Crow_River_RFQ_Attachments_.pdf

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Request for Qualifications (Phase 1) Crow River Bank Stabilization

Design‐Build Procurement

Feb 2018

Section 00 83 00 – Attachments

U.S. ARMY CORPS OF ENGINEERS

St. Paul District

W912ES18R0004

USACE St. Paul District Feb 2018

Solicitation No. W912ES18R0004 Section 00 83 00, Page 2

SECTION 00 83 00 ATTACHMENTS – RFQ (PHASE 1)

The following lists attachments that are included in this Phase 1 (RFQ) solicitation for the Offeror’s use and information. The attachments are informational only and may consist of conceptual documents, drawings, and reports generated from earlier phases of the project. These attachments are intended to provide the Offeror with a general understanding of the existing project elements, problems encountered, the target areas to be fixed in this Contract, and past permitting constraints and requirements that may be representative of future constraints and requirements.

The attachment information is provided electronically at www.fbo.gov.

PART 2 LIST OF ATTACHMENTS

Phase 1 attachments:

ATTACHMENT 1 ‐ Target Areas

ATTACHMENT 2 – April 7,2017 Memorandum

ATTACHMENT 3 – November 22, 2017 trip report

ATTACHMENT 4 – Previous Project Environmental Assessment (2011)

ATTACHMENT 5 – Previous Project Section 401 Certification

ATTACHMENT 6 – Previous Project Public Waters Permit

ATTACHMENT 7 ‐ Phase 1 Proposal Data Sheet

ATTACHMENT 8 – Customer Questionnaire

Proposed Phase 2 attachments: The following items will be provided to the Phase 2 list of offerors.

The following items will be provided for information only. The successful offeror will be responsible for the design and construction of all work elements.

http://www.fbo.gov/

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USACE St. Paul District Feb 2018

The following will be provided during the request for proposal phase 2.

1. Recent Surveys performed by Hennepin County.

2. Photos

3. Previous project Construction Drawings.

4. Previous project technical specifications.

5. Previous design calculations.

END OF SECTION

Crow River Bank Stabilization Solicitation No. W912ES18R0004 Section 00 83 00, Page 3

Solicitation W

912ES18R0004 –

Section 00 83 00 - Attachm ent 1 – Crow

River Bank Stabilization – Target Areas

Prepared For: Chief Engineering and Construction

April 7, 2016

Prepared By: Neil Schwanz, EC-G

Reviewed By: Tom Johnson, EC-C-E

Memorandum

CSAH 50 Section 14 Project Crow River, Hennepin Co., MN

DEPARTMENT OF THE ARMY

ST. PAUL DISTRICT, CORPS OF

ENGINEERS, 180 FIFTH STREET

EAST, SUITE 700 ST. PAUL MN

55101-1678

Solicitation W912ES18R0004 Sec00-83-00_Attachment_2

1.0 Purpose

This report provides a general overview of post construction performance issues associated with the tie-in’s at the upstream and downstream project limits. Between these limits the project is performing as designed but at the transitions to the existing banks there is surface sloughing likely due to rainfall saturating the grass cover that was placed on an overly steep slope. The transition slopes lack the surficial reinforcement from vegetative roots on the existing undisturbed banks that provide stability to the existing marginally stable slopes.

2.0 Background

The CSAH 50 Section 14 project is located in western Hennepin County about 1.6 miles north-northeast of the City of Delano, MN. The site is situated on the right descending bank of the

South Fork Crow River along an outside river bend. The approximately 55 ft high river bank is characterized by outwash sands from well below the channel invert (invert EL 898 ft NAVD88 approx.) to about EL 932 ft. Overlying the outwash sands is a 5 ft thick clayey sand transition layer mantled with about 20 ft of gravelly, sandy clay till.

Stream bank erosion at the toe of slope, along with expected runoff from the roadway, caused shallow sloughing of the unprotected outwash sands leading to loss of support and then collapse of the till overburden. A minor amount of seepage from perched water in a thin sand seam within the till overburden was observed but was not a major contributor to the instability of the original bank. Continued erosion resulted in bank sloughing that endanged CSAH 50.

The resulting bank was marginally stable with the exposed sand face that was easily raveled and standing at a slope of about 1V on 1.5H. The project created a stable slope with erosion protection but had to transition back to existing slopes that remain marginally stable and are revegetated, or are in the process of revegetating, but had experienced sloughing in the past.

The project consists of rock erosion protection placed to provide a hard armor to EL 911.5 ft or slightly above the 10-yr flood event. A geogrid reinforced soil slope (RSS) with a wrapped vegetated face was constructed above EL 910.0 ft. Figure 1 is a Google Earth imagery with a red work area outline showing project extents (based on rock erosion protection not project plans).

Figure 2 shows the same outline with pre-project imagery and identifies the vegetation that existed prior to project construction. Figures 3 and 4 show the steep tie-in slopes at the upstream and downstream ends of the project that are marginally stable primarily due to root reinforcement. Not shown on Figures 3 and 4 are the erosion extents at the toes of slopes.

Figure 1. Aerial photo with work extent outline, Sep 2012 Google Earth photograpjy.

Figure 2. Aerial photo with work extent outline, Apr 2011 Google Earth photograpy.

Figure 3. Pre-project existing slope at upstream end showing marginally stable slope. Note the historical slough area becoming revegetated upstream of existing raw bank.

Figure 4. Pre-project existing slope at downstream end showing marginally stable slope.

3.0 Discussion

While streambank erosion was the major cause of the bank failure, surface runoff added to instability while seepage from a perched sand strata and surface infiltration were additional minor contributors. The height of bank and the steep marginally stable existing banks on either end of the project created difficult transitions and very difficult access to the site for construction. Compounding these issues was a survey error during construction that resulted in over excavation by the construction contractor that resulted in additional disturbance of the bank and changed the upstream transition.

At the downstream end of the project the project plans identified an alignment for accessing the site but the alignment was not designed to the point of showing sections, details or completing analyses. The access ramp constructed followed the alignment as shown on the drawings which led to excavating and subsequently removing vegetation for construction purposes. This ramp is shown to the north of the red outline in Figure 1. As the construction of the RSS was completed the contractor had to fill in the ramp area leaving an overly steep slope with no vegetative roots providing shallow reinforcement and the overly steep slope promoted a veneer failure of grass that was becoming established. To create a stable slope from surficial sliding, extensive deeper roots would be needed or a more stable surface material should have been placed.

The steep slopes at the upstream and downstream transitions resulted in shallow sloughing during heavy rainfall events in 2012 and again in the spring of 2014 as seen in Figure 5. These sloughs are currently not endangering CSAH 50 but the project has not been completely successful because of the transition instability. The sloughed areas are currently becoming vegetated but will not reach the same level of reliability as adjacent existing (non-sloughed) banks until significant vegetation becomes established or the surface is strengthed, such as with riprap/rockfill.

The project issue at the upstream end is that sloughing could continue where the top of scarp may infringe on private property creating a safety issue. On the downstream end the removal of vegetation downstream of the riprap, and the riprap transition to existing bank, may allow continued streambank erosion that would again induce more extensive slope instability to again endanger CSAH 50.

Figure 5. Shallow surface sloughing at the downstream transition following heavy rainfall 2014.

4.0 After Action Comments

At the upstream transition the construction contractor should have been issued a stop order and submit a new transition plan for government approval. At the downstream transition a detailed access plan should have been provided in the plan set or restrictions included indicating critical features/aspects that must be maintained, such as not removing specific vegetation. While the original bank was not experiencing significant toe erosion and bank instability downstream of the end of ripap (as seen in Figure 2), the current condition requires additional riprap to be placed to minimize future streambank erosion and at the upstream end rock could be placed to protect against further slope degradation.

Crow River Site Visit

11/22/2017

Greg Wachman, EC-GG

I visited the site with Nate Anderson the morning of Wed, 22 November. The sky was mostly overcast and the air temperature was slightly above freezing. The following observations were made:

1) The sloughing originally observed in 2012, and repeated in 2014, on the downstream end of the project (the area that was cleared) appears stable at the mid-slope – vegetation cover has matured and appears to be providing some surficial stabilization. Aerial imagery from May 2017 (Figure 1) indicates the condition remains somewhat fragile – rills exist that could progress again under heavy runoff.

2) Historical aerial imagery and photographs indicate erosion at the toe of the downstream tie-in has continued to progress, perhaps due to an eddy effect as the high velocities adjacent to the protected bank contact the unprotected portion of the bank. Continued erosion at the toe could lead to destabilization of the mid-slope if left in its current condition.

3) There is significant channel-erosion-related sliding in the wooded area downstream of the original Section 14 project (Figure 2 through Figure 5) that was not documented previously.

Several major slide areas were observed in the wooded slope, the largest of which exposed sands within the slope and extended about 12-15 ft above the water surface (Figure 3 and Figure 4)

4) Riprap placed as part of the original project appeared to be in very good condition, with no observable displacement (Figure 8 and Figure 12)

5) Overall, the reinforced slope appeared to be in good condition. One item that may require repair is exposure and undermining of the turf reinforcement mat at the very top of the RSS (Figure 9) – it appears that erosion here began before vegetation could become well established, and there may be potential for eventual unraveling of the upper-most reinforced lift.

6) Upstream erosion is fairly stabilized on the middle and lower portions of the slope, but top of slope is still very steep with some exposed soil that will likely erode further (Figure 10). The 6 ft tall fence is approximately 3-5 ft from the escarpment.

7) The condition of the bank upstream of the project was documented (Figure 13). Upstream of the limits of riprap protection it appears that active erosion may be cutting the slope of the bank backwards, a condition that existed prior to construction of the project. This area is adjacent to the gun club, but not the highway.

Solicitation W912ES18R0004 Sec00-83-00_Attachment_3

Figure 1 - Aerial imagery 5/12/2017 from Google Earth).

Slope erosion initiated in

Previously undocumented bank erosion and sloughing

Figure 2 - Looking downstream from upstream tie-in. Areas of bank erosion are circled

Figure 3 -Active sloughing within the wooded area downstream of the project, apparently initiated by toe erosion (1/2)(11/

Figure 4 - Active sloughing within the wooded area downstream of the project, apparently initiated by toe erosion (2/2)(11/

Figure 5 - Bank erosion upstream of the sandy slough indicated in previous figures.

Figure 6 - Toe of downstream tie-in area (looking upstream)

Figure 7 - Edge of previously sloughed area (left)

Figure 8 - View of riprap protection and reinforced soil slope (RSS)

Figure 9 - Exposed turf reinforcement mat at the top of the reinforced soil slope.

Figure 10 - Top of upstream tie-in, where turf reinforcement mat has been exposed by erosion.

Figure 11 - View of project from upstream limits. Distance from 6 ft tall fence to top of slope is approx. 3-5 ft

Figure 12 - Looking downstream from upstream tie-in. Riprap appeared intact and in good condition. Sloughed area circled.

Wooded project limits in upper-right.

Figure 13 - View upstream of project

FINAL ENVIRONMENTAL ASSESSMENT

Hennepin County, Minnesota

March 21, 2011

Solicitation W912ES18R0004 Section_00-83-00_Attachment_4

ENVIRONMENTAL ASSESSMENT

TABLE OF CONTENTS

Item Page

1. SUMMARY EA-1

2. RELATIONSHIP TO ENVIRONMENTAL LAWS AND REGULATIONS EA-1

3. AUTHORITY EA-1

4. LOCATION, PURPOSE AND NEED EA-2

5. ALTERNATIVES EA-2

5.1 No Action Alternative EA-2

5.2 Proposed Alternative EA-3

5.3 Other Alternatives Considered EA-5

6. ENVIRONMENTAL RESOURCES INFORMATION EA-5

6.1 Watershed Characteristics EA-5

6.2 Aquatic Habitats and Biota EA-6

6.3 Terrestrial Habitats and Biota EA-6

6.4 Threatened and Endangered Species EA-6

6.5 Wetland Resources EA-6

6.6 Cultural Resources EA-7

6.7 Social and Economic Resources EA-7

6.8 Recreational Resources EA-8

7. ENVIRONMENTAL IMPACTS OF PROPOSED ACTION EA-8

7.1 Natural Resource Effects EA-10

7.1.1 Air Quality EA-10

7.1.2 Surface Water Quality EA-10

7.1.3 Aquatic Habitat and Biota EA-10

7.1.4 Terrestrial Habitat and Biota EA-11

7.1.5 Threatened and Endangered Species EA-12

7.1.6 Wetland resources EA-12

7.2 Cultural Resource Effects EA-12

7.3 Social and Economic Effects EA-13

7.3.1 Noise EA-13

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7.3.2 Aesthetics EA-13

7.3.3 Recreation EA-13

7.3.4 Safety EA-13

7.3.5 Economy and Employment EA-14

7.3.6 Environmental Justice EA-14

7.3.7 Public Facilities and Services EA-14

7.4 Cumulative Impacts EA-15

8.0 COORDINATION EA-15

BIBLIOGRAPHY EA-18

Findings of No Significant Impact EA-19

Figure 1 – Project Location EA-2 Figure 2 – Project Site (Aerial View) EA-2 Figure 3 – Project Site (Lateral View) EA-3 Figure 4 – Aerial Drawing of Proposed Alternative EA-4 Figure 5 – Cross Section Drawing of Proposed Alternative EA-4

Table 1 – Environmental Assessment Matrix EA-9

ATTACHMENTS

A - Section 404(b)(1) Evaluation B - Coordination C - Distribution

ENVIRONMENTAL ASSESSMENT

1. SUMMARY

The St. Paul District, Corps of Engineers, has prepared this assessment of the environmental effects that may result from the proposed construction of bank stabilization measures on the Crow River, Hennepin County, Minnesota. This assessment of the Corps of Engineers proposal is required by the National Environmental Policy Act of 1969 (NEPA), the Council on Environmental Quality Regulations (40 CFR 1500-1508), and the Corps of Engineers Procedures for Implementing NEPA (33 CFR, Part 230)..

This Environmental Assessment provides information to the St. Paul District Commander on the potential environmental effects of the proposed action and various alternatives for determining whether to prepare an Environmental Impact Statement or a Finding of No Significant Impact (FONSI) for the proposed action. This assessment includes the following:

a. A discussion of the need for proposed action.

b. Identification of alternatives, including the proposed action.

c. An assessment of the environmental impacts of the proposed action and alternatives.

d. Coordination activities.

The project involves the placement of fill in waters of the United States; therefore, a

Clean Water Act Section 404(b)(1) evaluation has been prepared.

2. RELATIONSHIP TO ENVIRONMENTAL LAWS AND REGULATIONS

The proposed action would comply with Federal environmental laws, executive orders, and policies, including the Clean Air Act, as amended; the Clean Water Act of 1977, as amended; the Endangered Species Act of 1973, as amended; the National Environmental Policy Act of 1969, as amended; the Land and Water Conservation Fund Act of 1965, as amended; the National Historic Preservation Act of 1966, as amended; the Fish and Wildlife Coordination Act of 1958, as amended; Executive Order 11988, Floodplain Management; and Executive Order 11990, Protection of Wetlands. The project would not result in the conversion of agricultural lands to nonagricultural purposes. Therefore, the provisions of the Farmland Protection Policy Act of 1981 do not apply.

3. AUTHORITY

The authorization for the planning and design of the proposed actions is Section 14 of the Flood Control Act of 1946, as amended. This legislation allows the Corps of Engineers to

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plan and construct emergency streambank and shoreline protection projects to protect highways, highway bridge approaches, public facilities such as water and sewer lines, and other nonprofit public services, such as schools and hospitals.

4. LOCATION, PURPOSE AND NEED

The proposed action would be located on and near the Crow River (also called the South Fork Crow River) in Hennepin County on Hennepin County Road 50. The project area is located between the cities of Delano and Rockford, Minnesota, and approximately 28 miles west of Minneapolis, Minnesota (Figure 1).

The proposed action is necessary because the existing conditions leave County Road 50 subject to complete failure from continued erosion by the Crow River. The river has already eroded up to the edge of the road, with a nearly-vertical bank that rises about 50 feet from the edge of the river (Figure 2). The edge of the eroded bank is as close as 10 feet to the road, and damage to the road appears imminent.

The purpose of this environmental evaluation is to assess the impacts of various measures to provide stabilization of a failed bank that is threatening the integrity of a road adjacent to the river.

5. ALTERNATIVES

5.1 No Action Alternative

The no-action alternative, or future without-project condition, depicts existing conditions in the area, and assumes the continuation of existing trends. This continuation would be expected to include continued erosion of the bank leading to eventual failure of the portion of the bank supporting the road surface. Failure of the road would require extensive reconstruction of the bank or relocation of the road. Reconstruction of the

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bank and highway would almost certainly be more expensive than the proposed alternative.

Road relocation would have impacts on private property owners as a result of right-of-way acquisition requirements, and possibly the need to relocate structures. Road relocation also would impact the Lake Rebecca Park Reserve, which could result in undesirable social and biological impacts.

5.2 Proposed Alternative

The St. Paul District proposes to stabilize the existing riverbank adjacent to County Road

50. The proposed alternative uses both riprap and bioengineered Reinforced Soil Slope (RSS) to achieve stability. This alternative would involve riprapping from the toe of the bank 10-15 feet up the existing bank (the top of the riprap equates to about a 10% chance exceedance flood frequency elevation) followed by reconstruction of the slope above the riprap using a reinforced soil slope (RSS) (Figures 3 and 4). Riprap would extend approximately 20 to 30 feet out into the water. The riprap bench at the toe serves as the foundation for the RSS which would vary in height throughout the project site ranging from 10-15 feet vertically. Above the RSS, the slope would be graded to an angle similar to the natural angle of repose and would be prepared to reestablish native vegetation following project completion. Approximately 500 feet of the bank would be stabilized with this approach. Access for construction activity would occur across existing Three Rivers Park District land (Lake Rebecca Park Reserve) and down the bank to gain access to the toe. The temporary access would be revegetated with a cover crop after the

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project is completed and prepared for installation of native trees and vegetation by the local sponsor. It is estimated that construction could be completed in less than a year, though additional time may be needed given site conditions and construction logistics (e.g., steep slopes that result in difficult access to the site with construction equipment and materials).

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5.3 Other Alternatives Considered

Nonstructural measures would not be practical for this project. If the road is to be preserved, the bank erosion must be halted, or, if allowed to continue, the road would require relocation. Relocating the highway further away from the river bluff would result in impacts to the adjacent regional park, its natural resources, as well as several private property owners lying in between the County right-of-way and the park. Also, relocation would incur real estate acquisition costs, which could themselves exceed the cost of the proposed alternative. Finally, Hennepin County is not in favor of road relocation. In light of these considerations, road relocation is not carried forward for further consideration.

Additional project designs similar to the proposed alternative also were considered. This included riprapping 500 feet along the bank toe with rock extending 10-15 feet up the existing bank to the elevation of a 10% chance exceedance flood frequency. A 10-foot wide riprap bench at the toe would be used for construction and provide stone for additional toe protection.

The key difference with this alternative is that the bank above the riprap would be allowed to reach a natural angle of repose. However, allowing the natural angle of repose to establish above the riprap assumes that bank sloughing would continue at the site to allow the bank to reach a stable condition. Given the angle necessary, the bank would continue to slough above the riprap. The extent of the sloughing could potentially grow large enough to destabilize portions of the County Highway before a stable, natural angle of repose would become established. The risk to the highway was considered too great to select this alternative.

Finally, a project design was considered that was based on bio-engineering. This would include techniques such as willow mats, reed rolls, aquatic plantings, grass and legume plantings, and shrub plantings to stabilize the toe of the bank. Areas above the bank toe would be allowed to reach a natural angle of repose. This alternative would be infeasible for several reasons. First, these techniques alone may not provide adequate protection to ensure stability of the bank toe over time. This is a particular concern given high flow velocities and the presence of ice during spring flood events in the project area, particularly at the toe of the slope.

Secondly, as with the previous alternative, allowing the natural angle of repose to establish above the riprap assumes that bank sloughing would continue at the site to allow the bank to reach a stable condition. Given the angle necessary, the bank would continue to slough above the riprap. The extent of the sloughing could potentially grow large enough to destabilize portions of the County Highway before a stable, natural angle of repose would become established. These collective risks to the highway were considered too great to select this alternative.

6. AFFECTED ENVIRONMENT

Existing environmental and socioeconomic conditions are described in the following paragraphs.

6.1 Watershed Characteristics

The Crow River watershed is about 2,640 square miles at Rockford, MN, and includes a mix of land uses including cultivated/agricultural lands, forested areas, wetland and rural/residential areas. The project area is a mix of wooded areas and agricultural uses

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between Rockford and Delano, MN. The area is also adjacent to the Lake Rebecca Park Reserve, which includes a diverse area of lakes, wetlands and wooded areas.

6.2 Aquatic Habitats and Biota

The fishery of the Crow River consists of a variety of cool and warmwater species, including species such as white sucker, redhorse species, channel catfish, smallmouth bass, walleye and northern pike. Typical aquatic vegetation could include river pondweed, softstem bulrush, hardstem bulrush, common cattail, coontail, and arrowhead.

The South Fork Crow River has existing water quality impairments for this river stretch

(Clean Water Act Section 303d listing). For this section of the Crow River, impairments have been identified for fecal coliform (aquatic recreation designated use); mercury (aquatic consumption); and turbidity, chloride and fish bioassessments (aquatic life designated use).

Total Maximum Daily Load (TMDL) studies are underway, or planned, to address these impairments.

6.3 Terrestrial Habitats and Biota

Riparian and nearby forest composition consists of species such as northern pin oak, bur oak, and red pine. Other common species found include hackberry, green ash, elm, black cherry, box elder, aspen, and scotch pine. Understory vegetation consists largely of hazel, prickly ash, elderberry, black raspberry, and buckthorn. Terrestrial wildlife in the area includes white-tailed deer, foxes, raccoons, squirrels, rabbits, and a variety of songbirds.

6.4 Threatened Or Endangered Species

The U.S. Fish and Wildlife Service’s Threatened and Endangered Species Database System was reviewed to identify potential presence of listed species in the project area. The only species identified for either Hennepin County or adjacent Wright County, Minnesota, was the Higgins eye mussel (Lampsilis higginsii). This mussel is found in the Mississippi River on the far southeastern-border of Hennepin County. Higgins eye mussels are not found in the Crow River, and would not live in the project area. No other federally-listed species have been documented in either Hennepin or Wright County.

The Minnesota Natural Heritage Database was checked; no rare species listings occur within the project area. Two unique communities or species that did occur within a mile of the project site included observations for trumpeter swan and tamarack forest. However, the project is removed from these unique resources, and wouldn’t be expected to significantly affect them.

6.5 Wetland Resources

A visual inspection was made of the project site. No wetlands are present.

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6.6 Cultural Resources

Hennepin County contains numerous cultural resources indicating continual human occupation for approximately 12,000 years (e.g., Dobbs 1988; Johnson 1988). Cultural resources include a variety of precontact and historic archaeological sites (e.g., Nowlin 1855;

Vermeer et al. 2008; Winchell 1911). Numerous precontact sites (lithic and artifact scatters, burial mounds) and historic sites (farmsteads, structures, transportation features) are located along the South Fork Crow River. Several of these cultural resource sites are considered eligible for listing on the National Register of Historic Places (NRHP).

Interest in the archaeological record of Minnesota in general has been ongoing since the late nineteenth century, where antiquarians examined numerous burial mounds across the state, including Hennepin County (e.g., Winchell 1911). However, scientific investigations in Hennepin County were not initiated until the middle of the 20th century when the Minnesota Archaeological Society investigated several mound groups in the area (Chamberlain 1972). By the later part of the twentieth century and early twenty-first century, several compliance driven and academic cultural resource investigations have been conducted in the area (e.g., Breakey and Dobbs 1995; Koenen 2010; Vermeer et al 2008).

The project area is near several recorded archaeological sites. Site 21HE74, once consisting of 13 burial mounds, was mapped by T.H. Lewis in 1887 (Winchell 1911:223).

Various investigations have attempted to re-locate the mounds without success, noted as “destroyed” by 1971 (e.g., Chamberlain 1972; OSA Files). The mounds are plotted immediately east of the project area across Hennepin County Highway 50 (CH 50) on a low ridge now occupied by private residences. Site 21HE74 was examined most recently in 1995 (Breakey and Dobbs 1995). Site 21HE125, a precontact artifact scatter and historic dump is located just north of 21HE74 and the project area and east of CH 50. Testing in this area for a pipeline project encountered a light scatter of precontact lithic debris and faunal material; evaluation of the site determined that it is not eligible for listing on the NRHP (Murray et al. 1995; Vermeer 2008). Both 21HE74 and 21HE125 may have contained the burial mounds recognized by Lewis. However, it appears that the mounds have been destroyed by cultivation, road construction, a pipeline and a recreation trail. Other sites north of the project area include 21HE124, a precontact lithic scatter and 21HE82, once a group of four burial mounds.

Between April and June 2010, a Phase I cultural resource survey was completed for the project by the University of Minnesota and Corps archaeologists. These investigations identified Site 21HE390, consisting of historic foundations and an associated historic artifact scatter that contains mixed precontact lithics. Site 21HE390 is situated approximately 50 meters north of the project’s work limits and will not be impacted by construction activities.

6.7 Social and Economic Resources

The proposed project area is in Hennepin County on the Crow River, which forms the boundary between Hennepin and Wright Counties, approximately 30 miles northwest of Minneapolis/St. Paul, Minnesota. The closest population centers are Rockford, about 2 miles to the north and Delano, about 1 mile to the south. Both are located in Wright County along the Crow River. The 2009 population estimate for Delano is 5,367, an increase of 40 percent from 2000 and for Rockford the 2009 population estimate is 4,214, an increase of 21 percent from 2000. Hennepin County’s 2009 population totaled 1,156,212, an increase of 3.6 percent from 2000 and Wright County’s 2009 population of 121,907 was a 35.5% increase from 2000.

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Wright County and Hennepin County had unemployment rates in June 2010 of 7.3 percent and 6.6 percent respectively, compared to 6.8 percent for the State of Minnesota and

9.5 percent for the United States. The most significant industries in Wright County are manufacturing (10.4 percent of employed persons); health and social services (9.1 percent);

retail trade (13.1 percent); and construction (9.8 percent). According to information from the U.S. Census Bureau, the 2008 per capita income for Wright County was $34,466 and for Hennepin County it was $56,564 compared to $42,953 for the State of Minnesota and $40,166 for the United States.

6.8 Recreational Resources

The project site is adjacent to the Lake Rebecca Park Reserve. A canoe launch and parking area is located immediately downstream of the project area. The Crow River is used for recreational activities such as canoeing and fishing. The MnDNR promotes the Crow River as one of 30 water trails for canoeing and kayaking in Minnesota.

7. ENVIRONMENTAL CONSEQUENCES

An environmental analysis has been conducted for the proposed action; a discussion of the impacts follows. No significant adverse impacts would result from construction of the proposed project. As specified by Section 122 of the 1970 Rivers and Harbors Act, the categories of impacts listed in Table 1 were reviewed and considered in arriving at the final determination. In accordance with the Clean Water Act, a Section 404(b)(1) evaluation is included with this report. The Corps has been coordinating with the Minnesota Pollution Control Agency regarding obtaining 401 certification for the project. Coordination will continue during the development of plans and specifications for the project, which will address construction methods and best management practices to avoid and minimize any turbidity issues. Section 401 certification will be obtained prior to awarding the construction contract.

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Table 1. Environmental Assessment Matrix.

Section 122 of the River and Harbor and Flood Control Act of 1970 (Public Law 91-611)

No Action Alternative Proposed Alternative

BENEFICIAL ADVERSE BENEFICIAL ADVERSE

PARAMETER

SI

G

N

IF

IC

A

N T

SU

B

ST

A

N

TI

A L

M

IN

O R

N

E

FF

EC

T

M

IN

SU

B

ST

A

N

TI

A L

SI

G

N

IF

IC

A

N T

SI

G

N

IF

IC

A

N T

SU

B

ST

A

N

TI

A L

M

IN

N

E

FF

EC

T

M

IN

SU

B

ST

A

N

TI

A L

SI

G

N

IF

IC

A

N T

A. SOCIAL EFFECTS X X

1. Noise Levels X T

2. Aesthetic Values X X

3. Recreational Opportunities X T

4. Transportation X X

5. Public Health and Safety X X

6. Community Cohesion (Sense of Unity) X X

7. Community Growth and Development X X

8. Business and Home Relocations X X

9. Existing/Potential Land Use X X

10. Controversy X X

B. ECONOMIC EFFECTS

1. Property Values X X

2. Tax Revenue X X

3. Public Facilities and Services X X

4. Regional Growth X X

5. Employment X X

6. Business Activity X X

7. Farmland/Food Supply X X

8. Commercial Navigation X X

9. Flooding Effects X X

10. Energy Needs and Resources X X

C. NATURAL RESOURCE EFFECTS

1. Air Quality X T

2. Terrestrial Habitat X X

3. Wetlands X X

4. Aquatic Habitat X T

5. Habitat Diversity and Interspersion X X

6. Biological Productivity X X

7. Surface Water Quality X T

8. Water Supply X X

9. Groundwater X X

10. Soils X X

11. Threatened or Endangered Species X X

D. CULTURAL RESOURCE EFFECTS

1. Historic Architectural Values X X

2. Prehistoric & Historic Archeological Values X X

T: Temporary Effect

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7.1 Natural Resource Effects

7.1.1 Air Quality

The operation of construction equipment may result in a short-tem localized reduction in air quality. Adverse effects would be limited and short-term because they are associated only with construction. It is estimated that construction could take up to one year, though additional time may be needed given site conditions and construction logistics.

7.1.2 Surface Water Quality

The proposed action would have no effect on long-term water quality of the Crow River.

Water quality, especially water clarity, may be briefly reduced during construction. Any reduction in clarity would fade immediately following construction.

Existing water quality impairments have been identified for fecal coliform, dissolved oxygen, turbidity, and fish bioassessments. Short-term changes in turbidity levels could occur as the result of construction activities. Placement of rip rap and grading actions could result in short-term increases in turbidity as a result of disturbing bottom sediments. To minimize this impact, construction activities will be conducted in compliance with necessary permit requirements, to include compliance with any conditions of the state water quality certification under section 401 of the Clean Water Act. This will include use of BMPs and potentially other measures to minimize short-term impacts. The specific construction methods, including identification of specific BMPs, have not yet been identified. These will be further specified during the next phase of planning – development of Plans and Specifications. Potential BMPs may include construction during low-flow periods, use of silt curtains, vegetation plans to minimize vegetation clear, minimizing the time period of exposed soils, control of stormwater flow from any upland areas disturbed during construction, and other methods. Given the Corps prior experience with similar bank stabilization projects, and its success in controlling short-term turbidity impacts from construction of those projects, it is reasonable to assume that no significant impacts would occur to water quality. BMPs have traditionally been successfully used to minimize short-term impacts associated with projects that focus on grading and rock along streams and rivers. Further, to the extent necessary, the 401 water quality certification may be conditioned on implementation of measures designed to reduce water quality impacts and the Corps will ensure any such measures are implemented.

Erosion at the rip rap boundary would be minimized with careful design and construction.

The rip rap boundary will be designed to blend back into the bank, minimizing turbulence at the rip rap/bank interface that could result in long-term erosion. Overall, stabilization of the eroding bank should minimize the amount of sediment entering the Crow River at the project site. This should provide a long-term benefit to sediment loading at the project site.

Construction activities will not contribute fecal coliform or chloride to the river.

Construction activities would not be expected to substantially change dissolved oxygen concentrations. Impacts to fish and invertebrates are discussed further below, but would not be expected to be significant.

7.1.3 Aquatic Habitat and Biota

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The proposed action would result in the placement of riprap along the outside bend of the river. The areal footprint extent of the proposed rip rap is estimated at less than 0.4 acres.

Rip rap would be placed up to an elevation that approximates a 10% annual discharge exceedence frequency (i.e., 10% chance exceedance flood event). Thus, much of the 0.4 acres identified would be above areas typically inundated to provide aquatic habitat (e.g., areas below the ordinary high water mark, or approximately a 50% chance annual exceedence discharge event). The project would include about 500 lineal feet of riprap placed along the river bank.

Invertebrates would be crushed by placement of the riprap, but they would quickly recolonize the new rock substrate. Fish may avoid the area during construction but would return upon completion. The new riprap may attract fish and provide some low level of habitat value. No long-term adverse impacts would be anticipated to aquatic habitat or biota. The project would not contribute toward the long-term impairments for fish and invertebrates that will be soon under assessment through a TMDL. The proposed action should stabilize the streambank, eliminate bank sloughing and erosion of bank materials, and in turn benefit Crow River aquatic habitat.

The proposed action would not significantly impact long-term stream erosion or stream stability at and downstream of the project site. A HEC-RAS hydraulic model was developed to analyze the potential impacts of the proposed placement of riprap in the existing channel of the Crow River. The model was based on the current Flood Insurance Study (FIS) modeling for the Crow River. A comparison of the FIS cross-section geometry with 2005 LIDAR data and 2009 survey information indicates that the proposed riprap placement will actually bring the river cross section back to its pre-eroded geometry, especially in the upstream portion of the project area. The model shows a slight increase in velocity at the downstream end of the project (e.g., few tenths a foot per second at a 100-year flood), but the velocities are not high enough for scour to be a concern with the proposed riprap in place to protect the bank.

It is possible that the placement of material in the existing channel could result in the channel adjusting to accommodate any loss of cross sectional area. If this did happen, it would be relatively minor, and would most likely occur on the west bank of the river, which is currently stable, with good ground cover. The west bank is not steep, and is not adjacent to any infrastructure that would be negatively affected by erosion if it were to occur (as is the case on the east bank of the river). The most likely scenario is that the river will adjust itself naturally, with very little impact to the west river bank, while the proposed riprap on the east bank will protect the area from continued erosion and bank instability. The reach immediately downstream of the project should not be impacted by the project, as this section of the river is relatively straight and the existing banks are stable. There will be no velocity increase in the river beyond the limits of the riprap placement.

7.1.4 Terrestrial Habitat and Biota

The aerial footprint extent of the proposed project, including the access corridor, is estimated at approximately 1 acre (planar area). The proposed action would result in the clearing of trees and understory vegetation within the footprint area. Some of these trees may be lost to erosion even if no action is taken. Otherwise, long-term impacts of to the project would be minimal. Wildlife may temporarily avoid the project area during construction, but would return following. The access corridor would be allowed to fully revegetate. No long-term adverse impacts would be anticipated to terrestrial habitat or biota outside of the immediate stabilization site.

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7.1.5 Threatened or Endangered Species

As part of this analysis, it has been concluded that the project would have no adverse effects on any federally listed endangered or threatened species.

7.1.6 Wetland Resources

No wetlands will be impacted at the project site.

7.2 Cultural Resource Effects

Between April and June 2010, a Phase I cultural resource survey was completed for the project by the University of Minnesota and Corps archaeologists. These investigations identified Site 21HE390, consisting of historic foundations and an associated historic artifact scatter that contains mixed precontact lithics. The site area is situated just north of the proposed construction limits.

The historic foundations (poured concrete) and associated historic materials (architectural and domestic items) appear to represent the house of a farmstead that likely dates from the early twentieth century. The foundations are located in the area of a structure represented in a 1937 aerial photograph that includes additional structures to the east and across CH 50 with one probably a barn. The structures east of CH 50 may relate to Site 21HE125, where a historic dump was identified along with precontact lithics. Diagnostic historic items include a 1959 penny, a 1959 Coca Cola bottle, and automobile license plates from 1954 and 1962. In addition, an abandoned buried utility cable divulged a date of 1962. Sometime between 1962 and 1964 the structure burned, as revealed by a thick deposit of charred and unburned timbers and other burned materials beneath collapsed lead and metal roofing materials within the foundation. No structures are visible in the area on a 1964 aerial photograph.

Several precontact lithics were present in mixed historic deposits north of the foundations. These too likely relate to the precontact component of Site 21HE125. Test excavations in and around the historic foundations suggest that the historic component of Site 21HE390 are relatively intact and potentially eligible for the NRHP. Because the precontact materials are mixed with historic materials and further disturbed by root and rodent activity it appears that the precontact component does not retain integrity and are not eligible for the NRHP. No evidence of burial mounds once associated with Site 21HE74 were detected in the project area.

Excavations elsewhere in the project area noted occasional historic items that are relatively recent and not significant. The middle stretch of the project area mostly consists of eroding slope and road ditch. The southern portion of the project area includes a landscaped portion of the Sportsman’s club. In this area, soil probes indicate that the topsoil has been removed and replaced with a small gravel parking lot, a picnic shelter on a concrete foundation, concrete pads and a mowed grassy area. A water line runs from the clubhouse to a faucet near the shelter.

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Site 21HE390 is located between an area approximately 50 m north of the northern limits of the work area/Area of Potential Effects between the river and CR50 and 15 m south of the canoe landing. The stabilization work will not occur in the area where the foundations and precontact materials are located. Therefore, the Corps has determined that proposed Project will have No Adverse Effect to historic properties.

7.3 Social And Economic Effects

7.3.1 Noise

Heavy equipment used for construction will generate noise. This noise may bother nearby residents. However, this impact will be short-term and relatively minor.

7.3.2 Aesthetics

Site preparation and the placement of materials for bank stabilization will result in a minor intrusion on the visual aesthetic environment. Construction activities will be short-term and relatively minor. The permanent placement of riprap will be a permanent intrusion.

However, the area of placement would be a relatively short stretch of river, and the overall impact will be minor.

7.3.3 Recreation

Use of the Lake Rebecca Park Reserve could be inconvenienced during construction.

The main park entrance is located on County Highway 50 approximately a mile north of the construction zone. Any road closures would eliminate park traffic arriving from south of the entrance. This inconvenience may reduce park use during periods when County Highway 50 is closed. It is unknown if or how long the road might be closed to all traffic during construction.

Construction activities could require closure of the canoe access immediately south of the project site. This area could be used for site access and staging of construction materials.

Closure of the boat ramp could extend throughout the construction period, which could extend over multiple construction seasons.

Once construction is completed, any effects from the project would cease. The proposed bank stabilization will have no permanent, long-term impacts on the recreational environment.

7.3.4 Safety

During construction, there would be an increase in heavy equipment traffic adjacent to the project site. To maintain safety at the project site, the project area could be temporarily closed to public access during construction. These effects would be attenuated through the appropriate placement of construction and safety signage, detours, or other safety measures.

These effects would be short lived and terminate when construction is complete.

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The proposed action will not have long-term adverse effects on public safety at the site.

In fact, the project will help protect the integrity of the road, which would provide an improvement to its safe use.

7.3.5 Economy and Employment

Hennepin County estimates that on average 2,725 vehicles use County Road 50 each day. Closure of the road would result in a 2.25 mile detour which would increase travel times for commuters, park users and delay the response of emergency vehicles to the area.

The proposed bank stabilization will have negligible impacts on the socioeconomic environment of Hennepin County or adjacent Wright County. The proposed action would have a positive long-term impact on transportation in the area after the project is complete. It is possible that construction activity could result in a minor short-term infusion of income into the local economy due to purchase of materials from local vendors or employment of persons from the local area, particularly if the construction work is awarded to a local contractor.

7.3.6 Environmental Justice

Environmental justice is a national goal and is defined as the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. The proposed project would be constructed on public lands; no private lands would be acquired. Public involvement, via distribution of information concerning the proposed project, has and will continue to be an integral part of planning for this project to ensure that concerns of all people will be fully considered in the decision making process.

7.3.7 Public Facilities and Services

County Highway 50 could be temporarily closed to public access during construction, which would likely lead to temporary disruption of normal community traffic patterns. This could be a temporary inconvenience, as Highway 50 is the major traffic corridor between Delano and Rockford, MN. Effects to traffic corridors would be attenuated through the appropriate signage and detour routes. Any detour routes would be determined during more detailed construction planning. These effects would be short lived and terminate when construction is complete. It is estimated that construction could take up to one construction season, though additional time may be needed given site conditions and construction logistics. Detours and road closures could be in effect throughout construction, though efforts would be made to minimize inconveniences.

The proposed fill activities would not have substantial impacts on river hydrologic regimes. Hydraulic modeling predicts a change to the 1% annual chance flood stage elevation of 0.05 ft at the upstream end of the project site. It does not appear that there are any structures within the existing 1% chance floodplain that would be affected by the 0.05 foot increase. Modeled stage increases for a 1% chance event decrease to 0.03ft by about a half-mile upstream, and decrease further to 0.02ft a little over a mile upstream of the project site.

Modeled increases this small are within error tolerances of the model. Ultimately, while there are modeled increases in the 1% chance flood elevation, these modeled increases are

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extremely small and would not be expected to result in any substantial increase in flood risk to properties upstream of the project area.

The proposed action will not have long-term substantial adverse effects public facilities or services. In fact, the project will help protect the integrity of the road, which would provide an improvement to its safe use.

7.4 Cumulative Impacts

Cumulative impacts on the environment are the result of the incremental impacts of past actions, the proposed project and reasonably foreseeable future actions. Significant changes to the environment were made through road construction and development within the project area.

This project is intended to provide long-term stability to failing of infrastructure. Effects of the construction would be minimal and mostly positive in maintaining the quality of the human environment.