fire hydrants along highways.
I~l COMMUNITY NOISE EXPOSURE LEVELS* _
Estimated 1980 Levels
Hi~wav 70+ dB 65-69 dB 60-64 dB
Boulevard - 21
Fullerton Road 15
Projected 2000 Levels
Boulevard 1-11 8-40 13-57
AzusaAvenue 5-36 11-65 20-116
Fullerton Road 5-37 12-67 20-118
Harbor Boulevard 4-20 9-37 16-78
* The figures in each decibel range indicate the potential number of dwelling units impacted.
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ENVIRONMENTAL RESOURCE MANAGEMENT
CONSERVATION AND OPEN SPACE
The Conservation Element is concerned with the conservation, development, and utilization of natural resources. open space may include open space for the preservation of natural resources; open space for the managed production of resources; open space for outdoor recreation; and open space for public health and safety. Although La Habra Heights is in close proximity to developed urban areas a great variety and amount of wildlife is found in the area, including deer, coyote, badger, bobcat, mountain lion, gray fox, and numerous bird species.
The larger open parcels provide a range of habitats: open grassland, coastal sage scrub (the brushiand), oak woodland (dominated by live oak and English walnut), and riparian. Many residential areas may also be considered as wildlife habitats because of the abundance and variety of mature trees and shrubs and the ample spacing between dwellings.
Professor Ray E. Williams of Rio Hondo Colleqe prepared an ecological assessment of the study area in 1974 (Ray E. Williams, An Ecological Assessment of La Habra Heights, California, Unpublished, Rio Hondo College, Whittier, California, Spring, 1974). The following comments
have been excerpted from page 4 of his report:
"Each species of wildlife has a critical minimum sized area in which it can exist. If the available habitat is reduced below that size, the species either disappears or moves away. Generally, larger forms require larger areas; thus, the tendency is to lose the larger species as human density increases.
Some forms of wildlife are very adaptable and can live in several habitats, perhaps even tolerating or benefiting from our presence. Others are more specific in their requirements and/or cannot tolerate people. There appear to be more of the latter. Species recognized as 'rare and endangered' are those whose numbers may never have been great or are those which are specialists in their requirements. Very often, today, endangered species result from the encroachment of people into a natural area; consequently, endangered species are often the products of endangered habitats. There appear to be no officially listed endangered species using the study area on a regular basis. Occasional use by eagles and peregrine falcons cannot be discounted, however."
In the previously mentioned assessment of La Habra Heights' natural resources, it was concluded that "in plauning for the future development of La Habra Heights, it should be recognized that the life style of the area is unique and worthwhile in offering a choice to people of the Los Angeles Basin. The tendency in today's residential developments is to create uniformity. Diversity of environments is desirable and beneficial in many ways, some of which cannot be measured in economic terms." If development is to occur and wildlife in the area be preserved, overall density should be low with significantly large habitats being retained.
The Powder Canyon region has been identified in the Los Angeles County General Plan as a Significant Ecological Area. Powder Canyon is one of three areas in the hilly region of eastern Los Angeles County that still supports a relatively undisturbed stand of the southern oak woodland, coastal sage scrub, and riparian woodland complex that was once common there. The remainder of this vegetation has been converted to agricultural and urban uses. This is true throughout the entire Southern California region, making it one of the most rapidly disappearing habitat types.
Powder Canyon is the only one of the three areas that contains an undisturbed portion of self-contained watershed. As a result of this, the vegetation is in good condition. Preservation of this type of area necessitates elimination of potential disturbances from upstream sources. If preserved, Powder Canyon is of sufficient size and in close enough proximity to the other recommended areas in the region that it should be able to continue to support relatively healthy anImal populations. The diversity of wildlife is greatly enhanced by the presence of riparian woodland habitat in the canyon bottom.
Agriculture historically has been an important use in the Heights. A 1930 survey indicates that 41% of the area was devoted to agriculture, including 1,292 acres of avocados and 282 acres of citrus. Agriculture continues in importance today with avocados remaining the predominant crop. Most of the existing avocado groves are quite small, being remnants of the original groves. Of the 486 groves in the City reported to the County Agricultural Commissioner in 1972-73, 337 were less than one acre m size. Most of these groves now have houses on the property and
provide supplemental income to the property owners.
In the past, traditional irrigation systems utilizing rigid pipes and sprinklers required grading and contouring preparatory-to planting avocados. This preliminary work is costly and by necessity confines the orchards to areas of moderate slope. Recently introduced drip irrigation systems require no preliminary grading, are being used on slopes as steep as 100%, and effect an economy in water use. However, certain problems may be caused by drip irrigation and caution should be exercised to ensure proper runoff.
Many smaller groves which are basically incidental to the residential use of the land could probably be improved by better care, including top working of trees and grafting to the Hass variety. A continuing educational program should be established to present these facts to property owners.
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Petroleum is the chief mineral resource of La Habra Heights and the surrounding Puente Hills area. The Sansinena oil field contains 655 proved acres with 109 producing wells. The 1979 65th Annual Report of the State Oil-and Gas Supervisor, published by the California Division of Oil and Gas, states that in 1979, oil production was estimated at 469,775 barrels leaving an e~im~ed reserve of 5,36l,000 barrels. Gas production totaled approximately 733,524,000 cubic feet leaving an estimated reserve of 5,783,000,000 cubic feet.
The only other significant mineral uses in the study area have been the extraction of gravel and sand. An abandoned quarry exists in the area but reserves are limited and no future production is anticipated.
The major natural resources of La Habra Heights are shown on the Land Use and Circulation Map on Page 3. Streams are shown on the map on Page 16.
The main recreational uses in La Habra Heights consist of the Hacienda Golf Club, the City Park and riding ring, and the Cypress and Las Palomas equestrian rings. Equestrian activities are very popular in the Heights and the City encourages the private development and maintenance of trails. In that regard, the City may require, upon subdivision through tentative tract maps of large undeveloped parcels in the City or through non-residential Conditional Use Permits, the development of equestrian and pedestrian routes for the express purpose of provided access to the Skyline Trail.
SAFETY AND SEISMIC SAFETY
La Habra Heights is located in the western section of the Transverse Hill and Mountain range referred to generally as the Puente Hills. The north dipping Whittier Fault Zone trends southeasterly across the northern and eastern portion of the area, marking a division between the Puente Hills to the north and northeast and west-trending La Habra Valley and Coyote Hills to the southwest. The area ranges in elevation from 400 feet at the lowest-point to 1,450 feet at the highest point, with ridges and valleys aligned more-or-less "en echelon" along the Whittier Fault Zone. Steep ridges and deep canyons lead to small valleys. Only 20% of the area is considered level (less than 8% slope). -Soil conditions vary accordingly, especially in relationship to the complex underlying rock formations.
No detailed soil survey is available for La Habra Heights. However, the U.S. Depart:ment of Agriculture Soil Conservation Service, working in cooperation with various Soil Conservation Districts, has prepared a soil report for Los Angeles County consisting of a generalized soil map and description of soil types. Information from this report as it applies to La Habra Heights is contained in the table and map on Pages 18 and 19.
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The presence of a high water table and expansive clay bedding has resulted in numerous landslides and potential landslides. Unrestricted development which adds more water into the ground from private waste systems can activate these existing and potential landslides.
Maps prepared by D.L. Durham and R.F. Yerkes (Geology and Oil Resources of the Eastern Puente Hills Area Southern California, Geological Survey Professional Paper 420-B, U.S. Government Printing Office, Washington, 1964) indicate that the land area north of the Whittier Fault has been thrust up several thousand feet exposing the relatively unconsolidated Puente formations. These formations contain bentonitic or other clayey strata which, when water soaked, are very prone to landslides. The La Habra formation, exposed to the south of the fault, is relatively more consolidated. As a result, few visible landslides have been found south of the Whittier and related fault zones.
Based on several different forrns of geologic evidence, the block north of the fault zone has moved upward and to the right (eastward) relative to the block south of the fault. Most of the upward movement is believed to have occurred on the southernmost continuous fault in the Whittier Fault Zone. The most recent known or inferred displacement on the Whittier Fault and its associated faults has taken place within the last 300,000 - 500,000 years; no known movement can be determined to have occurred in the last 11,000 years. In addition to displacement due to seismicity, reactivation of the Whittier Fault Zone due to earth movements on nearby faults or due to subsidence caused by oil pumping is possible, but not known to have occurred.
Although no evidence for movement for the last few thousand years in the Whittier Fault Zone has been found, no assurance can be given that movement will not occur in the future. Quoting Wentworth, Ziony, and Buchanan (C.M. Wentworth, et. al, Preliminary-Geologic Environmental Map, of-the Greater Los Angeles-Area--California United States Geological Survey, TID-25363, U.S. Government Printing Office, Washington, 1970, Plate I.):
"Even faults with late Quarternary displacement that have not moved in the past 11,000 years may be active, however, for this is a relatively short time when compared to geologic time and the probable rates of tectonic process".
These statements, while typical of previous references to activity of the Whittier Fault, have been reexamined in the light of recent findings. Newly published studies in the geologic literature reveal the presence of small scale seismic activity on the Whittier Fault.
The State of California and County of Los Angeles regard the Whittier Fault as potentially active. Under the auspices of the Alquist-Priolo Act, an area one-eighth of a mile on either side of the Whittier Fault and its associated traces will be established as a special study zone by the state. Geologic reports will be required before any developments are approved with this zone. Seismic hazard manifests itself in two ways: fault displacement, such as along the Whittier Fault Zone, and earthquake shaking which may be especially significant in areas containing alluvial materials such as along the valley floors and southwestern one-third of the community. Fault displacement is a fracture in the crust of the earth along which the sides move or are displaced, relative to each other, in a direction parallel to the fracture. Losses occur not only from displacement
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accompanying earthquakes, but also from fault creep, which displaces the ground along faults without violent earthquake shaking.
Losses due to earthquake shaking are greater than those from any other geologic hazard. Especially vulnerable are the structures built prior to the passing of the Field and Riley Acts in 1933. The County Assessor's records indicate that there are 105 pre-1933 homes in the city. Modern engineering technology, if applied to future construction in areas subject to earthquake shaking, could effect a 90% reduction of deaths and 50% reduction of dollar losses.
ENVIRONMENTAL RESOURCE MANAGEMENT POLICIES
1. Protect the Powder Canyon Significant Ecological Area.
2. Require preparation of a full environmental impact report before allowing any subdivision, development, or use of the Powder Canyon Significant Ecological Area.
3. In the Powder Canyon Significant Ecological Area, encourage clustering of dwellings so as to maximize environmental protection.
4. Preserve-drainage courses in a natural state.
5. Encourage the planting of streamside vegetation, preferably native plants, along La Mirada Creek.
6. Develop an educational program for property owners for care and upkeep of small groves.
7. Encourage the use of the drip irrigation system for orchards to eliminate the need for terracing and permit orchards on steep slopes.
8. Continue oil production, subject to Conditional Use Permit procedures.
9. Encourage the creation of a master plan of equestrian and pedestrian routes to be developed and maintained through private effort.
10. Develop zoning regulations which will protect the aforementioned resources.
11. Prepare a more precise plotting of the Whittier-Fault and associated traces and an appraisal of the area's seismic and-landslide hazards.
12. Designate special study zones along active and potentially active faults within which geologic reports will be required before new construction can begin.
13. Inspect pre-1933 masonry buildings, especially those located in areas subject to damage from shaking, and require that they meet current standards.
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14. Ensure that the existing circulation network can provide emergency service during a seismic or fire disaster.
Adoption of the La Habra Heights Community General Plan does not mark the end of the planhing process, but rather signals the beginning of activities designed to bring into reality the policies set forth in the plan.
The plan is a decision making tool which will guide public and private investment in the community. Proposals by public agencies to acquire or dispose of land or undertake construction projects in the community will be reviewed for consistency with the plan.
The City will initiate necessary changes in regulations, especially with respect to zoning and subdivision ordinances, to assure that private development also conforms to the goals and policies of the plan.
It is hoped that the various community groups will continue to be involved in preserving and fostering the La Habra Heights rural lifestyle.
Continuation of this community support demands that the plan be available, to and understood by the residents and property owners of La Habra Heights. The plan also must be periodically reviewed to reflect changing conditions.
The community is encouragcd to review and discuss all proposed development projects with the City government and other appropriate agencies.
RESOLUTION NO. 91-6
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF LA HABRA HEIGHTS AMENDING THE LAND USE ELEMENT OF THE GENERAL PLAN REGARDING THE USE OF THE SLOPE DENSITY FORMULA
THE CITY COUNCIL OF THE CITY OF LA HABRA HEIGHTS HEREBY FINDS, RESOLVES, AND ORDERS AS FOLLOWS:
Section 1. The Section of the General Plan entitled Land Use is hereby amended by amending the table setting forth the slope density formula on page 6 to read as follows:
Slope of Each Net
parcel of Project Dwelling Unit In Acres
than 30 1.00
41 & above 5.00
PASSED, APPROVED and ADOPTED this 21st day of
February , 1991.
\("' i_~~~ A'.
& ( CITY CL)ERK
AYES: COUNCILMEMBERS: Collins,
Newbre and Wible
NOES: COUNCILMEMBERS: None
ABSENT: COUNCILMEMBERS: None
901112 pir 0690306 (1) ABSTAIN: COUNCILMEMBERS: -None