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CITY OF PACIFICA COUNCIL AGENDA SUMMARY REPORT

3/23/2015

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SUBJECT: Wastewater Equalization Basin Site Feasibility Evaluation RECOMMENDED ACTION: Receive and discuss the Wastewater Department’s presentation of the Final Draft of the “Wet-Weather Equalization Basin Site Feasibility Evaluation”. This is an information only item.

ORIGINATED BY:

Wastewater Department

STAFF CONTACT:

Joshua Cosgrove, Assistant Superintendent (650) 738-7475 [email protected]

BACKGROUND/DISCUSSION:

Current Status of Pacifica’s Wastewater Collection System

The City of Pacifica’s Wastewater Collection System is an aging system that has been in

service for approximately 50 to 60 years. The various parts of the system like the pipes,

manholes, and pump stations are at the end of their service life or, as in some cases, the

service life has been exceeded. When a system exceeds its service life many problems like

sanitary sewer overflows (SSO) begin to occur which can negatively impact our waterways and

natural environment. One of the primary problems that occur involves an overloading of the

capacity of the system during a significant wet-weather event. The specific structural issues

that cause this capacity problem are termed by the wastewater industry as “infiltration and

inflow”. Infiltration is the “seepage of groundwater into a sewer system, including service

connections” and inflow is “water discharged into a sewer system and service connections from

such sources as, but not limited to, roof leaders, cellars, yard area drains, foundation drains,

around manhole covers or through holes in the covers, cross connections from storm systems,

catch basins, storm waters, surface runoff, or drainage” (California State University,

Sacramento, Office of Water Programs). Pacifica wastewater staff have identified infiltration

during significant wet-weather events as the primary system inadequacy leading to capacity

related SSOs and we often see a peaking wet-weather factor of 4 to 6 times. This means that

when significant wet-weather events take place the daily flow rate increases from the design

dry-weather flow rate of 4 Million Gallons per Day (MGD) to rates of 16 to 24 MGD. The Calera

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Pacifica City Council 2 March 23, 2015

Creek Water Recycling Plant (WRP) was designed to treat to a tertiary level a flow rate that

does not exceed 20 MGD for over a couple of hours. As an example, in the storm that came

through on December 11, 2014 the flow rate exceeded 20 MGD for over 10 hours.

Master Plan

To address the problems identified above, adequately plan for the replacing and upgrading of

Pacifica’s wastewater system over the next 20 years, and meet the requirements of our 2011

Cease and Desist Order and Consent Decree, staff hired RMC Water and Environment (RMC)

to collaborate with us in developing a Master Plan. A PDF of the Plan may be found on the

City’s website at (http://cityofpacifica.org/civica/filebank/blobdload.asp?BlobID=5267.). The Plan

was completed in 2011 and it identified three alternative sets of projects related to wet-weather

capacity improvements:

1. Improvements to the collection system, Calera Creek Water Recycling Plant

(WRP), Linda Mar Pump Station and the construction of a secondary force

main that runs from Linda Mar Pump Station to the Calera Creek WRP

2. Improvements to the collection system and construction of a wet-weather

equalization basin in the Lower Linda Mar area

3. Improvements to the collection system only

A detailed discussion of the alternatives may be found in Section 3.5 of the Plan. Staff and

RMC chose Alternative 2 as the most viable. The primary reasons we chose this alternative

was because of the lower estimated cost ($24 million compared to $27 and $34 million), short

construction timeline, and the comparative simplicity of the alternative. Alternative 1 consisted

of complex Coastal Commission and State Water Resources Control Board permit requirements

and Alternative 3 would take much too long for the improvements to have an effect on capacity

during wet-weather events (15 to 20 year project timeline). Based on this determination RMC

was hired to develop a Wet-Weather Equalization Basin Site Feasibility Evaluation.

Wet-Weather Equalization Basin Site Feasibility Evaluation

The Evaluation was completed in 2013 and a copy is attached to this report. The Evaluation

included analysis of six potential sites for an equalization basin in the Linda Mar area of which

the four chosen by staff and RMC as the most feasible are listed below:

1. Linda Mar Park and Ride Lot

2. Community Center Rear Parking Lot and Adjacent Undeveloped Area

3. Community Center Front Parking/Park and Ride Lot

4. Linda Mar Beach Parking Lot

The impact criteria used to create this short list included the disturbance to neighbors and

amenities, construction impacts to the public, a willing landowner, vulnerability to sea level rise

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and flooding, and cost. The findings in the Evaluation were presented to the City Council at the

March 25, 2013 regular public meeting and through a public outreach meeting held at the

Council Chamber August 14, 2013. The comments and feedback from these public meetings

involved, but are not limited to, concerns with the construction impact in the neighborhood, odor

control, impact on property values, Coastal Commission permit requirements, and a request to

examine examples of other similar basin projects. After these public meetings and further

analysis by staff and RMC the list of was reduced to two potential sites-(1) the Linda Mar Park

and Ride Lot and (2) the Community Center Front Parking/Park and Ride Lot.

Final Recommendation of an Equalization Basin Site

Wastewater staff recommends the Linda Mar Park and Ride Lot and Community Center Front

Parking/Park and Ride Lot as the two most viable sites. Staff’s analysis follows:

The Linda Mar Park and Ride has a relatively low estimated project cost of $12.8

million ($12.2 million for construction and net $600 thousand for land), is protected from

sea level rise, and will have relatively light construction impacts to the public. The

project at this site would be directly adjacent to approximately five homes and one

business but construction would be performed to minimize the impact to these homes,

the basin once it is completed would not be visible to the public, and the interior would

have atmospheric controls to eliminate odors.

The Community Center Front Parking/Park and Ride Lot has an estimated project

cost of $16.1 million ($14.5 million for construction and $1.6 million for land), is relatively

far from private structures, and is relatively protected from sea level rise. The project at

this site is not adjacent to any homes but is adjacent to the Community Center and the

project would impact activities at the Center and the Skatepark. The wetlands at this site

would also have to be purchased as part of the land and maintenance of these wetlands

that are adjacent to the Highway would have a significant recurring cost. This cost has

not yet been estimated by staff and would be an additional cost for this

alternative.

A final comparison between the two sites involves the ongoing maintenance of the piping

systems that would have to be constructed. At the Linda Mar Park and Ride site, 900 feet of

piping must be constructed while 1,800 feet of piping must be constructed at the Community

Center Front Parking/Park and Ride Lot. Maintenance of the piping at the Community Center

site will also be more complex and costly since there will be double the piping compared to

Linda Mar Park and Ride, and because of the proximity of the piping to the highway and

wetlands. (Please see Table 6-1 on page 6-2 in the Evaluation for a detailed discussion of the

positive and negative characteristics of the project sites excluding the cost of land.) The land

cost analysis was performed by the Wastewater Engineer. Below is a table summarizing the

above information.

Summary Table

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Advantages Disadvantages Cost (in millions)

SITE A - Linda Mar Park and Ride 1 Low cost 1 Exposed to potential flooding $ 12.76

2 Light construction impact to public 2 Directly adjacent to five homes and 1 business

3 Landowner indicated willingness to sell

4 East of Hwy 1 protects from sea level rise

SITE C1 - Community Center Front 1 Removed from private structures 1 Directly adjacent to Community Center $ 16.10

Parking/Park and Ride 2 Landowner indicated willingness to sell 2 Heavy construction impacts to public

3 East of Hwy 1 protects from sea level rise 3 Exposed to potential flooding

4 Significant site and piping maintenance costs

5 Wetlands at this site would have to be purchased

Cost of maintaining wetlands has not yet been

estimated by staff and would be an additional cost

SITE A COSTS LESS THAN SITE C1 BY: $ 3.34

EQUALIZATION BASIN SITE COMPARISON

Projected Construction Timeline for Either Site

Construction Element 1 2 3 4 5 6 7 8 9 10 11 12 13 14Cutter Soil Mix Wall

Excavation, Rebar, and Shotcrete PlacementConcrete Base

Concrete Deck and GirdersDiversion PipelineDischarge Pipeline

Electrical and InstrumentationMechanical

Month

In Closing This item is presented as an information only item and the Wastewater Department staff is providing it in this manner as an opportunity for the Council to review and discuss the Final Draft of the Feasability Evaluation and for any members of the public to provide comment without the need for a final decision. Staff believes the cost of the project, location of the equalization basin, and the long timeline warrants more than one Council meeting before a final decision is made on which site to build the facility. Staff will return with a Council agenda item at another meeting in the near future requesting a decision on the final site for the equalization basin.

FISCAL IMPACT: Because this is an information only agenda item there is no fiscal impact to this item. The project cost is discussed in the Background/Discussion section above and the financing of the project may be found in the Wastewater Department 20 Year Financial Plan - Construction (34 account) of which a PDF copy may be downloaded online here: (<http://www.cityofpacifica.org/civica/filebank/blobdload.asp?BlobID=7248>). The specific budget line item number in which you may find the cost schedule is 52800.C031.000 beginning in column Fiscal Year 2015/16 and ending in column Fiscal Year 2019/20. The financing schedule is located under the budget line item New Bond Issues 2016 and the amount is found in the Fiscal Year column 2016/17. ORIGINATED BY:

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Waste Water Treatment ATTACHMENT LIST: Final Site Feasibility Evaluation Report (PDF)

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February 2013

Wet Weather Equalization BasinSite Feasibility Evaluation FINAL REPORT

Concrete Deck

Max Water Level

Concrete Bottom

ShotcreteCutter Soil Mix

Prepared By

CITY OF PACIFICA

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Wet Weather Equalization Basin Site Feasibility Evaluation

Final Report

Prepared by:

February 2013

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Table of Contents Chapter 1 Summary of Findings ........................................................................................... 1-1 Chapter 2 Introduction ........................................................................................................... 2-1 Chapter 3 Potential Sites ....................................................................................................... 3-1 Chapter 4 Construction Methods .......................................................................................... 4-1 4.1 Equalization Basin ................................................................................................... 4-1 4.2 Pipelines .................................................................................................................. 4-3 4.3 Other Project Elements ........................................................................................... 4-4 4.4 Schedule ................................................................................................................. 4-6 Chapter 5 Site Analysis .......................................................................................................... 5-1 5.1 Site A: Linda Mar Park and Ride Lot ....................................................................... 5-4 5.2 Site B: Community Center Rear Parking Lot and Adjacent Undeveloped Area .... 5-10 5.3 Site C1: Community Center Front Parking/Park and Ride Lot .............................. 5-17 5.4 Site D: Linda Mar Pump Station Parking Lot ......................................................... 5-23 Chapter 6 Findings and Recommendations ......................................................................... 6-1 6.1 Site Findings ........................................................................................................... 6-1 6.2 Recommendations .................................................................................................. 6-3 6.3 Next Steps ............................................................................................................... 6-5

List of Tables Table 1-1: Site Evaluation Summary ...................................................................................... 1-5 Table 3-1: Preliminary Site Analysis Recommendations ..................................................... 3-1 Table 5-1: Site A Infrastructure Dimensions and Lengths ................................................... 5-4 Table 5-2: Total Project Costs for Site A ............................................................................... 5-8 Table 5-3: Site B Infrastructure Dimensions and Lengths ................................................. 5-10 Table 5-4: Site B Soil Condition Based on Boring .............................................................. 5-13 Table 5-5: Total Project Costs for Site B ............................................................................. 5-15 Table 5-6: Site C1 Infrastructure Dimensions and Lengths ............................................... 5-17 Table 5-7: Total Project Costs for Site C1 ........................................................................... 5-21 Table 5-8: Site D Infrastructure Dimensions and Lengths ................................................. 5-23 Table 5-9: Site D Soil Condition Based on Boring .............................................................. 5-26 Table 5-10: Total Project Costs for Site D ........................................................................... 5-28 Table 6-1: Summary of Findings and Costs for Shortlisted Sites ....................................... 6-2 Table 6-2: Site Priority Decision Matrix ................................................................................. 6-3 Table 6-3: Description of Criteria and Scores Used in Decision Matrix .............................. 6-4

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List of Figures Figure 1-1: Evaluated Site Location Overview ...................................................................... 1-2 Figure 3-1: Potential Site Location Overview ........................................................................ 3-2 Figure 4-1: Cutter Soil Mixing Equipment ............................................................................. 4-1 Figure 4-2: Plan View Excerpt of Cutter Soil Mixing Wall Panels ........................................ 4-2 Figure 4-3: Plan View Section of Basin Wall Primary Components .................................... 4-2 Figure 4-4: Basin Section Showing Primary Elements ........................................................ 4-3 Figure 4-5: Interior Basin Components ................................................................................. 4-6 Figure 4-6: Example Construction Sequence ....................................................................... 4-6 Figure 5-1: Schematic of Typical Equalization Basin Site and Pipelines ........................... 5-1 Figure 5-2: Diameter-Depth Relationship for Equalization Basin ........................................ 5-3 Figure 5-3: Potential Basin Location and Pipeline Alignment at Site A .............................. 5-5 Figure 5-4: Potential Basin Location and Pipeline Alignment at Site B ............................ 5-11 Figure 5-5: Hydraulic Grade Line for Site B 2.1 mgd Discharge to LH5 ........................... 5-12 Figure 5-6: Potential Basin Location and Pipeline Alignment at Site C1 .......................... 5-18 Figure 5-7: Potential Basin Location and Pipeline Alignment at Site D ............................ 5-24

Appendices Appendix A - Linda Mar Equalization Basin Preliminary Site Assessment Technical

Memorandum Appendix B - Preliminary Geotechnical Report

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February 2013

List of Abbreviations

gpd gallons per day

gpm gallons per minute

mgd million gallons per day

City City of Pacifica

CSM cutter soil mixing

HDD horizontal directional drilling

MG million gallons

Master Plan City of Pacifica Collection System Master Plan (2011)

PTGAB pilot tube guided auger boring

SSO sanitary sewer overflow

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 1 Summary of Findings

February 2013 1-1

Chapter 1 Summary of Findings

This report presents the results and recommendations of a site feasibility evaluation for a wet weather equalization storage basin for the City of Pacifica (City). The report was prepared by RMC Water and Environment (RMC) under a contract amendment to the City’s Collection System Master Plan completed in October 2011. The equalization basin is a key element of the program recommended in the Master Plan to eliminate storm-related sanitary sewer overflows (SSOs) in the City’s wastewater collection system and reduce peak wet weather flows to the City’s Calera Creek Water Recycling Plant. Based on the Master Plan findings, a wet weather equalization basin located in the vicinity of the Linda Mar Pump Station was identified as the most viable alternative (in addition to other recommended sewer improvements) for meeting regulatory requirements for eliminating capacity-related SSOs.

Based on preliminary analyses, six potential sites for an equalization basin were identified. These sites are shown in Figure 3-1. From these six sites, four sites were selected for further consideration based on a combination of ownership and permitting characteristics. Those sites included:

A park and ride lot near Linda Mar Blvd. (Site A),

The parking lot and open space area behind the Pacifica Community Center (Site B),

A park and ride parking lot in front of the Pacifica Community Center (Site C1), and

The parking lot of the Linda Mar Pump Station (Site D).

Further evaluation of Sites A, B, C1, and D, shown in Figure 1-1, highlighted similarities and differences between the sites as well as promoted further development of the construction and operational aspects. Two geotechnical borings were drilled to a depth of approximately 75 feet to provide a better sense of soil characteristics and stratigraphy that would be encountered during construction. Seventy-five feet was selected as the target depth for the borings based on an analysis of approximate basin depths for the four basins shown in Figure 1-1. Additionally, geotechnical engineering judgment suggested that soil conditions at that depth would be able to support the basin load.

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February 2013 1-3

Five criteria were identified as being particularly important to the recommendation of a preferred site, namely:

Disturbance to Neighbors and Amenities – This criterion focuses on the potential impacts, or perception of those impacts, to those residents and businesses that are located near the site. Although the construction methods considered in this report would allow the basin to be constructed in a manner that would not structurally impact nearby residences, there remains a risk that unjustified claims could be made at sites that are in close proximity to structures and amenities. Odor and noise nuisances near the basin should also be minimal after construction is over, but there could still be some complaints post-construction. The inconvenience and risk to all parties decreases with increased distance between the site and local structures.

Construction Impacts to Public - All of the evaluated sites are within parking lots of amenities

that are used by various sectors of the public. This criterion considers the inconvenience to citizens whose use of those amenities would be impacted by construction and loss of parking during construction.

Willing Landowner – It is preferable to locate the basin on a parcel either owned by the City or with a willing landowner. Without a landowner willing to sell the basin parcel to the City, the difficulty of obtaining the parcel could be a fatal flaw of the site.

Vulnerability to Sea Level Rise and Flooding – Sea level is anticipated to increase on the order of two feet over the lifetime of the equalization basin. Protecting the capital investment made in the basin is a primary concern. Site D (at Linda Mar Pump Station) is the only site of the four located on the ocean-side of Highway 1. We understand that the City is participating in a regional effort called the Coastal Regional Sediment Management Plan which will ultimately make recommendations regarding coastal erosion. Since the results of that project are not yet available, it is not clear whether the City will protect from future coastal erosion the Linda Mar Pump Station parcel and more generally the Linda Mar coastal area. It is therefore assumed that by locating basins further inland, the additional infrastructure and distance between the basin facilities and the ocean would provide more protection from sea level rise and erosion than could be afforded by a site closer to the ocean. For this reason, sites east of Highway 1 are preferred.

The City also prefers to have use of the facility during flood events to help reduce the potential for sewer surcharging and contamination. Sites that are less prone to flooding or could accommodate a design to remove the basin from a floodplain are preferable to those sites that are more likely to flood.

Cost – The equalization basin and associated facilities are significant capital investments for the

City. Therefore, lower cost alternatives are preferred, assuming benefits, impacts and risks are equal among the alternatives.

As the sites were evaluated, it was found that:

Construction of a basin at all four sites would be technically feasible;

All four sites were found to be either City-owned or have a willing seller (Caltrans);

Sites A and B are closer to residences than Sites C1 and D. Site C1 is closer to a regularly used

public facility (City of Pacifica Community Center) than the other three sites. City staff have

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February 2013 1-4

indicated that they are planning to perform public outreach and education that should reduce the number and type of concerns that the public might otherwise have.

Site A is anticipated to have a smaller construction impact than the other sites. The public use of

the Site A parcel is relatively unimpeded by the soon-to-be-removed Caltrans construction trailers and parking area that have been present for several years. Community center users take advantage of available parking at Sites B and C1 while beach users do the same at Sites D and C1. The parking lots at Sites A and C1 are options for carpooling and public transit, but Site A appears to be relatively underutilized compared to Site C1 (though it is not known whether parking utilization at Site C1 is from commuters or community center users). Accommodating lost parking spaces at the evaluated sites is relatively easy for Sites A and D compared to Sites B and C1. This assessment is based on factors such as commuter mobility and wider access to the beach for Sites A and D, and convenience/proximity to the community center for Sites B and C1.

The estimated project costs range from $11.2M to $14.5M (a difference of $3.3M, or about 23

percent from lowest to highest cost). These costs do not include the cost of land acquisition, which would be applicable for Sites A and C1;

Site D is likely the least protected site from impacts due to sea level rise and the site that is most

susceptible to flooding.

Table 1-1 summarizes the relationship of each basin site to the five primary criteria described above.

As shown in Table 1-1, Site A (Linda Mar park and ride lot) is the top ranked site. This site preference is due to the likelihood of protection against sea level rise and flooding as well as lower overall impact to the public, both during and after construction. Site A is the second least expensive of the equalization basin sites to use. Its estimated project cost is $12.2M (not including land acquisition). The cost differential between Site A and Site D, the next ranked site, is $1.0M. This incremental cost is considered reasonable because Site A has fewer construction impacts to the public, reduces the potential for impacts due sea level rise and flooding, will likely have reduced permitting requirements and hurdles, and likely reduces overall impacts of ocean effects such as salt and sand.

The estimated cost for the equalization basin and appurtenances at Site A is less than the $20M presented in the 2011 Master Plan.

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 2 Introduction

February 2013 2-1

Chapter 2 Introduction

The City of Pacifica prepared a Collection System Master Plan (RMC, October 2011) that described the development and use of a hydraulic model of the City’s wastewater collection system to evaluate system capacity and identify deficiencies. The Master Plan also included evaluation of multiple alternatives to provide the capacity improvements needed. The Capital Improvement Plan associated with the City’s preferred capacity assurance alternative included the following elements:

Twelve sewer improvement projects totaling approximately 11,000 feet of new or upsized sewer pipelines;

Increase in capacity of Linda Mar Pump Station by addition of a fourth pump; and

Wet weather equalization basin.

The wet weather equalization basin would reduce the impacts of collection system inflow and infiltration on the Linda Mar Pump Station and force main, as well as at the Calera Creek Water Recycling Plant, preventing the need for extensive collection system rehabilitation or a more significant retrofit at or replacement of the pump station and force main and potential need to increase the peak hydraulic capacity of the plant. Based on the 10-year design storm established in the Master Plan, the basin capacity should be approximately 2.1 million gallons. In addition to the basin, supporting facilities and appurtenances include a gravity diversion pipeline to the basin, a pump station and force main from the tank back to the existing collection system, power generator, odor control, and basin wash down equipment.

The Master Plan identifies a location on Linda Mar Blvd. as the potential location for the proposed equalization basin. Rather than move immediately to design based on the Master Plan, the City chose to perform this evaluation in order to:

Identify additional sites beyond the Master Plan site;

Identify a preferred site as the basis of design;

Refine the cost estimate for the preferred basin; and

Provide an increased level of confidence that the preferred site is feasible.

This report summarizes the analysis performed to achieve the above goals and the results of that analysis. Additionally, this report provides a recommendation for a preferred site based on the information available at this time. Work performed includes identification of alternative sites, a screening of those sites for further analysis, review of existing and development of new geotechnical information, analysis of hydraulic parameters, identification of feasible construction methods, development and application of evaluation criteria, and estimation of project costs.

After introducing the sites to be evaluated, this report describes the recommended construction methods and project elements that should be included in the design. Based on those elements and methods, each site is evaluated with respect to several criteria. The results of those evaluations are then compiled to recommend a site for further evaluation and design.

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 3 Potential Sites

February 2013 3-1

Chapter 3 Potential Sites

The City and RMC identified the following six potential sites for the equalization basin:

Site A: Linda Mar Park and Ride Lot

Site B: Community Center Rear Parking Lot and Adjacent Undeveloped Area

Site C1: Community Center Front Parking/Park and Ride Lot

Site C2: Community Center Front Open Space

Site D: Linda Mar Pump Station Parking Lot

Site E: Linda Mar Beach Parking Lot

These sites were selected based on their public ownership (owned either by the City or Caltrans), proximity to the Linda Mar Pump Station, and their size being large enough to accommodate the basin. Figure 3-1 shows the locations of the six basin sites.

As described in the Linda Mar Equalization Basin Preliminary Site Assessment Technical Memorandum (RMC, August 2012), included as Appendix A, there is little to differentiate the six sites based on their readily apparent characteristics. While developing the Preliminary Site Assessment TM, two non-physical characteristics, i.e. Caltrans’ willingness to sell the property and Coastal Commission permitting, were identified as primary selection characteristics. Should Caltrans be unwilling to sell the property, or the Coastal Commission raise significant objections/conditions, the site could be fatally flawed.

Table 3-1 summarizes the sites’ relation to these factors and a recommendation to shortlist or not shortlist the site for further analysis. Further discussions with Caltrans and the Coastal Commission regarding the four shortlisted sites are summarized and evaluated in Chapters 5 and 6.

Table 3-1: Preliminary Site Analysis Recommendations

Site Site Owner Within Coastal Commission

Zone Shortlist for Further Analysis?

A1 Caltrans No Yes

B City No Yes

C1 Caltrans No2 Yes

C2 Caltrans No2 No

Has no advantage over C1 and in a potentially sensitive environmental area

D City Yes Yes

E City Yes No

Has no advantage over D and further from the Linda Mar Pump Station

Notes: 1 The basin location at Site A has been updated since the referenced technical memorandum. 2 At the time that the Site Assessment TM was written, it had not yet been confirmed that these sites were outside of the

Coastal Commission zone.

The four shortlisted basin sites provide a selection of City and Caltrans properties within and outside of the Coastal Commission area of review.

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 4 Construction Methods

February 2013 4-1

Chapter 4 Construction Methods

The following recommendations for construction methods reflect consideration of the proposed basin shapes, subsurface conditions, and construction feasibility. Subsurface conditions, including the results of several borings, are summarized in Appendix B. Details regarding basin size, pipeline sizes and lengths, and return pumping capacity are presented in Chapter 5. The construction methods and project elements described in this chapter apply to all sites.

4.1 Equalization Basin The primary construction method for the equalization basin recommended for all four of the sites is called the cutter soil mixing (CSM) method. This method of construction is advantageous for deep excavations in poor soils and in close proximity to other structures.

CSM involves creating a series of vertical interlocking, waterproof panels for the walls of the basin that do not require formwork or abandonment of non-structural elements, such as sheet piles. It provides a higher level of confidence in placement of the panels than other shaft or basin construction methods. This reduces risk of structural defects (and corresponding loss of hoop compression strength) or loss of seal between panels. Should the cutter start to drift as it is lowered, an operator can readjust the location and direction of the equipment. Given the volume of storage and structural depth needed for this project (on the order of 60 feet), the resultant basin structure needs to be circular in shape so that the walls can be designed as compression hoops.

CSM equipment consists of a dual-wheel cutting head attached to a Kelly bar drilling rig for placement and transportation. Figure 4-1 shows an example of cutting head and rig (photo from the equipment manufacturer Bauer). Water, and sometimes bentonite, is added as the cutting head is lowered into the ground to keep the soil fluidized. After reaching the design panel depth, cement grout is pumped to the cutting head and mixed with the soil as the equipment is removed. Panels are dug in alternating spaces, as shown in Figure 4-2. This creates a slurry-type wall which, when interlocked with adjoining panels, hardens to create a solid wall.

Figure 4-1: Cutter Soil Mixing Equipment

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Figure 4-2: Plan View Excerpt of Cutter Soil Mixing Wall Panels

After completion of the circular basin wall, general excavation within the basin begins. After excavating the basin by approximately six to eight feet, a welded steel rebar is dowelled into the slurry panels. Shotcrete is applied as the structural component of the basin and to create the interior of the basin wall. The shotcrete can be finished like normal concrete to create a smooth surface to facilitate washdown. Figure 4-3 shows the basin wall elements described in this section. After completion of the shotcrete wall and installation of hangers and anchors for other appurtenances, such as a walkway, valve and piping, or blowers, the excavation continues in stages of six to eight feet until the full depth of the basin is reached.

Figure 4-3: Plan View Section of Basin Wall Primary Components

At the bottom of the basin, a concrete plug is poured monolithically to create the basin bottom and to create a counterweight to the hydrostatic uplift force that the basin will encounter. The concrete plug is held in place by keying it into the bottom of the shotcrete wall.

The land use at each of the four locations under consideration in this study is a parking lot. After the basin sides and bottom are compete, the existing parking lot can be restored by pouring a concrete deck over girders sized to support the existing and planned future traffic loads.

Figure 4-4 consists of a graphic with the described basin elements.

Primary Panel

Panel Overlap

Secondary Panel

Storage Basin Interior

Shotcrete Lining

Cutter Soil Mix Wall

Native Earth

Cutter Soil Mixing Wall

Reinforced Shotcrete

~30”

~12”

Exterior Wall Face

Interior Wall Face

Native Soil

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February 2013 4-3

Figure 4-4: Basin Section Showing Primary Elements

Secant pile construction was considered initially but is not recommended for basin construction. Secant piles are similar to the CSM panels except they are drilled, overlapping columns, usually with a steel rebar cage in every second pile. These are not recommended due to the higher risk of the piles being out of alignment at depth. Misaligned piles could create issues with:

Maintaining the cylindrical shape critical for beneficial compression. Since the piles are the structural element in secant pile construction, misalignment rapidly reduces the benefits of the circular construction. CSM relies on the interior shotcrete as the structural element of the basin, allowing better control in maintaining the roundness of the basin.

Creating a waterproof barrier. Water seepage between misaligned piles could be an issue,

particularly at the bottom of the basin where the hydrostatic pressure is anticipated to be the greatest and the deviation would be the worst. As described above, CSM allows greater control in placement and alignment of the panels.

4.2 Pipelines Two pipelines will need to be installed for operation of the equalization basin, regardless of location, namely a gravity influent pipeline and a force main effluent pipeline. Subsurface conditions and groundwater level, particularly when the pipeline is close to the ocean, can drive selection of an installation method. Material choice for the pipelines is influenced by construction method, anticipated settling, pipe performance requirements, and cost.

The gravity flow influent line will be relatively deep since, for most alternatives, it diverts flow from the existing gravity collection system just upstream of the Linda Mar Pump Station, the hydraulic low point of the local system. In the case of Site A, the diversion occurs further upstream in the collection system.

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February 2013 4-4

Additional geotechnical and utility information will be developed in future phases of the project. This more detailed information will allow optimization of the pipeline installation methods, alignments, and costs. Based on currently available geotechnical information, it appears that the pipeline will start very close to the groundwater surface and layers of cohesionless sand and will likely drop below the groundwater table and into cohesionless sand. Below is a brief summary of the various methods that were considered appropriate for these conditions.

Open Cut Installation. While preferred for many installations, it appears that this installation method would require significant dewatering and/or installation of sheet piles along both sides of the trench to prevent the trench from filling with water and collapsing on itself. This additional effort is assumed to drive the costs above some of the other alternatives described below. This method is not anticipated to be used except for a short distance near the flow diversion points (i.e. near Linda Mar Pump Station or, in the case of Site A, the gravity sewers). This method is also anticipated to be used at Site D, where the basin is located close enough to the pump station to make open cut work more cost efficient than tunneling methods.

Pilot Tube Guided Auger Boring. Pilot tube guided auger boring (PTGAB) relies on sight lines to confirm the line and grade of pipe segments between jacking and receiving pits. Since pipelines installed using PTGAB can have grades comparable to those installed by open cut methods, the pipes can be installed at a relatively flat grade compared to horizontal directional drilling. This method is has been applied on other projects where the hydrostatic groundwater levels are less than ten feet above the pipe. PTGAB is the basis of the pipe installation cost estimate elements for Sites A, B, and C1 of this study, but additional study during the design phase of the project will be necessary to confirm the applicability of this method.

Microtunneling. Microtunneling is a trenchless method that is technically feasible based on the known geotechnical information. However, it is more expensive than other alternatives while having a similar minimal surface impact as PTGAB.

Horizontal Directional Drilling. Horizontal directional drilling (HDD) has the smallest surface footprint compared to other pipeline installation alternatives described in this section since jacking and receiving pits are not needed. It is also relatively inexpensive for normal applications of the installation method. Gravity pipelines to basins are not the typical application of HDD however. Due to the need for steeper gradients on gravity lines (based on the methods guidance system), HDD would lead to deeper borings than other methods. Should it ever be necessary to expose the pipeline for maintenance or inspection, the deeper pipeline would make the excavation very expensive. The steep gradient and long distances (leading to large hydraulic head) also may lead to special construction requirements to control the bentonite used to lubricate the equipment and stabilize the boring. These and some other considerations, such as construction staging for pipeline lay length and bend radius, make other pipeline installation methods more attractive in this application than HDD.

The force main effluent pipeline will be shallower than the gravity pipeline. It is therefore assumed that an open cut method of installation would be feasible for the force main. The force main alignments shown in Chapter 5 do not cross Highway 1, which would have likely required a trenchless method.

4.3 Other Project Elements Other project elements, as described below, will be constructed in, around, or near to the basin or pipelines.

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February 2013 4-5

Pumps. It is assumed that the equalization basin will be emptied using a submersible pump. The pump will be located in a sump at the lowest point in the basin floor. Discharge piping, power cables, and instrumentation wiring will be mounted vertically to the side of the wall. A second pump will also be included for backup capacity. Pumps can be removed by portable hoist from the basin via a hatch at ground level.

Electrical Controls and Instrumentation. Electrical controls will be located in a small building

at ground level near the basin. Monitoring equipment, such as gas monitors, water level indicators, pump status, flow monitors, etc. will be located as appropriate. The data collection and logic center will also be located in the small structure. Operation of the basin system would occur within this structure.

Odor Control – Odor control can be achieved through either a soil bed filter or a carbon

scrubber. The soil bed filter consists of a perforated pipe network below a bed of organic material, often wood or bark chips. The carbon scrubber consists of an engineered system using cartridges of granular activated carbon or some other media. For purposes of this report, it is assumed that the soil bed filter will be used, primarily because it is more conservative from a project footprint perspective. For the volume associated with the empty basin, approximately 2,025 square feet (e.g. 45 feet x 45 feet) of bed surface area are required, whereas the carbon scrubber system is much more compact. (The selection of soil bed filter vs. carbon scrubber would be made in final design.)

Washdown System. Tipping troughs are recommended for washdown of the basin walls and

floor. The water dumped from the troughs will sluice waste into the sump. The troughs, tipping motors and actuators, and the water system to fill the troughs will be mounted on the walls of the basin.

Ventilation. Build-up of explosive and corrosive gasses will need to be avoided.

Also,ventilation will be required to allow maintenance and operations staff to access the basin interior. To achieve both of these objectives, ventilation will be provided by a fan with a duct to the bottom of the basin and an exhaust fan pulling air out of the basin and into the odor control system. The ventilation equipment will be mounted on the walls with access provided by a walkway. The mechanical equipment can be removed by portable hoist from the basin via a hatch at ground level.

Valves and Piping. Valves and piping will be located on the walls of the basin and accessible

from the walkway wherever possible.

Walkway. The walkway will be supported on the walls of the basin and designed to provide

maintenance access to equipment and for visual inspection.

Diversion Manhole. Diversion to the equalization basin will occur passively due to rising water

surfaces as the existing collection system approaches its capacity. For this diversion to occur, a new manhole will be constructed at each diversion point that includes a weir overflow to the diversion pipeline.

Figure 4-5 shows schematically the interior features of the basin above. A schematic of features exterior to the equalization basin is shown in Figure 5-1.

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February 2013 4-6

Figure 4-5: Interior Basin Components

4.4 Schedule A precise schedule for construction will be developed during the design phase of the project, but it is expected that overall construction will take approximately fourteen months. Figure 4-6 shows an example of the construction sequencing that could be used.

Figure 4-6: Example Construction Sequence

I I II I I II I I

Discharge Force Main

Discharge ValvingPerimeter Access Walkway

Perimeter WashdownTipping Troughs

Structural Deck

Dual Submersible PumpsBasin Floor Sloped to Drain

Influent Diversion Pipeline

Exhaust Fan to Odor Control Bed

Ventilation Fan andAir Distribution Duct

Not to Scale

Construction Element 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Cutter Soil Mix Wall

Excavation, Rebar, and Shotcrete Placement

Concrete Base

Concrete Deck and Girders

Diversion Pipeline

Discharge Pipeline

Electrical and Instrumentation

Mechanical

Month

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 5 Site Analysis

February 2013 5-1

Chapter 5 Site Analysis

Sites A, B, C1, and D are evaluated in this chapter. Each site is schematically the same as the others. Figure 5-1 shows:

The diversion from the existing collection system near the Linda Mar Pump Station;

A gravity diversion pipeline between the diversion point and the equalization basin;

An equalization basin site with the components exterior to the basin that were described in

Chapter 4; and

A force main leading back to an existing gravity sewer.

Figure 5-1: Schematic of Typical Equalization Basin Site and Pipelines

For each site, the following information is presented in the following sections:

Site Introduction – This section includes a description of the basin location, pipeline alignments, and some site specific details such as relative location to the coastline and dimensions.

Size and Suitability – This section includes discussion regarding the size of the site and its

existing and planned land use. As shown in Figure 5-2, the basin depth is parabolically related to the diameter of the basin. It is preferable to find a balance between width and depth so as to reduce project footprint without making the basin unnecessarily deep. It is also preferable to locate the basin where it is compatible with existing and future land use.

Adjacent Land Uses – The surroundings of the potential basin should also be considered when

evaluating a basin site. It is preferable to locate the basin away from residences and private commercial areas due to both the perception of the project and the potential for nuisance claims.

Linda Mar Pump Station

Collection System

Equalization Basin

Odor Control

Air Intake

Operations Building

Force Main toCalera Creek WRP

DiversionManhole

Pump andBasin Access

Basin Access

Gravity Diversion Pipeline

Force MainDischarge Pipeline

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February 2013 5-2

It is also preferable to locate the basin where there will be fewer construction impacts on the public.

Parcel Ownership – As described in another chapter, it is critical that the basin be located on a

parcel owned by an individual or organization willing to sell the necessary land to the City. This section includes some discussion about the current ownership status of the four sites.

Geotechnical Considerations – A brief summary of the site specific information available for

the basin site is presented in this section.

Pipeline Connections – This section includes discussion about the relative complexity of the

gravity and pressure pipelines that would be needed for operation of the basin at a given site, as well as a description of how flow would be returned to the sewer after a storage event.

Coastal Commission Jurisdiction – The Coastal Commission permitting process has the

potential to impede the project timeline and increase the cost of the project through permit requirements. Per Coastal Commission staff, the jurisdictional boundary of the Coastal Commission in this area is Highway 1. Therefore work east of Highway 1 would be outside of the Coastal Commission zone. Initial, informal discussions with the Coastal Commission staff have suggested that permitting requirements for the basin would be relatively minor should it be located west of Highway 1. Permit conditions may consist of restrictions on the operations building and construction best management practices. Without formal consultation, however, it is unclear what role the Coastal Commission would have in shaping the design of the basin, its construction, and its operation. We believe it is in the City’s best interest to continue to endeavor to engage the Coastal Commission formally.

Ocean Impacts – Proximity to the ocean impacts site selection in two ways. Most importantly,

sea level rise will impact facilities not protected against coastal erosion. Latest projections for global sea level rise are on the order of two feet over the next fifty years (Advancing the Science of Climate Change, Board on Atmospheric Sciences and Climate, 2010, viewed at http://www.nap.edu/openbook.php?record_id=12782&page=244 on August 22, 2012). Note that local rise may be more or less than the global average. In addition to the increased mean sea level, additional wave action is associated with sea level rise. These factors could produce erosion that would threaten the structural stability of coastal infrastructure. While the foundation of the basin would be expected to be below the impacts of coastal erosion, the appurtenances such as the pipelines, operations building, and odor control facilities could be impacted. In order to provide protection to these facilities, it is assumed that locating the basin site east of Highway 1 will provide more protection to these facilities due to the additional space and civil infrastructure between the site and the coast.

Closer proximity to the ocean also increases potential damages to the mechanical and electrical aspects of the equalization basin due to increased salt and sand. Although proper design can mitigate these impacts, salt and sand will lead to additional maintenance costs.

Flooding – This section reviews the potential for flooding at the basin site as well as an initial

assessment of the feasibility of reducing the potential for flooding of the equalization basin.

Estimated Project Costs – This section consists primarily of a table summarizing the project

cost estimate.

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Figure 5-2: Diameter-Depth Relationship for Equalization Basin

0

20

40

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80

100

120

140

160

180

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0 50 100 150 200 250 300

Storage

Depth

Inner Basin Diameter

2.1 MG Storage Volume

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5.1 Site A: Linda Mar Park and Ride Lot Site Introduction

The Site A basin and potential pipeline alignment are shown in Figure 5-3. As can be seen, the site is located in an asphalted parking lot on the east side of Highway 1. This site is relatively close to the Linda Mar Pump Station, with only Site D being closer. It is one of the furthest inland sites (along with Site B) being considered in this chapter. Table 5-1 summarizes some of the infrastructure characteristics proposed for this site. The sections below summarize some key considerations of the site analysis for Site A.

Table 5-1: Site A Infrastructure Dimensions and Lengths

Parameter Dimension

Basin Inner Diameter 82 feet

Depth from Ground to:

Maximum Water Surface

Basin Floor

15 feet

69 feet

Gravity Pipeline Length/Diameter

140 feet/24 inches

660 feet/18 inches

Force main Length/Diameter

100 feet (including vertical pump

discharge)/12 inches

Basin Drainage Time/Flow Rate

24 hours/2.1 mgd

The basin drainage time assumes a discharge to the sewer in Linda Mar Blvd., where there is adequate capacity to accommodate a return flow rate of at least 2.1 mgd.

Size and Suitability

This site currently functions as a bus station and parking lot. These types of uses are compatible with the post project site condition so there does not appear to be any long-term conflict with the current use. This parcel is zoned for single family residential, however it is identified as mixed use in the latest projection of land use for the Pacifica General Plan Update (General Plan Update March 7, 2012 Scoping Meeting Materials). Zoning and General Plan changes may be needed to site the equalization basin on this parcel.

The basin shown in Figure 5-3 assumes an inner diameter of approximately 82 feet. This should leave adequate room for construction at the surface, although it is limited. The site length allows for plenty of staging room for the contractor but at only approximately 100-130 feet wide (depending on location), this is considered to be a narrow site compared to the other three sites.

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Adjacent Land Uses

The site is bounded by a gas station to the northwest, Linda Mar Blvd to the southwest, residential structures to the northeast, and distantly to the southeast by De Solo Drive. Across Linda Mar Blvd. is a Safeway and shopping plaza. The proximity to the residences is the most critical aspect of the adjacent land uses. While construction methods can be implemented to reduce noise, dust, ground shaking, and other construction impacts, the potential risk of construction claims still exists. Considering public perception of wastewater projects and large construction in general, although this area currently serves as a bus station and parking lot, there may be some opposition to locating an equalization basin close to the residences. Public outreach and education would be an important component of a successful project at this location.

The eastern end of this parking lot, where the basin location is shown, is currently being used as the Caltrans Devils Slide field engineer’s office. As such, several large construction trailers and a separate parking area have removed a portion of the parcel from public use. It may be possible that the basin and associated facilities could occupy approximately the same footprint as the existing Caltrans field engineer’s area. The basin could also be moved to the west within the parcel, where the parcel is less constrained. Should this be necessary, the Caltrans area could be re-opened for public use but the transit options associated with the current operation of the parcel may need to be relocated. Additional siting analysis is necessary to further refine the proposed facility location.

Parcel Ownership

The Site A parcel is currently owned by Caltrans. Preliminary discussions and concept review with Caltrans representatives indicates that Caltrans is willing to sell the property to the City of Pacifica once departmental holds on the parcel are lifted. Caltrans is currently using this parcel as the site for their construction engineers trailers for the Devils Slide Project. Caltrans would prefer to sell the parcel after the Devils Slide Project is complete and the trailers have been removed from the site. Based on the current construction schedule for the Devils Slide Project and the anticipated construction schedule of the equalization basin, it appears that there should be no overlap in construction periods. Should the Devils Slide Project be extended, Caltrans staff indicated that it might be possible to develop an arrangement to allow the equalization basin project to move forward.

It is unknown at this time what the contractual agreement between Caltrans and Samtrans is for use of the site as a bus station. The bus station would likely need to be relocated during construction.

Geotechnical Considerations

Site A is underlain by primarily marine terrace deposits with a cover layer of artificial fill. The fill composition and compaction is highly variable. The site has historically been a part of one or more coastal lagoons and/or sand dune deposits. Monitoring by ADR Environmental Group of a nearby site indicates that groundwater levels are relatively shallow (1.8 to 7.86 feet deep) and could be tidally influenced. Due to the proximity of the site to several existing and former gas stations, groundwater and soil contamination may be an issue.

No site specific information for Site A was obtained as part of the geotechnical borings that were completed for this study.

Pipeline Connections

For the gravity influent line to avoid crossing Highway 1, two diversion points are recommended. The primary diversion would occur from the trunk sewer in Linda Mar Blvd. However, in order to passively activate this diversion, the hydraulic gradeline in the system would need to be raised to a point where the sewer in Arguello Blvd. would be significantly surcharged (to about ½ foot from the ground). Therefore a second diversion from Arguelo Blvd., as shown in Figure 5-3, is proposed. This diversion would require constructing a pipeline through an existing utility easement from Arguello Blvd. to the northwest

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corner of the Park and Ride lot and then along the perimeter of the parcel to the basin location. For both diversions, new manholes would be constructed on the existing sewers. Alternatives to the diversion strategy described above include:

Diversion of flow on the west side of Highway 1, closer to the pump station. This diversion strategy would require a pipeline crossing Highway 1 to get to the basin site and all associated permits and requirements to do so.

Diversion of flow from Linda Mar Blvd. downstream of the junction of the two Linda Mar Blvd.

sewers. This diversion strategy would include an automated valve remotely controlled based on Linda Mar Pump Station wet well level. Assuming the same diversion point, using the valve would allow diversions at lower hydraulic grade than the passive weir system assumed in other scenarios. This ability reduces sewer surcharging in the Arguello Blvd. sewer compared to a passive overflow.

The discharge force main would connect the submersible pump within the basin to the gravity sewer in Linda Mar Blvd. It is assumed at this time that an additional penetration could be made in an existing manhole to create this connection. This will need to be confirmed during design.

Coastal Commission Jurisdiction

Site A is located east of Highway 1 and is therefore considered to be removed from the Coastal Commission jurisdiction. If the diversion site were to be located on the west side of Highway 1, however, this would require some coordination and potentially a permit from the Coastal Commission. Additional coordination with the Coastal Commission would be necessary to confirm permit requirements.

Ocean Impacts

As mentioned above, Site A is one of the two farthest inland sites and is located east of Highway 1. It is therefore considered protected from the effects of sea level rise and will minimize maintenance requirements due to salt and sand.

Flooding

This site is within the 1% annual chance flood, more commonly known as the 100-year floodplain, and, additionally, City staff have noted that flooding has occurred at this site in the past. To reduce the risk of flooding the basin with stormwater, it would be necessary to raise the basin rim, create a berm around the completely buried basin, or include some other flood protection measure. The flood depth, and corresponding minimum elevation requirement, varies based on basin location within the parcel and design flood event. There are no apparent fatal flaws to protecting the basin from flooding at this site. The cost estimate for this site does not reflect a detailed cost associated with flood protection since there are multiple variables associated with providing this security but does include a placeholder of $100,000.

Estimated Project Costs

The estimated project costs for Site A are presented in Table 5-2. As can be seen in the table, the estimated cost for this project is approximately $12.2M.

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Table 5-2: Total Project Costs for Site A

Basin & Site Summary

Tank Inner Diameter 82 Ft Fill Depth 5 Ft

Cutter Soil Mix Wall Thickness 30 Inch Bay Mud/Peat Depth 15 Ft

Shotcrete Wall Thickness 12 Inch Native Soil Depth 54 Ft

Decking Thickness 8 Inch Total Excavation Depth 74 Ft

Girder Depth 4.5 Ft

Access Depth 7 Ft

Tipping Bucket Depth 2 Ft

Free Space Depth 1 Ft

Storage Depth 54 Ft

Foundation Thickness 5 Ft

Cutter Soil Mix Cutoff Wall Depth 10 Ft

Project Element Category Sub‐Category Quantity Unit Unit Cost Extended CostBasin Structure

Basin Walls

Cutter Soil Mix Wall 22,035 SF 20.00$ 440,703$

Shotcrete (w/Fiber Reinforcement) 17,646 SF 12.45$ 219,697$

Welded Wire Mesh (6x6 ‐ W4xW4) 176 CSF 78.50$ 13,852$

Smooth Finish 17,646 SF 0.75$ 13,235$

Concrete Base/Plug

Concrete/Rebar 1,026 CY 195.00$ 200,119$

Basin Cover

Decking (Concrete) 154 CY 850.00$ 130,567$

Decking (Rebar @ 205 lbs/CY concrete, FDOT) 31,490 LBS 1.10$ 34,639$

Precast/Prestressed I‐Girders (AASHTO Type IV) 796 LF 190.00$ 151,240$

Excavation

General 15,223 CY 70.00$ 1,065,593$

Anchoring

Tiedown Soil Anchors (10' on center) 0 EA 4,200.00$ ‐$

Spoil Offhaul and Disposal:

Fill (Assumes Class III) 1,732 TON 38.00$ 65,809$

Bay Mud/Peat (Assumes Class II) 4,156 TON 47.00$ 195,347$

Native Soil (Assumes Class III) 18,761 TON 38.00$ 712,926$

Elevated Equipment/Access Deck

Steel for Concrete Perimeter Beams (2@12"x12") 10 CY 259.00$ 2,501$

Angle Support (4.5' @12' OC) 22 EA 927.00$ 20,394$

1.5" Alum. Grating 1,030 SF 56.93$ 58,663$

C10x4.25 (2) 490 LF 163.58$ 80,169$

Guardrail 229 LF 106.95$ 24,528$

Subtotal 3,429,981$

Basin Appurtenances

Pumps 2 EA 53,000.00$ 106,000$

Controls 1 Allowance 80,000.00$ 80,000$

Standby Power 1 Allowance 150,000.00$ 150,000$

Foundation and Fencing 1 Allowance 64,000.00$ 64,000$

Washdown/10' of Header 26 EA 11,000.00$ 286,000$

Odor Control

Odor Control Bed (2,025 sf x 6 ft) 1 Allowance 100,000.00$ 100,000$

Ductwork and 2 Fans 1 Allowance 100,000.00$ 100,000$

Miscellaneous Piping 1 Allowance 80,000.00$ 80,000$

Subtotal 966,000$

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(Table 5-2 Continued)

Pipes

Diversion Manhole 2 EA 10,000.00$ 20,000$

24" Diameter Gravity (Pilot Guided Augur Boring) 140 LF 900.00$ 126,000$

18" Diameter Gravity (Pilot Guided Augure Boring) 660 LF 750.00$ 495,000$

Boring Pit 6 EA 100,000.00$ 600,000$

24" Diameter Gravity (Open Cut in Wet Sand) 15 LF 480.00$ 7,200$


Interlocking Sheet Piles (15' deep) 900 SF 25.00$ 22,500$

12" Diameter Force Main (Open Cut) 30 LF 240.00$ 7,200$

Subtotal 1,283,300$

Other

Dewatering (4 sump pumps and treatment) 1 Allowance 10,000.00$ 10,000$

Paving (Basin Diameter + 20' buffer) 1,037 SY 50.00$ 51,841$

Paving (Force main trench) 10 SY 50.00$ 500$

Sidewalks 10 SF 5.00$ 50$

Traffic Control 1 Allowance 53,000.00$ 53,000$

Lot Improvements

Install Turf 0 TSF 400.00$ ‐$

Shrubs 0 EA 50.00$ ‐$

Flood Protection Measures 1 Allowance 100,000.00$ 100,000$

Utility Relocation 1 Allowance 500,000.00$ 500,000$

Park and Ride Relocation 0 Allowance 100,000.00$ ‐$

Land Acquisition 1 Allowance ‐$ ‐$

Subtotal 715,391$

Construction Subtotal 6,394,672$

Contractor Costs

Mobilization/Demobilization % of Const. Subtotal 5% 319,734$

Contractor Overhead and Profit % of Const. Subtotal 15% 959,201$

Change Order Allowance % of Const. Subtotal 5% 319,734$

Subtotal 1,598,668$

Professional Services

Environmental Documentation/Permitting 1 Allowance 350,000.00$ 350,000$

Engineering % of Const. Subtotal 10% 639,467$

Legal % of Const. Subtotal 2% 127,893$

Construction Management % of Const. Subtotal 10% 639,467$

Subtotal 1,756,828$

Project Subtotal 9,750,167$

Contingency % of Project Subtotal 25% 2,437,542$

Total 12,200,000$

Note: Estimate does not include cost for land acquisition. Caltrans parcel to be acquired for this site is approximately 2 acres.

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5.2 Site B: Community Center Rear Parking Lot and Adjacent Undeveloped Area

Site Introduction

The Site B basin and potential pipeline alignment are shown in Figure 5-4. As can be seen, the site is located near the Pacifica skate park and Community Center on the east side of Highway 1. This site is one of the two furthest sites from the Linda Mar Pump Station. It is one of the furthest inland sites (along with Site A) being considered in this chapter. Table 5-3 summarizes some of the infrastructure characteristics proposed for this site. The sections below summarize some key considerations of the site analysis for Site B.

Table 5-3: Site B Infrastructure Dimensions and Lengths

Parameter Dimension




Basin Floor

15 feet

55 feet


1,400 feet/24 inches


580 feet (including vertical pump

discharge)/12 inches


30 hours/1.7 mgd

The basin drainage time assumes a discharge to the 12inch sewer in Crespi Drive, which extends across Highway 1 and then parallels the shoreline to the Linda Mar Pump Station. Modeling indicates that there is approximately 1.7 mgd capacity available within the existing sewer without causing additional surcharging through much of the sewer. As shown in Figure 5-5, if 2.1 mgd were to be discharged to the sewer (to drain the basin within 24 hours), the sewer would be significantly surcharged along Crespi Drive, resulting in a potential overflow. This is largely due to the apparent reverse grade in the sewer. However, the currently available data on the vertical alignment of this pipeline is not reliable; therefore, further field surveys are recommended to confirm the actual alignment of the pipeline. Should the reverse grade exist as shown in the model and if a faster drainage time than 30 hours is desired, the City could consider replacing the Crespi Dr. and beachfront sewer (approximately 2,200 feet) that discharges to the Linda Mar Pump Station. The cost of this work would likely be on the order of $800,000.

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Figure 5-5: Hydraulic Grade Line for Site B 2.1 mgd Discharge to LH5


This site is currently split between two uses. The western portion of the site is undeveloped, sandy open space. The eastern portion of the site is a parking lot for the Pacifica Community Center. These types of uses are compatible with the post project site condition so there does not appear to be any long-term conflict with the current uses. This parcel is zoned for controlled manufacturing, however, and is identified as park in the latest projection of land use for the Pacifica General Plan Update (General Plan Update March 7, 2012 Scoping Meeting Materials). While the basin is compatible for a park setting, zoning changes may be needed to site the equalization basin on this parcel.

The basin shown in Figure 5-4 assumes an inner diameter of approximately 95 feet. This should leave adequate room for construction at the surface but is somewhat limited. The parking lot behind the Community Center could be used as a staging area for the contractor.

Adjacent Land Uses

Site B is bounded by open space areas to the east and west, residential structures to the south, and the skate park and Community Center complex to the north. There is a large drainage/storm drain between Site B and the residences. The proximity to the residences is the most critical aspect of the adjacent land uses. While construction methods can be implemented to reduce noise, dust, ground shaking, and other construction impacts, the potential risk of construction claims still exists. Considering public perception of wastewater projects and large construction in general, there may be some opposition to locating an equalization basin close to the residences. Public outreach and education would be an important component of a successful project at this location.

Also of note is the adjacent natural area. Working close to this natural area may require some additional precautions and biological surveys during the construction period.

The parking lot at Site B would serve as a significant portion of the construction area and could be closed during construction due to limited access to the site. This parking lot serves both the skate park and the community center. There are some small private parking lots nearby that may or may not be available or

Overflow

Example SurchargedManhole

Reverse Grade

Sewer

Hydraulic Grade Line

Ground Surface

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for community center use. It is also unknown whether the nearby parking lots have an equivalent number of parking spaces to compensate for lost parking at Site B during construction.

Parcel Ownership

This site is owned by the City of Pacifica. It is therefore assumed that there would be no ownership conflict with construction of the basin.


Site B is underlain by primarily marine terrace deposits with a cover layer of artificial fill. The fill composition and compaction is highly variable. The site has historically been a part of one or more coastal lagoons and/or sand dune deposits.

A boring at Site B was completed for this study. Table 5-4 summarizes the soil encountered by this boring.

Table 5-4: Site B Soil Condition Based on Boring

Depth Encountered

0” – 2” Asphaltic concrete

2” – 5’ Fill consisting of clayey sand with gravel

5’ – 8’ High plasticity clay (soft with peaty soil layers)

8’ – 20’ High plasticity clay (very soft with peaty soil layers)

20’ – 76.5’

Interlayered deposits of: Stiff to hard lean clay with varying amounts of sand and gravel

Medium dense to very dense sand with varying amounts of gravel, silt, and clay

Dense to very dense gravels with varying amounts of sand, silt, and clay

Two reference borings were also available for the adjacent skate park. Findings from these borings supported the above layer descriptions with some variation as described in Appendix B.

Groundwater level was not available from the boring due to the drilling method, but it was noted that the moist soils were encountered at about 7 feet depth. Groundwater levels are expected to vary seasonally and may also be influenced by tidal fluctuations.


Pipeline connections for Site B are relatively complex compared to Sites A and D and roughly equivalent to Site C1. The diversion manhole would be located adjacent to the Linda Mar Pump Station, and the diversion pipeline would need to cross several major storm drains and sewers near the diversion point. Relocation of the conflicting pipelines, wet well work, or optimization of the diversion pipeline alignment should be investigated during detailed design to minimize the costs of pipeline costs. The diversion pipeline connection for Site B requires more pipeline length than the diversion pipeline connections for Site A. Crossing Highway 1 will require a permit from Caltrans and may require casing around the pipe.

The discharge force main would connect the submersible pump within the basin to the gravity sewer in Crespi Drive. It is assumed at this time that an additional penetration could be made in an existing manhole to create this connection. This will need to be confirmed during design.


Site B is located east of Highway 1 and is therefore considered to be removed from the Coastal Commission jurisdiction. The diversion manhole and some pipeline work are west of Highway 1 however, and would require some coordination and potentially a permit from the Coastal Commission.

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Additional coordination with the Coastal Commission would be necessary to determine any permit requirements.

Ocean Impacts

As mentioned above, Site B is one of the two farthest inland sites and is located east of Highway 1. It is therefore considered protected from the effects of sea level rise and will minimize maintenance requirements due to salt and sand.

Flooding

This site is within the 1% annual chance flood and, additionally, City staff have noted previous flooding at this site. To reduce the risk of flooding the basin with stormwater, it would be necessary to raise the basin rim, create a berm around the completely buried basin, or include some other measure. The flood depth, and corresponding minimum elevation requirement, varies based on the design flood event. There are no apparent fatal flaws to protecting the basin from flooding at this site. The cost estimate for this site does not reflect a detailed cost associated with flood protection since there are multiple variables associated with providing this security but does include a placeholder of $100,000.


The estimated project costs for Site B are presented in Table 5-5. As can be seen in the table, the estimated cost for this project is approximately $14.3M.

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Table 5-5: Total Project Costs for Site B






Girder Depth 4.5 Ft

Access Depth 7 Ft



Storage Depth 40 Ft




Basin Walls




Smooth Finish 16,266 SF 0.75$ 12,199$

Concrete Base/Plug


Basin Cover




Excavation

General 16,467 CY 70.00$ 1,152,719$

Anchoring







Concrete Perimeter Beams (2@12"x12") 11 CY 259.00$ 2,893$


1.5" Alum. Grating 1,194 SF 56.93$ 67,963$

C10x4.25 (2) 572 LF 163.58$ 93,530$

Guardrail 270 LF 106.95$ 28,895$

Subtotal 3,708,521$

Basin Appurtenances

Pumps 2 EA 53,000.00$ 106,000$





Odor Control




Subtotal 999,000$

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Pipes


24" Diameter Gravity (Pilot Guided Augur Boring) 1,360 LF 900.00$ 1,224,000$

Boring Pit 7 EA 100,000.00$ 700,000$


Interlocking Sheet Piles (15' deep) 1,200 SF 25.00$ 30,000$


Subtotal 2,110,400$

Other



Paving (Force main trench) 177 SY 50.00$ 8,833$

Sidewalks 0 SF 5.00$ ‐$


Lot Improvements

Install Turf 7 TSF 400.00$ 2,800$

Shrubs (10' OC) 70 EA 50.00$ 3,500$





Subtotal 743,077$


Contractor Costs


Contractor Overhead and Profit % of Const. Subtotal 15% 1,134,150$


Subtotal 1,890,249$






Subtotal 2,013,420$



Total 14,300,000$

Note: Estimate does not include cost for land acquisition. It is assumed that this City‐owned parcel is available for this project.

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5.3 Site C1: Community Center Front Parking/Park and Ride Lot Site Introduction

The Site C1 basin and potential pipeline alignment are shown in Figure 5-6. As can be seen, the site is located near the Pacifica skate park and Community Center on the east side of Highway 1. This site is the farthest site from the Linda Mar Pump Station by approximately 100 feet. It is the second closest site to the ocean being considered in this chapter. Table 5-6 summarizes some of the infrastructure characteristics proposed for this site. The sections below summarize some key considerations of the site analysis for Site C1.

Table 5-6: Site C1 Infrastructure Dimensions and Lengths

Parameter Dimension




Basin Floor

16 feet

52 feet


1,500 feet/24 inches


290 feet (including vertical pump discharge)/12 inches


30 hours/1.7 mgd

As with Site B, the use of Site C1 would assume a discharge to the sewer in Crespi Drive. The use of Site C1 would therefore have the same implications regarding the Crespi Drive and beachfront sewers as described for Site B.

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This site currently functions as a parking lot and park and ride. These types of uses are compatible with the post project site condition so there does not appear to be any long-term conflict with the current use. This parcel is zoned for controlled manufacturing, however, and is identified as beach/commuter parking in the latest projection of land use for the Pacifica General Plan Update (General Plan Update March 7, 2012 Scoping Meeting Materials). While the basin is compatible with surface parking lot use, zoning changes may be needed to site the equalization basin on this parcel.

The basin shown in Figure 5-6 assumes an inner diameter of approximately 100 feet. The parking lot has adequate room for construction and staging. To accommodate construction, however, the parking spaces would need to be relocated for the duration of construction.

Adjacent Land Uses

Site C1 is bounded by a bikepath and Highway 1 to the northwest, by an open space area to the southwest, by the Pacifica Community Center to the southeast, and Crespi Drive to the northeast. Except for the need to separate the construction site from public access areas in the bikepath and Community Center, the adjacent land uses are relatively good compared to Sites A and B. The closest residences and commercial structures are approximately 350 to 400 feet from the basin site. This distance will help to reduce perception of construction impacts to residents and privately owned structures.

A significant portion of the parking lot at Site C1 would serve as the construction area. It is unknown at this time whether the remaining portion of the parking lot would need to be closed to reduce public risk and construction interference. This parking lot is heavily used as it serves the skate park and the community center, is a park and ride commuter site, and also acts as overflow parking for beach access. There are some small private parking lots nearby that may or may not be available or for any of these uses. It is also unknown whether the nearby parking lots have an equivalent number of parking spaces to compensate for lost parking at Site C1 during construction.

Parcel Ownership

The Site C1 parcel is currently owned by Caltrans. Preliminary discussions and concept review with Caltrans representatives indicates that Caltrans is willing to sell the property to the City of Pacifica once departmental holds on the parcel are lifted. Caltrans staff review indicates that there are plaques within this parcel commemorating the site of the “Portola Expedition Camp” and the “Site of the Discovery of San Francisco Bay”. There is also a statue on the site that was a gift from Catalonia, Spain to commemorate the explorer Don Gaspar de Portola. Caltrans staff have indicated that prior to removing the departmental hold, a more thorough survey of the parcel boundary must be completed as well as establishment of the ability of the State to transfer ownership and maintenance responsibilities of the plaques and statue to the City. If the plaques and statue are not able to be transferred to the City, the State would require an easement for continued maintenance of the plaques and statue.


Site C1 is underlain by primarily marine terrace deposits with a cover layer of artificial fill. The fill composition and compaction is highly variable. The site has historically been a part of one or more coastal lagoons and/or sand dune deposits.

A boring at Site C1 was not completed for this study but subsurface conditions are anticipated to be similar to Site B due to their proximity to one another.


The use of Site C1 would have similar attributes as described for Site B with regard to pipeline connections, given that the two sites have similar hydraulic and geographic locations.

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Site C1 is located east of Highway 1 and is therefore considered to be removed from the Coastal Commission jurisdiction. The diversion manhole and some pipeline work is west of Highway 1 however and would require some coordination and potentially a permit from the Coastal Commission. Additional coordination with the Coastal Commission would be necessary to determine any permit requirements.

Ocean Impacts

Site C1 is located east of Highway 1. It is therefore considered protected from the effects of sea level rise and will have reduced maintenance requirements compared to Site D due to salt and sand.

Flooding

This site is only partially within the 1% annual chance flood. City staff have not noted any previous flooding at this site. Only minor measures would likely be needed to reduce the risk of flooding the basin with stormwater. There are no apparent fatal flaws to protecting the basin from flooding at this site. The cost estimate for this site does not reflect a detailed cost associated with flood protection since there are multiple variables associated with providing this security but does include a placeholder of $20,000.


The estimated project costs for Site C1 are presented in Table 5-7. As can be seen in the table, the estimated cost for this project is approximately $14.5M.

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Table 5-7: Total Project Costs for Site C1






Girder Depth 4.5 Ft

Access Depth 7 Ft



Storage Depth 36 Ft




Basin Walls




Smooth Finish 15,865 SF 0.75$ 11,899$

Concrete Base/Plug


Basin Cover




Excavation

General 16,998 CY 70.00$ 1,189,880$

Anchoring









1.5" Alum. Grating 1,257 SF 56.93$ 71,540$

C10x4.25 (2) 603 LF 163.58$ 98,669$

Guardrail 286 LF 106.95$ 30,575$

Subtotal 3,832,443$

Basin Appurtenances

Pumps 2 EA 53,000.00$ 106,000$





Odor Control




Subtotal 1,021,000$

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February 2013 5-22


Pipes


24" Diameter Gravity (Pilot Guided Augur Boring) 1,460 LF 900.00$ 1,314,000$

Boring Pit 7 EA 100,000.00$ 700,000$




Subtotal 2,130,800$

Other






Lot Improvements

Install Turf 1 TSF 400.00$ 400$

Shrubs (10' OC) 10 EA 50.00$ 500$





Subtotal 658,276$


Contractor Costs


Contractor Overhead and Profit % of Const. Subtotal 15% 1,146,378$


Subtotal 1,910,630$






Subtotal 2,031,354$



Total 14,500,000$

Note: Estimate does not include cost for land acquisition. Caltrans parcel to be acquired for this site is approximately 1.5 acres.

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February 2013 5-23

5.4 Site D: Linda Mar Pump Station Parking Lot Site Introduction

The Site D basin and potential pipeline alignment are shown in Figure 5-7. As can be seen, the site is located at the Linda Mar Pump Station. It is the closest site to the beach being considered in this chapter. Table 5-8 summarizes some of the infrastructure characteristics proposed for this site. The sections below summarize some key considerations of the site analysis for Site D.

Table 5-8: Site D Infrastructure Dimensions and Lengths

Parameter Dimension




Basin Floor

15 feet

51 feet


200 feet/24 inches


100 feet (including vertical pump discharge)/12 inches


30 hours/1.7 mgd

The basin drainage time assumes a discharge to the existing 12-inch sewer within the Linda Mar Pump Station parcel. Modeling indicates that there is approximately 1.7 mgd capacity available within the existing sewer without causing surcharging and a backwater condition upstream. If 2.1 mgd were to be discharged to the sewer (to drain the basin within 24 hours) surcharge and backwater would be expected but overflows would not be expected. Further field surveys are recommended to confirm the actual capacity and horizontal alignment of the pipeline. Should the capacity be shown to be limited, or if a faster drainage time than 30 hours is desired without additional surcharge, the City could consider replacing the last 100 feet of the sewer to the Linda Mar Pump Station with a larger pipe. The cost of this work would likely be on the order of $50,000.

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in S

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February 2013 5-25


This site currently functions as a parking lot providing access to the pump station and beach. This type of use is compatible with the post project site condition so there does not appear to be any long-term conflict with the current use. This parcel is zoned as a site for public facilities and is identified as beach/commuter parking in the latest projection of land use for the Pacifica General Plan Update (General Plan Update March 7, 2012 Scoping Meeting Materials). It appears therefore that there should not be any conflict with planned future uses either.

The basin shown in Figure 5-7 assumes an inner diameter of approximately 100 feet. The parking lot has adequate room for construction and staging. It is unknown at this time whether additional parking would need to be made available since there appear to be numerous parking spaces available for beach access. This construction impact would be evaluated during the environmental documentation phase of the project to determine appropriate mitigation.

Adjacent Land Uses

Site D is bounded by the Linda Mar Pump Station to the southwest, the beach to the northwest, an adjacent parking lot to the northeast, and Highway 1 to the southeast. There is a Taco Bell restaurant approximately 50 feet to 100 feet from the basin site. However, there are no residences within about 250 feet. This makes the adjacent land uses relatively good compared to Sites A and B but not as favorable as Site C1. It is anticipated that the entire pump station area would be closed to public access during construction to facilitate construction and reduce risk to the public.

A significant portion of the parking lot at Site D would serve as the construction area. It is unknown at this time whether the remaining portion of the parking lot would need to be closed to reduce public risk and construction interference. This parking lot is heavily used as it is parking for beach users. It is anticipated that parking lost during construction would likely be absorbed by other existing parking areas, decreasing the total number of parking spaces in the area.

Parcel Ownership

This site is owned by the City of Pacifica. It is therefore assumed that there would be no ownership conflict with construction of the basin.

Although this site is owned by the City, a significant consideration for selection of this site is the oversight that the Coastal Commission has west of Highway 1. Preliminary discussions with Coastal Commission staff have indicated that should a permit be required, there would be some permit conditions related to placement and appearance of the electrical building as well as construction BMPs. Coastal commission staff have also suggested that this project may qualify for a waiver. As no formal consultation has been performed, however, it is unknown what specific permit conditions would be required.


Site D is underlain by primarily sand dune deposits with a cover layer of artificial fill. The sand dune deposits consist predominately of loose medium-to coarse-grained sand and may also include gravel and cobbles. The depth of the deposits are reported to be typically less than 19 feet. Site D was likely located on the sand dune that separated the coastal lagoon from the Pacific Ocean.

A boring at Site D was completed for this study. Table 5-9 summarizes the soil encountered by this boring.

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February 2013 5-26

Table 5-9: Site D Soil Condition Based on Boring

Depth Encountered

0” – 3” Asphaltic concrete

3” – 7’ Fill consisting of clayey sand and graveland silty gravel with sand and cobbles. Fill was dry to moist and medium dense to dense

7’ – 9’ Sandy clay

9’ – 17’ Dense poorly-graded sand (i.e. old sand dune)

17’ – 23’ Medium stiff peat with organic silt and clay

23’ – 76.5’

Interlayered deposits of: Medium stiff to stiff clays

Medium dense to dense clayey/silty sand with gravel

Based on the condition of the existing pavement by the pump station, it appears that about 2 inches of differential settlement has occurred at this site. The settlement could be the result of densification of the retaining wall backfill, fill induced consolidation of underlying clays, and/or peat decomposition. The composition of the fill and this differential settlement indicates that some additional stabilization of the surface soils in the area may be required for construction at this site to occur.

Groundwater level was not available from the boring due to the drilling method, but it was noted that the moist soils were encountered at about 8 feet depth. City staff reported that groundwater flowed through the pump station basement during a repair, indicating that the groundwater level is above the base of the pump station basement. Groundwater levels are expected to vary seasonally and may also be influenced by tidal fluctuations.


Pipeline connections for Site D are relatively less complex compared to Site B and Site C1. The diversion manhole would be similar to the diversion manhole of Sites B and C1, and the diversion pipeline would need to cross several major storm drains and sewers near the diversion point. Relocation of the conflicting pipelines or wetwell work to avoid pipelines are options but a more cost-friendly option may be for the diversion pipeline to parallel the storm and sewer pipelines at a steep grade for a short distance and then make the turn towards the basin sites. The diversion pipeline connection for Site D does not however need to cross Highway 1, thus avoiding a Caltrans permit and casing.

The discharge force main would connect the submersible pump within the basin to the gravity sewer on-site just upstream of the pump station. It is assumed at this time that an additional penetration could be made in an existing manhole to create this connection. This will need to be confirmed during design.


Site D is located west of Highway 1 and is therefore considered to be within Coastal Commission jurisdiction. It should be considered likely at this time that additional coordination with the Coastal Commission and a Coastal Commission permit would be required.

Ocean Impacts

Site D is located west of Highway 1. It is therefore considered exposed to the effects of sea level rise and have relatively more maintenance requirements due to salt and sand than the other three sites.

Flooding

This site is within the 1% annual chance flood with additional wave hazards and, additionally, City staff have noted previous flooding at this site. To reduce the risk of flooding the basin with stormwater, it

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February 2013 5-27

would be necessary to raise the basin rim, create a berm around the completely buried basin, or include some other measure. The flood depth, and corresponding minimum elevation requirement, varies based on the design flood event. It should be noted that raising the basin or creating some type of flood barrier around the basin could make obtaining a Coastal Commission permit more difficult. Whether these flood protection measures would be a fatal flaw from the perspective of the Coastal Commission or what mitigation measures would be required from the Coastal Commission is unknown. The cost estimate for this site does not reflect a detailed cost associated with flood protection since there are multiple variables associated with providing this security but does include a placeholder of $100,000. The permitting allowance is also raised to reflect the additional permitting complexity.


The estimated project costs for Site D are presented in Table 5-10. As can be seen in the table, the estimated cost for this project is approximately $11.2M.

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February 2013 5-28

Table 5-10: Total Project Costs for Site D






Girder Depth 4.5 Ft

Access Depth 7 Ft



Storage Depth 36 Ft




Basin Walls




Smooth Finish 15,865 SF 0.75$ 11,899$

Concrete Base/Plug


Basin Cover




Excavation

General 16,998 CY 70.00$ 1,189,880$

Anchoring









1.5" Alum. Grating 1,257 SF 56.93$ 71,540$

C10x4.25 (2) 603 LF 163.58$ 98,669$

Guardrail 286 LF 106.95$ 30,575$

Subtotal 3,833,464$

Basin Appurtenances

Pumps 2 EA 53,000.00$ 106,000$





Odor Control




Subtotal 1,021,000$

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February 2013 5-29


Pipes


24" Diameter Gravity (Pilot Guided Augur Boring) 0 LF 900.00$ ‐$

Boring Pit 0 EA 100,000.00$ ‐$




Subtotal 270,400$

Other





Traffic Control 0 Allowance 53,000.00$ ‐$

Lot Improvements

Install Turf 1 TSF 400.00$ 400$

Shrubs (5' OC) 40 EA 50.00$ 2,000$





Subtotal 683,776$


Contractor Costs


Contractor Overhead and Profit % of Const. Subtotal 15% 871,296$


Subtotal 1,452,160$






Subtotal 1,677,901$



Total 11,200,000$

Note: Estimate does not include cost for land acquisition. It is assumed that this City‐owned parcel is available for this project.

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Wet Weather Equalization Basin Site Feasibility Evaluation Chapter 6 Findings and Recommendations

February 2013 6-1

Chapter 6 Findings and Recommendations

6.1 Site Findings This evaluation has identified four equalization basin sites that are considered feasible. A brief summary of each site, highlighting the most significant advantages and disadvantages and information discussed in the previous chapters is provided in Table 6-1.

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Wet

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Eq

ual

izat

ion

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in S

ite

Fea

sib

ility

Eva

luat

ion

C

hap

ter

6F

ind

ing

s an

d R

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end

atio

ns

Feb

ruar

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13

6-

2

Tab

le 6

-1:

Su

mm

ary

of

Fin

din

gs

and

Co

sts

for

Sh

ort

liste

d S

ites

Item

S

ite

A

Sit

e B

S

ite

C1

S

ite

D

Lo

cati

on

Li

nda

Mar

Par

k an

d R

ide

Lot

Com

mun

ity C

ente

r R

ear

Pa

rkin

g Lo

t and

A

djac

ent U

ndev

elop

ed A

rea

Com

mun

ity C

ente

r F

ront

Par

king

/Par

k an

d R

ide

Lot

Lind

a M

ar P

um

p S

tatio

n P

ark

ing

Lot

Pri

nci

pal

Ad

van

tag

e(s)

In

land

of H

igh

wa

y 1

so b

asin

is p

rote

cted

from

sea

leve

l ris

e an

d ou

tsid

e of

the

Coa

stal

Com

mis

sion

rev

iew

zon

e.

R

elat

ivel

y fa

r fr

om th

e sh

orel

ine

so fa

cilit

ies

are

less

ex

pose

d to

oce

an im

pact

s su

ch a

s sa

lt an

d sa

nd.

R

elat

ivel

y cl

ose

to th

e di

vers

ion

poin

t and

ver

y cl

ose

to t

he

disc

harg

e po

int,

redu

cing

pip

elin

e in

stal

latio

n co

st a

nd

impa

cts.

Le

ast i

mpa

ct t

o ex

istin

g us

e of

all

of th

e si

tes

durin

g co

nstr

uctio

n b

ecau

se o

f exi

stin

g C

altr

ans

par

cel u

se.

In

land

of H

igh

wa

y 1

so b

asin

is

prot

ecte

d fr

om s

ea le

vel r

ise

and

outs

ide

of th

e C

oast

al C

omm

issi

on

revi

ew

zon

e.

M

oder

atel

y fa

r fr

om th

e sh

orel

ine

so

faci

litie

s ar

e le

ss e

xpos

ed to

oce

an

impa

cts

such

as

salt

and

sand

.

In

land

of H

igh

wa

y 1

so b

asin

is p

rote

cted

from

se

a le

vel r

ise

and

outs

ide

of th

e C

oast

al

Com

mis

sion

rev

iew

zon

e.

M

oder

atel

y fa

r fr

om th

e sh

orel

ine

so fa

cilit

ies

are

less

exp

osed

to

ocea

n im

pact

s su

ch a

s sa

lt an

d sa

nd.

R

elat

ivel

y fa

r fr

om p

rivat

ely

own

ed s

truc

ture

s an

d re

side

nce

s re

duci

ng th

e c

hanc

e of

ne

gativ

e pe

rcep

tion

and

clai

ms.

A

ppea

rs to

be

the

easi

est s

ite to

pro

vide

floo

d pr

otec

tion

sinc

e it

is a

t the

edg

e of

the

map

ped

flood

plai

n.

Lo

cate

s ba

sin

on s

ame

site

as

Lind

a M

ar

Pum

p S

tatio

n.

R

elat

ivel

y fa

r fr

om p

rivat

ely

own

ed

stru

ctur

es a

nd r

esid

ence

s re

duci

ng th

e ch

ance

of n

egat

ive

perc

eptio

n an

d cl

aim

s.

R

elat

ive

clo

se to

div

ersi

on p

oint

, red

ucin

g pi

pelin

e in

stal

latio

n co

sts

and

impa

cts.

Pri

nci

pal

Dis

adva

nta

ge(

s)

S

mal

ler

site

whi

ch m

ay in

cre

ase

cost

due

to

inco

nven

ien

ce

to c

ontr

acto

r.

C

lose

to p

rivat

ely

ow

ned

stru

ctur

es a

nd r

esid

ence

s in

crea

sing

the

cha

nce

of n

ega

tive

perc

eptio

n an

d cl

aim

s.

S

mal

ler

site

whi

ch m

ay in

cre

ase

cost

du

e to

inco

nven

ienc

e to

co

ntra

ctor

.

C

lose

to p

rivat

ely

ow

ned

stru

ctur

es a

nd

resi

denc

es in

crea

sing

the

chan

ce o

f ne

gativ

e pe

rcep

tion

and

clai

ms.

R

elat

ivel

y fa

r fr

om th

e di

vers

ion

poin

t, in

crea

sing

pip

elin

e in

stal

latio

n co

sts

and

impa

cts.

R

elat

ivel

y fa

r fr

om th

e di

vers

ion

poin

t, in

crea

sing

pi

pelin

e in

stal

latio

n co

sts

and

impa

cts.

M

ost i

mpa

ct to

exi

stin

g us

e of

all

of th

e si

tes

durin

g co

nstr

uctio

n be

caus

e of

the

mul

tiple

am

eniti

es th

at a

re a

ssoc

iate

d w

ith th

is p

arki

ng

lot a

nd th

e re

lativ

ely

high

usa

ge.

W

est o

f Hig

hw

ay 1

, pot

entia

lly e

xpo

sing

ba

sin

to th

e ef

fect

s of

sea

leve

l ris

e an

d pu

tting

the

basi

n w

ithin

the

Coa

stal

C

omm

issi

on r

evie

w z

one.

F

lood

pro

tect

ion

for

this

site

may

intr

oduc

e ad

ditio

nal p

roje

ct s

crut

iny

from

the

Coa

stal

C

omm

issi

on.

C

lose

st s

ite to

sho

relin

e so

fac

ilitie

s ar

e th

e m

ost e

xpo

sed

to o

cean

imp

acts

suc

h as

sal

t an

d sa

nd.

Sit

e O

wn

ersh

ip

Cal

tran

s C

ity

Cal

tran

s C

ity

Ow

ner

Wil

lin

g t

o S

ell?

Yes

, afte

r co

mpl

etio

n of

the

Dev

ils S

lide

cons

truc

tion.

Not

app

licab

le a

s th

is p

rope

rty

is C

ity-

own

ed.

Y

es, c

ondi

tion

al o

n de

term

inat

ion

of s

tew

ard

ship

of

gift

s an

d hi

stor

ic m

arke

rs.

N

ot a

pplic

able

as

this

pro

pert

y is

City

-ow

ned

.

Per

mit

tin

g

N

o sp

ecia

l req

uire

men

ts c

ompa

red

to S

ites

B a

nd C

1.

P

erm

it fr

om C

altr

ans

requ

ired

for

Hig

hw

ay 1

cro

ssin

g.

P

erm

it fr

om C

altr

ans

requ

ired

for

Hig

hw

ay 1

cr

ossi

ng.

B

asin

wou

ld r

equi

re r

evie

w a

nd li

kely

pe

rmitt

ing

from

the

Coa

stal

Com

mis

sion

for

ba

sin,

pip

elin

es,

and

ass

ocia

ted

faci

litie

s.

Oth

er C

on

sid

erat

ion

s

T

his

site

is r

elat

ivel

y cl

ose

to e

xist

ing

and

past

gas

sta

tions

, in

crea

sing

the

ris

k fo

r so

il co

ntam

inat

ion.

T

his

site

has

a jo

int u

se a

s a

bus

stat

ion

that

may

nee

d to

be

rel

ocat

ed d

urin

g co

nstr

uctio

n ba

sed

on f

inal

siti

ng.

F

rom

a g

eote

chni

cal p

ersp

ectiv

e, th

is s

ite h

as th

e m

ost

unkn

ow

ns.

T

his

site

wou

ld r

equi

re a

tren

chle

ss

met

hod

unde

r a

natu

ral a

rea

and

cons

truc

tion

nex

t to

a na

tura

l are

a. T

his

coul

d le

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ootn

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.

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February 2013 6-3

6.2 Recommendations The matrix shown below in Table 6-2 quantifies how well each site meets the evaluation criteria used in this analysis. The criteria and scoring system are described on the following page in Table 6-3. As can be seen in the weighting, Willing Landowner, Disturbance to Neighbors and Amenities, Construction Impact to Public, Cost, and Vulnerability to Sea Level Rise and Flooding are considered to be the primary drivers for selection of the preferred site.

Table 6-2: Site Priority Decision Matrix

Although Site A is not the least expensive site, we believe that, based on the criteria summarized in Table 6-3, it provides the best combination of benefits for the City.

CriteriaWeighting

FactorRelative

Importance A B C1 D

Willing Landowner 4 15% 1 2 1 2

Disturbance to Neighbors and Amenities 4 15% ‐1 ‐1 ‐1 1

Compatibility with Existing and Planned Landuse 1 4% ‐1 1 1 2

Construction Impact to Public 4 15% 1 ‐2 ‐2 ‐1

Cost 4 15% 2 1 1 2

Permitting 2 8% 2 1 1 ‐1

Vulnerability to Sea Level Rise and Flooding 4 15% 1 1 1 ‐1

Exposure to Salt and Sand Impacts 1 4% 2 2 1 ‐1

Geotechnical Considerations 2 8% 0 2 2 1

Sum of Weighting Factors 26 100%

Constructable Yes Yes Yes Yes

Score 21 13 8 13

Rank 1 2 4 2

Sites

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February 2013 6-4

Table 6-3: Description of Criteria and Scores Used in Decision Matrix

Criteria Description Additional Notes

Willing Landowner/Manager

Project would be located on a site that is owned by the City or could be purchased by the City

Considered to be a primary factor

Disturbance to Neighbors and Amenities

Project will not be noticed by the facility neighbors nor impact local amenities during or after construction


Compatibility with Existing and Planned Land Use

Installed project fits well with the existing and future surrounding land use

Construction Impact to General Public

Project does not impact the daily activities of the public during construction


Cost Project has a relatively low cost compared to the other project alternatives

Based on relative amount of new and relocated/ refurbished facilities required

Permitting Project has a relatively low cost/level of effort in obtaining required permits

Vulnerability to Sea Level Rise and Flooding

Project is geographically located in an area less susceptible to the impacts of sea level rise. Site is not susceptible to flooding or the flood risk can be reasonably reduced.


Exposure to Salt and Sand Impacts

Project is geographically located in an area less susceptible to the products of the ocean such as salt and sand


Project is located in an area that requires relatively little special geotechnical treatment

Constructable Pass/Fail test for the project alternative

Scores Description Additional Notes

2 Direct feedback that is positive; Strong indication that criteria and project are a good fit

1 Positive indication or anticipated positive response; Likely a good fit between the criteria and project

0 Neutral or unknown

-1 Negative indication or anticipated negative response; Likely to be a poor fit between the criteria and project

-2 Direct feedback that is negative; Strong indication that criteria and project are not a good fit

Yes Constructible Applies to Constructible criteria

No Not Constructible - Fatal Flaw Applies to Constructible criteria

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February 2013 6-5

6.3 Next Steps As this project moves toward the design phase, it will be important to ascertain certain information to confirm the selection of the preferred basin site and design elements of the project. This information includes:

The ability of Caltrans to declare the Site A parcel as excess and the cost (short term and long

term) associated with the sale of the parcel. This process should begin as soon as selection of the preferred site is finalized.

Direct geotechnical information that indicates that Site A does not have subsurface conditions

that would make another site more preferable.

Additional siting information that will support both public outreach and provide additional data to

inform the City about construction limitations and further the understanding of the specific location of the basin within the parcel.

Permitting requirements of the Coastal Commission. While the basin and diversion pipelines are

recommended to be located outside of the Coastal Commission review zone, pipeline installation and some earthwork may be necessary on the west side of Highway 1 (within the review zone) should an alternate diversion strategy be needed. Additional consultation with the Coastal Commission should occur to better understand permit requirements and better understand potential schedule impacts.

After selection of a preferred site, more site specific information should be obtained. As part of the design phase, or in preparation for the design phase, the following information should be developed:

Subsurface conditions at the basin site and along the pipeline alignments. Additional

geotechnical information will allow more thorough calculation of basin parameters and evaluation of pipeline installation options.

Location of utilities around the basin site and along the pipeline routes. The cost of utility

relocation has not been addressed on a site specific basis and is accounted for with a placeholder value. It is unknown what other utilities might be impacted by construction of the facilities described in this report. Careful planning will be necessary to minimize the relocation of utilities.

Identification of environmental resources and hazardous materials. Some preliminary

consideration was given to these factors but additional effort is needed to characterize and quantify the impacts they will have on the project cost and feasibility.

Topographic survey at the basin site and along the pipeline alignments. This information will

help to refine design parameters and the construction cost estimate.

While there are clearly unknowns related to selection of a preferred equalization basin site, this report concludes that there are a number of feasible options that could be implemented to achieve the goals described in the Master Plan. As outstanding questions are resolved, there will be additional confidence in selection of the preferred alternative.

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Appendices A and B

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Concrete Deck

Max Water Level

Concrete Bottom

ShotcreteCutter Soil Mix

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