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TECHNICAL MEMORANDUM 
 
 
CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                          1 
West Palouse River Drive Feasibility Study 
 Overview 
Upgrades are proposed on West Palouse River Drive to meet current City standards with sidewalk and 
curb and gutter extending to the city limits. Portions of the 0.95-mile segment have installed sidewalk and 
curb and gutter already; however, a cohesive road section for traffic and pedestrian flow is desired. The 
primary intent of this project is to fill in the gaps of the sidewalk and curb and gutter while minimizing 
street reconstruction. This project, along with county road improvements in Whitman County, Washington, 
will also provide a truck bypass route to Highway 270, allowing trucks an alternative route that avoids 
both downtown Moscow and Pullman. Refer to Exhibit 1 below for an overview of the upgrades that are 
under consideration for West Palouse River Drive. 
 
Exhibit 1 – Project Map 
 
Prepared For: City of Moscow 
Prepared By: Great West Engineering 
Date: August 1, 2025 
Project Number: 1-24191 
Revision No.:
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         2 
1.1 Design Standards and Existing Conditions 
The existing route has a mix of urban and rural features from the intersection of Hwy 95/Main Street and 
West Palouse River Drive to the end of the western City Limits. From Main Street to Conestoga Drive, the 
current route is primarily an urban streetscape with the following features:  
 A sidewalk is present along the south side of  the road, with a monolithic curb on the older 
portions nearer Main Street and combination curb and gutter on the newer portions nearer 
Conestoga Drive.    
 Portions of sidewalk and combination curb an d gutter are present along the north side of the 
road, starting just east of Sunnyside Avenue and continuing to Conestoga Drive.  
From Conestoga Drive to the west City Limits, West Palouse River Drive is primarily a rural route with 
narrower driving lanes, roadside ditches, and no sidewalk or curb and gutters. 
The conceptual design followed the City of Moscow Design Standards for a minor arterial route and was 
based on publicly available imagery and data. The following geometric road parameters and design 
criteria were used in the conceptual design: 
Existing Road Surface Paved (see Exhibits 2 & 3 below) 
Existing Road Width ~34 feet where existing curb and gutter 
~24 feet where there is no curb and gutter 
Existing Road Easement or  
Public Right-of-Way 
60 feet (typical), 50 feet at the intersection 
with Main Street 
Proposed Road Surface Paved (See Typical Section in Appendix A) 
Proposed Road Width 12-foot lane, 5-foot shoulder, 6-foot sidewalks 
(See Typical Section in Appendix A) 
Design Speed 35 mph
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         3 
  
Exhibit 2 – Existing Road Section Looking East on West Palouse River Drive at the Intersection with Hwy 95/Main Street 
 
 
Exhibit 3 – Existing Road Section Looking West at West Palouse River Drive from Conestoga Drive 
 Road Improvements 
2.1 Proposed Typical Section 
The proposed minor arterial typical section included two 12-foot wide travel lanes and 5-foot wide bike 
lanes on each side with curb and gutter, providing 34 feet of total width. The 5-foot wide bike lane utilizes 
18 inches of curb and gutter, resulting in a total pavement width of 31 feet. A boulevard of varying width 
typically separates the road from the 6-foot sidewalk. The sidewalk is adjacent to the curb and gutter 
where additional right-of-way is unavailable or in areas with topographic constraints. A 2-inch asphalt mill 
and overlay is proposed for areas with existing asphalt, and a full-depth pavement section will be used for
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         4 
any widening areas. The full-depth pavement section is shown on sheet 4 in Appendix A, and the depths 
are listed below: 
Bituminous Pavement Surface  4 inches 
¾”-Minus Aggregate Base 6 inches 
1-¼”-Minus Aggregate Base 8 inches 
Sidewalk 5 inches (6-inch reinforced concrete at 
approaches) 
 
2.2 Intersection Improvements (Hwy 95/Main St & West Palouse River 
Drive) 
Proposed improvements to the intersection include widening the northwest corner with a double radius 
curb return. Truck turning movements were considered at the intersection of Highway 95/Main Street and 
West Palouse River Drive.  Based on comments from the Idaho Transportation Department, a WB-67 
design vehicle was evaluated without any encroachment into oncoming lanes. The current intersection at 
Hwy 95/Main St and West Palouse River Drive cannot support the turn movements of a WB-67 truck 
when traveling southbound on Main Street and turning right onto West Palouse River Drive, as shown in 
Appendix B. The improvements to the intersection assume only a single traffic signal will be relocated, 
and all other signals at the intersection can be maintained.  
To improve traffic queuing, a 36-foot road width is proposed to start approximately 210 feet west of the 
intersection (~Station 58+40) and continue through the intersection. The proposed road width consists of 
three 12-foot lanes with additional widening at the curb return, as described above. This allows for one 
westbound lane, one eastbound left turn lane, and one eastbound through/right turn lane.  
2.3 Road, Curb and Gutter, a nd Sidewalk Improvements 
Proposed improvements to West Palouse River Drive will provide two 12-foot lanes, two 5-foot bike lanes, 
combination curb and gutter, and a 6-foot sidewalk on each side of the road from the intersection with 
Hwy 95/Main Street to the City Limits just west of the bridge as shown in Exhibit 1. A 2-inch mill and 
asphalt overlay will be utilized over areas of existing asphalt, and a full-depth pavement section with 
aggregate base and subbase will be built where widening is necessary.  
The proposed sidewalk is set 0.5 feet off the approximate right-of-way, wherever practical, as shown in 
the typical section in Appendix A on sheet 4.  Select areas of the sidewalk are set right off the top back of 
the curb to avoid taller cut or fill sections or potential retaining walls.  
Two new retaining walls are proposed along the north side of West Palouse River Drive due to steep 
slopes at the proposed sidewalk locations, as shown in Appendix A. One new 135-foot-long retaining wall 
is required just west of Conestoga Drive from station 28+85 to station 30+20, and one 100-foot-long 
retaining wall is required as a continuation of the existing retaining wall east of Conestoga Drive from 
station 35+85 to 36+85. See Exhibits 4 and 5 below and sheets 2 and 3 of Appendix A.
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         5 
 
Exhibit 4 – Location of Proposed 135-foot Long Retaining Wall (Conceptual Wall Overlay Shown, ~Sta. 28+85 to Sta. 
30+20) 
 
Exhibit 5 – Location of Proposed Retaining Wall (~Sta. 35+85 to Sta. 36+85) 
The approximately 25-foot-wide x 52-foot-long bridge over the South Fork Palouse River on the west end 
of the project will be replaced outside of this project. It is assumed the bridge replacement will occur 
before this project and will be designed to match the typical section above.   
2.4 Right-of-Way 
The City of Moscow requires a 90-foot minimum right-of-way for all newly constructed minor arterial 
routes. The improvements shown in Appendix A assume all new work will be completed within the 
existing 60-foot right-of-way, with the exception of the intersection of Hwy 95/Main Street and West 
Palouse River Drive. New right-of-way will need to be acquired at the intersection of Hwy 95/Main Street 
and West Palouse River Drive to accommodate truck turning movements. Construction agreements are 
anticipated to construct cut/fill slopes from the sidewalk outside the existing right-of-way. The City of 
Moscow owns the parcel south of Palouse River Drive from approximately 270 feet east of Conestoga 
Drive to the bridge over the South Fork Palouse River.   
Project Area Estimated Acquisition Area (Minimum) 
Intersection of Hwy95/Main Street and 
West Palouse River Drive  1,700 SF = 0.04 Acres 
Increasing existing right-of-way to new 90-
foot right-of-way (Entire Project) 113,200 SF = 2.60 Acres 
Total  114,900 SF = 2.64 Acres 
 
Sta. 28+85 
Sta. 30+20 
Sta. 36+85 
Sta. 35+85
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         6 
2.5 Environmental Considerations 
The anticipated environmental services and permits to be addressed during the design phase include, but 
are not limited to: 
 Wetland surveys and delineations 
 Research on threatened and endangered (T&E) species 
 Evaluations of cultural resources 
 Compliance with the National Environmental Policy Act (NEPA)  
 Stormwater management requirements 
 Hazardous material checks through the Depa rtment of Environmental Quality (DEQ)  
 DEQ requirements for water distribution and sanitary sewer 
 Floodplain permitting.  
o Portions of the project lie within a mappe d floodplain zone A4 as shown on the Federal 
Emergency Management Agency’s (FEMA) FIRM Panel 1600860330 D. This floodplain 
will likely be impacted during both the bridge replacement and road widening east of the 
bridge, requiring a floodplain permit. See Exhibit 6 below.   
If the project only has minimal impacts on cultural and environmental features, it will likely qualify for a 
Categorical Exclusion. Preliminary findings show wetlands present along the South Fork Palouse River 
that crosses under West Palouse River Drive. The proposed bridge replacement may have impacts to the 
existing wetlands, but will be completed outside of this project. The wetlands shown in Appendix A are 
based on National Wetland Inventory data. A wetland field survey will need to be completed during final 
design.  
 
Exhibit 6 – FEMA Floodplain Map (Red = 100 Year Floodplain, Orange = 500 Year Floodplain) 
2.6 Utility Impacts 
Existing utilities located on Palouse River drive include, but at not limited to, overhead power, overhead 
communication, underground power, underground communication, natural gas, water, sanitary sewer, 
and storm drain. Impacts are anticipated throughout the project. Most of the utility impacts are due to the 
proposed intersection improvements including relocating an overhead power pole and guy wires, several 
communication vaults, a power transformer, and underground power to the billboards. See sheet 5 of 
Appendix A for a map of utilities impacted.  City-owned utility improvements including water distribution, 
sanitary sewer, and storm drains are discussed below. All City-owned utility improvements will be
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study                                                                                                                         7 
designed and constructed to meet Idaho Public Works Standards, the City of Moscow Design Standards, 
and all applicable rules and codes laid out by the Idaho Administrative Procedure Act (IDAPA). The cost 
for utility relocations of other, privately-owned utilities (power, communication, etc.) are anticipated to be 
the responsibility of the respective utility companies/owners. The following narratives on water, sewer and 
storm drain provide conceptual guidance to consider during subsequent phases of the project.   
 
Water Distribution 
Existing water distribution mains are present from Hwy 95/Main Street east to Conestoga Street, 
serving adjacent developments, homes, and businesses.  To maximize service area, serve future 
developments, and prevent utility trenching and patching in newly constructed roads, early analysis 
on the City’s Water Comprehensive Plan update recommends a 12-inch water main extension from 
Conestoga Street to Augustine Avenue. The current water distribution extension is shown dead-
ending at Augustine Avenue; however, a looping configuration may be needed to provide adequate 
fire flows.  Further investigation into the feasibility of connecting to water mains within the Edington 
Subdivision south of West Palouse River Drive should be performed. 
The proposed extents of the water distribution extension involves crossing the South Fork Palouse 
River with a horizontal directional drilled (HDD) crossing outside the limits of the bridge.  This will 
minimize environmental impacts and construction risk. 
Sanitary Sewer 
The existing sanitary sewer service area extends from Hwy 95/Main Street to Conestoga Street.  The 
existing topography slopes to the west towards the crossing of the South Fork Palouse River making 
a gravity sewer extension impossible.  A sanitary sewer lift station is required to extend the sanitary 
sewer service area beyond its current limits.  A gravity sanitary sewer main would provide collection 
and flow to a lift station located northeast of the bridge.  The lift station would pump sewage through a 
force main back along the north side of West Palouse River Drive and connect into the westernmost 
existing sewer manhole located at Conestoga Street. 
A lift station and sanitary sewer service area expansion could serve numerous future developments 
adjacent to the proposed project and connect existing septic systems to the new collection 
infrastructure. 
Storm Drain 
Existing storm drain infrastructure along West Palouse River Drive is present at the intersection with 
Hwy 95/Main Street and between Sunnyside Avenue and Willow View Place.  The inlets and manhole 
at the intersection are part of the Hwy 95/Main Street corridor storm drain system.  The existing storm 
drain system in the middle of this project collects stormwater and discharges it south to the Edington 
Subdivision between Sunnyside Avenue and Willow View Place. 
The project involves adding curb and gutter and eliminating roadside drainage ditches.  Therefore, 
storm drain systems are necessary to collect and convey stormwater away from the roadway without 
impacting surrounding property.  Proposed stormwater improvements include one new storm drain 
system serving the western portion of the project and an extension to the system at Hwy 95/Main 
Street to serve the eastern portion of the project. 
The new storm drain system will use curb inlets, manholes, and storm drain pipe to collect runoff from 
Conestoga Street west to the South Fork Palouse River. Consideration should be given to the new 
system discharging to wetlands adjacent to the river.
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CITY OF MOSCOW | West Palouse River Drive Feasibility Study        8 
The extension of the Hwy 95/Main Street storm drain serves the area from the highway west to 
approximately Sunnyside Avenue.  Currently a roadside ditch on the north side of West Palouse River 
Drive and curb and gutter on the south side appear to be the only stormwater improvements in this 
area.  The new extension would include new curb inlets and manholes in the unserviced area and 
replace existing inlets and a manhole at the Hwy 95/Main Street intersection and accommodate the 
new intersection layout widened for turning movements. 
Opinion of Probable Cost 
The opinion of probable cost includes an estimated base cost with allowances for engineering design, 
construction engineering, contingency, and inflation. The cost range below shows a -20% factor up to a 
+30% factor of the estimated overall cost. The estimated cost for the intersection improvements assumes
only one traffic signal will be replaced and relocated, and all other members will be maintained. See
Appendi
x C for a detailed probable cost. The estimated costs shown assume a 2028 construction with a
3% pe
r year inflation factor applied.
Base Roadway Improvements Cost Estimated Cost 
Base Roadway Improvements Cost $3,236,000 – $5,258,000 
Intersection Improvements (Single Member) $211,000 - $342,000 
Right-of-Way Costs TBD 
Stormwater Improvements $1,219,000 - $1,981,000 
Sanitary Sewer Improvements $1,195,000 - $1,942,000 
Water Distribution Improvements $651,000 - $ 1,057,000
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APPENDIX A 
Conceptual Plans
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1SHEET NO.
PROJECT:DATE:SHEET  INDEXCONCEPTUAL PLANS
PALOUSE RIVER DRIVE
NOT TO SCALE
SHEET 1COVERSHEETS 2-4ROADWAY AND SIDEWALK PLANSSHEET 4MINOR ARTERIAL TYPICAL SECTIONSHEET 5UTILITY PLAN
SECTIONS 18 & 19, TOWNSHIP 39 NORTH, AND RANGE 5 WESTSECTION 24, TOWNSHIP 39 NORTH, RANGE 6 WEST
AUGUST 1, 20251-24210
N
CITY OF MOSCOWWEST PALOUSERIVER DRIVE
2501 BELT VIEW DRIVEHELENA, MT   59601(406)449-8627
TO COUR D'ALENE, ID270
MAIN STREETTO TROY, ID
PROJECT STARTTO KIRKENDAHL ROAD, WA
LOCATION MAP
PocatelloIdahoFallsSalmon
Twin FallsBoise
LewistonCoeurD'Alene
SunValley
GrangevilleMoscow90
84848615
15WYOMING
MONTANA
UTAHNEVADAOREGONWASHINGTON
CANADABonnersFerrySandpoint
Elk CityPROJECT LOCATION
PLANS PREPARED FOR:CITY OF MOSCOW, IDAHO
PROJECT END
MOSCOW, ID
95
8
PALOUSE RIVER DRIVESAND ROAD
8
TO PULLMAN, WA95WASHINGTONIDAHO
REISENAUER ROAD
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PLAN VIEW OF WEST PALOUSE RIVER DRIVE
MOSCOW PALOUSE RIVER DRIVECITY OF MOSCOWPROJECT:DESIGNED:DRAWN:CHECKED:APPROVED:DATE:NO.DATEBYREVISION DESCRIPTION
SHEET NO.2501 BELT VIEW DRIVEHELENA, MT   59601(406)449-8627
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MOSCOW PALOUSE RIVER DRIVECITY OF MOSCOWPROJECT:DESIGNED:DRAWN:CHECKED:APPROVED:DATE:NO.DATEBYREVISION DESCRIPTION
SHEET NO.2501 BELT VIEW DRIVEHELENA, MT   59601(406)449-8627
DRAFT
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LEGEND:
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MOSCOW PALOUSE RIVER DRIVECITY OF MOSCOWPROJECT:DESIGNED:DRAWN:CHECKED:APPROVED:DATE:NO.DATEBYREVISION DESCRIPTION
SHEET NO.2501 BELT VIEW DRIVEHELENA, MT   59601(406)449-8627
DRAFT
PALOUSE RIVER DRIVEMAIN STREETLEGEND:
12
MINOR ARTERIAL TYPICAL SECTION
2LENTER STREET1
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MOSCOW PALOUSE RIVER DRIVECITY OF MOSCOWPROJECT:DESIGNED:DRAWN:CHECKED:APPROVED:DATE:NO.DATEBYREVISION DESCRIPTION
SHEET NO.2501 BELT VIEW DRIVEHELENA, MT   59601(406)449-8627
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APPENDIX B 
Hwy 95/Main Street & West Palouse River 
Drive Truck Turning Movements
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 INTERSECTION OFHWY 95/MAIN STREET &WEST PALOUSE RIVER DRIVEWB-67 TRUCK TURNING MOVEMENTSCITY OF MOSCOWMOSCOW PALOUSE RIVER DRIVE
NORTH
HWY95/MAIN STREET
WEST PALOUSE RIVER DRIVE6'12' (TYP.)
WB-67 WHEEL TRACKING
PROPOSED CURB AND GUTTER (TYP.)PROPOSED SIDEWALK IMPROVEMENTS
PROPOSED NEW SIDEWALKMISC. UTILITIES, SIGNS, BILLBOARDS, TO BE MOVED BY OTHERS
TRAFFIC SIGNAL TO BE MOVED
PROPOSED INTERSECTION LANE LINES (TYP.)
R248.5'R43.5'
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APPENDIX C 
Opinion of Probable Cost
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OPINION OF PROBABLE COST
PROJECT DATE
Moscow Palouse River Drive 8/1/2025
Base Cost
ITEM NO. DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL PRICE
1 Mobilization 1 LS $228,000.00 $228,000
2 Excavation and Embankment 1 LS $20,000.00 $20,000
3 Mill Asphalt 15,300 SY $3.00 $45,900
4 Superpave HMA Pavement (Asphalt Overlay - 2" Depth ) 1,700 TON $150.00 $255,000
5 Superpave HMA Pavement (Full-Depth Section - 4" Depth) 490 TON $150.00 $73,500
6 3/4"-Minus Compacted Aggregate Base 670 TON $40.00 $26,800
7 1-1/4"-Minus Compacted Aggregate Base 890 TON $35.00 $31,150
8 Subgrade Separation Geotextile Fabric 2,200 SY $4.50 $9,900
9 Remove/Dispose of Concrete Sidewalk 260 SY $50.00 $13,000
10 Remove/Dispose of Concrete Curb 560 LF $10.00 $5,600
11 Concrete Sidewalk (5-inch) 3,560 SY $150.00 $534,000
12 Concrete Sidewalk (6-inch reinforced) 260 SY $175.00 $45,500
13 Combination Curb and Gutter Type B 6,290 LF $100.00 $629,000
14 Pedestrian Ramp with Detectable Warning Domes 7 EA $2,000.00 $14,000
15 Retaining Wall 940 SF $50.00 $47,000
16 Topsoil 1,260 CY $40.00 $50,400
17 Seeding, Fertilizing, and Mulching 0.6 ACRE $5,000.00 $3,000
18 Sodding 2,900 SY $20.00 $58,000
19 Paint Line 22,500 LS $0.50 $11,250
20 Signing 1 LS $50,000.00 $50,000
21 Traffic Control 1 LS $125,000.00 $125,000
BASE ROADWAY IMPROVEMENTS SUBTOTAL $2,276,000
2028 CONSTRUCTION COST (3% / YEAR) 3% $2,487,047
ENGINEERING DESIGN 15% $374,000
CONSTRUCTION ENG 10% $249,000
SUBTOTAL $3,110,047
CONTINGENCY 30% $934,000
BASE ROADWAY IMPROVEMENTS TOTAL $4,044,047
LOW COST RANGE -20% $3,236,000
HIGH COST RANGE 30% $5,258,000
Intersection Improvements
ITEM NO. DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL PRICE
101 Traffic Signal Replacement (Single Member) 1 LS $90,000.00 $90,000
102 Superpave HMA Pavement (Full-Depth Section - 4" Depth) 30 TON $150.00 $4,500
103 3/4"-Minus Compacted Aggregate Base 40 TON $40.00 $1,600
104 1-1/4"-Minus Compacted Aggregate Base 60 TON $35.00 $2,100
105 Subgrade Separation Geotextile Fabric 120 SY $4.50 $540
106 Remove/Dispose of Concrete Sidewalk 87 SY $50.00 $4,350
107 Remove/Dispose of Concrete Curb 140 LF $10.00 $1,400
108 Concrete Sidewalk (5-inch) 160 SY $150.00 $24,000
109 Combination Curb and Gutter Type B 160 LF $100.00 $16,000
110 Pedestrian Ramp with Detectable Warning Domes 1 EA $2,000.00 $2,000
INTERSECTION IMPROVEMENTS SUBTOTAL $146,490
2028 CONSTRUCTION COST (3% / YEAR) 3% $160,074
ENGINEERING DESIGN 15% $25,000
CONSTRUCTION ENG 10% $17,000
SUBTOTAL $202,074
CONTINGENCY 30% $61,000
INTERSECTION IMPROVEMENTS TOTAL $263,074
LOW COST RANGE -20% $211,000
HIGH COST RANGE 30% $342,000
--- Page 19 ---
Stormwater Improvements
ITEM NO. DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL PRICE
201 Stormwater Improvements 1 LS $857,125.00 $857,125
STORMWATER IMPROVEMENTS SUBTOTAL $857,125
2028 CONSTRUCTION COST (3% / YEAR) 3% $936,604
ENGINEERING DESIGN 15% $141,000
CONSTRUCTION ENG 10% $94,000
SUBTOTAL $1,171,604
CONTINGENCY 30% $352,000
STORMWATER IMPROVEMENTS TOTAL $1,523,604
LOW COST RANGE -20% $1,219,000
HIGH COST RANGE 30% $1,981,000
Sanitary Sewer Improvements
ITEM NO. DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL PRICE
301 Sanitary Sewer Improvements 1 LS $840,550.00 $840,550
SANITARY SEWER IMPROVEMENTS SUBTOTAL $840,550
2028 CONSTRUCTION COST (3% / YEAR) 3% $918,492
ENGINEERING DESIGN 15% $138,000
CONSTRUCTION ENG 10% $92,000
SUBTOTAL $1,148,492
CONTINGENCY 30% $345,000
SANITARY SEWER IMPROVEMENTS TOTAL $1,493,492
LOW COST RANGE -20% $1,195,000
HIGH COST RANGE 30% $1,942,000
Water Distribution Improvements
ITEM NO. DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL PRICE
401 Water Distribution Improvements 1 LS $457,500.00 $457,500
WATER DISTRIBUTION IMPROVEMENTS SUBTOTAL $457,500
2028 CONSTRUCTION COST (3% / YEAR) 3% $499,923
ENGINEERING DESIGN 15% $75,000
CONSTRUCTION ENG 10% $50,000
SUBTOTAL $624,923
CONTINGENCY 30% $188,000
WATER DISTRIBUTION IMPROVEMENTS TOTAL $812,923
LOW COST RANGE -20% $651,000
HIGH COST RANGE 30% $1,057,000
This Opinion of Probable Cost is the opinion of the engineer of the probable construction cost, and is supplied as a guide only. Since the engineer has no control over the 
costs of labor and materials or over competitive bidding and market conditions, the engineer does not guarantee the accuracy of such opinion as compared to contractor's 
bids or actual costs to the owner. Estimate is calculated in 2025 dollars.