reference: task 2 offsite sampling plan addendum, city of ...summary of the laboratory methodology...

Stantec Consulting Services Inc. 3875 Atherton Road, Rocklin CA 95765-3716

September 21, 2016

Attention: Mr. Karl Kurka Environmental Program Manager City of Sacramento General Services 915 I Street, 2nd Floor Sacramento, CA 95814

Dear Mr. Kurka,

Reference: Task 2 Offsite Sampling Plan Addendum, City of Sacramento Mangan Pistol and Rifle Range, 2140 34th Avenue, Sacramento, CA

Stantec Consulting Services, Inc. (Stantec) has prepared this Task 2 Offsite Sampling Plan Addendum for the City of Sacramento (the City), pertaining to the Mangan Pistol and Rifle Range located at 2140 34th Avenue, Sacramento, California (the Site). This Addendum further describes proposed offsite investigation and sampling activities, as requested by the County of Sacramento Environmental Management Department (Sacramento EMD) during a meeting between the City, Stantec, and Sacramento EMD on August 31, 2016. Offsite investigation activities were originally described in the Task 1 Site Data Report and Proposed Task 2 Offsite Sampling Plan (Task 1/Task Report) dated August 5, 2016. The Task 1/Task 2 Report was approved by Sacramento EMD in correspondence dated September 19, 2016, and that approval letter also requested a detailed offsite investigation work plan. This Addendum complies with that request.

Response to Comments

In the August 2016 meeting and subsequent work plan approval letter, Sacramento EMD requested modification of the proposed Tier 1 offsite sampling area, and clarification regarding incremental sampling methodology (ISM) procedures presented in the Task 1/Task 2 Report. The scope of work presented herein satisfies this request and consists of the following:

Modification of the proposed Tier 1 sampling area to include properties where modeled lead deposition rates are 0.1 milligrams per square foot (mg/ft2) or higher;

Discussion of the ISM planning process, including identification of decision units (DUs), selection of number of increments for each DU, and sampling strategy;

Description of sampling grid layout and controls for each DU;

Sample collection and handling procedures; and

September 21, 2016 Mr. Karl Kurka of 6


Summary of the laboratory methodology to be implemented for the collected ISM samples.

Revised Tier 1 Offsite Investigation Area

As described in the Task 1/Task 2 Report, results of the AERMOD atmospheric model suggested the highest cumulative deposition of lead originating from the Site was to the north across 34th Avenue. Based on this distribution, Stantec proposed a Tier 1 offsite sampling area as described below:

• Western section – the portion of the city block northwest of the intersection of 34th Avenue and Nolder Way, consisting of ten residential parcels.

• Central section – the portion of the city block north of the site, bordered by 34th Avenue to the south, Nolder Way to the west, and Bradd Way to the east, consisting of ten residential parcels.

• Eastern section – the portion of the city block northeast of the Site, bordered by 34th Avenue to the south, Bradd Way to the west, and Dana Way to the east, consisting of ten residential parcels.

At the request of Sacramento EMD, Stantec proposes expanding the Tier 1 sampling area to encompass properties corresponding to a modeled lead deposition of 0.1 mg/ft2 or greater. This modification results in expanding the central section by three additional parcels and the eastern section by eight additional parcels. The revised Tier 1 sampling area is illustrated on Figure 1, along with lead deposition predicted by the AERMOD atmospheric model.

Incremental Sampling Methodology

ISM is a structured composite sampling and processing protocol that typically reduces data variability and provides a reasonably unbiased estimate of a mean concentration of an analyte in a given volume of soil. The purpose of using ISM in the current investigation is to provide an estimate of the mean concentration of lead within surface soils (upper 1 inch or 2.5 cm) across each DU.

The ISM program presented in this Addendum is based on the Interstate Technology Regulatory Council (ITRC) subject matter document found on their website (http://www.itrcweb.org/ism-1/Executive_Summary.html), and on guidance documents published by Alaska Department of Environmental Quality and Hawai’i Department of Health (HDOH). Practical elements of the



proposed ISM sampling program are based on the HDOH document entitled Technical Guidance Manual Notes: Decision Units and Multi-Increment Sample Investigations (March 2011).

Selection of Decision Units

The proposed Tier 1 investigation area uniformly consists of residential parcels, and each parcel shall be designated a discrete decision unit (DU). The maximum number of DUs is 41, depending on the number of property owners that ultimately provide access for sampling. Based on metrics compiled for each of the parcels, the size of the residential lots in the study area is reasonably uniform, ranging from approximately 5,000 to 6,500 square feet, and potential exposure scenarios would be expected to be uniform given the residential use. Approximate measurements of lot size, structure size, and estimated landscaped area available for sampling are tabulated on Figure 2.

Establishment of ISM Sampling Grids and Selection of Sample Locations

Stantec proposes collecting at least 30 incremental soil samples from each DU, and assumes that landscaped areas in the front, side, and rear of the properties will be available for sampling. The approximate extent of landscaped areas across each potential DU is illustrated on Figure 2.

ISM sampling will be conducted using a systematic random sampling approach, whereby each DU is overlain with a sampling grid scaled to delineate 30 cells across the available sampling area. This method provides an unbiased representative sample across the entire decision unit. The sampling grid will originate at the northwest corner of each property, and the spacing of the sampling grid sectors will be determined based on the following equation, as presented in the HDOH guidance document:

Increment Spacing (30increments) =

This approach allows the spacing of the sampling grid to be scaled up or down depending on the area available for sampling, with the appropriate number of increment samples being collected from the entirety of each DU. Note that site evaluation results and property-specific metrics presented on Figure 2 are preliminary, and that the total DU sampling area may be reduced based on the presence of hardscape (such as patio structures, swimming pools, etc.). For each property evaluated, Stantec will measure the amount of yard available for sampling, and scale the sampling grid appropriately. Samples will be collected from random locations within each cell of the sampling grid. The sampling location within each cell of the grid will be determined by dividing the cell into nine sub-cells, assigning each sub-cell a number 1 through 9, and using a

DU Area20



random number generator to establish the sampling location within each cell. Figure 3 illustrates an example ISM sampling grid, overlain on a property with an average amount of available yard space for properties within the study area (2,124 ft2 of estimated available space. Note that as illustrated in the example presented on Figure 3, increment samples will be collected from each cell that at least partially overlays available softscape sampling area. For cells representing less than the area of a ‘full’ cell, the sub-cells grid will be scaled appropriately, and the random sampling location identified as described above.

Field Procedures

The Stantec sampling team will establish each sampling grid using measuring tape, rope, and pin flags, as necessary. All information pertinent to the field sampling effort will be entered into a field log book and recorded on project-specific field form, and site controls installed within the DU sampling area will be photographed.

Stantec proposes using a specialized multi-increment sampling tool (CREEL MIS tool or equivalent) for collection of increment samples. The benefits of using such a tool are improved ergonomics for field staff (no bending over), reduced damage to turf and landscaping, reduced need for decontamination due to stainless construction, and collection of controlled and repeatable sample volumes. Sample increments will be collected from the upper 3 cm of soil using a nominal 4-cm-diameter sampling barrel. During sample collection, Stantec will remove non-soil material (i.e. grass, leaves, root material, etc.) from the samples and combine increments from each DU into a single sample bag for delivery to the analytical laboratory. The sampling tool will be decontaminated between each DU by removing visible dirt and residue using a brush or disposable paper towels, and liquid soap and potable water if necessary. New nitrile gloves will be donned prior to collecting samples at each DU to minimize the potential for cross contamination.

Laboratory Practices and Procedures

Soil samples will be delivered to Curtis & Tompkins, Ltd. in Berkeley, California for sample processing and analysis. Laboratory preparation of ISM samples consists of the following steps.

Samples are dried and extraneous material (twigs, large stones, etc.) are removed. The remaining sample is then sieved through a #10 (2 mm) sieve. For the current investigation, samples will be additionally sieved through a #60 (0.250 mm) sieve. Aggregations of soil are considered part of the sample and are manually broken up to pass through the sieve screens.

The material passing through the #60 sieve is homogenized and distributed across a pan to a depth of 0.25- to 0.5-inch. The material is sub-sampled by applying a random grid pattern across the sample material and collecting 30 aliquots of 0.33 grams each. A small



spatula or scoop with a flat bottom and rectangular shape is used to ensure a representative distribution of particle sizes. Quality control samples (replicates) are collected at this time.

The final weight of the sample is weighed and recorded, and the sample proceeds to the applicable digestion or extraction procedure. The remaining sample material is retained.

Soil samples will be analyzed for total lead using EPA Method 6010B with a reporting limit of 0.25 milligrams per kilogram (mg/kg).

Quality Assurance / Quality Control Samples

In order to assist evaluating uncertainty of the estimate of the mean concentration provided by the ISM methodology, Stantec proposes collecting replicate samples from ten percent of the DUs investigated, with a minimum of two sets of replicate samples. Replicate samples are analogous to ‘blind duplicate’ samples collected in discrete sampling programs. Replicate samples will be collected from at least two DUs, spaced across the study area to evaluate the potential range of concentrations due to proximity to the source of lead (the gun range). For example, at least one replicate DU will be located adjacent to 34th Avenue, and one will be located as far north of 34th Avenue as possible, based on access provided by residents within the Tier 1 study area.

Three field replicate samples (the initial ISM sample plus two additional samples) will be collected from select DUs. Each set of replicate samples will be collected in a manner identical to that of the primary sample, but located at a separate randomly-selected location within each cell. Sample processing and analytical methodology will be identical to those for primary samples.

Data Analysis and Reporting

Analytical data will undergo quality control/quality assessment to ensure the data is valid and is suitable for the intended use. Verified data points from each DU will be compared to the health-protective soil screening criterion of 80 mg/kg, as described in the Task 1/Task 2 Report.



Proposed Schedule

The City intends to distribute access requests to property tenants and owners on September 23, 2016, pending review and approval of this work plan by Sacramento EMD. Offsite sampling will commence once access agreements have been finalized. Sacramento EMD staff will be notified in advance of commencing field activities.

If you have any questions regarding the work to be performed, please contact the undersigned.

Regards,

Stantec Consulting Services Inc.

Neil Doran, P.G. Dan Schreiner, P.G. Senior Geologist Senior Geologist Phone: (916) 472-3933 Phone: (916) 472-3915 [email protected] [email protected]

Attachments:

Figure 1 – Revised Tier 1 Sampling Areas Figure 2 – Tier 1 Sampling Area Parcel Metrics Figure 3 – Proposed ISM Sample Grid – Example Property Within Tier 1 Sampling Aea

FILEPATH:M:\ESA\34th Avenue Sacramento\NEW FIGURES\FIG 2_MANGAN PARK_SACRAMENTO_7-28-16.dwg | Layout Tab: DATA | Drafter: miramirez | Sep 15, 2016 at 9:33

REVISED TIER 1

SAMPLING AREAS

FOR:

JOB NUMBER: DRAWN BY: CHECKED BY: APPROVED BY: DATE:

FIGURE:

1

No warranty is made by Stantec Consulting Services Inc. as to the accuracy, reliability, or completeness of these data. Original data werecompiled from various sources. This information may not meet National Map Accuracy Standards. This product was developedelectronically, and may be updated without notification. Any reproduction may result in a loss of scale and or information.

185703375 MDR DM ND 07/28/16

CITY OF SACRAMENTOMANGAN PARK

MANGAN PISTOL & RIFLE RANGE2140 34th AVENUE

SACRAMENTO, CALIFORNIA

APPROXIMATE SCALE IN FEET

3000 150N

PROPOSED TIER 1 SAMPLING AREAS

MODELED LEAD DEPOSITION USING AERMOD (mg/ft²)°0.76

NOTE: FIGURE BASED ON FIGURE 5.2-ATMOSPHERIC MODELING REPORT (STANTEC 2016)

LEGEND

SACRAMENTO EXECUTIVE AIRPORTWIND SPEED DIRECTION

# ADDRESS PARCEL (sq ft) HOUSE (sq ft) YARD (sq ft)

1 5640 Dana Way 5457 2617 815

2 5644 Dana Way 5752 1682 2109

3 5648 Dana Way 5138 1243 2827

4 5652 Dana Way 5215 1821 1927

5 5656 Dana Way 5046 1749 1939

6 5660 Dana Way 5150 2941 273

7 5664 Dana Way 5120 1359 2704

8 5668 Dana Way 5118 2080 1765

9 5672 Dana Way 6166 2070 2862

10 5641 Bradd Way 5499 1566 2257

11 5645 Bradd Way 5874 1989 2110

12 5649 Bradd Way 5374 2370 1124

13 5653 Bradd Way 5280 1578 2637

14 5657 Bradd Way 5300 2091 1095

15 5661 Bradd Way 5343 2314 542

16 5665 Bradd Way 5223 1290 3218

17 5669 Bradd Way 5206 1440 2598

18 5673 Bradd Way 6206 1922 2725

19 5644 Bradd Way 5647 1832 2082

20 5648 Bradd Way 5150 1556 2501

21 5652 Bradd Way 5127 1618 2208

22 5656 Bradd Way 5194 2280 1762

23 5660 Bradd Way 5150 1943 1813

24 5664 Bradd Way 5169 1512 2565

25 5668 Bradd Way 5155 1796 2071

26 5672 Bradd Way 6198 2421 1380

27 5657 Nolder Way 5252 1370 2541

28 5661 Nolder Way 5368 1607 2324

29 5665 Nolder Way 5175 1342 2673

30 5669 Nolder Way 5279 1914 1875

31 5673 Nolder Way 6343 2166 2866

32 5656 Nolder Way 5137 1818 2291

33 5660 Nolder Way 5282 1955 2073

34 5664 Nolder Way 5122 1627 1996

35 5668 Nolder Way 5138 2043 1790

36 5672 Nolder Way 6326 1662 3257

37 5657 Helen Way 5063 1908 1793

38 5661 Helen Way 5204 1523 2412

39 5665 Helen Way 5220 1900 2124

40 5669 Helen Way 5160 1516 2413

41 5673 Helen Way 6514 2190 2277

min 5,046 1,243 273

max 6,514 2,941 3,257

average 5,411 1,844 2,113

median 3,994 1,949 2,124

1

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817

18 9

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19

20

21

22

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25

2631

30

29

28

273237

38 33

3439

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41 36

35

FOR:


FIGURE:


NHDNHD

2

MLM185703375.200.006 09/15/16

TIER 1 SAMPLING AREAPARCEL METRICS



SACRAMENTO, CA 95822-3157

N

0 75 150


V:\1857\active\185703375\03_data\neighborhood_evaluation\graphics\mangan_neighborhood_eval.ai mlm 9-13-2016

LEGENDPARCEL LINE

HOUSE/STRUCTURE

YARD/VEGETATION

PROPOSED ISM SAMPLE GRID BASED ON 30 INCREMENTS ACROSS EACH DECISION UNIT - 10’x10’ GRID IN THIS EXAMPLE

EXAMPLE RANDOM INCREMENT SAMPLE LOCATIONS


N

0 20 40


# ADDRESS PARCEL (sq ft) HOUSE (sq ft) YARD (sq ft)

1

2

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4

5

6

7

817

18 9

16

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13

12

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19

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21

22

23

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25

2631

30

29

28

273237

38 33

3439

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41 36

35

FOR:


FIGURE:


NHDNHD

2

MLM185703375.200.006 09/15/16

TIER 1 SAMPLING AREAPARCEL METRICS



SACRAMENTO, CA 95822-3157

N

0 75 150


V:\1857\active\185703375\03_data\neighborhood_evaluation\graphics\mangan_neighborhood_eval.ai mlm 9-13-2016 V:\1857\active\185703375\03_data\neighborhood_evaluation\graphics\mangan_home_grid.ai mlm 9-13-2016

PROPOSED ISM SAMPLE GRID - EXAMPLE PROPERTY WITHIN

TIER 1 SAMPLING AREA

NHD 09/15/16NHDMLM

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reference: task 2 offsite sampling plan addendum, city of ...summary of the laboratory methodology...

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