APPLICANT/

PROPERTY

OWNER: Ron Metzler, Shea Homes, 603 S. Valencia Ave., Ste. 200, Brea, CA 92823

LOCATION: 17301 Graham St. (West side of Graham Street, south of Kenilworth Drive, adjacent to the East Garden Grove-Wintersburg Channel)

STATEMENT OF ISSUE:

• Environmental Impact Report No. 97-2 (EIR No. 97-2):

- Analyzes proposed development on an approximate 49 acre vacant site for the purpose of constructing up to 208 homes, associated infrastructure and private and public open space.

- Documents potential impacts to land use compatibility, aesthetics/light glare, transportation/ circulation, air quality, noise, earth resources, drainage/hydrology, biological resources, cultural resources and public services and utilities.

- Evaluates nine alternatives to the originally-proposed 208 unit project.

- Concludes that Alternatives 1, 7 and 9 are the environmentally superior alternatives.

- Concludes that potential impacts can be mitigated to less than significant levels for the original project and all of the alternatives.

• Continued Item

- Planning Commission meeting September 10, 2002. Planning Commission requested clarification regarding nine items pertaining to the EIR.

• Staffs Recommendation:

- Certify EIR No. 97-2 because it adequately analyzes the potential environmental impacts associated with the project and identifies project alternatives and mitigation measures to lessen the project's impacts consistent with General Plan policies.

RECOMMENDATION:

Motion to:

"Certify Environmental Impact Report No. 97-2 as adequate and complete in accordance with CEQA requirements by approving Resolution No. 1574 (Attachment No. 1)."

^I^-S-^S^-

ALTERNATIVE Actions):

The Planning Commission may take alternative actions such as:

A. "Deny certification of Environmental Impact Report No. 97-2 and direct staff accordingly." B. "Continue certification of Environmental Impact Report No. 97-2 and direct staff accordingly." PROJECT PROPOSAL:

Environmental Impact Report No. 97-2 (EIR No. 97-2) represents an analysis of potential environmental impacts associated with the subdivision of approximately 49 acres of vacant land for the purpose of developing up to 208 single family residential units, associated infrastructure and private and public open space. The project includes the annexation of approximately five acres of unincorporated area into the City's jurisdiction, a general plan amendment, zoning map amendment and local coastal program amendment.

At the September 10, 2002 Planning Commission meeting, the Planning Commission continued action on EIR No. 97-2 and requested that staff provide written responses to issues pertaining to the Environmental Impact Report regarding the following topics:

1. Coastal Commission staff correspondence dated September 9, 2002

2. Subsidence (including water migration and legal implications thereof)

3. Fault lines

4. Flooding (flow of water, including back to back El Nino storms)

5. Flood Control capacity

6. City's Master Plan of Storm Drainage [comparison of methods used for '93 (4597 cfs) and '00 (1310 cfs) studies]

7. Fire Department response times

8. Maximum capacity for Slater Pump Station (what is our limit, has it been exceeded)

9. Liquefaction

ANALYSIS:

Staff has provided written responses to address the above topics. The responses are based on information in the EIR, its Technical Appendices and the Response to Comments. A summary response is provided in the body of the staff report, and additional information is provided in the attachments as backup material. Staff has attached reference documents and correspondence that were discussed at the September 10^th meeting to facilitate your review of the material.

In addition to the information requested by the Planning Commission, the analysis includes responses to outstanding issues raised in the written correspondence that was attached to the staff report as well as late communication that was received after the September 10, 2002 meeting.

..Staff Report -9/24/02 -2- (02sr40 EIR 97-2)

Information requested by the Planning Commission 1. Coastal Commission staff correspondence dated September 9, 2002

On September 9, 2002, the Department of Planning received correspondence from Coastal Commission (CCC) staff regarding the EIR. This was distributed to the Planning Commission at the September 10, 2002 Study Session (Attachment No. 3.1-3.8). The correspondence recommended that the EIR not be certified based on water quality concerns and also noted that other Coastal Act concerns discussed in their prior letters on the EIR remain.

In response to this, City staff contacted the CCC staff and provided them with a memorandum from Mr. Hasan Nouri, Rivertech, Inc., the water quality consultant on the project, (Attachment No. 3.9-3.10) and a copy of the recommended condition on the Tentative Tract Maps, etc. regarding water quality. At approximately 5:18 p.m. on September 10^th, the CCC staff sent an additional correspondence to staff regarding the project. This was handed out to the Planning Commission at the September 10, 2002 Meeting (Attachment No. 3.11). The Planning Commission requested that staff respond.

The EIR was prepared to meet the requirements of CEQA, i.e., to consider the significance of the changes to the environment caused by implementation of the residential development project and alternatives. CEQA does not require, nor does EIR analysis typically include a detailed Urban Runoff Management Plan (URMP) as requested by CCC staff because the plan is prepared once final design plans/site plans are in process. CEQA documents, for a project of this nature, typically only provide the general level of analysis provided on pages 5-138, 5-141 through 5-142 of the EIR including mitigation measures 2 and 3 ' (recommended by the Regional Water Quality Control Board), which require the applicant comply with NPDES requirements and obtain the necessary permits prior to the issuance of grading permits. The Rivertech reports of 1998 and 2002, which are part of the EIR, provide additional quantitative information related to water quality impacts in response to public comments. It would be premature to prepare a detailed URMP at this stage of the project, because the final project design may change or be further refined upon project approval via conditions of that approval.

Based on the comments from CCC staff, it appears that they are requesting information that is normally associated with a permit application, e.g. coastal development permit application to the Coastal Commission, and using the Coastal Act as the level of review instead of CEQA. The level of detail they have requested is unprecedented to the City's and its consultant's knowledge or experience for a project at this stage. The City has routinely indicated in its environmental documents that a Water Quality Management Plan would be prepared, including specific BMPs, prior to issuance of grading or building permits. We believe that the CCC staffs recent assertions and requests for more detailed plans is without sufficient merit or bearing at this stage to deem it inconsistent with CEQA requirements and that the EIR is adequate. City staff has communicated this to the Coastal Commission and will forward any response that it receives to the Planning Commission.

Notwithstanding the above, we did respond to the request for information regarding various BMPs and other items in their correspondence. The project water quality consultant has provided a response memorandum that is attached for your information (Attachment No. 3.12-3.16).

The CCC staff September 10^th letter states "the EIR did not indicate that the future plans would include, more protective BMPs." We believe that this is an inaccurate statement. Mitigation Measure 3, Drainage/Hydrology, states:

Staff Report - 9/24/02 -3- (02sr40 EIR 97-2)

"Prior to issuance of the grading permits, the applicant shall provide a Water Quality Management Plan showing conformance to the Orange County Drainage Area Management Plan and NPDES requirements (enacted by the EPA) for review and approval by the City Engineer. The plan shall reduce the discharge of pollutants to the maximum extent practical using management practices, control techniques and system, design and engineering methods, and such other provisions which are appropriate."

It is clear to City staff that this means a variety of feasible BMPs will be evaluated. The mitigation measure does not say that only the BMPs that were mentioned in the EIR or its technical studies will be employed but rather that this project will be held to the same standard as every other development project in terms of complying with accepted standards.

Moreover, the EIR itself does not indicate a certain set of BMPs. On page 5-141, it reads:

"Stormwater flows from the future buildout of the residential project will be subject to the NPDES permit process. Throughout the NPDES Permit process, the City currently requires contributors to non-point runoff pollution to establish Best Management Practices (BMPs) to minimize the potential for pollution. Under this program the developer is responsible for identification and implementation of a program of BMPs which can include special scheduling of project activities, prohibitions of certain practices, establishment of certain maintenance procedures, and other management practices to prevent or reduce the pollution of downstream waters. Typical elements of such a BMP program include..."

While the Addendum reports in the Technical Appendices do evaluate specific BMPs, e.g. CDS units, these reports are intended to provide a conceptual level of analysis regarding possible options/ recommendations for the project. They do not override or negate the mitigation measure and EIR discussion excerpted above. Thus, staff believes that the CCC staff is inaccurate in its conclusion.

Regarding the "many Coastal Act concerns discussed in our prior letters remain" statement from the September 9^th letter, staff spoke with CCC staff. CCC staff indicated that they did not intend for that to have a bearing on the EIR discussion, but rather when the City submits its LCPA to the CCC, CCC staff will be evaluating the project regarding the various comments they have had on the project in the comment letters, which are contained in the EIR. CCC staff indicated that they will review the LCPA application to see if those previous issues "are still relevant." In terms of those previous issues, City staff believes they have been responded to and that once CCC staff reviews the information this will become evident.

Finally, it is important to note that the City hired a water quality engineer in the Public Works Department, Ms. Geraldine Lucas. Ms. Lucas is the project manager for the citywide Water Quality Master Plan and is involved in the review of all project components as they pertain to water quality. Ms. Lucas has been involved in the review of documentation for the Parkside Estates project and believes that it is consistent with industry practice.

Staff Report - 9/24/02 -4- (02sr40 EIR 97-2)

2. Subsidence (dewatering, including water migration and legal implications thereof)

Questions were raised regarding the potential impacts associated with dewatering, i.e. subsidence, to the property to the north. The information below is excerpted from the Response to Comments for the EIR and consultation with the geotechnical consultant and applicant.

Groundwater has been observed below the subject site at depths varying from approximately four feet to as much as 19 feet below ground surface (bgs). Groundwater at the site takes two forms. First, a regional groundwater surface exists below the site with seasonal elevations varying from approximately 9 feet below mean sea level (msl) to 19 feet below msl. These levels have been observed to vary seasonally. Shallower groundwater has been observed below portions of the site and consists of localized concentrations of perched water. The source of the water is not regional, but rather is derived from local irrigation and precipitation sources. Based upon excavations that were monitored in March and May 1998, digging to depths of approximately 10 feet, water levels at that period were approximately 6 feet below ground surface (bgs).

The remedial grading necessary to mitigate potential settlement includes overexcavation of loose/soft, compressible soils to depths varying from 5 to 19 feet. The grading and construction dewatering effort will consist of a combination of several techniques. The primary technique, which will be used in proximity to the northerly project development limit, will be initiated approximately 40 feet south of the north boundary and will consist of accomplishing the excavation of the upper 4± feet with conventional earth moving equipment (scrapers). At that point, further excavation of wetter materials will be accomplished with a large excavator (backhoe). The excavation will predominately be 10 feet deep or less except for the extreme easterly one-third of the boundary where removals will be on the order of 15 feet.

Dewatering of this northerly boundary area will be accomplished by surface pumps within the excavation. The excavations will be segmented in approximate 200 x 200 feet+-: increments that will be refilled with a mixture of materials from an adjacent excavation and drier import materials as needed. Within the interior of the project, dewatering will be accomplished with similar surface pumps, supplemented with local shallow well points, and dewatering wells. Remedial grading activities will be setback from the north property line by at least 40 feet at the top of excavation and 50 feet at the bottom. Neither dewatering nor remedial grading will be required for the Paseo Park area, thus, activities will occur no closer than 40 feet to the north property line or 50 to 75 feet from existing residences.

The local grading dewatering efforts are not expected to affect existing properties to the north. Accomplishment of the remedial grading in relatively small (200± feet wide) segments will allow replacement of the overexcavated volume within one to two days after achieving the overexcavation bottom. Thus, grading activities, including local dewatering efforts in proximity to any given adjacent property, will be complete within a few days after initiation of grading activities at that location. Local dewatering of the perched water zones and timely refilling of the overexcavation voids will not affect the groundwater conditions below offsite residences. Dewatering efforts in proximity to Wintersburg Channel will likely require the assistance of dewatering wells; however, the channel is some 400 feet to 1000 feet south of the north boundary and the temporary drawdown influence from these extraction wells will not extend to northerly offsite areas. Since the regional groundwater regime below the offsite structures is unaffected by the proposed activities, a subsidence response is not a necessary consequence.

Staff Report - 9/24/02 -5- (02sr40 EIR 97-2)

It should be noted that similar conditions have been encountered elsewhere and procedures similar to those proposed for this site have been successfully implemented on numerous projects throughout the Huntington Beach, Fountain Valley, and Westminster areas. Specifically, within the City of Huntington Beach, similar mitigation techniques have been successful in construction of a shopping center at the northeast comer of Goldenwest and Warner and a residential development at the southeast comer of Beach and Adams. There is no indication that adjoining properties were impacted in other projects.

Although subsidence impacts are not expected for the properties to the north, the project includes a mitigation measure that requires monitoring the boundary conditions and adjusting dewatering activities immediately if monitoring wells show ground water level changes which may affect subsidence of adjacent properties. This will be completed for two basic reasons: 1) to detect if there is a change in conditions and impacts to the adjacent property to the north and 2) to document existing conditions. As has been indicated in verbal and written testimony on this project, the existing property owners to the north believe that their properties have already experienced settlement. This may be due to a number of factors including the construction standards, methods and controls that were required when their homes were built. In such a case, no matter what may be developed on the adjacent property, their properties may continue to experience settlement effects. The proposed monitoring includes the following tasks that are planned to be accomplished prior to and/or during site grading:

1. Conduct a topographic survey of existing conditions;

2. Install piezometers to monitor groundwater levels;

3. Install and monitor survey monuments;

4. Prepare a detailed dewatering plan for review by the governing agency(s).

Staff believes that the proposed dewatering methods are time-tested and that sufficient analysis has been included in the EIR regarding potential subsidence impacts associated with dewatering. The proposed monitoring will allow the developer and the City inspectors to quickly identify any problems related to the project that may arise, even though they are not expected due to the distance between the existing homes and the dewatering effort and the proposed grading/overexcavation procedure. The mitigation measure requires that the dewatering plan be prepared by an expert in the field and submitted to the City for review and approval (Condition 5.ss. on Attachment No. 1.15 of the September 10^th Tentative Tract staff report). Although staff does not believe it necessary, the Planning Commission could add a condition regarding the dewatering effort that the dewatering plan be reviewed by a third party geotechnical consultant and/or that a third party geotechnical inspector be available on-site during dewatering to monitor the conditions.

In terms of legal implications related to potential impacts, staff believes that documentation (evidence) would need to be provided that can distinguish pre-existing or current settlement conditions on the properties and the potential impact associated with the project, if any, as distinguished from continued settlement impacts unassociated with the project. Affected parties could pursue legal means if they so chose. Staff believes that the proposed monitoring, including documenting existing conditions, would assist both the developer and property owners to the north in this regard.

Staff Report - 9/24/02 -6- (02sr40 EIR 97-2)

3. Fault lines

A question was raised as to whether the EIR adequately analyzed potential impacts associated with the Newport-Inglewood (N-I) Fault as well as the Bolsa-Fairview (B-F) Fault. The summary below is based on information provided in the EIR and Response to Comments. Attachment No. 4.1-4.4 contains the detailed response BW-2 in its entirety, including referenced figures.

Bolsa-Fairview Fault

According to the geotechnical consultant, PSE, the EIR discussed both the N-I fault zone and the B-F Fault as mapped by the California Dept. of Water Resources (CDWR). PSE also summarized the reasons the B-F is neither included in an Alquist-Priolo zone, nor afforded a structural setback on the study site. The activity-level of the B-F is particularly important because it has been inferred to underlie the site, hence its importance relative to the potential for fault ground rupture.

According to PSE, the B-F was first mapped at and near the study site by CDWR in 1968. The City of Huntington Beach General Plan EIR and the State of California in 1986 indicate, however, that the fault is not active based on a variety of arguments. A map of the N-I zone depicts the B-F as "inactive or non-existent." Several lines of evidence lead to the conclusion that the B-F, if extant, is pre-Holocene. These reasons are detailed in Attachment No. 4. From a site-specific standpoint, examination of both hollowstem-auger borings and cone penetrometer test (CPT) soundings in the context of the regional geology suggests that if indeed the B-F is present beneath the surface at the study site, it is pre-Holocene and thus not active according to Alquist-Priolo standards and City policies. Therefore, no fault setbacks are recommended.

In summary, PSE completed a site-specific investigation, using methodologies accepted by the City for similar projects near the N-I, that indicates that the site is not underlain by active faults. Specifically, PSE developed a site-specific stratigraphy, based on Pleistocene/Holocene climatic and sea level changes that is useful for judging fault activity levels, and demonstrated absence of Holocene displacement in CPT correlation lines. Thus, tectonic surface displacement emanating from slip along the B-F is not a constraint to the proposed development.

Newport-Inglewood Fault

Based on the Alquist-Priolo Map, the surface trace of the N-I is about 0.4 mile south of Parkside Estates. The site is also north of the Special Studies Zone (requiring subsurface investigation) placed along the fault Tectonic surface rupture resultant from the fault is thus not anticipated on-site. Ground acceleration from a moderate to strong earthquake along the N-I fault was considered in the ground motion analysis for the site, particularly regarding liquefaction potential. PSE used a probabilistic seismic analysis that assessed potential on-site accelerations. The methodology is recommended by the State for determining ground accelerations useful for evaluating liquefaction potential. The derived acceleration was 0.39g, but a more conservative acceleration of0.5g was used in the PSE liquefaction potential analyses, based on suggestions by the Orange County Technical Advisory Board for a nearby project. That number is higher than the acceleration used by the California Division of Mines and Geology to prepare its Seismic Hazard Zone map of the area; CDMG used 0.45g.

Staff believes that the EIR document regarding fault lines is adequate and consistent with accepted geotechnical methodologies and CEQA requirements.

Staff Report - 9/24/02 -7- (02sr40 EIR 97-2)

4. Flooding (flow of water, including back to back El Nino storms)

There are two aspects of the flooding issue, both of which have been answered in the detailed flood insurance study submittals to the Federal Emergency Management Agency (FEMA), which resulted in their issuing the Conditional Letter of Map Revision (CLOMR) dated June 6, 2002.

Common to both aspects of the flooding issue is the hydraulic model and the hydraulic model "control" or water surface elevation in Huntington Harbour. The hydraulic model is UNET, One-Dimensional Unsteady Flow through a Full Network of Open Channels, from the U.S. Army Corps of Engineers. UNET is used, for example, by the Corps of Engineers for Mississippi River/New Orleans flood protection and by FEMA for the Talbert Valley flood insurance study. The control for all hydraulic models is extreme ("El Nino") high tide for the most conservative 12-hour long storm runoff duration, which includes wave set up and a 1.84 ft factor of safety.

The first aspect is flooding related to flood insurance, represented by the Certified Topographic Work Map. Federal regulations in FEMA 44 CFR 65.10 require that when modeling for flood insurance studies, levees that are not certified or certifiable by FEMA must be considered both to exist and not to exist such as to produce the highest depths of flooding.

Furthermore, pump stations must be modeled as operating and not operating such as to produce the highest depths of flooding. These situations are very highly unlikely to occur simultaneously, yet FEMA uses this extremely conservative approach to estimate worst case scenarios. Following the example of the FEMA detailed flood insurance study for Talbert Valley, there are seven hydraulically independent leveed reaches from Bolsa Chica to 1-405 freeway. The left levee, right levee, or both levees in each of these seven reaches are assumed to exist, or not to exist, to produce the highest theoretical flooding depths. There are 127 combinations of failure events, each of which could occur three ways, totaling 381 separate hydraulic models. Two additional models, one of which includes all levees in place, are also included in the FEMA submittal.

Slater, Marilyn, and Shields pump stations are modeled in both "on" and "off" conditions. The completely "off condition is more conservative than "throttle-back," because the pump station is modeled to not exist. The highest depths of flooding for each of the model storage areas for each of the 383 hydraulic models is considered to be the depth of flooding for flood insurance purposes, and is accordingly mapped on the Certified Topographic Work Map. In flood insurance study modeling, no single flood event is mapped, just the highest combined effects of many theoretical flood events and theoretical levee failures.

The detailed flood insurance study, summarized by the Certified Topographic Work Map, shows a very conservative representation of the results of FEMA's 100-year (1 percent annual chance) existing condition flooding. The study is also responsive to the question of whether throttle-back conditions have been addressed by looking at the flooding condition when the pumps are not running during peak discharge.

The second aspect is flooding related to actual flood protection. That is, levees that are not overtopped are expected to remain in place during an actual flood event. Pump stations are expected to operate. The detailed flood .insurance study hydraulic model that includes all levees remaining in place provides a response to analysis of flow of water from extreme storm events.

Staff Report - 9/24/02 -8- (02sr40 EIR 97-2)

For the East Garden Grove-Wintersburg (C05) channel, FEMA required a peak discharge [flow in cubic | feet per second (cfs)] of 4,000 cfs, and a total volume of 3,330 acre-feet measured at the Gothard Street stream gage. Because the hydraulic model begins at 1-405 freeway, a greater discharge and volume is required at the freeway to account for losses between the freeway and Gothard Street. For the hydraulic model with intact levees, the combined East Garden Grove-Wintersburg (COS) and Ocean View (C06) channel discharge at 1-405 is 9,236 cfs. The 100-year (1% annual chance) combined discharge calculated using the Orange County Hydrology Manual, and used in the County Approximate Study, is only 6,650 cfs. The detailed flood insurance study discharge exceeds the 100-year Orange County design discharge. Using Orange County Hydrology Manual calibration data, a combined discharge of 9,630 cfs is approximately equal to a 500-year (0.2% annual chance) flood event. Therefore, the combined C05 and C06 channel discharge of 9,236 cfs is very nearly the equivalent of a 500 year storm event.

The engineering design standard for upgrading existing flood control facilities is the 100-year design discharge. The input discharge used in the FEMA hydraulic model that most closely approximates the behavior of the existing and proposed flood control systems downstream of 1-405 substantially exceeds the 100-year discharge design standard.

The detailed flood insurance submittals to FEMA, which resulted in their issuing the CLOMR dated June 6, 2002 include the combined discharge event that approximates the 500-year (0.2% annual chance) flood event The water surface elevation in East Garden Grove-Wintersburg (C05) Channel at Slater pump station will increase less than three inches to a water surface elevation less than 8 ft MSL NGVD 29. The County permitted water surface elevation for Slater pump station at this location is 9 ft MSL NGVD 29. _ The top of levee is over 2 ft. above the extreme water surface elevation. Water surface elevations ^R adjacent to the proposed development site and to the south of the C05 channel remain the same, or are ^^ slightly lower, compared to the existing condition. In no case is there an adverse impact to any property. The proposed flood control improvements, the existing flood control structures, and property withstand this higher level or more conservative test. The Environmental Impact Report is valid, and responsive to additional concerns brought before the Planning Commission. Attachment No. 4.11 - 4.12 contains excerpted response to comments regarding flooding.

The impacts of the proposed project will be mitigated by storm drainage and flood control channel improvements to be constructed by the development. There will be no adverse impact to property either to the south of the flood control channel or along the proposed development frontages to the north, northeast, and east as a consequence of this development. As a condition of development, the project proponent is required to make the intersection of Graham Street and Kenilworth Drive passable during a 100-year storm based on future development conditions. New catch basins and storm drains will pick up storm water in the intersection and convey the flow through a new 120-inch storm drain to Slater Channel where it will be pumped into the EGGW flood control channel.

In relation to the potential for flooding of the adjacent neighborhoods as a result of development of this project, detailed topography shows that the neighboring property is already one to three feet lower than the existing elevation of the proposed development site. The neighboring property would be substantially flooded before flooding occurs on the proposed development site. There is no displacement effect possible until the neighboring property is already flooded. If the proposed project were theoretically constructed without the proposed flood control improvements, rising flood waters exceeding the pre-development property elevation would likely be displaced. However, since approval of the project is coupled with the entitlement conditions, the development will not be constructed without the drainage and pumping improvements that effectively mitigate any effect of displacement

Staff Report-9/24/02 -9- (02sr40 Effi. 97-2)

Additionally, upgrading of the Graham Street System will not prevent nor will it provoke flooding of the EGGW Channel (For additional information, see "Flooding", Pages 5-136 through 5-138 of the EIR). Analysis has shown that potential overtopping of the EGGW Channel is not a result of the Graham Street Storm Drain System because Graham Street Storm Drain discharges (and the proposed 120-inch drain will discharge) into Slater Channel, which in turn is pumped into the East Garden Grove-Wintersburg flood control channel. Discharge into EGGW channel is limited by the pumping capacity of Slater pump station. Pumping from the proposed seven pumps would raise the water surface elevation in EGGW channel only a few inches, to a water surface elevation slightly less than 8 ft MSL NGVD 29. This elevation is over a foot below the County permitted water surface elevation of 9 ft MSL NGVD 29. At Slater pump station, there is over 2 ft of freeboard above the County permitted water surface elevation. The potential for overtopping occurs upstream of me site and the Graham Street Bridge, and would not be caused or exacerbated by the subject project.

The City has adopted by reference in the Municipal Code regulations set by federal and state agencies as they relate to flooding. Currently, these regulations call for any new development to be built at an elevation, which is one foot above the 100-year base flood elevation as designated on the FEMA maps or flooding elevations established by the best available information. In the case of this development, the City has requested additional regional improvements to be made to the storm drain system to ensure that the intersection of Graham Street and Kenilworth Drive will also meet the 100-year flood protection, which it currently does not have.

The City's responsibility is to approve the construction of new development with entitlement requirements that are in conformance with federal, state and local regulations and guidelines.

5. Flood Control capacity

Flood control capacity of Slater Channel can be described in two ways: its capacity to convey water, and its capacity to store water. Slater Channel flood control conveyance capacity is directly related to the capacity of Slater pump station to discharge flood water from Slater Channel into East Garden Grove-Wintersburg (C05) Channel. Slater Channel flood control storage Capacity is also directly related to the geometry of Slater channel and the water surface elevation in the channel before and during a storm event.

With respect to Slater Channel flood control conveyance capacity, the Slater Channel Flood Hazard Mitigation Study prepared by Simons, Li & Associates in June, 2000 reports that Slater Channel can convey 1,310 cubic ft per second (cfs), provided that Slater pump station could discharge that quantity;

that is, if Slater pump station had eight pumps with a combined capacity of 1310 cfs. For situations where Slater Channel inflow is greater than pumping capacity. Slater Channel acts more as a retarding basin than a flood control channel, and during the time that inflow exceeds capacity, the forebay water surface elevation would rise. The Mitigation Study based its conclusions on a pump inlet (forebay) water surface elevation of-6 ft MSL NGVD 29.

However, pump capacity ,is a variable that depends on total difference in elevation between forebay elevation and discharge (flap gate) elevation. This was investigated as part of the detailed flood insurance study submittals to the Federal Emergency Management Agency (FEMA), which resulted in their issuing the Conditional Letter of Map Revision (CLOMR) dated June 6,2002. Using pump information and consultation from Johnston Pump Co., if Slater Channel inflow should exceed pump capacity and the forebay water surface elevation should temporarily rise 5 ft to an elevation of-1 ft MSL NGVD 29, the capacity of each 147 cfs pump would increase about 6,000 gallons per minute or 13 cfs, to a new capacity of 160cfs. Individual pump capacity used in the detailed flood insurance study was conservatively set at 147 cfs.

Staff Report-9/24/02 -10- (02sr40 EIR 97-2)

t With respect to Slater Channel flood control storage capacity, the conservative capacity of Slater Channel itself, not including culverts and laterals, between empty and elevation 0 ft MSL NGVD 29 is about 180 acre-feet. According to the Orange County Hydrology Report No. C05S04-1, the total volume in the 100-year flood hydrograph is 170 acre-feet. If Slater Channel were empty at the beginning of the 100-year runoff event, the entire storm volume could be stored in the channel without pumping, and without overflowing.

The operational goal of the system, however, is to maintain Slater pump station forebay and channel water surface elevation as far below "full" as possible, to facilitate street drainage entering the storm drains which flow into Slater Channel. Slater Channel is customarily maintained at elevation -6 ft MSL NGVD 29. The storage volume up to this elevation is about 90 acre-feet, leaving about 90-acre feet to be pumped without having the forebay water surface elevation rise above 0 ft MSL NGVD 29. Each pump is capable of discharging 147 cfs, or about 290 acre-feet per day or 12 acre-feet per hour. One pump could discharge 90 acre-feet in about 7-1/2 hours. Five pumps could do the task in an hour and a half, which is about the total length of the 100-year flood flow hydrograph peak.

The proposed Parkside Estates has been conditioned by the City and County to mitigate its impact on local and regional flood control: a peak discharge of 126 cfs, and 2 acre-feet of "new" water. The project proponent will provide new pumps for Slater pump station, and reconstruct Parkside Estates frontage on COS channel with vertical sheet piling.

In the absence of additional pumping, or before pumping begins, 2 acre-feet of "new" water from I Parkside Estates would raise Slater pump station forebay elevation from -6.00 ft MSL NGVD 29 to -5.85 ft MSL NGVD 29, in other words an increase of 0.15 ft or less than 2 inches.

One additional 147-cfs pump in Slater pump station is more than adequate to discharge the peak flow of 126 cfs from Parkside Estates. During peak flows, though, storage effects of Slater Channel become more important Since one pump is capable of discharging 12 acre-feet per hour, the pump can discharge all of the 2 acre-feet of "new" water in only 10 minutes. Therefore, nearly all the capacity of the two new pumps will be devoted to off-site benefit

Storage effects also apply to the County C05 channel. Widening the channel by construction of the sheet pile system along the levee will add at least 5 acre-feet of additional capacity to the C05 channel volume, more than sufficient to mitigate the 2 acre-feet of "new" water from Parkside Estates.

Staff Report-9/24/02 -11- (02sr40 EIR 97-2)

6. City's Master Plan of Storm Drainage [comparison of methods used for '93 (4597 cfs) and '00 (1310 cfs) studies]

In 1993, an updated Master Plan of Drainage (MPD) was prepared for the City of Huntington Beach by Williamson & Schmid to revise as needed the previous master plan prepared by L.D. King and Associates in 1979, based upon the construction of new storm drain facilities and new areas of development and changed land uses within the City. Both studies included a watershed boundary of 26.5 square miles, which included portions of the City of Westminster and the City of Fountain Valley.

One of the key distinctions of the approach taken in preparing the 1993 MPD, which was also the case for the 1979 MPD, was the exclusion of any existing or proposed retention or detention within the watershed. As noted on page 5 of the 1993 MPD, "all storm drain facilities are analyzed and sized on a free flowing system." It also goes on to state that "In this Master Plan of Drainage (MPD) only the Rational Method model (per 1986 OCEMA Hydrology Manual) is utilized. Since there are no drainage areas greater than one square mile (640 acres) and no detention/retention basins considered (see Section 2.9), the unit hydrograph model was not needed."

The net result of this approach overestimated the peak discharges in the watershed by nearly 4 times.

The Rational Method was originally developed to estimate peak discharge from small (less than one square mile or 640 acres) of urban and developed areas. As noted in the County's Hydrology Manual, 1986 Ed., page D-2, "The rational method equation is only applicable where the rainfall intensity (I) can be assumed to be uniformly distributed over the drainage area at a uniform rate throughout the duration of the storm. This assumption only applies fairly well to small areas of less than 640 acres. Beyond this limit, the rainfall distribution may vary considerably from the point values given in rainfall isohyetal maps and the rational method equation should not be used." In recognition of the limitations of this approach, the 1993 MPD states on page 6 that "It should be recognized that this MPD is a conceptual study which identifies facilities needed to effectively control and convey runoff in Huntington Beach based on the City's drainage policies. This plan is not, however, detailed enough for design purposes and additional engineering studies should be completed prior to the design or construction of any facilities."

The net result of using the Rational Method on large drainage areas is over estimation of the peak discharge. If this peak discharge is used to derive a runoff volume, the volume would accordingly be overestimated. For this reason, the City of Huntington Beach contracted with Simons, Li & Associates in 2000 to produce an updated and precise hydrology/hydraulics and design study for the Slater Channel and its watershed of 2,706 acres, or 4.2 square miles. The study used the Unit Hydrograph Method for flood routing for a two-day storm. The routing included parks, natural drainage courses, and the detention areas of Huntington Lake, Sully Miller Lake, Talbert Lake and the Shipley Nature Center Lake. The Rational Method was only used to determine the initial time of concentration for each subbasin in the model, of which there were a total of 16 subbasins.

The 1993 MPD had estimated the 100-year peak discharge at the Slater pump station to be 4,597 cubic feet per second (cfs) without detention or retention in the lakes and other areas of the watershed, but provided no runoff hydrograph or estimate of total runoff volume needed to properly judge Slater pump station performance in an actual flooding situation. However, the SL&A study more accurately estimates the peak discharge and runoff volume within the watershed at 1,310 cfs, or nearly one quarter of the 1993 MPD estimate. These values are very close to earlier estimates by the Orange County Flood Control District of 1,400 cfs..

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7. Fire Department response times

In response to issues raised at Study Sessions, staff prepared three revised errata pages for the Final EIR addressing Fire Dept. response times. These pages were included in the Sept. 10,2002 EIR Staff Report. Staff believes that they also address comment letters that have been received. The Planning Commission requested further information regarding response times. The following is a response from the Fire Dept.

The General Plan has a Fire and Paramedic goal to "Ensure adequate protection from fire and medical emergencies for Huntington Beach residents and property owners." One of the polices identified to accomplish that goal is to "Locate fire stations in a manner which will enable emergency fire response times to meet a five minute standard, 80 percent of the time." For more than twenty five years, the Fire Department has been guided by this goal and policy for strategic planning of station locations.

However, it must be understood that this goal allows for 20 percent of emergency responses to exceed the 5 minute standard. The probability of meeting this standard for any given area of the City is based on the response time from a fire station. Fire stations are normally located so their response area has a radius of 1.5-2 miles. This response area also takes into consideration the expected call load, administrative workload, geographic restrictions, and roadways (planned or present). All of these factors will help determine the best location that serves the greatest number of citizens, ensures adequate response coverage and is fiscally responsible for the community.

At the time of an emergency any location within a fire station's first due area may be outside of this response standard because the fire company is not at the station. Actual driving time from a fire station to t any location in the city is only representative of what can be expected for response times. The driving time estimates are conservative times as they are conducted in a non-emergency status without signalized intersection preemption, observing stop signs and may be impacted by traffic flow. A response with warning lights/sirens improves the Dept.'s ability to ensure faster response times during an emergency.

The success of the Fire Department in meeting the General Plan goal is based on the actual response times of emergency incidents, not driving time studies. These response times during the emergency can have several factors, other than station location, that contribute to the total time required: 1) the engine location at the time of the alarm, sometimes further away than the station; 2) the traffic volume, which can affect response at various times of the day; 3) the time of the incident, during normal work hours or at night; and 4) the availability of the first due fire company and required response from another company.

The construction and staffing of Station 6 has mitigated the deficiency for a very large number of homes previously outside of the 5 minute response standard goal. But there may be some locations in the area of the Parkside Project that remain outside of this standard, just as other sections of the City remain in a deficient response area. Several driving time runs were made from the proposed relocation site of Station 8 to the intersection of Slater and Graham, these times indicate that the new site will provide response times within 5 minutes. These and prior studies show that response times from three stations to this area of the City will range from 4 minutes 30 seconds to 5 minutes 30 seconds. This provides an exceptional degree of overlapping coverage from these fire stations.

The Parkside Project has substantially reduced the impact on Fire Department resources because of the inclusion of a residential sprinkler system. Fewer companies will be committed to handle a structure fire at Parkside Estates, which will reduce the time these companies are unavailable for the surrounding community when multiple emergencies occur at the same time.

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8. Maximum capacity for Slater Pump Station (what is our limit) has it been exceeded)

The Slater pump station was estimated in the 1993 MPD to pump around 697 cfs with the existing five pumps installed, which is approximately 139.4 cfs per pump. This estimate was a conservative number adopted by the study engineer. The recent flood insurance study submitted by the developer and approved by FEMA used a pumping capacity of 147 cfs per pump based upon the 1979 L.D. King MPD, which is closer to actual pump performance. The 697 cfs is significantly less than the estimated capacity of 1400 cfs for the Slater channel. The Simons, Li & Associates study estimated, as did the 1993 MPD, that the station could pump approximately 1,300 cfs with the installation of three more pumps with a 200 cfs capacity in the remaining three bays. Again, this is still well within the original estimates for the design of the station. Incorporating these figures in the analysis, the addition of two pumps to the existing five pumps already installed and operating in the station will increase the volume of water to be pumped, but will still be less than the design 1,400 cfs of the channel. This is also consistent with the earlier Slater Channel and Pump Station report prepared by the County of Orange in 1976.

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9. Liquefaction

A question was raised as to whether the EIR adequately analyzed potential impacts associated with liquefaction. The response below is based on the EIR and Response to Comments.

In March, 1997, the state of California Department of Conservation, Division of Mines and Geology adopted Special Publication 117, Guidelines for Evaluating and Mitigating Seismic Hazards in California. That document provides definitions, sets objectives, provides suggested analytic methodologies, and offers mitigation alternatives for development of potentially liquefiable sites.

The project geotechnical consultant, PSE, has performed site investigation and liquefaction analysis consistent with the state Guidelines, including 26 borings, 17 test pits and 65 Cone Penetrometer soundings. The analysis indicates that potentially liquefiable soils exist at the site. Those potentially liquefiable strata consist of sands and silts that exist in the upper 30 to 35 feet and are interbedded with more cohesive clayey silts and silty clays that are not susceptible to liquefaction. The major peat concentrations are in the upper 5 to 6 feet and thus will necessarily be removed in accomplishing the recommended site overexcavation/recompaction

SP 117 guidelines suggest suitable mitigation alternatives may include one or more of the following:

1) Excavation and removal or recompaction of potentially liquefiable soils; 2) In-situ ground densification (e.g., compaction with vibratory probes, dynamic consolidation, compaction piles, blasting densification, compaction grouting); 3) Other types of ground improvement (e.g., permeation grouting, columnar jet grouting, deep mixing, gravel drains or other drains, surcharge pre-loading, structural fills, dewatering); 4) Deep foundations (e.g., piles, piers), that have been designed to accommodate liquefaction effects; 5) Reinforced shallow foundations (e.g., grade beams, combined footings, reinforced or post-tensioned slabs, rigid raft foundations); and 6) Design of the proposed structures or facilities to withstand predicted ground softening and/or predicted vertical and lateral ground displacements to an acceptable level of risk.

PSE has designed a mitigation consisting of a combination of alternatives 1,5, and 6. Summarized, the mitigation will consist of overexcavating and recompacting to sufficient depths to provide a compacted fill mantle over the underlying potentially liquefiable soils. Depths of removal will vary from elevation minus 3 to elevation minus 19. The mantle is designed to provide sufficient thickness of non-liquefiable material such that surface manifestation in the form of fissuring and sand boils is prevented. This is because an important factor influencing whether liquefaction is manifested at the ground surface is the thickness of the mantle of non-liquefiable soil above the liquefiable layers. If the mantle of non-liquefiable soil is sufficiently thick, the uplift force due to the excess pore water pressure will not be large enough to cause a breach in the surface layers even if liquefaction occurs in the deeper deposits.

Liquefaction of some of the remaining deeper deposits could occur during a major seismic event in proximity to the site. The analyses indicate that, after overexcavation, recompaction, and placement of design fills, potential settlements of one to four inches could occur. To mitigate this potential, PSE has further recommended that the foundation systems consist of either post-tensioned slab/foundations or mat foundations designed to resist potential differential settlements. Staff believes that the EIR adequately analyzes potential liquefaction impacts and has appropriate mitigation measures supported by accepted geotechnical methods and guidelines.

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Information related to various issues raised in written correspondence

Several additional issues have been raised in correspondence either attached to the Planning Commission staff report of September 10,2002 or in correspondence received after the September 10^th meeting (and attached to this report) that staff believes would benefit from clarification. Staff has consulted with its technical consultants regarding these issues to provide the following information, organized by issue area.

• Cultural Resources

On September 11^th, the Planning Department received a letter from the Gabrielino Tongva Indians of California Tribal Council (Attachment No. 5). In response to the correspondence the following information from the EIR is summarized below. Page 5-165 of the EIR discusses the CA-ORA-83 site and indicates that a majority of this archaeological site is located off the project property. Page 5-165 goes on to acknowledge the following information regarding ancestral remains of the ORA-83 site, "Other new discoveries are a human burial component at the site. Mason (OCEMA, 1996:

4.12-16-18), concludes that no total estimate of burials is possible, given present information and the fragmentary nature of the finds. He further concludes that a count of at least 19 individuals is possible, and that most if not all represent secondary reburials."

Page 5-171 of the EIR provides an evaluation of archaeological site significance based on three significance criteria. After a detailed comparative analysis using volumes of prior studies and the project's archaeological evaluation, the EIR archeological assessment concludes that the portion of the CA-ORA-83 site, which is contained by the Shea Homes project, is only of moderate significance, specifically in relation to other better studied portions of the same archaeological site. Although this portion of CA-ORA-83 was concluded to be of moderate significance, the proposed project will not impact any portion of this site. All burials known to exist at the ORA-83 are on the top of the mesa, well away from the Shea property, and the boundaries of the proposed development down on the flats below the mesa were contracted away from the toe of the slope specifically so as to avoid any part of the ORA-83 site, thereby preserving and protecting it.

Further CA-ORA-1308 and 1309 were found to be of minimal and of very low significance because of their lack of artifacts, extremely disturbed state, and in me case ofORA-1308, the extreme admixture of modem garbage within the deposit. Mitigation measures 1-3 do require preparation of a cultural resource management plan be developed in consultation with appropriate Native American organizations should the subsurface test results of the CA-ORA-1308 and 1309 determine that a plan is necessary. Although not required by CEQA based on the conclusions of the EIR, the Planning Commission could condition the project to have a Gabrielino Tongva Indian monitor the implementation of Mitigation Measure 1 (i.e., subsurface testing for ORA-1308 and 1309). This condition would be associated with the staff report for the Tentative Tract Maps. Specifically the Planning Commission could amend Condition No. 5.kk on the Tentative Tract Map, which is located on Attachment No. 1.14 of that staff report from September 10^th.

• Transportation/Circulation

In response to a question regarding the adequacy of the traffic study conducted in 1997 given the new Home Depot, staff contacted the traffic consultant The consultant indicated that there is no unaccounted for impact from the Home Depot now located at Goldenwest and Warner for two reasons: "1) Shopping trips are already factored into trips generated from residences. A new retail

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business may relocate a shopping trip from one travel corridor to another but not create a new trip from a residence; and 2) The Home Depot previously was located at Goldenwest and Edinger, which is in the same travel corridor for Graham Street."

Staff believes that the traffic study is adequate and appropriately analyzes impacts associated with the project. Moreover, the traffic study is augmented by the additional traffic counts conducted on September 4^th and 5^th that were presented to the Planning Commission on September 10^th. These data provide verification that traffic volumes in the area have not significantly changed since the original report was prepared. Also, the new data show that the cumulative analysis contained in the March 21,2001 report overestimated traffic volumes, and the conclusions reached and recommended mitigation measures contained in the March 21,2001 report are still valid and no additional mitigation measures are required.

• Noise

In response to a question regarding the possibility of increased noise associated with installation of a traffic signal at the project entry on Graham Street, staff contacted the noise consultant, Giroux & Associates. Mr. Giroux indicated that "noise measurements at numerous intersections have found that the speed reduction associated with signalization balances any acceleration effects unless there are very high percentages of trucks on the affected streets. A typical accelerating passenger car at slow initial speed is no louder than the same vehicle moving at free-flow traffic speed. Installation of traffic signals is considered a "non-Type I" project under federal noise analysis requirements unless the signal is on a truck route," which this segment of Graham is not. Staff would also note that there are traffic signals in close proximity to residential neighborhoods throughout the City that do not result in noise complaints or compatibility issues. In conclusion, there are no significant noise implications from installing a traffic signal at the proposed location.

SUMMARY:

Environmental Impact Report No. 97-2 serves as an informational document with the sole purpose of identifying potential environmental impacts associated with the proposed Parkside Estates project, alternatives which minimize those impacts and appropriate mitigation measures.

Staff recommends that the Planning Commission certify EIR No. 97-2 because:

• The EIR adequately addresses the environmental impacts associated with the proposed project, and

• Identifies project alternatives and mitigation measures to lessen the project's impacts consistent with General Plan policies.

ATTACHMENTS;

1. Resolution No. 1574 (Final EIR No. 97-2)

2. Planning Commission Staff Report dated September 10,2002 (under separate cover - not attached)

3. Coastal Commission correspondence and Associated Water Quality Memoranda

4. Excerpted Response to Comments

5. Cultural Resources Letter

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