tm snail to sucker draft - rwmwd.org · pdf fileto: tina carstens, rwmwd from: lulu fang, matt...

Memorandum

To: Ramsey-Washington Metro Watershed District (RWMWD) Board of Managers and staff

From: Lulu Fang, Matt Metzger, Erin Anderson Wenz and Brad Lindaman

Subject: Snail Lake overflow/Grass Lake Optimization Feasibility Study, Phase II(a)

Snail Lake to Sucker Lake pumping evaluation

Date: February 5, 2018

Project team

RWMWD: Project manager: Tina Carstens

Barr: Principal in charge: Brad Lindaman, PE

Project manager: Brian LeMon, PE

Project team: Erin Anderson-Wenz PE; Lulu Fang; Matt Metzger, PE

Scope of work

The 2017 Grass Lake/Snail Lake optimization study recommended exploring the potential option for

reducing the volume in Snail Lake during high water periods- pumping Snail Lake water to Sucker Lake.

The purpose of this study is to screen the feasibility and estimate the construction costs of a system that

would allow water to be pumped from Snail Lake into Sucker Lake as part of an attempt to provide relief

to the current high water levels in Snail Lake. Even if Sucker Lake has the capacity to take on more water,

there will be special considerations in transferring water between Snail and Sucker Lake, as Sucker Lake is

part of the chain of waterbodies that delivers water to East Vadnais Lake (and into the St. Paul water

supply). The RWMWD met on November 1, 2017 with the Vadnais Lake Area Watershed Management

Organization and the St. Paul Regional Water Service (SPRWS) to discuss the potential for this option.

Compatibility of Snail Lake water with SPRWS requirements has not yet been verified or endorsed by

SPRWS, as these discussions are in the early stages.

The estimated construction costs and feasibility issues associated with this option are intended to be

evaluated against and compared to:

o The 2017 study Grass Lake/Snail Lake Optimization Study. This study includes a concept for

constructing a 15” gravity pipe system to deliver Snail Lake water to Grass Lake. For

comparison purposes, the same starting water elevation and discharge rates will be assumed.

o The 2018 study underway: Snail Lake overflow/Grass Lake Optimization Feasibility Study,

Phase II(b), West Vadnais Lake to East Vadnais Lake water-quality treatment study. This study

is investigating the concept of delivering water from West Vadnais Lake to East Vadnais Lake.

Background Information

One of the primary goals of the RWMWD is to: Reduce the public’s risk to life and property from flooding

through programs and projects that protect public safety and well-being (Barr, RWMWD Strategic Overview

To: Tina Carstens, RWMWD

From: Lulu Fang, Matt Metzger, Erin Anderson Wenz, Brad Lindaman

Subject: Snail Lake overflow/Grass Lake optimization feasibility study, Phase II(a)



of the Watershed Management Plan, 2017). As such, in 2016, the RWMWD began to evaluate high water

conditions in the Snail Lake area.

The Snail Lake and Grass Lake subwatersheds are located in the northwestern corner of the RWMWD

(Figure 1). West Vadnais Lake and its subwatershed are not a part of the RWMWD, although West

Vadnais Lake receives water from the Grass Lake area, and ultimately drains to the Phalen Chain of Lakes

through a 15-inch reinforced concrete pipe under Hwy 694.

In recent years, high levels of surface water and groundwater have increased flood risk at Snail Lake. The

City of Shoreview has identified homes around Snail Lake that are potentially vulnerable to rising

floodwaters under existing conditions. Low entry elevations of these six homes were surveyed in 2017 to

help guide the design of a potential outlet for Snail Lake and to determine how much freeboard

protection these homes would have during the 100-year, 96-hour storm event at different Snail Lake

outlet elevations (see Table 1).

Table 1 – Summary of 2017 Survey of Low Habitable Structures at Snail Lake

Snail Lake Habitable Structure Unofficial 2017 Survey of Low Elevation at

Habitable Structure (NAVD88)

4322 Lake Point 893.65

668 Highway 96 891.32

4154 Reiland Lane 889.66



4380 Reiland Lane 886.01

Snail Lake is currently landlocked; it has no piped outlet. In the past, lake level changes in Snail Lake have

been attributable to runoff from the lake’s tributary watershed, seepage to groundwater, evaporation, and

at times, augmentation water pumped from Sucker Lake. Above an elevation of approximately 883, Snail

Lake equilibrates with the wetland area that is immediately west of the north end of the lake (shown in

green in Figure 1). The lake’s existing overflow elevation (887.9) is via the “back-door” route, as shown in

Figure 1.

��

� � � ��

� � � � � � � � � � � ��

� ! " " #$ ! % &� � � �' � ( � � �

) * � � � � � �

) + , � - � � ��

. / 0 1 2 3 4 0 5 6 7 7 4 2 4 8 9 : 0 7 0 1 2 / 4 ; 9 < = 9 9 0 >? 9 ; 4 > @ ; A 0 ? 0 B 8 9 7 ; / CD 3 0 / E > 8 5 F 8 = 2 0 G H H I J

? 9 ; 4 > @ ; A 0 : / 4 K ; / CD 3 0 / E > 8 5 F 8 = 2 0 G H H L M I JN O P ; B A 7 8 8 / F 8 = 2 0 O Q R / ; 1 1 @ ; A 0D = 2 > 0 2 G H H S M T J

U 0 1 2 V ; 7 9 ; 4 1 @ ; A 0D = 2 > 0 2 G H H S M H J' � � W X � Y * � � � � � � �

) Z [ � * * �\ * Y' � W � * Y ]

R / ; K 1 4 0 F 8 ; 7_̂ ` abc daace , � � � � � � �

f g h f g if g jf g k

l mnno ppq rnst nuvwxyz {| {y }~zy� �yz �~�yz szyo�� rsw s�� r�q�� m��r� �� m�� q p� �� rq np �� pn� �� n� rn��~zy� �o rm��q � �xq �� r��~zy�z��y �x �m�� v nm�� m� r �� q� �� mq� p�� m�� r�pnq�o rm��q � �xq �� o� ��nry �x �m�� m� r� �rn�� r� �� q� �� p��q� p�� {�� rnsnu�~

�� ¡ ¢ £ ¤ ¡ ¥ ¡ ¦ §¨ © ¥ ª ¡ ¥ §¨ « ¡ ¦ ¬ ª £ §� ¡ ® ¡ § ¥ ¦ ¯ ° ± © ° ° ¡ ª² ¦ ¥ ³ ¯ ª ´ ¡ ¥ ª ¯ ° ® § ¯ ° ®� £ ° ® ° µ ¶ ¦ ¡ ¯ §· ¯ ¸ ¡ § ¯ ° ® � £ ° ® §¹ ¯ º £ ¦ » © ¼ ¯ ¥ ¡ ¦ § ½ ¡ ® §¾ ´ ¹ ´ ¿À © ¦ § ® ³ ¥ £ ° ¯ ªÁ £ © ° ® ¯ ¦ Â ÃNÄ Å Æ Ç È Ä Ç Æ È Ä ÄÉ Ê Ê ËS 4 9 B Ì Í S Î Ï Ð Ñ E 0 0 2» £ © ¦ ³ ¡ Ò ¹ ¡ ¥ ¦ £ Ó £ ª ¥ ¯ ° ² £ © ° ³ ª Ô Õ Ö × Ö

Ø Ù Ú Û Ü Ý Þß à á â ã ã á ä å æ ç å è ç â å éå ê â ß ë â à ì í æ à î â ë â æ à ßè ï ð ñ Ý ò ó é ï ñ ô Ù õ Ú ö ÷ õ ø Ý ö Ü ÷ é ï ö Ý Ü ñ ô Ý ù






This evaluation assumes a target lake level of 882 feet. Figure 2 illustrates the target lake level versus

historical Snail Lake Elevations.

Figure 2 – Snail Lake Historical Elevations

Although they have receded somewhat since fall 2016, the high water levels in the area have largely

persisted through 2017 due to diminished seepage rates to groundwater (because of currently high

regional groundwater levels) and the restricted nature of the Grass Lake outlet system that drains the

entire area. The system’s ultimate outlet is located south of West Vadnais Lake; it is a 15-inch reinforced

concrete pipe under Highway 694. Pumping from Snail Lake to Sucker Lake is one possible strategy to

reduce lake levels in this constrained system of lakes and wetlands.

Snail Lake is within the City of Shoreview. Its watershed area is 987 acres, surface area is 190 acres with a

maximum depth 28 feet. Snail Lake currently has good water quality and is suitable for swimming;

however the lake is listed as impaired for high levels of mercury in fish. Water quality goals and a plan to

maintain them are included in the new RWMWD Watershed Management Plan. Water quality monitoring

data is available from the MPCA’s Environmental Data – Surface Water and from RWMWD. The observed

Total Phosphorus concentrations in the lake between 2003 and 2016 were at or below 30 ug/l, which is

below the District Goal and TMDL Goal. Eurasion watermilfoil is present in Snail Lake. Zebra mussels have

not been observed in Snail Lake to date.






Sucker Lake is within the VLAWMO in the City of Vadnais Heights. The lake is part of the St. Paul Regional

Water System’s (SPRWS) chain of lakes that delivers water from the Mississippi River to the McCarrons

water treatment plant in Maplewood, just south of Little Canada and just north of St. Paul. Sucker Lake

was chosen as a potential recipient of the water because of its proximity to Snail Lake, and because Sucker

Lake serves as an augmentation resource in times of low water in Snail Lake. An existing project along

Snail Lake Road was installed to pump from Sucker Lake to Snail Lake. The assumption is that the

pumping system and associated piping would be installed along an east-west alignment that follows Snail

Lake Road and the extension of that alignment into Snail Lake and Sucker Lake, similar to the

augmentation system alignment. The proposed alignment spans two cities (Shoreview and Vadnais

Heights) and three water jurisdictions (RWMWD, VLAWMO and SPRWS).

If water is to be pumped into Sucker Lake from Snail Lake, it will need to meet certain water quality

standards so that it does not disrupt SPRWS’s treatment process. For this alternatives evaluation, however,

it is assumed that the water quality in Snail Lake is adequate to meet those standards without some form

of treatment.

Figure 3 – Overview: SPRWS Supply System and Service Area

Image courtesy of Saint Paul Regional Water Services. The Saint Paul Regional Water System 2016

average annual water use was 14,603 million gallons with a maximum pumping capacity of 144 million

gallons per day for an average 2016 daily water use of 38.2 million gallons (59 cfs).






Sucker Lake is surrounded by land managed by Ramsey County. Its watershed area is 1085 acres, surface

area is 61 acres with maximum depth 26 feet. Invasive species (zebra mussels, Eurasian watermilfoil) have

been observe it its waters. Sucker Lake is fed by flow from Pleasant Lake and Charley Lake, where St. Paul

Regional Water Service (SPRWS) continuously delivers pumped supply water to its treatment facility in

Maplewood. Pleasant Lake is on the Impaired Waters List for high nutrient levels and is actively managed

by the SPRWS. Sucker Lake drains to East Vadnais Lake, where it is pumped to the St. Paul Regional

Water Service (SPRWS) treatment plant. Eurasian watermilfoil and zebra mussels are present in Sucker

Lake.

The City of Shoreview implemented the Snail Lake Augmentation project in 1993 to manage Snail Lake

water levels. Water is pumped at a rate of 1700-1800 gallons per minute from Sucker Lake to Snail Lake.

The existing system includes a screening system (250 microns and 25 microns) to prevent transport of

adult and adolescent zebra mussels to Snail Lake. Water is pumped into a public gravity storm sewer that

drains to Snail Lake.

Task 1: Permitting review

Permit requirements for transferring water from Snail Lake to Sucker Lake were identified and are listed

below.






Table 2 – Permitting Considerations

Approval Entity Permit/Approval Justification

U.S. Army Corps of

Engineers

Section 404 Permit Required for work activities below the

ordinary high water level (OHWL) of

waters/wetlands under agency jurisdiction.

U.S. Fish and Wildlife Service Section 7 (Endangered Species Act)

compliance

Required as part of USACE’s Section 404

permitting process.

Minnesota Department of

Natural Resources

• Work in Public Waters Permit

• Water Appropriations Permit

• Required for work activities below the

OHWL of a designated public water

• Required for withdrawing more than

10,000 gallons of water per day or 1

million gallons per year. Also required

to appropriate or transport any amount

of infested water

Minnesota Pollution Control

Agency

General Stormwater Permit for

Construction

Required for projects that result in more

than 1 acre of ground disturbance

Minnesota Wetland

Conservation Act

Project compliance` Required for impacts to wetlands that are

not under the jurisdiction of the USACE or

MNDNR. Administered by the VLAWMO

and RWMWD in their jurisdiction.

State Historic Preservation

Office

Section 106 (National Historic

Preservation Act) compliance

Required as part of USACE’s Section 404

permitting process.

City of Shoreview

(Snail Lake is in Shoreview)

• Erosion/Excavating/Grading Permit

• Right-of-Way Excavation Permit

• Floodplain Management Special

District compliance

• Shoreland Management Special

District compliance

• Project activities are expected to

require movement of more than 10

cubic yards of soil and disturb an area

of more than 1,000 square feet.

• Construction would occur in City of

Shoreview right-of-way

• Required for projects in floodplain

overlay district

• Applied to all projects within 1,000 feet

of a protected waterbody

City of Vadnais Heights

(Sucker Lake is in Vadnais

Heights)

• Excavation Permit

• Engineering and Public Works

Approval

• Utilities Approval

• Floodplain Area Approval

• Shoreland Area Approval

• Project activities are expected to

require movement of more than 6

cubic yards of soil

• Engineering and Public Works

Department typically provides input on

significant projects.

• Project will require modifications to

city utilities

• Required for projects that take place

within designated Floodplain Area

• Required for all work within 1,000 feet

of designated Shoreland Area






The VLAWMO does not operate a regulatory program for development review applications. Member

cities, townships or MS4s with approved permits to discharge stormwater are responsible for NPDES

regulatory requirements.

The project was reviewed for applicability under the Mandatory Environmental Assessment Worksheet

(EAW) or Environmental Impact Statement categories established by Minnesota Rules Chapter 4410.

Subpart 24 of Chapter 4410.4300 identifies that an EAW would be required for new appropriation for

commercial or industrial purposes averaging 30,000,000 gallons per month. The project is anticipated to

appropriate an average between 81 million gallons and 171 million gallons per summer season,

depending on pumping rate. If the average diversion per month is less than 30 million gallons per month,

an EAW would likely not be required. If the average diversion per month is greater than 30 million gallons

per month and the water would be used for municipal purposes rather than commercial or industrial

purposes; as such, it is likely an EAW may not be required.

Beyond permitting, several entities are anticipated to be engaged with project review, including:

• Saint Paul Regional Water Services & Board of Water Commissioners

• RWMWD & Board of Managers

• Vadnais Lake Area Watershed Management Organization

• MnDOT (two state-aid road crossings at Hodgson Road and Rice Street)

• City of Saint Paul (landowner of Vadnais-Snail Lakes Regional Park at Sucker Lake)

• Ramsey County Parks and Recreation (construction at Snail Lake on property owned by

Ramsey County Parks and Recreation)

• Ramsey County Public Works Department (two state-aid road crossings at Hodgson and Rice)

• Xcel Energy (electricity and gas in Shoreview, gas in Vadnais Heights)

• Connexus (electricity in Vadnais Heights)

• CenturyLink, Comcast communication utilities in Shoreview

• Communication utilities in Vadnais Heights

It should be noted that the MNDNR may be interested in the Project due to its proximity to White Bear

Lake and ongoing concerns related to the effects that water appropriations may have on lake levels.

Analysis & Methodology

Hydrologic and hydraulic modeling was performed using XP-SWMM to perform an assessment of Snail

lake level drawdown under existing conditions versus under proposed pumping scenarios. The assumed

critical event for this subwatershed is the 100-year, 96-hour rainfall event. In a typical summer season,

modeling indicates this event bounces Snail Lake from elevation 882 feet to 884.2 feet with infiltration

drawing down the lake over several months to elevation 883 feet, as shown in Figure 4 below.






Figure 4 – XP SWMMM Hydrologic Model Results:

Typical Snail Lake Water Surface Elevation Response to 100-yr, 96-hr Critical Event vs. No. Drawdown Days

A simplified model run, neglecting evaporation or infiltration, indicated a 10-cfs pump might provide

drawdown from 884 feet to 882 feet over a 24-day period.

A review of previous studies indicates that a net infiltration rate from Snail Lake to groundwater might be

on the order of 0.0062 feet-per-day, when groundwater levels are at normal levels. During periods of

high groundwater levels, as has been the case of the last several years, infiltration of water from the lake

to groundwater is inhibited.

Model scenarios were run to evaluate pumping conditions that could be considered for lake drawdown to

elevation 882 feet, commencing pumping when lake levels reach 882.5 feet, which include:

• Pumping at the rate of 1.2 cfs (similar to the 15” gravity pipe capacity of the Snail Lake outlet

alternative presented in the 2017 study), for a total diversion volume of 250 acre-feet (80 million

gallons) for the critical event drawdown; • Pumping at the rate of 10 cfs from Snail Lake to Sucker Lake, for a total diversion of 480 acre-feet

(160 million gallons) for the critical event drawdown; • Pumping at the rate of 20 cfs from Snail Lake to Sucker Lake, for a total diversion of 520 acre-feet

(170 million gallons) for the critical event drawdown;

884.23

884.18884.01

883.90

881.5

882

882.5

883

883.5

884

884.5

1/1 1/8 1/15 1/22 1/29

100-year,96-hour Event

Only Infiltration Infiltration+15" pipe capacity Infiltration+10cfs Pump Infiltration+20cfs Pump






The estimated drawdown times (in days) for the alternatives to reach a target elevation of 882 feet after a

100-year, 96-hour event are compared in the table below:

Table 3 – Summary of Snail Lake Drawdown Time for Pumping Alternatives

Alternative No Pumping

Pumping at 15”

West Vadnais

Lake Outlet Pipe

Capacity (1.2 cfs)

Pumping at 10 cfs Pumping at 20 cfs

Estimated No. of

Drawdown Days >200 days >100 days 24 days 13 days

A combination of pumped flow in forcemain pipes and gravity storm sewer flow were evaluated for two

alternative conceptual alignments to route flow from Snail Lake to Sucker Lake.

1. Snail Lake Road Option: Construct a new pump station on the public parcel at the west end

of Snail Lake Road. Construct a 4,200 LF pipe along Snail Lake Road to convey flow to Sucker

Lake. A combination of gravity pipe and forcemain is assumed. Construct an energy

dissipation structure at Snail Lake. The preliminary design has not identified if property

acquisition along Snail Lake Road is required. The concept assumes the pipe can be installed

alongside the roadways without needing to remove and replace the roadway pavement.

Capital costs were estimated for 10-cfs and 20-cfs pumping systems. A preliminary plan and

profile of the proposed pipe is shown in Figure ALT-1.

2. Dennison Avenue Option: Construct a new pump station on the public parcel at the west

end of Dennison Road. Construct a 4,200 LF pipe along Dennison Avenue to convey flow to

Sucker Lake. A combination of gravity pipe and forcemain is assumed. Construct an energy

dissipation structure at Snail Lake. The preliminary design has not identified if property

acquisition along Dennison Avenue is required. The concept assumes the pipe can be

installed alongside the roadways without needing to remove and replace the roadway

pavement. Capital costs were estimated for 10-cfs and 20-cfs pumping systems. A

preliminary plan and profile of the proposed pipe is shown in Figure ALT-2.






Task 2: Conceptual cost estimate

A screening-level estimate of capital costs for designing and constructing this system was developed.

Costs include allowances for construction, planning, engineering and design and construction

management.

Table 4 Summary of Snail Lake Pumping Alternatives: Opinion of Cost Ranges

Item Description

Pumping

Rate

1, 2, 3, 4, 5, 6, 7

Anticipated Cost (Low

End of Range -50%)

$

1, 2, 3, 4, 5, 6, 7

Anticipated Cost

(Point Estimate)

$

1, 2, 3, 4, 5, 6, 7

Anticipated Cost

(High End of

Range +100%)

$

Pumped Diversion:

Snail Lake Road Alignment

1.2 cfs 0.5 million 0.9 million 1.8 million

10 cfs 1.0 million 2.1 million 4.2 million


Pumped Diversion:

Dennison Avenue Alignment

1.2 cfs 0.6 million 1.1 million 2.2 million



1 Limited design work completed (<5%). Based on screening-level project definition. 2 Quantities based on design work completed. 3 Unit prices based on information available at this time from comparable projects. 4 Limited soil boring and field investigation information available.

5 This screening-level (Class 5, <5% design completion per ASTM E 2516-06. Cost estimate is based on screening-level

designs, alignments, quantities, and unit prices. Costs will change with completion of further design. A construction

schedule is not available at this time. Contingency is added as an allowance for the net sum of costs that will be in the

opinion of probable cost at the time of the completion of design, but are not included at this level of project definition. The

estimated accuracy range for the total project cost as the project is defined is -50% to +100%. This accuracy range is based

on professional judgment considering the level of design completed, the complexity of the project, and the uncertainties in

the project as scoped. The contingency and the accuracy range are not intended to include costs for future scope changes

that are not part of the project as currently scoped or costs for risk contingency.

6 Escalation for time is not included.

7 Costs include 30% contingency, assume 20% for Permitting, Planning, Engineering & Design, 5% for Construction

Management. Costs do not include any land acquisitions or easements.

Estimated capital costs have been developed for the pumping alternatives and should be considered

screening-level, order of magnitude estimates, based on the limited level of project definition available at

this time. The cost estimates are valid in the framework of a relative comparison of alternatives, therefore






they should not be assumed as absolute values for given alternatives. These costs are intended to be

used as a one assessment factor in evaluating alternatives’ implimentability.

The anticipated cost for each alternative is based on screening level design. The opinion of cost should

be considered a screening-level, order-of-magnitude estimate that generally corresponds to a Class 5

estimate based on standards established by the Association for the Advancement of Cost Engineering

(AACE) and American Society for Testing and Materials (ASTM). A Class 5 cost estimate is characterized

by limited project definition (less than 5%), wide-scale use of parametric models (i.e. making extensive use

of order-of-magnitude costs from similar projects or proposals) to calculate estimated costs, and a high

uncertainty. The estimated cost of each alternative is a point estimate within a range of possible costs for

the alternative. The selected accuracy range for these point estimates is -50% to +100%.

The estimated costs include up-front costs associated with estimated planning, engineering, design,

construction management, construction, land acquisition and contingency. A construction schedule or

duration based on start dates and end dates is not used for this estimate. All costs presented are in

February 2017 US dollars. Escalation, operation and maintenance costs are not included.

As indicated above, the opinion of probable cost for each alternative was developed for comparative

purposes only using information from similar projects and the consulting team’s experience and

qualifications. The opinion of cost represents the team’s best judgment as experienced and qualified

professionals familiar with the project, based on project-related information available at this time,

available cost information from other projects and a screening level design for each alternative. The

opinion of probable cost will change as more information becomes available and the level of design detail

is advanced. In addition, since the team has no control over the cost of labor, materials, equipment, or

services furnished by others, or over the contractor’s methods of determining prices, or over competitive

bidding or market conditions, it can be expected that proposals, bids, or actual construction costs will vary

from this opinion of probable cost. If a more accurate opinion of probable cost is desired, a more

detailed study including a more detailed definition of the alternatives would be necessary.

Task 3 : Final memo report

The scenarios evaluated assume pumps begin to operate when Snail Lake elevation is 882.5 feet. The

model indicates peak Snail lake elevation would reach an elevation around 884 feet, which is close to

providing the necessary 2 feet of minimum freeboard for all six low homes on Snail Lake.

The study indicates that costs are likely to increase as system pumping rate increases. The benefit of

more rapid lake drawdown would be partly offset by increased construction costs for additional pumps

and pipes.

The study indicates that costs and permitting may be comparable for either the Snail Lake Road or

Dennison Avenue alignments. Additional design work is required to better characterize possible utility

conflicts and possible need for land acquisitions and easements.

Areas of concern or risk include the following:

o SPRWS will likely have requirements for supply water and certainty of quality, volume, timing

of available water which could affect the system feasibility, configuration and costs.






o Invasive species transport is a concern. The current augmentation system that pumps water

from Sucker Lake into Snail Lake requires a basket screen to prevent the transfer of invasive

species (zebra mussels) into Snail Lake. It remains to be seen if the MnDNR would require

any measures to prevent migration of invasive species with a Snail to Sucker pumping system

(for any potential system backflow, for example). Zebra mussels have not been observed in

Snail Lake but are present in Sucker Lake. Eurasion watermilfoil has been observed in both

lakes.

o Local infrastructure relocations along proposed alignment(s) need to be evaluated in greater

detail during detailed design, which could affect the system feasibility, configuration and

costs.

o The perceptions of residents and stakeholders in the project area about changes to the lakes

and groundwater as a result of implementing new pumping. It will be important to keep the

residents informed.

o If easement and property acquisitions are required, the effort to acquire property could add

to the project complexity and increase capital costs.

Recommendation and Next Steps

The costs and feasibility issues associated with this conceptual option will be evaluated against and

compared to the other conceptual options for managing Snail Lake listed below.

o The 2017 study Grass Lake/Snail Lake Optimization Study. This study includes a concept for

constructing a 15” gravity pipe system to deliver Snail Lake water to Grass Lake.

o The 2018 study underway: Snail Lake overflow/Grass Lake Optimization Feasibility Study,

Phase II(b), West Vadnais Lake to East Vadnais Lake water-quality treatment study. This study

is investigating the concept of delivering water from West Vadnais Lake to East Vadnais Lake.

We recommend comparing and contrasting the alternatives after completion of the studies to select the

option that best serves the District’s needs and expectations.

Reach out to SPRWS staff to understand what water supply constraints may need to be considered,

relative to water quality, water quantity and seasonal availability and timing of water diversion into the

SPRWS lakes.

Engage permitting agencies, stakeholders, SPRWS and VLAWMO in discussions about design and

operational constraints associated with diverting Snail Lake water within RWMWD and City of Shoreview

into Sucker Lake within Vadnais Heights, VLAWMO and into the SPRWS water supply.

tm snail to sucker draft - rwmwd.org · pdf fileto: tina carstens, rwmwd from: lulu fang, matt...

Documents