Engineering Design Cost Estimates

Results

continued

water enters culverts near the sediment and leaves culverts near the water surface). The residence time for water within the pool would be four days, which is less than the residence time for water in Capitol Lake under current summer conditions (11 days). Installing the reflecting pool barrier would increase restoration costs by $14.9 – 22.6 million.

CAPITOL LAKE Adaptive Management Plan

Pre-Dredging of Sediment

Spring 2007

Engineering Design and Cost Estimates Report

For any of the estuary restoration alternatives, it is recommended that the main channel of the restored estuary be dredged before the tide is restored, and that the dredged materials are placed along Deschutes Parkway. This would reduce the need for dredging in Port of Olympia and associated marine facilities and cover the rock slope stabilization along Deschutes Parkway, providing additional intertidal habitat in North and Middle Basins.

Study Background

This Fact Sheet is a summary of major findings from Study Background the Deschutes Estuary Feasibility Study. It presents information third in of a series of technical This Fact from Sheet the is a summary major findings from the Deschutes Estuary Feasibility Study. It presents information reports. The Deschutes Estuary Feasibility Study, rd in a series of technical reports. The Deschutes from the 3 Engineering Design and Cost Estimates report was Estuary Feasibility Study, Engineering Design and Cost prepared by Moffa� and Nicholby(Sea�le, WA), in (Seattle, Estimates report was prepared Moffatt and Nichol association EDAW, andInc. GeoEngineers. WA), in with association withInc. EDAW, and GeoEngineers.

If the Capitol Lake dam were removed, a new channel would form in the middle of the lake, initially eroding a large amount of sediment (predicted by the USGS Hydraulic Model). If this area is pre-dredged, the initial pulse of sediment will not end up in Budd Inlet and will not have to be dredged from the Port of Olympia and associated marine facilities. But how would the dredged sediment be disposed of? Deschutes Parkway, along the west side of the North and Middle Basins, is constructed on roadway fill. Generally, such fill consists of gravelly sand overlaid on native soils (a mixture of loose silts, sands, and some gravel). During earthquake conditions, these native materials liquefy and spread, resulting in shallow and deep-seated slope failures, such as those seen after the 2001 Nisqually Earthquake. To stabilize this area in preparation for estuary restoration, significant amounts of rock would be added to weigh down and confine the soft slope.

Capitol Lake and Capitol Building photo

The full report can be downloaded from the Washington The full report can be downloaded from the Washington Dept. of General Administration website at: Department of General Administration website at: http://www.ga.wa.gov/CLAMP/EstuaryStudy.htm www.ga.wa.gov/CLAMP/EstuaryStudy.htm Pre-Dredge Channel Areas to deposit dredged sediment

The pre-dredge sediment could be placed over the rock that is required to stabilize Deschutes Parkway, creating about 5 acres of new high marsh, a rare and valuable habitat in south Puget Sound.

The Deschutes Estuary Feasibility Study, Engineering heDesign Deschutes Estuary Feasibility Study, Engineering and Cost Estimates report describes the results of an of the engineering feasibility and likely cost analysis Design and Cost Estimates report describes theof the restoration alternatives thatofarethe under three estuary engineering feasibility and likely costs three This analysis willthat help are evaluate the consideration. estuary restoration alternatives under Capitol an estuarythe of the feasibility ofThis restoring consideration. analysis will Lake helptoevaluate Deschutes River. Capitol LakeLake is part the Washington feasibility of restoring Capitol inof Olympia and Campus and is located in Olympia and State Capitol Tumwater, Washington, to an estuary of the Deschutes River.Tumwater, Washington.

T

answers three major This report communicates This report communicates thethe answers to to three major would physicalconditions conditions in in a questions. questions. First,First, howhow would thethe physical

For Alternatives A and B, between 180,000 and 360,000 cubic yards of material would be dredged from Middle Basin and along the main tidal channel and placed over the rock along Deschutes Parkway. This pre-dredging would cost between $8.7 and $19.8 million, depending on the quantity of sediment that is dredged from Middle Basin.

Estuary Restoration Estuary Restoration Alternatives

Funding for this study was provided by: Figure 4. Areas of channel pre-dredging and slope stabilization/habitat creation along the edges of the basins.

For additional questions, please contact: Nathaniel Jones, Facilities Division Phone: 360-902-0944 • E-mail: [email protected]

restored estuary affect existing infrastructure, such as roads Second, areexisting there feasible engineeringsuch designs and bridges? a restored estuary affect infrastructure, of the restoration alternatives, and does existing for each as roads and bridges? Second, are there feasible to function in a infrastructure require enhancements engineering designs for each of the restoration Third, what is the range of cost estimates restored estuary? alternatives? Third, what is the range of cost estimates alternatives? To answer for each of the restoration for each of the restoration alternatives? To answer these engineers studied data data from from earlierearlier technical questions, these questions, engineers studied tides, movement of sediment, flooding, reports about technical reports about tides, movement of sediment, a restored estuary. Please see salinity, and water in flow flooding, salinity, and flow water in a restored estuary. CLAMP Fact Sheet #3 and #4 for further discussion of this data.

Alternatives

The DEFS considers three estuaryrestoration restoration alternatives. The DEFS considers three estuary includevarious variousmodifications modifications to to the These alternatives alternatives, which include Avenue and and the the Burlington Burlington openings beneath beneath Fifth the openings Fifth Avenue Northern Santa Fe (BNSF) railroad crossing, well Northern Santa Fe (BNSF) railroad crossing, as as well as as modifications to the North Basin of Capitol Lake. modifications to the North Basin of Capitol Lake. � AlternativeAAincludes includes aa500-foot opening width at the • Alternative 500-foot opening width necessary current FifthFifth Avenue dam, with at the current Avenue dam, with necessary modifications existinginfrastructure. infrastructure. This modifications totoexisting This leavesthe the existing Avenue Bridge alternative alternative leaves existingFourth Fourth Avenue restoration full tidal in place and leads Bridge in place andtorestores fulloftidal hydrology. hydrology with minimum effects on current land use • Alternative B includes the changes in Alternative and infrastructure. A plus an increased opening width at the � Alternative includes the in Alternative A BNSF railroadBcrossing, at changes the division between opening width at the BNSF plus an increased the North and Middle Basins of Capitol Lake. is located at thefeet division whichbridge The railroad span ofcrossing, the current is 200 and between the North and Middle Basins of Capitol Lake. The span of the current bridge is 200 feet and increasing this span is thought to improve tidal

circulation reduce hydraulictostress (e.g. scour) increasing thisand span is thought improve tidal at this crossing. circulation and reduce scour at this crossing. � AlternativeDDincludes includes the in Alternative A • Alternative thechanges changes in Alternative basin design. This design divides the plus a split A plus a split basin design. This design divides North Basin a north-south line, creating the North Basin,along creating a reflecting pool a the east and a free flowing estuary reflecting pool to to the east and a free flowing estuary to the alternative recognizes the value to the west. This west. This alternative recognizes the value of of a statethe capitol while at theand same pool for the for bothreflecting a reflecting pool state capitol the Deschutes River with Budd time reconnecting reconnecting the Deschutes River with Budd Inlet. Inlet. C was considered earlier in the Deschutes Alternative Alternative C was considered earlier in the Deschutes Study. This design included Alternative Estuary Feasibility Estuary Feasibility Study. Alternative C was rejected width to Percival Cove. B plus an increased opening because hydrodynamic modeling showed it did not Alternative C was rejected because hydrodynamic cause significant changes to the conditions within modeling showed it did not cause significant changes to the Percival Cove. Please see CLAMP Fact Sheet #2 for conditions within Percival Cove. Please see CLAMP Fact more information on estuary restoration alternatives. Sheet #2 for more information on estuary restoration alternatives.

CLAMP Fact Sheet #5

Results

Resulsts

continued

The preliminary conclusions of the engineering analysis are as follows. • No fatal flaws have been identified that would rule out any of the restoration alternatives as completely infeasible from an engineering point of view. • For any of the alternatives, it is recommended that the main channel of the restored estuary be dredged before the tide is restored, and that the dredged materials are placed along Deschutes Parkway. In addition to the habitat benefits, this would decrease the quantity of navigation dredging required at the marinas along Percival Landing and at the Port of Olympia in the years immediately following the restoration of tidal flow in the restored estuary. See back page of this Fact Sheet. • Construction for all alternatives could be achieved within three to four years, under the assumption that only the Chinook salmon and bull trout windows for in-water work are observed.

Cost Estimates

RESULTS______________________________

Table 1 shows the preliminary cost estimates for each The preliminary conclusions of the engineering analysis are as follows. Ranges of costs are estuary restoration alternative. No fatal flaws have been identified that would rule provided, including a� minimum (most optimistic), out any of the restoration alternatives as completely average (most likely), and maximum (pessimistic but infeasible from an engineering point of view. excluding very remote eventualities). Approximately � For any of the alternatives, it is recommended that half of the variability in project costsof is the main channel theassociated restored estuary be dredged before the tideand is restored, and that the dredged with initial dredging of the basin placement of materials are placed along Deschutes Parkway. In the dredged materials along Deschutes Parkway to addition to the habitat benefits, this would decrease provide intertidal habitat. Theseoffigures both atthe the quantity navigationinclude dredging required the marinas along Percival and at the Port of construction costs and “soft” costs suchLanding as engineering, Olympia in the years immediately following the permitting, and the acquisition oftidal the project right-ofrestoration of flow in the restored estuary. See way. back page of this Fact Sheet.

Low Cost

Avg. Cost

High Cost

Alternative A Construction Cost

$46.3

$53.3

$61.0

Total Project Cost

$65.9

$76.1

$87.2

Construction Cost

$55.9

$63.3

$71.6

Total Project Cost

$79.6

$90.3

$102.3

Construction Cost

$65.9

$74.5

$84.1

Total Project Cost

$93.8

$106.2

$120.0

Alternative B

Alternative D

Construction for all alternatives could be achieved The project costs are�given in 2006 dollars, but the Table Preliminarycost cost estimate ranges for estuary restoration in within three to four years, under the assumption Table 1.1. Preliminary estimate ranges for estuary restoration in millions actual year in which thethat project is implemented affects only the Chinook salmon and bull trout of 2006 dollars. ofmillions 2006 dollars. windowsAn for annual in-water work are observed. the total cost of the project. inflation rate of 3.5% is based on the Cost average inflation rate experienced Estimates for construction projects and 2005, and can the values Table 1 to estimate Table between 1 shows the1990 preliminary cost estimates for be eachapplied given in 2006 dollars, but the how actual Theto project costs are in costs may change if estuary the project is implemented in future years. rate beis recalculated asthe more of costs are This average restoration alternative. Ranges year in which thecan project implemented affects total a minimum (most optimistic), average provided, including project. An annual inflation rate of 3.5% is cost of the recent data about average inflation rates for heavy construction becomes available.

(most likely), and maximum (pessimistic but excluding very remote eventualities). Approximately half of the variability in project costs is associated with initial dredging of the basin and placement of the dredged materials along Deschutes Parkway to provide intertidal habitat. These figures include both the raw construction costs and “soft” costs such as engineering, permitting, and the acquisition of the project right-of-way.

based on the average inflation rate experienced for construction projects between 1990 and 2005, and can be applied to the values in Table 1 to estimate how costs may is implemented years. This the projectcommon Thechange main ifelement to in allfuture alternatives rate can be recalculated as more recent data about average is a new Fifth Avenue Bridge with a 500-foot average inflation rates for heavy construction becomes span to allow free tidal flow. The aesthetics of available.

New Fi�h Avenue Bridge

the new Fourth Avenue Bridge are continued in this plan, creating an architecturally unified New Fifth Avenue Bridge impression. The new bridge provides four lanes The main element common to all alternatives is a new Fifth Avenue Bridge with a 500-foot span to allow free tidal flow. of traffic, bicycle and pedestrian lanes onThe aesthetics of the new Fourth Avenue Bridge are continued in this plan, creating an architecturally unified impression. The new each side, and crossingbridge for all current utilities. of provides four lanes This new configuration addresses and and pedestrian traffic, bicycletraffic on that each side, andincrossing pedestrian congestion lanes issues exist the for all current utilities. This current Fifth Avenue configuration. In addition, new configuration addresses the plan accommodates City of Olympia traffic and pedestrian plans to construct a pedestrian trail that along congestion issues exist in thecorridor. current FifthAAvenue the abandoned railroad separate In addition, pedestrian trail will passconfiguration. over the bridge tothe plan accommodates City of downtown Olympia. Figure 1 illustrates a Figure 1. Alternative A: New 5th Ave. Bridge (also included in Alternatives B and D). Olympia plans to construct a possible bridge and roadway trail along the pedestrianalignment that would allow for a 500-foot opening andA abandoned railroad corridor. separate pedestrian minimize effects on surrounding land trail usewill and pass over the bridge to commerce. downtown Olympia. Figure 1

Figure 1. Alternative A: New 5th Ave Bridge (also included in Alternatives B and D)

illustrates a possible bridge and roadway alignment that would allow for a 500-foot opening and minimize effects on surrounding land use and commerce.

New Railroad Bridge

Alternative B includes a new railroad bridge and pedestrian bridge adjacent to Marathon Park, between the North and Middle Basins. The purpose of the new bridge would be to provide a 500-foot opening that is consistent with the opening at the entrance to Budd Inlet, assuring that the constraint to tidal flow is not simply moved “upstream” in the restored estuary. The USGS Hydraulics and Sediment Transport Modeling report found that providing a 500-foot opening here would decrease the peak speed of tidal flow under the railroad bridge by 40%. The Engineering Design and Cost Estimates report (this report) determined, however, that the existing railroad bridge could be reinforced to withstand Figure 2. Alternative B: New railroad and pedestrian bridge. the increased water speed due to tidal flow without being replaced. Replacing the railroad bridge increases restoration costs by $9.1 – 11 million.

Barrier for Reflecting Pool

The purpose of the reflecting pool barrier in Alternative D would be to provide for the uninterrupted reflection of the State Capitol. The barrier would cut across the North Basin, preventing the water in the eastern part of the basin from emptying during low tide. A concrete pedestrian walkway would run from one shore of the North Basin to the other on top of a sheet pile wall. A sheet pile wall was chosen because creating a rubble-mound dike would would present significant construction challenges and risks. Although a freshwater pool was originally envisioned, the problems associated with maintaining water quality in a closed system proved complicated and

Figure 3. Alternative D: Barrier creating reflecting pool.

costly; a saltwater pool refreshed by tidal action results in a more self-sustaining system. At the north end of the wall, a set of culverts with tide gates would allow water into the pool, while a similar set of culverts at the south end of the wall would only let water out. Water would flow out with the tide until it reaches a depth that is high enough to maintain the appearance of a reflecting pool. Water in the pool would stay at this depth until the incoming tide causes water to flow in through the inlet culverts and rise to the high water mark. This would cause an overall circulation of water within the reflecting pool – both horizontally (north to south) and vertically (since

Results

Resulsts

continued

The preliminary conclusions of the engineering analysis are as follows. • No fatal flaws have been identified that would rule out any of the restoration alternatives as completely infeasible from an engineering point of view. • For any of the alternatives, it is recommended that the main channel of the restored estuary be dredged before the tide is restored, and that the dredged materials are placed along Deschutes Parkway. In addition to the habitat benefits, this would decrease the quantity of navigation dredging required at the marinas along Percival Landing and at the Port of Olympia in the years immediately following the restoration of tidal flow in the restored estuary. See back page of this Fact Sheet. • Construction for all alternatives could be achieved within three to four years, under the assumption that only the Chinook salmon and bull trout windows for in-water work are observed.

Cost Estimates

RESULTS______________________________

Table 1 shows the preliminary cost estimates for each The preliminary conclusions of the engineering analysis are as follows. Ranges of costs are estuary restoration alternative. No fatal flaws have been identified that would rule provided, including a� minimum (most optimistic), out any of the restoration alternatives as completely average (most likely), and maximum (pessimistic but infeasible from an engineering point of view. excluding very remote eventualities). Approximately � For any of the alternatives, it is recommended that half of the variability in project costsof is the main channel theassociated restored estuary be dredged before the tideand is restored, and that the dredged with initial dredging of the basin placement of materials are placed along Deschutes Parkway. In the dredged materials along Deschutes Parkway to addition to the habitat benefits, this would decrease provide intertidal habitat. Theseoffigures both atthe the quantity navigationinclude dredging required the marinas along Percival and at the Port of construction costs and “soft” costs suchLanding as engineering, Olympia in the years immediately following the permitting, and the acquisition oftidal the project right-ofrestoration of flow in the restored estuary. See way. back page of this Fact Sheet.

Low Cost

Avg. Cost

High Cost

Alternative A Construction Cost

$46.3

$53.3

$61.0

Total Project Cost

$65.9

$76.1

$87.2

Construction Cost

$55.9

$63.3

$71.6

Total Project Cost

$79.6

$90.3

$102.3

Construction Cost

$65.9

$74.5

$84.1

Total Project Cost

$93.8

$106.2

$120.0

Alternative B

Alternative D

Construction for all alternatives could be achieved The project costs are�given in 2006 dollars, but the Table Preliminarycost cost estimate ranges for estuary restoration in within three to four years, under the assumption Table 1.1. Preliminary estimate ranges for estuary restoration in millions actual year in which thethat project is implemented affects only the Chinook salmon and bull trout of 2006 dollars. ofmillions 2006 dollars. windowsAn for annual in-water work are observed. the total cost of the project. inflation rate of 3.5% is based on the Cost average inflation rate experienced Estimates for construction projects and 2005, and can the values Table 1 to estimate Table between 1 shows the1990 preliminary cost estimates for be eachapplied given in 2006 dollars, but the how actual Theto project costs are in costs may change if estuary the project is implemented in future years. rate beis recalculated asthe more of costs are This average restoration alternative. Ranges year in which thecan project implemented affects total a minimum (most optimistic), average provided, including project. An annual inflation rate of 3.5% is cost of the recent data about average inflation rates for heavy construction becomes available.

(most likely), and maximum (pessimistic but excluding very remote eventualities). Approximately half of the variability in project costs is associated with initial dredging of the basin and placement of the dredged materials along Deschutes Parkway to provide intertidal habitat. These figures include both the raw construction costs and “soft” costs such as engineering, permitting, and the acquisition of the project right-of-way.

based on the average inflation rate experienced for construction projects between 1990 and 2005, and can be applied to the values in Table 1 to estimate how costs may is implemented years. This the projectcommon Thechange main ifelement to in allfuture alternatives rate can be recalculated as more recent data about average is a new Fifth Avenue Bridge with a 500-foot average inflation rates for heavy construction becomes span to allow free tidal flow. The aesthetics of available.

New Fi�h Avenue Bridge

the new Fourth Avenue Bridge are continued in this plan, creating an architecturally unified New Fifth Avenue Bridge impression. The new bridge provides four lanes The main element common to all alternatives is a new Fifth Avenue Bridge with a 500-foot span to allow free tidal flow. of traffic, bicycle and pedestrian lanes onThe aesthetics of the new Fourth Avenue Bridge are continued in this plan, creating an architecturally unified impression. The new each side, and crossingbridge for all current utilities. of provides four lanes This new configuration addresses and and pedestrian traffic, bicycletraffic on that each side, andincrossing pedestrian congestion lanes issues exist the for all current utilities. This current Fifth Avenue configuration. In addition, new configuration addresses the plan accommodates City of Olympia traffic and pedestrian plans to construct a pedestrian trail that along congestion issues exist in thecorridor. current FifthAAvenue the abandoned railroad separate In addition, pedestrian trail will passconfiguration. over the bridge tothe plan accommodates City of downtown Olympia. Figure 1 illustrates a Figure 1. Alternative A: New 5th Ave. Bridge (also included in Alternatives B and D). Olympia plans to construct a possible bridge and roadway trail along the pedestrianalignment that would allow for a 500-foot opening andA abandoned railroad corridor. separate pedestrian minimize effects on surrounding land trail usewill and pass over the bridge to commerce. downtown Olympia. Figure 1

Figure 1. Alternative A: New 5th Ave Bridge (also included in Alternatives B and D)

illustrates a possible bridge and roadway alignment that would allow for a 500-foot opening and minimize effects on surrounding land use and commerce.

New Railroad Bridge

Alternative B includes a new railroad bridge and pedestrian bridge adjacent to Marathon Park, between the North and Middle Basins. The purpose of the new bridge would be to provide a 500-foot opening that is consistent with the opening at the entrance to Budd Inlet, assuring that the constraint to tidal flow is not simply moved “upstream” in the restored estuary. The USGS Hydraulics and Sediment Transport Modeling report found that providing a 500-foot opening here would decrease the peak speed of tidal flow under the railroad bridge by 40%. The Engineering Design and Cost Estimates report (this report) determined, however, that the existing railroad bridge could be reinforced to withstand Figure 2. Alternative B: New railroad and pedestrian bridge. the increased water speed due to tidal flow without being replaced. Replacing the railroad bridge increases restoration costs by $9.1 – 11 million.

Barrier for Reflecting Pool

The purpose of the reflecting pool barrier in Alternative D would be to provide for the uninterrupted reflection of the State Capitol. The barrier would cut across the North Basin, preventing the water in the eastern part of the basin from emptying during low tide. A concrete pedestrian walkway would run from one shore of the North Basin to the other on top of a sheet pile wall. A sheet pile wall was chosen because creating a rubble-mound dike would would present significant construction challenges and risks. Although a freshwater pool was originally envisioned, the problems associated with maintaining water quality in a closed system proved complicated and

Figure 3. Alternative D: Barrier creating reflecting pool.

costly; a saltwater pool refreshed by tidal action results in a more self-sustaining system. At the north end of the wall, a set of culverts with tide gates would allow water into the pool, while a similar set of culverts at the south end of the wall would only let water out. Water would flow out with the tide until it reaches a depth that is high enough to maintain the appearance of a reflecting pool. Water in the pool would stay at this depth until the incoming tide causes water to flow in through the inlet culverts and rise to the high water mark. This would cause an overall circulation of water within the reflecting pool – both horizontally (north to south) and vertically (since

Results

continued

water enters culverts near the sediment and leaves culverts near the water surface). The residence time for water within the pool would be four days, which is less than the residence time for water in Capitol Lake under current summer conditions (11 days). Installing the reflecting pool barrier would increase restoration costs by $14.9 – 22.6 million.

CAPITOL LAKE Adaptive Management Plan

Pre-Dredging of Sediment

Spring 2007

Engineering Design and Cost Estimates Report

For any of the estuary restoration alternatives, it is recommended that the main channel of the restored estuary be dredged before the tide is restored, and that the dredged materials are placed along Deschutes Parkway. This would reduce the need for dredging in Port of Olympia and associated marine facilities and cover the rock slope stabilization along Deschutes Parkway, providing additional intertidal habitat in North and Middle Basins.

Study Background

This Fact Sheet is a summary of major findings from Study Background the Deschutes Estuary Feasibility Study. It presents information third in of a series of technical This Fact from Sheet the is a summary major findings from the Deschutes Estuary Feasibility Study. It presents information reports. The Deschutes Estuary Feasibility Study, rd in a series of technical reports. The Deschutes from the 3 Engineering Design and Cost Estimates report was Estuary Feasibility Study, Engineering Design and Cost prepared by Moffa� and Nicholby(Sea�le, WA), in (Seattle, Estimates report was prepared Moffatt and Nichol association EDAW, andInc. GeoEngineers. WA), in with association withInc. EDAW, and GeoEngineers.

If the Capitol Lake dam were removed, a new channel would form in the middle of the lake, initially eroding a large amount of sediment (predicted by the USGS Hydraulic Model). If this area is pre-dredged, the initial pulse of sediment will not end up in Budd Inlet and will not have to be dredged from the Port of Olympia and associated marine facilities. But how would the dredged sediment be disposed of? Deschutes Parkway, along the west side of the North and Middle Basins, is constructed on roadway fill. Generally, such fill consists of gravelly sand overlaid on native soils (a mixture of loose silts, sands, and some gravel). During earthquake conditions, these native materials liquefy and spread, resulting in shallow and deep-seated slope failures, such as those seen after the 2001 Nisqually Earthquake. To stabilize this area in preparation for estuary restoration, significant amounts of rock would be added to weigh down and confine the soft slope.

Capitol Lake and Capitol Building photo

The full report can be downloaded from the Washington The full report can be downloaded from the Washington Dept. of General Administration website at: Department of General Administration website at: http://www.ga.wa.gov/CLAMP/EstuaryStudy.htm www.ga.wa.gov/CLAMP/EstuaryStudy.htm Pre-Dredge Channel Areas to deposit dredged sediment

The pre-dredge sediment could be placed over the rock that is required to stabilize Deschutes Parkway, creating about 5 acres of new high marsh, a rare and valuable habitat in south Puget Sound.

The Deschutes Estuary Feasibility Study, Engineering heDesign Deschutes Estuary Feasibility Study, Engineering and Cost Estimates report describes the results of an of the engineering feasibility and likely cost analysis Design and Cost Estimates report describes theof the restoration alternatives thatofarethe under three estuary engineering feasibility and likely costs three This analysis willthat help are evaluate the consideration. estuary restoration alternatives under Capitol an estuarythe of the feasibility ofThis restoring consideration. analysis will Lake helptoevaluate Deschutes River. Capitol LakeLake is part the Washington feasibility of restoring Capitol inof Olympia and Campus and is located in Olympia and State Capitol Tumwater, Washington, to an estuary of the Deschutes River.Tumwater, Washington.

T

answers three major This report communicates This report communicates thethe answers to to three major would physicalconditions conditions in in a questions. questions. First,First, howhow would thethe physical

For Alternatives A and B, between 180,000 and 360,000 cubic yards of material would be dredged from Middle Basin and along the main tidal channel and placed over the rock along Deschutes Parkway. This pre-dredging would cost between $8.7 and $19.8 million, depending on the quantity of sediment that is dredged from Middle Basin.

Estuary Restoration Estuary Restoration Alternatives

Funding for this study was provided by: Figure 4. Areas of channel pre-dredging and slope stabilization/habitat creation along the edges of the basins.

For additional questions, please contact: Nathaniel Jones, Facilities Division Phone: 360-902-0944 • E-mail: [email protected]

restored estuary affect existing infrastructure, such as roads Second, areexisting there feasible engineeringsuch designs and bridges? a restored estuary affect infrastructure, of the restoration alternatives, and does existing for each as roads and bridges? Second, are there feasible to function in a infrastructure require enhancements engineering designs for each of the restoration Third, what is the range of cost estimates restored estuary? alternatives? Third, what is the range of cost estimates alternatives? To answer for each of the restoration for each of the restoration alternatives? To answer these engineers studied data data from from earlierearlier technical questions, these questions, engineers studied tides, movement of sediment, flooding, reports about technical reports about tides, movement of sediment, a restored estuary. Please see salinity, and water in flow flooding, salinity, and flow water in a restored estuary. CLAMP Fact Sheet #3 and #4 for further discussion of this data.

Alternatives

The DEFS considers three estuaryrestoration restoration alternatives. The DEFS considers three estuary includevarious variousmodifications modifications to to the These alternatives alternatives, which include Avenue and and the the Burlington Burlington openings beneath beneath Fifth the openings Fifth Avenue Northern Santa Fe (BNSF) railroad crossing, well Northern Santa Fe (BNSF) railroad crossing, as as well as as modifications to the North Basin of Capitol Lake. modifications to the North Basin of Capitol Lake. � AlternativeAAincludes includes aa500-foot opening width at the • Alternative 500-foot opening width necessary current FifthFifth Avenue dam, with at the current Avenue dam, with necessary modifications existinginfrastructure. infrastructure. This modifications totoexisting This leavesthe the existing Avenue Bridge alternative alternative leaves existingFourth Fourth Avenue restoration full tidal in place and leads Bridge in place andtorestores fulloftidal hydrology. hydrology with minimum effects on current land use • Alternative B includes the changes in Alternative and infrastructure. A plus an increased opening width at the � Alternative includes the in Alternative A BNSF railroadBcrossing, at changes the division between opening width at the BNSF plus an increased the North and Middle Basins of Capitol Lake. is located at thefeet division whichbridge The railroad span ofcrossing, the current is 200 and between the North and Middle Basins of Capitol Lake. The span of the current bridge is 200 feet and increasing this span is thought to improve tidal

circulation reduce hydraulictostress (e.g. scour) increasing thisand span is thought improve tidal at this crossing. circulation and reduce scour at this crossing. � AlternativeDDincludes includes the in Alternative A • Alternative thechanges changes in Alternative basin design. This design divides the plus a split A plus a split basin design. This design divides North Basin a north-south line, creating the North Basin,along creating a reflecting pool a the east and a free flowing estuary reflecting pool to to the east and a free flowing estuary to the alternative recognizes the value to the west. This west. This alternative recognizes the value of of a statethe capitol while at theand same pool for the for bothreflecting a reflecting pool state capitol the Deschutes River with Budd time reconnecting reconnecting the Deschutes River with Budd Inlet. Inlet. C was considered earlier in the Deschutes Alternative Alternative C was considered earlier in the Deschutes Study. This design included Alternative Estuary Feasibility Estuary Feasibility Study. Alternative C was rejected width to Percival Cove. B plus an increased opening because hydrodynamic modeling showed it did not Alternative C was rejected because hydrodynamic cause significant changes to the conditions within modeling showed it did not cause significant changes to the Percival Cove. Please see CLAMP Fact Sheet #2 for conditions within Percival Cove. Please see CLAMP Fact more information on estuary restoration alternatives. Sheet #2 for more information on estuary restoration alternatives.

CLAMP Fact Sheet #5